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Pioneer Tuners

Tuners are listed in alphabetical and numerical sequence by model number. In parentheses after the model number are the year of introduction and most recent list price, and/or the original list price if indicated by "orig." Special thanks to David Rich of The Audio Critic for copies of historical material from his reference library.

There are many Pioneer tuners in our On-Deck Circle that we'd like to consider listing here if we can get some basic information on them (types of controls and features, and any personal anecdotes or comparisons to other tuners). Please post in our FMtuners group if you have any information about any of them.

Pioneer F-5 (1981, $225, photo) search eBay
Pioneer F-7 (1981, $325, closed, open) search eBay
Just a guess, but based on the sleeper status of the F-9, either of its little brothers might also be a nice pickup in their usual eBay sale price ranges of just $20-40 for the F-5 and $30-60 for the F-7. But don't overpay: one mint F-7 sold for $125 in 11/08 and another fetched $90 in 4/09, and one F-5 went for $89 in 12/06.

Pioneer F-9 (1981, $425, closed, open, back, detector/MPX stage, RF front end, schematic, Audio review) search eBay
The F-9 is a digital synthesizer tuner that is fairly similar to the later F-90 and F-99X in construction. One difference noted by our contributor Ryan is that the output filter in the F-9 is passive, unlike the active filter in the later two that he feels works very well. But our panelist Bob has spent considerable time tweaking, measuring and modding his F-9, and had this report: "The F-9 was the top of the line follow-on to the TX-9800 tuner, and somewhat similar to the F-90/F-99X in operation, but the cosmetics are totally different. It is like a 'Frank Lloyd Wright' design tuner, with very minimal design exterior, and ultra-thin 1.75" tall case. Most controls are hidden behind a swing-down door, except for power, station selector, and large AM/FM metal buttons. The case finish is Champagne in color. The AM section appears to have been given special attention, with an AM wide/narrow selector and AM stereo out jack on the rear panel. Controls for FM include wide/narrow IF filter, auto mute stereo/mono selector, and tuning mode auto/manual. There are 6 presets and a 5-segment signal meter. Inside, we find 4 gangs, but a novel dual MOSFET RF amp, likely run in parallel to reduce noise. There are 3 IF 3-pin filters, two of which are blue MX GDT type. All the IC chips are Pioneer custom made, with the pulse counter type detector used, again similar to the F-90/F-99X. There are two transformers in the power supply, to keep digital noise from analog circuits. Sound impressions are very good, with clear midrange and highs. The unit under review had two oversize Black Gate caps in the output, and with these bass response was fairly solid and deep. Although some may not like the looks, I find it very attractive and unique. With some work, the F-9 is really a bona fide hot tuner in every respect. It's a very nice sleeper tuner if you can live with the gold 'pizza box' looks."

Bob followed up with more technical detail: "The F-9 has an RF stage that, despite being only 4 gangs, is quite uncommon. It has a balanced push-pull RF gain stage, and a balanced mixer, which is missing in other most other tuners one can buy for under $50 [maybe not anymore - Editor]. Astute fans of RF front ends will notice some cool things in the F-9's design. The T2 transformer, which has a center-tapped secondary, drives two dual-gate MOSFETS, which then feed a center-tapped primary on T3. This would appear to lower the noise floor and likely increase dyamic range. Then T4 feeds a differential amp, driving a FET, which drives a typical IF output transformer. This is a nice front end, and it happens to work pretty well. I was impressed by the measurements of my F-9. The dynamic range on a strong 1000 uV into 75 Ohms RF signal tested my 16-bit FFT - it was 95 dB (less distortion components). Mono distortion measured .007%, stereo .01%, at 1 kHz full modulation. The F-9 also happens to sound very nice, with a clean top end and solid bass. It has two power transformers inside, likely to keep analog and digital separate. The one I measured has two Black Gate caps at the audio out, so it's not totally stock, but the F-9 seems to be pretty consistent from model to model, which you don't always see. It has selectable wide-narrow AM filters, and an AM section that is not an afterthought. It seems like this feature went away on later Pioneer models. You can hear a big tone difference even on male voice when making the switch between wide and narrow on this model. The lack of any noise, like low-volume hiss, at loud volume on local classical stations does make this one special among tuners of any vintage. Note that the F-9 has the same board inside as the Phase Linear 5200. The 5200 uses different buttons, and has a single power t-x instead of two as in the F-9."

Our contributor Bill Ammons reports: "The 4-gang Pioneer F-9 uses a balanced D-MOS FET amp for the RF section, followed by a balanced bipolar mixer. In the Wide IF mode there is tuned 10.7 LC can and one ceramic filter in the signal path. In the Narrow IF mode, two additional ceramic filters are switched into the IF signal path before the Wide mode ceramic filter. The IF signal then goes to a PA3007 limiter IC. This IC then feeds a second mixer that downconverts the IF signal to 1.26 MHz. The IF signal is run through a RF low-pass filter into a PA5002 IC that is a pulse detector. The demodulated signal then goes through a composite low-pass filter to the PA4006 IC. This IC is the stereo decoder and audio output IC. There are a total of three electrolytic capacitors in the audio path and none in the composite (stereo) signal path. One limitation of the F-9 is a single separation adjustment control. This will only let you optimize the separation in the Wide IF mode. The F-9's specifications list 55 dB of separation, and 0.05% THD at 1 kHz in Wide stereo mode."

Our contributor Gary is another fan of the F-9: "I picked up an F-9 dirt cheap on eBay and it appears to be a very nice digital tuner. It handles the weak adjacent channel signals from NYC just as well or perhaps slightly better than the TX-9500II. The sound is not nearly as transparent as my modified TX-9500II, but its sins are errors of omission. The F-9 has a slightly dark sound that is quite listenable, if not the most exciting in the world. I think a bit of tweaking in this unit would go a long way." And then Gary tweaked it: "All I can say is that my aligned and modified F-9 is a great tuner and a remarkable bargain. The stock tuner takes the audio output directly from the MPX chip. I added some BUF04 output buffers along with a small transformer and LT1085/LT1033 regulated supply, which really opened up the sound. Stock it just sounds OK, but with the added buffering, the sound enters a whole new league." Read our contributor Radu's comparison of one F-9 to a Pioneer F-90 and a Hitachi FT-5500 MKII on our Shootouts 2.0 page. The F-9 usually sells for $60-100 on eBay, with a high of $181 in 2/08.

Pioneer Series 20 F-26 (1979, $1,000, photo, detailed specs) search eBay
The quartz-synthesized FM-only F-26 was Pioneer's most expensive tuner and our panelist David "A," on his Ricochets page, calls it one of the three best tuners ever. It has 7 gangs and 4 ceramic filters, and its quartz lock kicks in when the tuning knob is released. See detailed specs and measurements for the F-26 compared to those of 17 other top tuners in David "A"'s tuner comparison spreadsheet.

The F-26 is excruciatingly rare and shows up only 2-3 times a year on eBay. Prices escalated from $770-785 in 2002 to typically $1,200-1,550 by 2005-2007. Some sample sale prices were $976 in 11/07, $1,750 for a typical one and $2,427 for one with a wooden cabinet in 3/08, $1,525 in 6/08, $842 in 5/09 for a beat-up one with no power switch, and $2,199 in 6/09. The all-time record was a stunning $3,305 for a "new-in-box" one in 6/05.

Pioneer Series 20 F-28 (1979, $690, photo1, photo2, inside, detailed specs) search eBay
The F-28 is a rare quartz-synthesized FM-only tuner with 6 gangs and selectable wide and narrow bandwidths. The front end is especially interesting, and is unlike any other tuner we know of except perhaps the Kenwood 700T. Five of the gangs are traditional analog gangs, while the 6th gang is a varicap diode. The 6th digital gang controls the local oscillator which is used to set the station frequency. This is accomplished by reading a plate behind the analog dial scale which is encoded with an 8-bit binary code that tells the tuner where the dial pointer is set. The wide IF strip uses a fairly elaborate scheme of individually tuned LC filters preceded by one very wide flat group delay ceramic filter. The narrow bandwidth adds three more flat group delay ceramic filters, for a total of 4 ceramic filters plus the LC section in narrow mode. The F-28 also incorporates a signal meter with readout in dBf, a record level switch, selectable muting, selectable mono/stereo switch, multiplex noise filter, and a front panel output level knob.

Our contributor Ryan, who provided the above analysis, feels that the F-28 bests any other vintage analog tuner he has yet heard, including the Pioneer TX-9800 and Nikko Gamma V. Ryan adds, "As far as DX performance is concerned, the F-28 equals or bests the Kenwood KT-8300 in virtually every aspect: It picked up more stations across the dial, picked them up more quietly, and dropped into fully quieted stereo when the KT-8300 would only do mono. Only on the rare station did the KT-8300 have quieter reception than the F-28. In any respect, the F-28 is an absolutely remarkable tuner - a true sleeper in my opinion." Another contributor reports that the F-28 outperforms his Technics ST-9030. The F-28 may not be suitable for a true DXer because its unusual tuning mechanism prevents one from intentionally tuning off-frequency, which is sometimes helpful in evading adjacent channel splatter.

See detailed specs and measurements for the F-28 compared to those of 17 other top tuners in our panelist David "A"'s tuner comparison spreadsheet. The F-28 usually sells for anywhere from $450-825 on eBay, with a low as $343 in 7/07 and a high of $1,082 in 11/04 for a supposedly new-old-stock F-28.

Pioneer F-51 (1991, $350, front, left, right, back) search eBay
This little brother of the F-91 and/or F-93 appears to be a fine tuner in its own right, although the F-51's specs suggest that it might have problems with images from strong stations. The F-51's front panel has confusingly labeled "MPX NR" (noise reduction) and "MPX.Mode Auto/Mono" buttons, an "SSS" button and indicator light, and RF Attenuation and Antenna A/B buttons, along with an "IF Band Normal/Super Narrow" button and 36 presets. "SSS" stands for "Spectrum Simulated Stereo," as described in the service manual for the F-93. Our contributor Rick tells us that the "CONTROL IN/OUT" jacks on the back panel use monophonic 1/8" cables to connect the tuner to a Pioneer preamp or receiver.

Pioneer F-90 (1982, $320, photo) search eBay
The F-90 is a simple but good-sounding tuner. Our contributor Bill Ammons offers this review: "The F-90 is a slim-line, dual-bandwidth tuner that has the same feel as its cousins, the F-91, 93 and 99X. I have serviced quite a few of them. The F-90 is a 4-gang synthesized tuner with a DMOS front end (one gang input - two gangs output tuning). It used a balanced FET mixer which feeds both IF strips in parallel. The wide path consists of two 280 kHz filters and one tuned 10.7 MHz LC filter can. The narrow path consists of three 230 kHz ceramic filters. The signal is routed through an IF limiter amp. The IF is then doubled to 21.4 MHz, filtered and down-converted to 1.26 MHz, where it is demodulated using a pulse detector. By doubling the IF, the deviation increases to 150 kHz peak. Having 150 kHz of deviation on a 1.26 MHz signal means a very good signal-to-noise ratio. This pulse detector is the 'Direct Digital Decoder' that Pioneer had hyped up. Pioneer claimed 90 dB S/N in mono, but the FM exciter I used was only good to about -85 dB.

"Since the F-90 only tunes in 100 kHz or 50 kHz steps, it is not the ultimate DX machine. I have modified one using my IF Filter Adder PCB in two narrow positions, which increases the IF filter count to five in the narrow IF mode and adds about 6 dB of IF gain. With five 150 kHz filters in narrow this is an extremely selective tuner, with a very quickly rising FM quieting curve. The DMOS front end is very overload resistant and the double-balanced mixer performs very well also. The main PCB must be removed to do any modifications or servicing. Please note that many F-90s are sold DOA or partly working. The most common problem is the high B+ supply for the PLL tuning voltage. The supply consists of a voltage doubler with a 47 µF/50 volt cap which can fail due to heat from the heat sink nearby."

When our contributor Brian Beezley told us that his F-90 tuned only in 100 kHz steps and had a different arrangement of filters than Bill's, Bill added this clarification: "There are three versions of the F-90. One only has 100 kHz tuning steps and was sold in the US/Canada market. A second version has a 450 kHz IF output for an AM stereo decoder, and a AM/FM tuning step selector switch for 100 kHz FM and 10 kHz AM versus 50 kHz FM and 9 kHz AM. The third version has the tuning step switch and a 110/220 volt selector on the rear panel. Looking at the schematics, all three versions use a single 280 kHz input filter. In wide mode there is one more filter. When the unit is switched to narrow mode, the signal routes through 3 narrow filters. The original F-90 I owned had 230 kHz filters in narrow."

Brian offers his first impressions of his F-90: "The F-90 is the thinnest tuner I've seen, with a two-inch front panel. It has nice big buttons and a pleasing digital frequency readout. No signal-strength meter, which will take some getting used to. None of the preset switches worked because the foam between the button and the switch had degraded over the years into a gummy mess. I snipped some weather sealing into little pieces and got the switches going again. The tuner zips right across the dial when auto-tuning. Unlike other tuners, if you hold down the tuning bar to slew across the dial, the tuner will not pause at each station it finds before continuing.

"I was interested in this tuner mainly because of its overload-resistant front end with balanced mixer and its low-distortion pulse-count detector. Both showed their strengths right away. I could hear no evidence of the RF IMD [intermodulation distortion - Editor] that trips up many other tuners in my signal-rich environment. The circuit board has remarkably few parts. Several custom Pioneer ICs do most of the work. I located the two wide filters right away. One is a blue MX, 250 kHz I believe, and the other looks like a tan 280. The tuner has three narrow filters, one of which is a 280. The other two, hidden in a sea of tan disc ceramics, are marked 10.7S and I measured them as 180s. One of the filters has a white dot, one has a red stripe, and the rest are red dots. Quite a mixture. The bottom of the PCB is inaccessible without removing the board from the chassis.

"The tuner has one annoyance: the Wide/Narrow setting is not stored in memory. I found this to be very inconvenient. The stations I listen to are about evenly divided between Wide and Narrow. That means I average 1.5 button pushes to change stations, and each time I do I have to figure out whether to press the bandwidth button. Without paying close attention I got it wrong about half the time when changing stations. Also, the tuner has no blend circuit. The button that selects manual scan also forces mono and mute off. There appears to be no way to receive unmuted stereo, but the muting pot is marked on the PCB and can be turned way down. The F-90 sounds exactly the same to me as all my other tuners. I think this is a really neat little tuner. It does most of what my Sony ST-S555ES does, and just about as well, with perhaps half the parts."

Here's a follow-up from Brian: "I just bought an F-90 for a friend. Fixing it up reminded me what a great tuner this is. Spectacularly low stereo distortion (no harmonics visible in the noise below -80 dB), zero HD Radio self-noise without modification, easy filter mod (got 36 dB IEEE adjacent channel selectivity with three Murata 150s), more than 60 dB separation, and sensitivity matching the best I've yet measured (15 dBf in mono for 50 dB quieting). I found it on eBay for a total of $47.55 delivered. I think it may be the best deal in tuners if all you want is performance." And one more: "One neat thing I found is that Pioneer provides stereo-separation compensation in narrow-IF mode. I never realized that until I spotted a mysterious FET and resistor near the stereo decoder in the schematic. Changing the resistor value greatly improves separation if you replace the stock narrow filters, which I always do. In the one unit I've modified so far, narrow separation increased from the low 20s to over 60 dB. That 60 dB is more like 50 dB if you account for the temperature rise that occurs when you replace the enclosure and don't attempt a hot alignment." Brian has a more detailed review of the F-90 on his website.

Our panelist Bob adds, "I'm happy that Brian mentioned the use of parallel JFETS in the IF stage. The F-90 was possibly the first tuner ever to feature this. Also of note, but not mentioned, is the use of paralleled JFETS in the buffer amp after the local oscillator to drive the balanced mixer, and a single JFET to buffer the LO feedback to the pre-scalar. The use of four active devices in the local oscillator shows the designers were cutting no corners, and had intentions that went far beyond the 'me too' '80s cosmetic exterior. This unit had some really groundbreaking circuits that worked very well. I wonder if possibly the team listed on the patents was disappointed that this tuner ended up being sold as mainstream item, versus being packaged better and touted as the breakthrough high-end unit it was."

Our contributor István says, "The F-90 has a general problem: The soldering quality is not good, it's better if you resolder all solder joints." István offers this review, excerpted from his website writeup. "The F-90 is very similar to the latest and famous F-99X model, excepting the 2 IF amplifier stages, separate for Wide and Narrow IF circuit, for better selectivity. To greatly increase the modulation percentage, the IF signal is doubled to 21.4 MHz and then heterodyned to 1.26 MHz. This enhances S/N. The patented Digital Direct Decoder uses two proprietary ICs. One includes a pulse-count detector (PA5006). The decoder phase locks a 38 kHz sine wave to the 19 kHz pilot. The pulses gate the sine wave to the left and right channels (the multiplication circuits are analog switches). Because the pulse rate is well beyond the spectrum of the composite stereo signal, no spurious mixing products result. In particular, the decoder is immune to HD Radio self-noise. The circuit includes pilot cancellation (PA5007). The AM section uses a Sanyo LA1247, which performs somewhat better than the usual LA1245.

"As usual for such old tuners, it was necessary to change all electrolytic capacitors." See all of István's suggested mods to the F-90 on his website or our DIY Mods page. In summary, he found that the F-90 "is a good tuner, a fine basis for improvements, and has a very good, pleasant sound on FM and also on AM." However, his sample's sensitivity fell short of Pioneer's published specifications, which means it is not a DX tuner.

Our contributor John M. also solved the preset problem mentioned by Brian above: "There are little foam pads on the back of the F-90's station preset buttons. The pads are supposed to press against the switch actuators on the PCB. After a while, the foam material breaks down, and it becomes very hard to get the presets to change. I pulled mine apart and replaced the crumbling mess with carved-up double-sided adhesive pads, leaving the cover strip on each padlet on the switch side. That fix has lasted 4 years, and seems to be holding." See how our panelist Jim thought one F-90 sounded compared to other top tuners on our Shootouts page. Read our contributor Radu's comparison of one F-90 to a Pioneer F-9 and a Hitachi FT-5500 MKII on our Shootouts 2.0 page. The F-90 is very common and usually sells for $40-100 on eBay, with a low of $25 in 9/08 and a bizarre all-time high of $245 in 5/09 when a clueless bidder hit the "Buy-It-Now" button.

Pioneer F-91 (1987, $600, photo, service manual, Audio review) search eBay
The F-91 was part of Pioneer's "Elite" series. It's quite sensitive and has excellent sound, with particularly superb bass. Our contributor PZ says: "I find the F-91 to be an interesting unit. It adjusts the IF bandwidth and tuning frequency automatically to match the need of the signal, called ARTS for Active Real-time Tracing System. [This sounds similar to Onkyo's "APR" system, with one critical difference: one can always manually override the APR settings on all Onkyo tuners. - Editor] So DXers don't have anything to fiddle with. In fact, the 8-segment meter starts at 30 dBf and goes up to 77 dBf, so it doesn't help you find the weak stations. On the other hand, 50 dB quieting in stereo is achieved at 34 dBf, better than most. So even with one bar lighted on the meter, one gets decent stereo reception." David Rich discusses the ARTS system in his article in The Audio Critic. As our panelist Bob then understood it, ARTS "uses a real time moving IF filter that moves around with the IF signal. So I believe this means it is incredibly narrow by default, and its center is moved around on the fly. I don't understand how they do it, but apparently it was so complex to build and keep aligned that they never used it again in any other model."

After all of the foregoing was written, PZ obtained a copy of the Circuit Description which, for those who can decipher it, should clarify the operation of the ARTS. Bob comments, "It apprears to be very similar, if not identical, to the 'active tracking' used in the H/K Citation 23." Our contributors Tim and Ann, who did a multi-tuner shootout, would "pick the F-91 for its sound quality unless we absolutely needed the superior sensitivity and selectivity of the McIntosh MR 78." Read the entire F-91 vs. McIntosh MR 74 vs. Modafferi-modded MR 78 vs. Sansui TU-919 vs. Sony ST-730ES extravaganza on our Shootouts 2.0 page. The F-91 also "was significantly better sounding and more sensitive than the Kenwood KT-815, particularly in the public radio range," and was much more sensitive and much quieter on weak signals than the Magnum Dynalab tuner they tested.

Here's some more info on the F-91, in Pioneer's own words: "Elite Reference Digital Synthesizer Super Tuner: We've pushed the level of FM sound quality to record highs with the addition of two Pioneer exclusives to the F-91. The first is the ARTS (Active Real-Time Tracing System) included in the IF section of the tuner. With some tuners, especially expensive ones, you have the choice of using a narrow or wide IF bandwidth. The first lets you avoid interference, but you have to settle for an increase in distortion. The second provides lower distortion and better sound, but interference may get in the way. Pioneer ARTS - it's simply the best of both worlds: its IF filter actively follows the desired signal while rejecting interference. Now you can enjoy both the low distortion of a wide bandpass and the high selectivity of a narrow bandpass. Sensitivity is much improved, too. The second Pioneer feature is the Digital Direct Decoder Type III. It takes the output from the ARTS IF circuitry and converts it into digital form before directly turning it into stereo analog signals. Thanks to pure digital operation, our DDD Type III is less prone to signal degradation. Moreover, in the Type III, we've simplified the circuitry using a new PLL detector, which has reduced noise even much further. Improvements extend to other circuits of the tuner as well. The front end, for instance, features an ID MOSFET to improve reception. Indeed, the front end is as highly sensitive and selective as an elaborate 4-ganged tuning capacitor. The F-91, like Pioneer amps and CD players, is designed based on our anti-vibration concept to damp harmful resonance and vibration for improved sound. We've turned circuits into modules and filled them with epoxy resin. And we've added honeycomb ribs to the chassis and used large insulators to shut out external vibration."

See how one F-91 sounded compared to other top tuners on our Shootouts page, and read our panelist David "A"'s Ricochet. The F-91 is a fairly common tuner and its eBay sale prices can be all over the place. The typical range seems to be $150-225 but as low as $90-100 and as high as around $400 are both possible. One went for just $67 in 8/07 for no discernible reason and a scratched one fetched just $53 in 6/09, while another inexplicably sold for $1,001 in 11/06 (now that is one BAD investment). An F-91 with rare rack handles went for just $108 in 9/07.

Pioneer F-93 (1991, $900, photos, brochure photo, service manual) search eBay
Part of Pioneer's "Elite" series, the fiendishly complicated and very rare F-93 was a highly sensitive digital tuner that was not known for good sound. With five ceramic filters, it seems that Pioneer was shooting for good selectivity. We'd like to get more information about the F-93 so if you've used one, please post in our FMtuners group and tell us about it. So far, we know that it had an analog-style tuning knob, and also push-button tuning behind the front-panel door; dual antenna inputs; and fixed and variable outputs. Sale prices for the F-93 on eBay are extremely erratic: $240-300 seems to be the most common range, but up to around $500 is possible. The all-time high is $788 in 11/06.

Pioneer F-99X (1985, $325, front1, front2, back, schematic, Audio review) search eBay
The F-99X was Pioneer's update to the earlier F-90, and made a number of improvements that contributed to better specifications and performance across the board. The front end is very similar, using the same excellent balanced FET mixer used in the F-90. The IF strip in the F-99X, however, is very different. Pioneer used multiple pairs of GDT ceramic filters tuned with separate 10.7 MHz transformers, 6 very wide filters in total for wide mode and 3 much narrower filters for narrow mode, with 2 more filters in narrow shared with wide mode. The basic detector and multiplex scheme appear to be similar to that used in the F-90, but Pioneer does report better performance figures. The multiplex used in these tuners is based on two integrated circuits which are proprietary to Pioneer. The scheme is based around a variant of the analog multiplier multiplex, and works by multiplying the output of the pulse count detector with a 38 kHz sinewave generated by a tuned circuit.

Our contributor Ryan measured an F-99X extensively and reported that it works very well, providing low measured THDs, as well as very low intermodulation. It is also extremely sensitive, with a very good quieting curve. Ryan adds, "This is one of the few stock tuners that I have seen to use audiophile grade parts where it counts. The F-99X uses numerous Nichicon Muse capacitors and other high-spec parts, but modders should be aware that the main PCB must be removed to desolder any parts. I would also note the complete lack of high blend, which could be a big annoyance factor. Finally, the U.S.-specific KU model is quite a bit better on paper than the non-U.S. version (the one with 50 kHz tuning steps) in terms of sensitivity, which I would expect to translate into the real world to some degree. It is very likely that this is due to the elimination of extraneous circuitry."

Our contributor David Rich tells us what he sees when he looks inside: "One tuned stage at the antenna, one RF amp, two tuned stages before the mixer. One tuned stage in the oscillator. The mixer is balanced. In wide mode 5 ceramic filters are the IF path. In narrow mode the first filter is replaced by two new ones and the second and third filter get replaced by two new ones. A second mixer is needed to produce the low IF needed for digital direct decoder chip. I also reported on this demodulator in issue 24 of The Audio Critic."

Our contributor Thrassyvoulos says that his F-99X has "very natural mids and highs but not much of a soundstage and almost zero bass extension." See how one F-99X sounded compared to other top tuners on our Shootouts page. The F-99X usually sells for $40-100 on eBay, with a low of just $24 in 4/08 and a high of $162 in 9/08.

Pioneer F-551 (photo) search eBay
Our contributor Brian Beezley offers this review: "The Pioneer F-551 is a small, black, synthesized FM/AM tuner. It has 24 presets in two groups of 12, three-speed manual/automatic tuning, and a novel adaptive RF-alignment system. The rear panel has thumbscrew antenna terminals, wired remote control jacks, and a switch for 9-50/10-100 kHz AM-FM channel steps. Pressing a button momentarily displays signal strength as a single digit. AM covers the extended band to 1700 kHz. Inside I found what at first appeared to be a basic tuner circuit, with two RF tuned circuits in the signal path, two IF filters (280 and 180 kHz), and a single-tuned quadrature detector. The tuner uses a 2SK241 RF amp, HA11225 IF amp/detector, AN7470 stereo decoder, LA1247 AM chip, LC7217 PLL, and M5223 varactor driver op-amp. There is no pilot cancellation or supersonic filtering.

"I wondered what the CCTS function did. Enabling it and poking around with a scope, I discovered that the tuner scans the RF-amplifier varactor voltage over a small range whenever the tuned frequency changes. It then uses the voltage that yielded maximum signal. I intentionally misaligned the front end and found that CCTS very effectively restored proper tuning. After I carefully reset the alignment, I was impressed that CCTS was able to slightly improve it. In addition to correcting a sloppy factory alignment, CCTS can compensate for temperature variation or component aging. CCTS is fun to watch as it displays signal strength before and after adjustment. It takes a second or two to operate, so you can disable it when you want to tune across the band more rapidly. You can also leave it off if you don't tune weak signals.

"I replaced the IF filters with matched 180 kHz Muratas. 1 kHz stereo THD was about 0.15%. The front end has no trimmer caps or inductor slugs, but the coils are easy to deform with a plastic tool. I was surprised to find that sensitivity was 2-3 dB higher than what I normally measure for most tuners. With the 180s installed, HD Radio self-noise was not objectionable. I heard a little background noise on a couple of strong signals, an indication of RF intermod in my high-RF location, but it wasn't all that serious. Some high-end tuners I've tried performed a lot worse." The F-551 can be found for less than $50 on eBay.

Pioneer F-717 (1987, $325) search eBay
We don't know a thing about F-717, but figured we should look it up after a guy posted a rather bizarre eBay auction listing calling this tuner "very rare" and saying, "Good luck walking into your local electronics retailer and finding a 'separate AM/FM tuner'! The kid forced to wait on you will look at you like you have Three Heads!" We can't figure out why this seller thought tuners are such rare pieces of equipment, and in any event rarity does not equate to quality. However, based on its original list price and the quality of some other Pioneer digitals, the F-717 may actually be worth a try for $30 or so.

Pioneer TX-1000 (1971, $300) search eBay
This predecessor of the TX-9100 had 4 gangs and good sensitivity specs. Our contributor Scott reports: "The TX-1000 is a well-built unit with a large power supply. The headphone output and control is very handy. It is reasonably selective for a single-bandwidth tuner and has good to very good DX capabilities for a 4-gang unit. The AM and FM sections have rich audio. The FM sound is a bit darker than the Pioneer SX-727's, and the AM is richer than the 727's and is better for DXing. The automatic gain control of the AM section is excellent. Two things I don't like: The vinyl cover is blah, and the plastic/bakelite knobs always lose their brass caps (it's a really excellent quality plastic/bakelite, though)." The TX-1000 usually sells for $25-40 on eBay, with occasional overpayments when an ignorant bidder seems to think it's comparable to a TX-9500. The high was $137 in 2/05 as two dummies fought it out.

There's a page on the TX-1000 with photos, specs and brochure excerpts (with some typos) on the Stereonomono website. We believe the Pioneer brochure description read substantially as follows: "The TX-1000 from Pioneer is a one of a kind stereo component, one of the new breed of AM/FM tuners that offers professional sophistication, sensitivity and extra-low distortion along with a host of new, advanced features for outstanding FM reception. Complete with the very latest design components and transistors, the TX-1000 provides all the requirements that the audio enthusiast demands in a tuner - and then some. MOS-type FETs in the front-end, an IF section featuring ultra-sharp crystal filters and ICs with outstanding limiting effect provide unsurpassed capture ratio and selectivity. The wide linear dial scale works with two sensitive tuning meters for pinpoint precision, and is complemented by multipath terminals and other refined features for perfect reception. Both AM and FM have separate output level controls. And even without an amplifier you can still listen to this unit through headphones plugged into the headphone jack. The Pioneer TX-1000 puts it all together for convenience and superb reception. Read on to learn why it's the finest component of its kind for your stereo money.

"Designed to play a key role in obtaining optimum reception even in areas of weak signals, the front-end section of the TX-1000 provides excellent sensitivity and signal-to-noise ratio as well as outstanding image rejection, cross-modulation rejection and spurious signal rejection. The circuitry employs four gang variable capacitors. In the first stage dual gate MOS-type FET is used, while the second stage features junction-type FET. Additionally, FETs are also used in the mixing circuit, which complements the stabilized Colpitts-type mixing oscillator. The result of these components is an image rejection ratio of 90 dB, spurious response of 95 dB and excellent interference rejection characteristics. The S/N ratio is also improved, and sensitivity is an excellent 1.7 μV. All of these key front-end features add up to provide outstanding FM reception, even in weak signal areas, with freedom from signal overlap and noise.

"The FM IF section determines the tuner's effective selectivity. In the TX-1000 the IF section circuitry employs four ICs and a pair of crystal filters and IC filter. The ICs provide an excellent limiting effect for stable performance, while the outstanding selectivity of the crystal filters assures sharp signal reception. The result is a constant performance unaffected by temperature, humidity or age and ideal selectivity characteristics of over 70 dB and a 1.5 dB capture ratio. Simply flicking the noise filter to the ON position will correct high-frequency MPX noise which is often created during reception of FM stereo broadcasts. The large TX-1000 dial scale was specially designed to be read at a glance. The linear design is not only easy-to-read, but also brings all stations closer together for easy tuning. The TX-1000 uses two extra-large tuning meters, a signal strength meter and a center tuning meter. This permits precision tuning for minimum noise and maximum stereo separation. The TX-1000 features separate AM and FM output level controls. Both can be set to compensate for differences in AM and FM signal strengths, so that the amplifier's master volume control does not require readjustment when the selector is switched. The TX-1000 is a handsome stereo component with stylish front panel and natural wooden case. Dimensions and styling are matched to complement other Pioneer hi-fi components to let you create an installation of systemized elegance."

Pioneer TX-5500II (1977, $150, photo 1, cabinet) search eBay
Pioneer TX-6500 (1977, $175, photo) search eBay
Pioneer TX-6500II (1977, $200, photo) search eBay
At the low end of Pioneer's TX-5500/6500/7500/8500/9500 series, these tuners all had 3 gangs and 2 ceramic filters. With so many better Pioneers available inexpensively on eBay, we can't see why anyone would want to pay more than $15-20 for any of the three, and they do often sell in that range, but up to $60-75 is possible. And here's the sad story of two clueless eBay newbies who ran up the price of an ordinary TX-6500II from $3.00 to $89 in 5/04: They were apparently befuddled by a very creative seller who said, "I have never seen a vintage tuner that had manual sliding (adjustable) controllers for stations! The dealer informed me that this is extremely rare and makes this tuner highly sought after for high-end collectors!" Actually, the TX-7500II, 8500II and 9500II also have the little sliders, but none of us at TIC ever thought they were even worth mentioning, let alone something that would cause a tuner to be "sought after." Who knew?

Pioneer TX-6200 (1973, $130) search eBay
Our panelist Ray tells us about his mods to the TX-6200 that he bought on eBay for $1.00 plus shipping: It's "a 3-FM gang, 2-AM gang monster 8:-)). In the center of the main board, the two adjacent ceramic filters have been placed in sockets. The sockets will eventually hold a pair of Bill Ammons's amplified filter boards. At the bottom left corner of the main board are new polypropylene de-emphasis caps. Not only are they better than the stock mylars, they correct the de-emphasis time constant from 62.8 µS, in stock form, to 75 µS. The top board is the audio and power supply circuits. The supply filter caps are upgraded to Panasonic FMs and the audio couplers are now big polyprops or Panasonic FMs bypassed with .01 µF polys. An access hatch was cut from beneath the main board so as not to have to disrupt the dial cord by removing the board for changes. The hatch was made to be bolt-on replaceable. RFM also did a 'poor man's alignment' to this victim. Using a CCrane stereo FM transmitter ($70) as a calibrated source, he was able to tweak the trimmer caps and slugs of the RF stages using a scope to watch the output amplitude of the mixer. That worked very successfully and much improved the sensitivity. In an attempt to adjust the centering meter, the upper and lower frequencies at which the stereo beacon would light were noted, the tuner set twixt those points and the meter centered there... seems to work OK. For anyone still reading this drivel, the TX-6200 had the right stuff for good sound." Here's an inside photo, post-mods. Ray subsequently theorized that tuners at the lower end of a brand's line were intentionally given a compromise time constant so as to be close in both the 50 µS and 75 µS markets. In addition to the TX-6200, other examples of this that he found are the Fisher FM-2310, Harman/Kardon TU615 and Realistic TM-1000.

There's a page on the TX-6200 with photos, specs and brochure excerpts on the Stereonomono website. Here's Pioneer's own description: "Pioneer's easy-to-operate high quality tuner. A compact, sensitive, practically-priced tuner. Low-noise junction FET in FM front end. Exclusive FM IC with 5-stage limiter. MPX circuit with high-performance IC for wide separation. Large signal meter and wide linear FM dial scale for easy tuning. MPX noise filter."

Pioneer TX-6800 (1979, $200, photo) search eBay
The baby of Pioneer's TX-6800/7800/9800 line has 3 gangs and 2 ceramic filters, and should be roughly comparable in performance to Kenwood's KT-5500 or 6500. The TX-6800 has one IF gain stage, which gives it good sensitivity. Our contributor Bill Ammons calls it "a great performer in stock form, both in higher RF and rural environments." See Bob's Filter Corner for a description of Bill's PCB filter mod. The TX-6800's circuit board is easy to access for service or mods, which can turn it into an excellent budget tuner for DXers. There's a page on the TX-6800 with photos, specs and brochure excerpts (with some typos) on the Stereonomono website. The TX-6800 usually sells for $20-30 on eBay. Occasionally, someone will overpay for a TX-6800 ($66 in 2/08, $82 in 6/08) when he doesn't know he can get a TX-7800 for that price. In our favorite TX-6800 auction in 11/02, the "winner" paid $60, just nosing out another dummy who bid $59.99 (a great way to bid if you're a shill bidder, or just trying to lose by a penny).

Pioneer TX-7100 (1973, $200, photo) search eBay
The baby of Pioneer's TX-7100/8100/9100 line has 4 gangs, 2 ceramic filters and one IF gain stage. In stock form, it's nothing special and is difficult to modify due to its circuit board configuration. Our contributor Bill Ammons says the TX-7100 "has a good RF front end, but with only two filters and one IF gain stage, it limps along. When modified with an improved IF stage, the TX-7100 is an excellent performer that easily beats my Carver TX-11a (stock) in fringe station grabbing power." From Pioneer's brochure or manual: "It features a frequency linear, 4 gang variable capacitor and a dual gate MOS FET in the FM front-end, plus phase linear ceramic filters with excellent phase characteristics and 5 stage limiter for high performance in the FM IF section. An exclusive signal strength meter coupled with the centre tuning meter and wide linear dial scale offers precise easy tuning convenience. Other features include fixed and variable output level controls, multipath output terminals and an MPX noise filter." The TX-7100 usually sells for $40-70 on eBay, but almost anything is possible ($1.00 in 5/07, $18 in 4/08, $101 in 4/09). One poor naive soul in 2/03 was the only bidder over $49 for a nice TX-7100 with cabinet - and he paid $229!

Pioneer TX-7500 (1976, $250, photo) search eBay
This little brother of the TX-9500 is a good tuner in its own right, according to our contributor Bill Ammons. The 4-gang TX-7500 has a similar front end to that of the TX-8500II. The TX-7500's single-bandwidth IF stage consists of 3 ceramic filters and one gain stage. The FM quad chip is an HA1137 which is followed by an HA1156 stereo demod chip. The audio output is discrete. The AM section uses an HA1138 chip. Bill adds, "The higher Q design of the RF front end allows better operation in strong signal environments. The construction of the unit makes it very easy to service and modify. The TX-7500 and TX-8500II have many similar parts. I modified the TX-7500 with two IF FILTER ADDER PCB (TM) boards. This brought the IF ceramic filter count up to 5, and added two gain stages for a total of 3. When modified, the TX-7500 is just as sensitive as a TX-8500II." The TX-7500's back pamel includes fixed and variable audio outputs, multipath outputs for a oscilloscope, and a switch to change the de-emphasis. The TX-7500 is very common on eBay; almost any sale price is possible up to $100, but most sell for $40-60.

Pioneer TX-7500II (1977, $250) search eBay
We don't know much about the rare 4-gang TX-7500II, which can sell for $40-100 on eBay, but it's supposedly pretty good. Since Bill Ammons observes that the TX-7500 is very similar to the TX-8500II, that certainly must be the case for the TX-7500II as well.

Pioneer TX-7800 (1979, $350, search eBay
This little brother of the TX-9800 has 4 gangs and 3 filters, like the Kenwood KT-7300, but its performance is stunning: more sensitive than a modified Onkyo T-9090, and just about as selective as the T-9090 when modified with one 110 kHz and two 150 kHz filters. The TX-7800 has only one IF setting for FM so it's not likely to satisfy the competing desires of an audiophile-DXer as well as a KT-7500 (for example) might, because a filter mod to maximize selectivity in the TX-7800 will necessarily affect its audio quality. (In the KT-7500 and other dual-IF tuners, a wide-bandwidth ceramic filter may be left in the wide IF mode for great sound on local stations while narrower filters can be installed in the narrow IF mode to improve selectivity for DXing.) But a modified TX-7800 might be superior to a modified KT-7500 for DXing, with terrific adjacent channel rejection. It does, however, have an annoying combined "Muting On/Stereo" and "Muting Off/Mono" switch that prevents one from choosing to listen to a weak signal in slightly noisy stereo. The TX-7800 is one of the very few tuners with wide and narrow bandwidth settings for the AM band, and our contributor Bill K. confirms that it "has a pretty hot AM section." Bill adds, "I have a Marantz 10B and a Scott 310E, and the McIntosh MR 74 will best either of those for pulling a weak station out of the dirt. My Pioneer TX-7800 will run head-to-head with the MR 74 for reception but sounds drier than any of the other three, though still very pleasant to listen to compared to many modern tuners." Our contributor Roger says the TX-7800 only has two gangs for AM, but switching to Narrow mode ups the selectivity to 50 dB vs. 15 dB in Wide mode (according to the published specs). In comparison, Roger's TX-9100, with a 3-gang AM section, has a single bandwidth setting with selectivity of 40 dB.

There's a page on the TX-7800 with photos, specs and brochure excerpts (with some typos) on the Stereonomono website. The TX-7800 usually sells for $50-100 on eBay but almost any sale price is possible, based primarily on condition. Just a sample of the variability: $200 and $225 in 9/04; $56, $62 and $190 in 2-3/05; $18 in 6/05; $276 in 10/05 (two crazy bidders); $31 in 12/05; $152 in 7/07; $52, $86 and $60 in 9/07; $250 for a mint one in 12/07; $150, $177 and $51 in early 2008; $129 in 7/08; $37 and $10 in 9/08; and $111 for a mint one in 4/09.

Pioneer TX-8100 (1973, $250, photo) search eBay
The little brother of the TX-9100 has 4 FM gangs and 3 AM gangs and might be available at a bargain price on eBay. Our contributor Steve reports: "I replaced all of the electrolytics in a TX-8100 that I picked up quite cheap. Panasonic FCs in power supply and in 'non-critical' positions and Black Gates in the rest (various series, depending upon value and position). Also rerouted a lot of the wiring and replaced it with Cat 5e - IMHO, this tuner has been transformed. It had a very 'transistor radio' sound before, and now sounds very good." The TX-8100 usually sells for $50-100 on eBay but its prices are almost as unpredictable as the TX-7800's: some sell for less than $30, and $150 or higher is also possible (with a high of $182 in 1/09).

There's a page on the TX-8100 with photos, specs and brochure excerpts (with some typos) on the Stereonomono website. We believe the Pioneer brochure description read substantially as follows: "A high-performance AM/FM stereo tuner, featuring new IF IC and phase linear ceramic filters for excellent selectivity and phase characteristics, the TX-8100 is one of Pioneer's new breed of stereo tuners. Featuring a broad range of newly-developed circuit elements, an accomplished front-end and near-perfect performance characteristics, it offers unique value and even more sensitivity and selectivity. Its front-end section employs dual gate MOS-type FETs in the RF stage and mixing stage, coupled with a frequency linear 4-gang variable capacitor, the entire package adding up to sensitivity rated at 1.8 µV (IHF). For even greater performance, the TX-8100's IF section uses new IC and phase linear ceramic filters to achieve a selectivity ratio of more than 80 dB (IHF) and capture ratio of 1 dB (IHF).

"Additionally, in the important MPX circuit, a high performance IC is employed for stability and reliability. Overall, this is a first-rate unit for advanced stereo component applications. Among its features are an FM muting switch that cancels inter-station noise, an MPX noise filter for enhancing tonal quality by suppressing irritating high frequency noise in stereo broadcasts, and multipath output terminals to permit accurate antenna direction. Output level controls for AM and FM are independently adjustable. And because output terminals of the TX-8100 are both fixed and variable, it is possible (by utilizing the fixed output) to direct-record from the tuner by bypassing your amplifier. Other features are equally significant. The FM dial scale is the wide linear type for precise, easy station tuning. There is a headphone output jack with an adjustable level control so that you can enjoy stereo listening with the tuner only. And much more. If you have been seeking an AM/FM stereo tuner offering the rare blend of advanced electronics plus a practical price, the TX-8100 is for you. A very important addition to the Pioneer line of quality stereo components.

"Special Features
4-Gang variable capacitor and dual-gate MOS type FETs in FM front-end.
Local oscillator with buffer circuit.
New high-performance large scale integrated circuits for FM IF section.
Phase-linear ceramic filters in the FM IF section for excellent selectivity characteristics.
MPX IC for excellent separation and SCA Beat rejection.
FM Multipath output terminals.
Double-Action FM Muting circuit with read relay.
MPX noise filter.
Precise flexible signal meter.
Improved AM tuner performance.
Exclusive AM IC with superb AGC (Automatic Gain Control) characteristics.
Ceramic filters in the AM IF section.
Headphone output jack provided.
Fixed and variable output level controls."

Pioneer TX-8500II (1977, $300, photo, block diagram, schematic) search eBay
Some say that the TX-8500II is almost as good a tuner as the TX-9500II. It has 4 gangs (vs. 5 for the TX-9500II) and wide and narrow IF bandwidth settings like the TX-9500II. Our contributor Bill Ammons says, "In the wide mode there is one ceramic filter followed by a tuned 10.7 MHz LC circuit. In narrow, the signal routes through the wide filter and consists of 3 more ceramic filters and one additional tuned LC. In stock form all of the ceramic filters are 280 kHz. The front end (in my opinion) works great in high-RF signal environments." Our panelist Bob adds, "These are a nice deal. Four gangs, single RF amp. In narrow, 4 filters plus 2 LC = roughly 5 ceramic filters. The sound is unrated at this point as it needs alignment and switch cleaning. The filters are quite easy to get to. Sensitivity is pretty good. I would say these are a bargain for $80 or so. Audio mods appear likely, but the supply is single-sided +13V." The TX-8500II usually sells for $50-80 on eBay, with a high of $179 in 3/08 for a used one and a stunning $325 in 6/08 for a "new old stock" TX-8500II. Nice TX-8500IIs with rare rack handles can sell for $150 or more.

Pioneer TX-8800 (1976) and TX-8800II
The 4-gang TX-8800 and 5-gang TX-8800II are believed to have been sold only in Japan. Pioneer guru Dave Swaffer reports that the TX-8800 is basically identical to the TX-7500, except that it lacked a de-emphasis switch on the back panel and tuned the Japanese FM band, 76-90 MHz. Our contributor Lorne tells us that the TX-8800II, in addition to the extra gang, has wide and narrow IF bandwidth settings, a larger chassis and a bigger circuit board. The layout of the board is somewhat similar to the TX-8800's, but is about a third again as large. The TX-8800II has a different power supply board with fewer electrolytic caps and one fuse, compared to the TX-8800's bank of four or five. The TX-8800II has some other interesting features, including a recording level calibration signal. Both units have a variable output option controlled by a pot operated on the faceplate. Lorne adds that the TX-8800II has "a wide-open sound, with bags of detail and impressive bass." The only TX-8800 we've seen on eBay-U.S. sold for $31 in 2/07.

Pioneer TX-9100 (1973, $350, photo, schematic, alignment info, specs and graphs, service manual, detailed specs) search eBay
A very nice, solid, but not fancy tuner, the TX-9100 has 5 FM and 3 AM gangs, 4 ceramic filters and 3 IF gain stages, and is very sensitive and has decent selectivity in stock (unmodified) form. Unfortunately, it can't be modified for optimal selectivity without taking it apart because of the way the circuit board is constructed and wired. The TX-9100 uses discrete transistors in its output stage (no op-amps) and has a smooth, powerful sound that some prefer to that of later Pioneers. It has exactly the same RF front end as the TX-9500 and 9800, with differences only in the IF and audio circuit areas. Our contributor David Rich describes the TX-9100's front end as follows: "One tuned stage at the antenna followed by the first RF amp. Then comes a double-tuned stage followed by another RF stage (never a good sign - this means they were going for a good sensitivity number at the cost of IM [intermodulation - Editor] problems). The final RF stage is single-tuned, as is the oscillator. This is the same front end found on most Pioneer tuners and receivers including the SX-1010, SX-1250 and SX-1980 receivers. The 4 ceramic filters in the IF are followed by a ratio detector. The unit uses a PA1310P MPX chip with PLL. It has a strange noise pulse blanking circuit, said to cut pulse noise from automobile ignitions?!?" The TX-9100's 3 AM gangs and a tuned RF stage give it an excellent AM section as well, although it does not have wide and narrow IF bandwidth settings for AM as the TX-7800 and TX-9800 have. The TX-9100 is one of the few tuners with a front-panel headphone jack with volume control. Other controls include separate output level controls for AM and FM, an MPX filter, and a muting switch offering two levels of muting or off. Of course, there are center-tuning and signal-strength meters. On the rear are fixed and variable RCA outputs and multiplex outputs for an oscilloscope.

Our panelist David "A," who believes that many Pioneer tuners are highly underrated, reports: "I bought one TX-9100 recently for $10 mint and it blew away every [Yamaha] CT-7000 I have tried! [Editor's Note: David acquired a couple of superior CT-7000s after writing this.] This TX-9100 was clearly better than the other three 9100s that I have owned." David adds that the TX-9100's quieting curve is steeper than that of the Yamaha CT-7000, and comparable to the Kenwood 600T's. See detailed specs and measurements for the TX-9100 compared to those of 17 other top tuners in David's tuner comparison spreadsheet.

Our contributor Tom B. says, "I have dusted off a TX-9100 that I had recapped a while ago and find that it sounds fantastic. When compared to a Sony ST-S730ES, the Pioneer has more detail and depth of soundstage. I also find the Pioneer to be in a league with my Sanyo Plus T55. The Sanyo is perhaps a little smoother in the midrange." Our contributor Robert agrees that his stock TX-9100 "sounds fantastic; I find it particularly rich in the midrange and powerful in the lower registers." Robert posted in our FMtuners discussion group that he finds the TX-9100 "remarkably unelectronic. Harmonically rich, full and with quite good low end extension and spatial portrayal - polite and lifelike."

Our contributor Bill Ammons adds, "The TX-9100 is not a bad-sounding unit, but the measured numbers (separation, distortion) are nothing special. It wins the award for the hardest to service/modify. When serviced, it's an excellent RF performer; its weakness is the audio section. Bypassing most of it makes it a great-sounding tuner! But I would have to add two hours of bench time just to service this one. I could bypass about 75% of the audio path to make a much better-sounding unit. The TX-9100's biggest flaw is the noise reduction that it uses. A FET in each channel is used as a variable resistor with the de-emphasis network that follows the FET. The normal value of de-emphasis (assuming R ON of the FET = 0 ohms) is 72.5 microseconds. Turning off the FET slightly so that R ON is 10 K or so increases the de-emphasis to a few hundred microseconds. Not a very good design based on a very nonlinear control signal being applied to the FETS. This is followed by an older style LPF filter block that is not overshoot compensated. And lastly, there is a 12 dB per high pass filter in each channel with a -3dB point of 23 Hz. Add in the unshielded wiring going to and fro in the unit and you get marginal performance. I increased some of the AF coupling caps, dropped the HPF to 5 Hz and used shielded wiring in a few places. I also upped the power supply and bypass caps. RF-wise, with a Filter Adder PCB in the first IF filter position and a narrower IF chain, this one will do as well as the TX-9500."

Our contributor Eric B. responds to Bill's criticism of the stock TX-9100: "The control signal mentioned is nonlinear because the FETs are switches, not variable resistors. They are not used in a slightly turned off mode. They totally blank the output signal if pulse noise is detected and the pulse noise filter is set to the 'cut' position. Since there is a finite time delay needed to detect a substantial pulse and generate the blanking signal, the signal path is delayed by a delay line (filter). This circuit removes unwanted pulse noise such as that from a weed eater. I have recently aligned several TX-9100s and could not find ANY unshielded wiring in the signal path! Pioneer's fully shielded coax may be mistaken for plain wire because it is smaller than typical RF coax and there is a bulge along the side for a solid wire used for ground connections. The unit is hard to modify because it is so well shielded, top and bottom of all circuit boards. But it has no need for modification, since the IF strip has four filters and three limiters yielding 90 dB alternate channel selectivity. In stock form this model performs very nicely." Sale prices for the TX-9100 on eBay are unpredictable: while the normal range is $80-125 for one in "average" condition and much less for one with minor cosmetic issues (with a low of $52 in 2/09), the price can sometimes skyrocket. Two "mint in box" TX-9100s sold for identical $330 prices in 4/06 and 5/08, while several other nice ones went for $275-280 in 2008 and 2009.

There's a page on the TX-9100 with photos, specs and brochure excerpts (with some typos) on the Stereonomono website. We believe the Pioneer brochure description read substantially as follows: "An advanced professional AM/FM stereo tuner, with unique P.L.L. MPX circuit, dual-gate MOS type FETs in the FM front end, and outstanding performance. The TX-9100 is Pioneer's finest tuner, a stereo achievement designed to significantly reduce the distance between your music listening room and broadcast stations. Offering what is certainly one of the finest FM sensitivity ratings ever built-in to a tuner, the TX-9100 is an incomparable blend of solid state circuitry and design, the most advanced unit of its kind available today at any price. The TX-9100 employs a 5-gang variable capacitor and low-noise dual-gate MOS-type FETs in its FM front end, resulting in a 1.5 µV (IHF) sensitivity. Pioneer has employed "phase-linear" ceramic filters in the IF section, coupled with a 6-stage limiter by monolithic ICs with differential amplifiers. All of this circuitry results in a 90 dB (IHF) selectivity characteristic, as well as improved phase characteristics and signal-to-noise ratio of 75 dB. Capture ratio is also distinctive, measured at 1 dB (IHF).

"Performance characteristics aside, the TX-9100 is a superb example of the application of advanced circuitry to music enjoyment. Its new-dimensional PLL (Phase Lock Loop) multiplex circuit improves the multiplex function considerably and is based on an entirely new principle. Since the coils and capacitors of the conventional 19 kHz and 38 kHz resonance circuits are immensely durable, reliability and stability are assured. There is also a special PNS (Pulse Noise Suppressor) built-in to the TX-9100 that cancels irritating pulse noise such as automobile or motorcycle ignition noise. But more than any one thing, excellent sensitivity stands together with excellent rejection characteristics. And what this means is the finest performance ever offered by a tuner, under all common, and some uncommon, operating circumstances.

"Special Features:
Outstanding FM front-end section with dual-gate MOS FETs, 5-Gang variable capacitor and two-stage RF amplifiers.
Phase-linear ceramic filters in the FM IF section for excellent selectivity and phase characteristics.
Local oscillator with buffer circuit.
6-stage limiter in FM IF section with all-stage differential monolithic ICs.
New dimensional Phase Lock Loop (PLL) MPX circuit.
Sharp low-pass filter that cancels carrier leaks.
Two-step FM muting switch.
Double action FM muting with read relay.
Pulse Noise Suppressor.
Signal strength meter with excellent linearity.
MPX Noise filter.
Multipath output terminals.
AM tuner section with 3-gang variable capacitor and resonance type one-stage RF amplifier.
High-Performance AM IC.
Independent AM, FM output level controls.
Headphone output jack provided.
Smooth tuning mechanism."

Pioneer TX-9500 (1976, $400, photo, rack mount, schematic, alignment guide, schematic left, schematic middle, schematic right, detailed specs) search eBay
The TX-9500 has 5 gangs and 4 filters and is roughly equivalent in performance to a Kenwood KT-7500, but is built even more solidly and we think it sounds great (although two contributors thought it was "bright"). The TX-9500 has exactly the same RF front end as the TX-9100 and 9800, with differences only in the IF and audio circuit areas. Our contributor David Rich describes what's inside: "In the IF we have 4 ceramic filter followed by 5 stages of bandpass limiting. The detector is based on a M5109PR chip. I do not have any details on this device, but it sure looks to be balanced. I have only the schematic of the full tuner. Maybe the full service manual or the data sheet gives more details. A HA1156 IC does all the MPX decoding. A HA1137 single chip IF amp and discriminator is used for the signal-strength meter. It is connected before all the limiters so that the meter does not saturate too quickly. In the Pioneer SX-1250 receiver, which goes for big bucks on eBay, the HA1137 is the chip used in the main signal path." The TX-9500 uses discrete transistors in its output stage, rather than op-amps. Unlike the TX-9500II, the TX-9500 has only one IF bandwidth (i.e., no wide/narrow switch).

Here's Pioneer's own description of the TX-9500: "Inside it's one of the most circuit-packed AM/FM tuners Pioneer have ever built. And outside it's one of the cleanest and most simple to use. The Pioneer TX-9500 has a new streamlined look, logically-arranged switches and controls, and a scientifically-designed tuning system that makes it all look so easy.

"But it's what's inside that counts: dual-gate MOS FETs and a 5-gang variable capacitor boost FM front end sensitivity to a superb 1.5uV (IHF). The FM IF has 7 ICs with differential amps, 4 ceramic filters (with 2 elements each) and a wide-band linear detector to pinpoint selectivity at 85dB or better and beef up the capture ratio to 1.0dB (IHF). Even in stereo the S/N is a super high 75dB, with total harmonic distortion of 0.2% at 1KHz.

"Thanks to the PLL MPX (phase lock loop multiplex) demodulator, stereo separation stretches to a wide 35dB over the 50 to 10,000Hz range. Stability? Even in signal-weak or signal-strong areas your station comes in clean and fresh.

"Planning to record off the air? Hit the switch for the built-in 440Hz test signal generator and check the output level against your deck's VUs for optimum adjustment before the music begins."

See detailed specs and measurements for the TX-9500 compared to those of 17 other top tuners in our panelist David "A"'s tuner comparison spreadsheet. Sale prices for the TX-9500 on eBay are very inconsistent, as with many Pioneers, and the averages dropped noticeably from $125-185 in 2004, to $65-110 in 2005, to just $45-100 in 2007, but $80-130 seems to be the current range. Over $200 is still possible for one with a nice wooden cabinet or the rare rack-mount shelf (with a high of $355 in 11/08).

Pioneer TX-9500II (1977, $400, front, back, inside, with amp, ad 1, ad 2, brochure, detailed specs) search eBay
"A sweet, well-built tuner that looks great!" (according to our contributor Mike M.), the TX-9500II has 5 gangs and a very unusual configuration of filters: an LC filter and an SAW (surface acoustic wave) filter for the wide IF bandwidth mode and 5 normal 3-pin ceramic filters for narrow mode. The Wide/Narrow switch and filter configuration distinguish the TX-9500II from its virtually identical predecessor, the TX-9500. Our contributor David Rich describes what's inside: "Same front end as the TX-9100. In the IF the main signal path has an 8-pole LC filter followed by a SAW filter. The narrow path has 5 ceramic filters. Both IF paths go through 5 stages of bandpass limiting similar to the TX-9500, but a pair of multiple-section LA1222 chips are used instead of the five single-stage limiter chips in the TX-9500. The TX-9500II's FM detector is the same M5109PR chip used in the TX-9500. The MPX chip is a PA1001. The MPX outputs are buffered by a PA1002 which appears to be a Pioneer quad op-amp with some extra function that is not clear from the schematic. A PA3001 chip replaces the HA1137 for the meter drive. In the SX-1980 receiver that goes for really really big bucks on eBay, there is a PA3001 in the main signal path. The PA1001 and PA1002 based MPX stage of the SX-1980 are the same as in this tuner. The big difference is that the TX-9500II has the big LC filter, the SAW filter, the five stages of narrow-band limiting, and that strange M5109PR FM decoder."

Our panelist David "A" says that the TX-9500II and the TX-9800 "convey bass up with some of the best in this area (Accuphase T-100 or Technics ST-9030). The TX-9500II may be the high-water mark for Pioneer other than the Series 20 (F-26 and F-28) line. You can make the TX-9500II a DX tuner, but its magic is the SAW filter-based wide IF section. I think the Pioneers are neither 'transistory' (unless outright defective) nor fairly reviewed by most. They show large amounts of quality engineering and proper construction practices that are not seen as much in other brands." See detailed specs and measurements for the TX-9500II compared to those of 17 other top tuners in David "A"'s tuner comparison spreadsheet.

Our panelist Bob says, "I dragged out the TX-9500II and gave it a total alignment. Wow, it was not easy. There were a million adjustments and almost more cans than the Charlie (and I could *touch* these!). I was amazed when finished. The distortion in wide was 0.015%, narrow 0.02%. This is the lowest I have ever seen, and signal-to-noise is awesome also, as well as signal-pulling power. I am disappointed in the ability to add narrow filters so far, though. Easy to get in, but they want to throw the whole tuning off-center, and I think I know why. But I need more filters that go a bit above 10.7. All my 150s, if off, mostly are off below 10.7. I think the SAW filter is at about 10.75, and all mine are at 10.7 - it makes a difference! But with 5 filters in there stock, it does great anyway. I am thinking that this is the most desirable one of the series, even above the TX-9800. The TX-9500II is built a little better, they deleted a bunch of stuff in the TX-9800 but added the crystal tuning. No sound judgments yet, but in good alignment, this is a very hot tuner for sensitiviy and clarity of reception. I counted 12 L-type cans in the 9500II, with 4 around the detector. This very sophisticated detector, I think, is part of the key to the excellent reception. I was just reading the Audio Critic article again, and David Rich made a reference to good detectors being able to demodulate noisy signals better than other lesser ones. The TX-9500II has the best detector of the Pioneer series, and better than most Kenwoods or Sansuis, except the 600T, KT-917, and maybe KT-8300." Bob adds, "The wide filter is LC with adjustable inductors, working with a Murata SAW. These were all the rage for maybe two years in the '70s. Likely the only way they could do phase linear low GDT filters then -- the ceramic versions came later."

Our contributor Bruce reports, "I recently bought a TX-9500II that needed some work, but sounds very nice. I modified it by taking out the five Murata 280 kHz filters in the IF section and soldering in sockets to accept new filters. I currently am using three Murata 230's and two Toko 110's and find that it has amazing selectivity with that combo. It does seem to cut out a bit of the highs now on narrow, so I will replace the 110's with Murata 150's as soon as my backorder comes in. The new Murata 230's make a big difference in signal strength - about 1/2 notch improvement on the signal meter. Anyway, you mentioned that someone said that the TX-9500II was hard to modify, but I had no trouble making the mods, and it has been awhile since I picked up a soldering iron, so anyone who is reasonably handy and careful should be able to perform this mod."

Our contributor Gary adds, "The TX-9500II does the best job to date of picking out weak stations in narrow mode. Sound quality is good but not great. Following the lead of the mods on TIC, I upgraded the power supply with Schottky diodes and new electrolytics and replaced all electrolytic and tantalum caps in the audio signal path. I used a combination of Black Gate caps and some aluminum polymer electrolytic caps. When I first turned on the tuner after the modification, the sound was rather bright and not very pleasant to listen to. I suspected that this might be the classic Black Gate sound, since these caps are notorious for taking a very long time to burn in. There seems to be some truth in this, since it took about three weeks for the sound to smooth out and become listenable. The end result is quite an improvement over the stock TX-9500II, but it took much longer to settle in than I had expected or experienced with previous mods."

See our contributor Greg's comments on the TX-9500II's AM section in the TX-9800 writeup below. See how one TX-9500II sounded compared to other top tuners on our Shootouts page, and read David "A"'s Ricochet. Additional information on the TX-9500II is available at classic-audio.com. As with most Pioneers, sale prices for the TX-9500II on eBay are very inconsistent, although the TX-9500II tends to sell for more than the TX-9500, on average. Anything over $100 is possible, depending on condition and fluctuations in demand, with $160-200 the most common range. TX-9500IIs with wooden cabinets are scarce and tend to sell for higher prices, and those with the rare rack adaptor (handle and tray) can sell for $300-400. The record high sale price for an ordinary-looking TX-9500II was $500 in 5/03, and one went for $455 in 8/05. More recent highs were $368 in 2/08 and $299 in 12/08.

Pioneer TX-9800 (1979, $450, photo, block diagram, schematic, alignment guide 1 2 3, ad, Audio review) search eBay
The TX-9800 has 5 gangs and 5 filters, one for the wide IF bandwidth mode and 4 for narrow, and is solidly built. The TX-9800 has exactly the same RF front end as the TX-9100 and TX-9500/TX-9500II, with differences only in the IF and audio circuit areas. From a technical standpoint, however, the TX-9800's complex crystal referenced oscillator sets it apart from those other Pioneers. According to our panelist David "A," although it has excellent bass, "the TX-9800 shows that it was cost-reduced compared to the TX-9500II. The shields for each section that are present on all TX-9100s, all TX-9500s and most TX-9500IIs (ones that I have seen, anyway) are gone in the TX-9800, and the TX-9800's parts quality is worse overall." Chuck Rippel of Audio Video Service Labs describes the TX-9800's circuit that operates the two indicators 'TUNE' and 'LOCKED': "What that circuit is looking for is a null in the discriminator offset. In all tuners, that null should also be coincident with the point of lowest distortion (established, in part, by the adjustment of the discriminator secondary). In this tuner, that circuit works correctly and it's clearly audible. Slowly tune through the station, the red 'TUNE' indicator will illuminate and the 'LOCKED' indicator will illuminate when you release the tuning control. The tuner is then at the point of least distortion. The AFC will maintain lock at that point."

Our panelist Ray, who has owned many tuners, says "When it comes to low end of the band sensitivity, the TX-9800 is my best." Ray did a DXing shootout among his TX-9800, a Kenwood KT-8300 and an Optonica ST-7405: "The TX-9800 won the pure sensitivity challenge, but not by as much [over the KT-8300] as with most. When I tested them for adjacent-channel performance, the TX-9800 and KT-8300 could both ignore the adjacent, but the ST-7405 had lots of interfering hash." And in Ray's shootout between the TX-9800 and the Sony XDR-F1HD, "the Sony would easily find a DX candidate and then, with much tweaking, the TX-9800 would get it also but not as quietly. That is, to a point. If the signal was really weak, i.e., less than 18 dBf, the Sony would be totally deaf and the TX-9800 would know it was there. It seems the Sony has great quieting but more limited ultimate sensitivity."

The TX-9800 has a 3-gang AM section with wide and narrow bandwidth settings, so it may be a good choice for those who listen to AM radio. Pioneer's published specs for AM show selectivity of 50 dB in Narrow mode vs. 20 dB in Wide mode. Our contributor Greg says, "The TX-9800 and TX-9500II have WAY better than average AM sections, both with a TRF section (not common in modern tuners) and good IF sections. The 9800 also has selectable AM IF bandwidth (can't remember if the 9500II has this) which is a great help in DXing on the AM band." Those who want to work on their TX-9800s should read the discussion in our FMtuners group that begins here.

On eBay, the TX-9800 can sell for almost any price depending on condition, fluctuations in demand and whether it has a wooden cabinet, but prices have been trending higher since 2005 and two garden-variety ones sold for $500 and $530 in 10/07 for no apparent reason. On the low side, two sold for $77 and $84 in 7-8/05. Mint TX-9800s can sell for $300-380, the same price range for those with the rare rack-mount tray. See how one stock TX-9800 sounded compared to other top tuners on our Shootouts page, and read David "A"'s Ricochet. Additional information on the TX-9800 is available at classic-audio.com.

Pioneer TX-D1000 (photo) search eBay
The TX-D1000 is a slim, attractive digital synthesizer tuner with the equivalent of 4 gangs, 2 ceramic filters and one IF bandwidth. It was Pioneer's first digital tuner and the only one designed to match their other vintage equipment. Both of the IF filters are GDT flat group delay type for minimum distortion. Internally, the TX-D1000 uses most of the same parts as Pioneer's other top vintage tuners, and our contributor Ryan claims that it sounded very similar to his TX-9800. The TX-D1000 is similar to the Phase Linear Model 5100 Series Two tuner (which was built by Pioneer) in most respects, except that the TX-D1000 tunes in 25 kHz (.025 MHz) increments, allowing one to detune slightly to avoid adjacent channel splatter. TX-D1000 sale prices on eBay are all over the place, as evidenced by sales of $232, $175 and $33, all in 2/08; $185 in 4/08; $41 in 6/08; and $20 in 9/08. The record highs were $308 in 3/05 and $317 in 4/06.

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