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Tuner Reviews D-G
Tuners are listed alphabetically by manufacturer and 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). Please see the On-Deck Circle for tuners that we know very little about or that we're not sure merit a writeup.
Please post in our FMtuners group if you have any information about any dbx tuner. We're tracking eBay sale prices for a few of them in the On-Deck Circle.
Denon TU-280 (1992, $275, schematic)
Here's our panelist JohnC's review: "The TU-280 FM/AM tuner implements a varactor, 3-gang equivalent front end feeding an IF strip with 2 ceramic filters and a single IF bandwidth. The IF strip is initiated with a 2SK161 MOSFET, and a 2SC2839 bipolar intermediate gain stage, fed directly into a Sanyo LA1851N DTS single-chip tuner IC. The tuner IC supplies everything between the IF and audio stages. The audio stage itself is formed in discrete components, with no buffer and a discretely formed low-pass filter. The front panel houses a digital station frequency readout, mono/stereo lights, but no signal-strength meter. There are 30 station presets and a remote sensor, paddle tuning, Power, Auto/Manual, Memory and Band rounds out the controls.
"The remote control unit shares its control codes with the TU-380/460/660 and others. The tuner is bass-shy and the top end is reasonable, very similar to the Philips FT920 in sonic character. There is no bottom panel in the chassis, but board removal is very easy. A recap helps, and rebuilding the LPF in the audio section with film caps also improves the sound quality. All in all, not a bad tuner, but you can get a lot more bang for your buck exploring other Denon tuners like the TU-460." Regarding the use of the LA1851N, John adds, "Needless to day this is not a TOTL unit - it was designed to what must have been a very low price point. Denon to their credit abandoned the 1851 in the next higher model, the TU380RD." The TU-280 usually sells for $20-40 on eBay, with a high of $140 in 7/03 for a mint one with the original box, and a low of $2.75 in 11/08.
Denon TU-380RD (1994, $325, front, back, inside, board, schematic, front end)
Our panelist JohnC offers this review: "The RDS-capable FM/AM TU-380RD is the next tuner in the TU-280 series, with the TU-650RD completing the run. The 650 may seem out of place but when you pull the cover it's apparent that the 380 is just a downsized 650. Although the TU-380RD is the next model above the unremarkable TU-280, don't assume it inherited the limitations of the 280. Aside from its RDS display, the 380 includes 40 presets that maintain all the specific settings invoked when the preset was saved. The tuner is remote-capable and includes front-panel switches for Power, RF Attenuation, Band, and Tuning Mode, along with all the requisite RDS mode and Memory settings. The rear panel houses the FM 75-ohm coax and AM connections, RCA audio, and a polarized C7 power connection. The chassis is typical Denon with an easily removable main board, and no bottom panel.
"On the technical side, the TU-380 starts with a 3-gang equivalent varactor front end, and a 3-ceramic filter, single-bandwidth IF. The IF strip begins with a 2SK211 MOSFET with the 3 filters separated by two gain stages, discretely implemented using paired 2SC2996 transistors. The IF strip feeds an LA1265 FM/AM IC which employs a quadrature detector. Composite signal, with a single cap in the signal path, is routed to an LA3401 IC for MPX services and an active de-emphasis circuit. A post-detection filter in the composite signal path is added on European and UK models of the 380. Audio is run through an MPX filter, BA4558 output buffer and on to the RCAs.
"There are some things to note if you're planning on any mods to the 380 which, when completed, leave you with a very nice sounder for those who appreciate the simplicity of the circuit. With a 1994 manufacture date, Denon finally got around to adequately heat sinking the two regulators in the power supply (long overdue) and there is a preponderance of surface mount components on the main board, which includes the 4558 audio buffer. All the signal path 'lytics are through-hole and easily replaced. If you have the skill set, the surface mount 4558 can be replaced with a Texas Instruments OPA2134UA/2K5 op-amp, which works well. Stock, the 380 sounds as good as, if not better than, a TU-460. The bass is rolled off but easily addressed with larger caps in the audio output -- 3.3 µF films are nice. After both are recapped, the 380 wins in both selectivity and audio." The TU-380RD usually sells for $50-90 on eBay, with a low of $20 in 7/05.
Our panelist Bob reports, "I bought a TU-460 on a recommendation from a friend. It meets the goal: it sounds incredible for a little tuner. Those inclined to pop the lid will be horrified, because there's very little there. Two filters, who knows what on the number of gangs. It has one of those micro-miniature RF front ends that is soldered shut, so I cannot easily tell how many gangs, but I would guess 3 or 4 at most. But forget all that - it easily beats the pants off many of my other 'better' tuners sound-wise, but is NOT a DX machine. Strong signals above 40-ish dBf are incredible-sounding, though. I can't explain it, I just shut up and listen. The tuner's biggest failing is no blend or MPX filter to remove noise on weak stations. It goes to mono on its own, but stays in stereo to the bitter end, with noise, and without a filter or a way to get mono, it makes very weak stations unlistenable for me. Many people will have a mono switch on their preamp, which will do the trick and make it noise-free. There is a muting defeat switch, but strangely enough, unlike many other units, it does NOT also go to mono. It is decently sensitive, and for $50 beats many more expensive units, stock." Read our panelist JohnC's suggested mods to the TU-460 on our DIY Mods page. The TU-460 is extremely common and usually sells for $20-50 on eBay.
Denon TU-500 (1978, $415)
The very rare TU-500 is a 5-gang FM-only tuner that our contributor Thomas calls the forerunner of the much better TU-850. The TU-500 had only one bandwidth setting but did have multipath outputs for an oscilloscope, a front-panel headphone jack with output level control, and a left/right balance control. Check The Vintage Knob for a nice photo, although they err in saying that the TU-850 was "in the same league" as the TU-500. There's also some confusion about the year in which the TU-500 was introduced -- TVK and some other non-U.S. websites suggest that it debuted in Asia and Europe as early as 1974 or 1975, but we have confirmed that it made its first appearance in U.S. buyer's guide yearbooks in 1978. The TU-500 usually sells for $165-270 on eBay.
Denon TU-501 (1978, $340)
We don't know much about the rare TU-501, which was the lesser sibling of the TU-500. It usually sells for $50-100 on eBay, with a high of $116 in 4/07.
Denon TU-530 (1979, $275, photo, schematic)
This scarce silver-faced FM-AM tuner was the little brother of the TU-630 and uses the same FM and MPX ICs. It doesn't look like much from the outside and has only a single IF bandwidth, but does have 4 gangs. Our panelist JohnC tells us that like the TU-630, the TU-530 "sounds pretty damn good." Our contributor Jeff picked one up for $32 on eBay and reports, "The TU-530 has a pretty green backlight and switchable Servo Lock, Hi-Blend and Muting buttons. It's pretty heavy but I'm still guessing it will be pretty empty inside. On the selector knob is AM, FM Mono - Auto and then Recording Level. That is a nifty feature. I guess I could run this with a db meter to set levels on my surround, instead of that horrid white noise. The tuner works fine, sounds ok." The TU-530 had some good specs: usable sensitivity of 1.7 µV, image rejection 90 dB, IF rejection 100 dB, spurious response: rejection 90 dB, and signal-to-noise ratio of 82 dB mono, 79 dB stereo.
Denon TU-550 (1988, $300)
We hope our panelist JohnC will have a review of this tuner eventually. The TU-550 usually sells for $55-120 on eBay, with a low of $25 in 1/04.
We believe that the TU-580RD was the virtually identical European version of the TU-650RD, reviewed below.
Denon TU-600 (1987, $400, photo)
The very common TU-600 is supposedly a decent tuner, if you have a good sample that has been aligned, but is no comparison to its well-regarded sibling, the TU-800. Our panelist Jim says he has tried several TU-600s and the sensitivity of each example was quite poor. See how Jim ranked one of these TU-600s in comparison to many top tuners on our Shootouts page. Our contributor Dave N. adds, "I know of an inverse Lirpa, available usually <$50. It combines the best sound with worst reception, rumored to be a one-of-a-kind example of genuine engineering entropy. Of course I mean the Denon TU-600. In a class with few mates, all four available stations will bring tears to your ears. Rosewood sides are a must for full ambiance." The TU-600 generally sells for $20-40 on eBay, but some people still overpay (like the guy who paid a ridiculous $136 in 1/08).
Denon TU-630 (1979, $340, photo, inside, schematic)
The rare TU-630 has 5 gangs and Wide and Narrow IF bandwidth settings, and our panelist JohnC says it "sounds pretty damn good." Our panelist Ray points out that the TU-630 and its little brother, the TU-530, "have the same interesting audio stages and I heartily approve! Passive de-emphasis after the MPX and then a polarity correcting buffer. (That MPX chip is a flipper.) Denon's designers were consistently good with their audio circuits from the TU-530 to the 767." Our panelist Bob calls the TU-630 "likely either the world's most powerful FM stereo tuner, or the least powerful stereo receiver, or maybe both at the same time. It boasts 3W per channel in stereo, to rear speaker outputs or the headphone jack. It's a great tuner, but fairly rare. I had one here and enjoyed it for a while. Most unique is the ability to turn the servo (crystal) lock off via the front panel. I wish similar tuners from that time, like the Sansui TU-919 and Pioneer TX-9800, had that."
Here's JohnC's full review: "For the last 10 years or so a TU-630 has been sitting in storage, alone, neglected and seldom used in rotation. A couple of weeks ago, after there was a request for the schematic, the 630 was pulled from storage and placed in the shop system. With the schematic in hand and with a fresh set of eyes and ears, the thought occurred that it was time to lift the cover and see what could be done with the unit. You'll read in a minute why it took so long.
"First, some of the basics. The 630 was introduced in 1979, a year after the well-respected TU-850 and a couple of years before the TU-900, and in reviewing the schematic it appears to be an evolutionary half-step of the basic design of the 850 into the 900. The 630 is an FM-only, 5 gang, 5 filter, dual IF unit using what, at the time, was near top-of-the-line components. The front end employs an air gap oscillator trim cap, 3 silicon N-FET transistors and an AFC circuit feeding the IF which includes 5 low GDT filters. The 2 filters in the Wide IF are Murata MLs and the Narrow IF adds 3 Murata MMs to the lineup. The IF system IC is the Hitachi HA11225 which implements a quadrature detector and the MPX IC is the venerable Hitachi HA11223W PLL demodulator. A passive de-emphasis is implemented with independent separation adjustments for Wide and Narrow IFs. There's also a 3W amplifier section with volume control for both speaker and headphone accessories. The power supply is a convoluted affair with a dedicated 22.9V rail for the monitor amps and two separate secondary windings for -9.7V, 23.5V, 12.1V and 13.6V.
"The front panel has the usual buttons for IF Band, Power, Muting and Servo Lock. The Function rotary knob has detents for Mono/Hi Blend/Auto and Recording Level. The servo lock as implemented is a completely manual affair. In other words, a station is selected with the servo lock circuit off, and after the selected station is manually tuned the servo can be turned back on to lock the station or left off which allows off-center tuning, if the situation requires. Included on the front panel is a 1/4 inch headphone jack for your listening pleasure. The back panel houses both 75 Ohm F and 300 Ohm twin-lead antenna connections along with the previously mentioned speaker connections, fixed output audio, and H/V scope RCAs.
"Construction is the typical Denon steel tub affair with no bottom plate. If you're anticipating a recap or repair, removing the board is easier than it appears. There are 7 wire looms on Molex connectors, one solder connection on a lead from the front panel display, 5 screws into the chassis, 2 lock nuts on the front rotary switches behind the faceplate, and last but not least, removal of the pulley from the tuning capacitor. That sounds worse than it really is: fully open the tuning cap, and the dial should stop on or about 109 MHz. This positions the pulley retention screw at 12 o'clock. Loosen the screw, slide the pulley off the shaft, while maintaining some tension on the dial string, and lay it down out of the way. You can now lift out the board, tuning cap and all. Done carefully, upon reassembly all that's required is to reinstall the board, replace the screws and locknuts in the chassis, and replace the pulley, making sure that the dial pointer is located precisely where it was upon removal. Tighten the pulley retention screw, replace the wires and you're done. See, easy. The reason you have to deal with the pulley is that the tuning cap itself is mounted directly to the tuner board with no way to remove without first getting the board out of the chassis first.
"The recap is pretty straightforward and definitely worth the work. These units are very sensitive and fairly selective. They sound very good with a nice soundstage. Bass goes low enough, but a tad loose compared with some other exceptional tuners. Separation is notably very good." JohnC added, "Having lived with it for a month now and spending way too much time looking at the schematic, there are some things that I wish I could change. Specifically the power supply, which is single-sided, a ratio detector instead of the quadrature, and last but not least, a buffered audio output." The TU-630 usually sells for less than $50 on eBay, with a high of $149 in 1/04 for one that was aligned and had an F-connector jack added.
(1993, $375, front, back, inside, board)
The RDS-capable TU-650RD is the scarce big brother of the very good sounding TU-380RD, and was in production a year prior to the TU-380RD. The Euro version of the TU-650RD was the TU-580RD. Our panelist JohnC says, "The TU-650RD is the top dog in the 280/380/650 lineage, completing the X80 series topology that started with the 280. The Stereo AM and FM TU-680NAB, though sharing the X80 model number, is a radically different design and shares nothing but a similar face with its predecessors, but more on that at a later date." John provides this review of the 650:
"What the 650 does give you that is missing from the 380 is a 4-gang equivalent varactor front end, wide and narrow IF bandwidths, 4 ceramic filters (at least 2 of which are GDTs) rather than 3 in the 380, and the missing post-detection, anti-birdie filter in the composite signal path. At least two of the 650's filters are GDTs feeding an LA1235 FM IF chip which implements a quadrature detector. The MPX IC is the respected LA3401, with an active de-emphasis circuit, MPX filter, and a BA4558 audio buffer in the output. From the LA3401 out, the circuit appears to be very close if not identical to the 380's. All my comments in the TU-380RD review regarding board layout and morphology of the 380 also apply to the 650. Of particular note is that there are functions built into the remote that are not available on the front panel of the 650, including preset scan, RF attenuation, and a 4-step front panel dimmer just to name a few. In OEM condition, the unit is very quiet, with good sensitivity, and rolled off in the bass, which should be expected considering it's the same circuit as the 380. Separation is good to excellent, presenting a wide soundstage with good depth. Overall, the TU-650RD is a much underappreciated model."
John adds, "There's not much documentation available for the 650, but if you have the 380 schematic you can pretty much think your way through a 650. If anyone out there has a schematic or service manual, or knows where one is available, please let me know. I'd really like to get my hands on the info." The TU-650RD usually sells for $30-75 on eBay.
(1990, $350, front, back, inside, service manual, specs)
The all-black digital TU-660 is the big brother of the TU-460 and TU-560. The TU-660's front panel includes MPX noise reduction, IF Band and Auto Mute/Manual switches, 30 presets, and an LED signal strength meter. Inside, our panelist Ray reports that it has a varactor-tuned stage feeding a dual-gate RF amp feeding a double-tuned stage. This in turn feeds a balanced FET mixer which is also fed by a balanced local oscillator buffered by another FET. There are two varactor-tuned circuits in the L.O. Here's Ray full review: "The TU-660 appears to have been meant as a 'budget' variant of the highly regarded TU-800. It shares many of the TU-800's attributes in both the RF-in and audio-out circuitry. It lacks the Super Narrow IF path but retains the Wide/Narrow bandwidth selection. Audio-wise, it has an LA1235 detector, LA3401 MPX and NJM4558 output buffer -- all good stuff. It also features a post-detector low-pass filter (anti-birdie, per Denon). The TU-660 came in a confusing variety of two-band (FM/AM) and three-band (LW/MW/FM) models and power inputs, 120v, 220v, 240v and multi-voltage models. Compounding this confusion was the FM de-emphasis contained within. I believe it can be summarized as all models except the fixed 120v units (USA and Canada) are 50 µS. Mine is the multi-voltage model and thus to change it to 75 µS I had to change the de-emphasis filter caps from 820 pF to 1200 pF. I didn't intend to mod this fine unit but since I had to pull the PC board for the de-emphasis I did some audio and power supply cap upgrades.
"Spec-wise, the TU-660 is pretty typical of 4-gang varactor tuners except for the signal-to-noise ratio which is very good, probably due to the double-tuned balanced and buffered L.O. feeding a balanced FET mixer. In this it can be called a 'TU-800 Lite.' S/N is rated at 88 dB in mono and 82 dB in stereo. Subjectively, it also quiets quickly and well. The LED string signal-strength meter is nicely calibrated. Overall, one nice tuner, IMHO. Mine cost $59.99 plus shipping so I'll qualify it as 'sparrow feed.'"
Our panelist JohnC sent Ray a Sony ST-J75 for a shootout, and Ray reported: "The ST-S75 is in very good condition and totally stock, while the TU-660 has minor upgrades, i.e., corrected de-emph and audio caps changed to Panasonic FC's. Both have very accurate de-emph response as measured. With my new-old speakers I can detect a very minor audible difference: The Denon has more midrange heft/life and background vocals are better resolved. I don't think I could pick them out except via quick A/B switching. The differences may be due to the Sony's old and cheap audio electrolytics, and that will soon change...."
JohnC's response: "On Ray's evaluation of his 660, J75, and Hitachi FT-5500 MKII, compared with my notes on a similar pairing and my 5500 MKII with RFM buffer board -- they are indeed very close. I still think the 75 is on the dry side. To me, it seems to lose some hall ambiance. There are two stations out of Louisville, one classical and one AAA, which broadcast about three hours each of live programs per week. They both use the same performance space, and I have been an attendee at that venue on many occasions, so I know what it should sound like. The 660 and the 5500 are closer to that acoustic signature. The bass on the 5500 goes deeper than both, but doesn't have the stage width. All in all these three are very, very close, and it absolutely comes down to some very small personal preferences. As Ray has stated, replacement of the tired 'lytics could/will juggle all of this."
Back to Ray: "The promised mods have been made to my ST-J75 and the components duly burned in, and the Sony and the Denon are now actually indistinguishable when A/B'd. Bottom line, the mods were effective and now the ST-J75 deserves a seat upon the topmost shelf. Those mods consisted of OPA2134s in place of NJM4560s, upgrade of all signal passing caps from detector out to the output jacks, and a few power supply cap upgrades. I did all changes at once and did not try to evaluate each change, and honestly there was not all that much room for improvement, anyway." Read JohnC's suggested mods to the TU-660 on our DIY Mods page. The TU-660 is relatively scarce on eBay and usually sells for $40-80.
Denon TU-720 (1983, $225)
The TU-720 had the lowest list price of the 22 Denon tuners listed in the Orion Blue Book, and usually sells for $35 or less on eBay (and sometimes as low as $10-15). But despite its position at the bottom of the line, the TU-720 had excellent published specs, particularly for sensitivity and signal-to-noise ratio. It had some sort of servo-lock circuit and what Denon's marketing materials called a "high-performance front end." It can be dirt cheap on eBay (usually $20 or less, with lows of $1.00 in 3/06 and 8/06 and a high of $70 in 4/07 in an auction with only one bidder) and might be fun to play with or modify.
Denon TU-747 ($250, photo)
The TU-747 is a basic, inexpensive digital tuner that can have either a black or silver face. It is solidly built and compares favorably with its sibling, the TU-767, for audio quality. The TU-747 tunes in 0.1 MHz increments like the 767, but lacks the confusing muting/lock circuit of its big brother. It has the electronic equivalent of 4 gangs and 2 ceramic filters (there's a space on the board for a third filter, but it's filled with a cap instead). Sensitivity is good and selectivity is decent considering that there are only two filters. The TU-747 usually sells for $20 or less on eBay (and sometimes $5 or less), with a high of $67 in 12/09.
(1985, $350, photo, closeup, user manual, service manual)
A digital tuner that can have either a black or silver face, the TU-767 tunes in increments of .1 MHz and has unusual muting/signal locking circuitry that is not intuitive. Still, it looks good, sounds great, and for DXing is on a par with mid-line Kenwoods like the KT-7300 and KT-6500 when modified. Stereophile considered the TU-767 to be one of the cleanest-sounding tuners of its era, with the best stereo separation available at the time. Our panelist Ray called the TU-767 a "great sounder and finder and
spooky quiet - quieter than the well-regarded Sony ST-J75, methinks. For no technical reason I can find, it even quiets AM reception better than all with equal antenna help." Ray gives us the definitive report:
"The TU-767 was a mid-eighties product that seemed to be market targeted for the 'upscale' end. It's stylish in black or light and came with nice but faux wood cheek plates in a low, wide-profile package. Too wide to fit in a standard rack unless the cheeks are removed. One feature deserving special mention is the 'SSS' or super searcher system. This was a very novel circuit designed to reduce front end intermodulation by strong stations in close frequency proximity to one the user wants to hear. Other tuners have used added gangs and reduced sensitivity to sharply tune 'in' the desired signal. SSS adds separately tuned gangs to tune 'out' the interfering signal. It's a bit fiddly to use but it's definitely effective. I once wanted to listen to a local high school football game being broadcast from a 50 mile distant, 60 KW, 99.1 MHz station from compass point 186 degrees. This is normally blocked by an 8 mile distant 51 KW, 105.7 MHz station from point 160 degrees. The antenna is a rotating Winegard 6065. Use of the TU-767's 'SSS' allowed clean and clear reception where none other of my flock were acceptable. (Alas, my home team lost the game.)
"I also found the TU-767 to be a fine sounder which agrees with its old reviews from the audio press. But, as usual, it was still attacked by my hot iron. Nine power supply caps, 9 audio chain caps and an output buffer transplant (as well as tightening up its stock passive de-emphasis) later, it still sounds great! Maybe even a bit better. I got mine for $79.99 shipped and consider that a true bargain." The TU-767 usually sells for $40-80 on eBay, with a low of $11 in 8/09. In 6/04 two lunatics bid up a mint one from $58 to a bizarre $395, and then three hours later the "loser" bought another one for $110!
(1988, $500, photo, brochure, front panel operation, owner's manual part 1, part 2, service manual part 1, part 2, schematic, parts)
A black-faced digital tuner, the TU-800 was a Stereophile favorite that was compared to the Onkyo T-9090 and "enthusiastically recommended." It has 3 IF bandwidth settings (Wide/Narrow/Super Narrow) like the Onkyos, and 8 ceramic filters. There are 2 filters in Wide, 2 more added for Narrow (4 total), then a totally different path with 4 different filters for Super Narrow. The TU-800 is reputed to be better-sounding than the T-9090, on average, but our panelist Eric had a unit that was out of alignment so its sensitivity and selectivity were not up to spec. When our panelist Bob got that TU-800 to work on, he "noticed the MPX filter does nothing - then I reread Don Scott's review, and he said the same thing." After tweaking a second TU-800, Bob called it "an incredible tuner for selectivity, sensitivity and sound, when working correctly. It beat the pants off a new Fanfare." Bob later added, "I have seen 2 or 3 TU-800s and it is one of the best late high-end FM digital display tuners. Some have a little mismatch in the narrow IF filters, but they have very good reception when the filters are perfect, one of the best. Stock sound is also very good. I certainly think it is one of the top 5 or so best digital tuners ever made that are affordable - discounting ultra-rare and ultra-expensive ones."
Here's Bob's description of the TU-800's circuit path: "After the antenna input, there is a tuned varactor stage, then a dual-gate MOSFET, then two more tuned varactor stages, then the mixer, a dual-gate MOSFET. After the mixer is an IF transformer, then a real nice touch, two FETs in parallel driving the first ceramic filter. In the linear oscillator, there is a tuned varactor generating the LO, followed by a FET buffer, followed by another tuned varactor stage, and then this signal drives the LO input on the mixer. So I count 5 gangs total, with 2 in the LO area, so it's the equivalent of 4 gangs by the 'traditional' count." The detector is a phase-locked loop type that is shared by the Wide/Narrow and Super Narrow IF paths.
Our panelist JohnC reports: "My initial impression of the TU-800 was quite favorable. My biggest complaint was that the bass
wasn't where it needed to be, but the midrange and highs were nice, separation was good and wide, and it was very, very quiet, which was nice in today's HD-infected world. It is also one of those tuners that makes the speakers in both of my systems here completely disappear, leaving a convincing audio hologram in their place. I attribute this to phase coherence across the audio bandwidth. On the DX side, I was interested in seeing how good it would be against the other tuners in residence.
The test stations that I use are:
WNAS 88.1 - 2850W - 40 miles LOS to the stick
WARA 88.3 - 950W - 15 miles LOS to the stick
WJIE 88.5 - 24,500W - 50 miles LOS to the stick
"All stations are aligned along a single antenna vector. The TU-800 easily resolved each station cleanly, in stereo. The Super Narrow IF setting is a wonderful thing. I've been told that with a matched set of filters and a good alignment the TU-800 rivals the Sony XDR-F1HD for reception. With
its DX performance probably better than anything else I have here, I decided on a simple cap upgrade and, in the process, an attempt to address the rolled-off bass issue.
"Construction of the tuner is quite nice: an anodized extruded aluminum front panel and steel tub chassis. Unfortunately there is no bottom plate to provide access. Without a bottom plate, you have to remove the system board from the chassis to replace anything. At first, this appeared to be harder than it actually was. Two board screws, 3 back panel screws, 2 wire loom connectors, 2 chassis ground solder joints, and 3 wire wraps from the transformer, and the board simply lifts out - 15 minutes of work and it's done." JohnC's mods to the TU-800 can be found on our DIY Mods page, and read his favorable comparison of the TU-800 to the Sansui TU-X701 and TU-X711 in our writeup on the X701.
Our contributor Paul E. says, "I've got quite a few tuners (although not as many as a lot of people), but if I could only keep one, it would be the TU-800. It has superb sound quality, and the super-narrow filters mean it is good for DXing without needing any modifications." However, our panelist Ray's TU-800 finished fourth in a DXing shootout that you can read about in our Technics ST-S8 writeup. Our contributor Tim compares a modded TU-800 to a couple of other top modded tuners on our Shootouts 2.0 page, where you can also find extensive before-and-after technical comments from Bill Ammons. Our contributor Nick says, "Out of all the conventional tuners I've used, the TU-800 had the most symmetrical IF filter response, even bettering my Sony ST-SA3ES which was bought new. The Denon is a bit bass light and lacking richness compared to my Kenwood L-1000T which has, I think the best audio quality of all the digital tuners I've heard." The TU-800 usually sells for $75-200 on eBay.
The following is the text of a Denon sales brochure on the TU-800, as retyped by an eBay seller:
The TU-800 incorporates DENON's latest and most advanced FM front end. This circuit helps to ensure superior performance characteristics in every respect. It precisely picks out the desired reception frequency even among very closely spaced stations. Signal-to-noise ratio and freedom of distortion do full justice to CDs. Other outstanding features include a DTD (Dynamic Twin Drive) demodulator, automatic IF bandwidth selection in three steps, and a 30-station random preset memory. The TU-800 is everything a state-of-the-art tuner should be. An AM/FM stereo tuner for the age of high-quality digital audio.
New Design FM Front End
The front end uses stringently selected components in a highly perfected circuit structure. It has a low-noise RF stage and a mixer stage capable of withstanding powerful input levels, achieving high sensitivity and a wide RF dynamic range. Thus it is fully compatible with cable systems delivering multiple, powerful input signals.
Newly Developed FM Demodulator Circuit
DTD (Dynamic Twin Drive) demodulator phase-locked loop (PLL) circuits provide superior FM demodulation, but usually suffer from a high distortion rate. DENON's new high-S/N, ultralow-distortion DTD demodulator overcomes this problem perfectly. Central to this circuit is the newly developed V.C.O. (Voltage-Controlled Oscillator), which is equipped with four varactor diodes configured in two mutually cooperative sets of two. For a frequency/voltage curve based on the main set of varactors, the other set inverts the instantaneous voltage applied to it, thus preserving excellent signal linearity and incredibly low demodulator distortion.
New CPU for Easy Operation
The amazingly easy operation of this tuner proves that indeed, "simple is best." This level of easy operability is attained by equipping it with new computer-controlled functions.
3-Step IF Bandwidth Selection
When FM broadcasting is received, the tuner automatically discerns the strength of the incoming signal and the amount of noise generated by obstacles, etc, and the optimum IF bandwidth (wide, narrow, super narrow) is selected accordingly (manual selection is also possible). As a result, the signal is always received in the ideal mode.
30-Station Random Preset Memory
Up to 30 AM/FM stations can be preset at random; that is, any stations desired can be present on channels 1-30. When a desired station is recalled, both the frequency and the channel number are displayed. Of course, this also works perfectly with cable systems.
Storing broadcast stations into memory is now easier than ever before. You can specify a range of preset numbers, such as for example 3 through 20, and let the tuner automatically assign the stations receive by auto scan to those presets.
This feature lets you listen to each memorized station for 5 seconds. The tuner skips stations whose current field strength or reception conditions are poor, so that you can quickly find the broadcasts that you want.
Noise is often a problem when receiving stereo broadcasts from weak FM stations. By setting the Multiplex Noise Reduction switch to auto position, a high-blend function is activated which significantly reduces noise to create a highly listenable signal. The high-blend function is automatically defeated when strong signals are received.
The low-impedance output of approximately 600 ohms is compatible with all amplifiers.
Large FL Display
The large fluorescent display numerically indicates the reception frequency and preset channel number as well as other functions, for extreme ease of operation.
(1978, $480, photo, audio board, block diagram and specs)
A large, heavy analog FM-only tuner with 5 gangs and 5 filters, the TU-850 was another Stereophile favorite. It has wide and narrow IF bandwidth settings, manual high blend, manual muting, and "gimmicky power meters that can be hooked to an amp for your visual pleasure" (thanks Jim) and also double as multipath and signal-strength meters. The TU-850 has a thick aluminum front panel and a steel case painted in brown crackle finish and is solidly built, inside and out. It is very selective unmodified and our contributor Tuck found it to be a sensitive and quiet tuner, beating a Kenwood KT-7500 in a side-by-side test of sound quality and selectivity. Our panelist Jim praised the TU-850 in a shootout with other top tuners: "This is a very nice-sounding tuner with a very pleasant midrange and highs with well-controlled sibilance. The only drawback is the bass, which is a touch light or rolled off" when compared to the best. Another feature is that the meters can be set to display modulation for each channel simultaneously and even at the same time."
Our contributor Ed B. says that out of his many top tuners, "the TU-850 is the present king; in narrow mode with the high blend selected it's the quietest and best of the bunch, and it's really decent in wide mode even without the blend. The sonics are great on my tube amplified office system, but it's true that that bass isn't as deep as some of the others on the big solid state living room system. This tuner could be killer if the bass delivery could be improved." Our contributor Gary adds, "It sounds great and has no issues. I read of its bass response weakness, but I run a subwoofer on the system it is hooked up to. I think it has great sound. It is really big and heavy, and I like the unusual looks. It is so neatly laid out under the hood as well." Our contributor Giovanni is "fairly happy" with his: "I think the sound quality is not up to the best I've owned so far (Sherwood S-3000V and McIntosh MR 67) and slightly below very good solid state tuners (the MR 77, for instance)."
Our panelist JohnC says the TU-850 is "a truly sweet, not little, tuner. Another feature is that the meters can be set to display modulation for each channel simultaneously and even at the same time." Read JohnC's suggested mods to the TU-850 on our DIY Mods page, and see our panelist David "A"'s Ricochet. There's also a nice writeup of the TU-850 at The Vintage Knob website. The TU-850 usually sells for $150-300 on eBay.
Denon TU-900(1981, $590, photo)
The TU-900 is a very rare FM-only tuner with an analog-style tuning knob and both analog and digital tuning readouts. The digital readout is behind a thick polished and beveled glass that one user said gives a "floating" or "3D" effect to the display. The TU-900 has Wide and Narrow IF bandwidth settings, a muting switch, and a calibration tone to set recording levels. The unusual quartz-lock tuning is defeated when the touch-sensitive tuning knob is touched, and reactivated when one's hand comes off the knob. Rosewood side panels complete the tuner's elegant look. Here's our panelist Ray's report: "The Denon TU-900 was a late analog/early digital model sporting both methods of frequency readout. Its features, style and price made it an upper-end model. It has 4 gangs, 2 ceramic filters in Wide IF mode and 3 more added for 5 CFs in Narrow. Denon did some IC shopping at the Hitachi store as the detector is an HA12412 and the MPX an HA11223W. The audio buffer is an NJM4558. Low-pass filters between the MPX and buffers provide pilot filtering and de-emphasis is done via feedback on the buffers. It's interesting to note that the Japan 'in country' TU-900 had a 5-gang front end but the export models were 4-gang. With its 5 CFs in narrow IF mode, the TU-900 can be very selective (90 dB) but that only holds if you hold onto the tuning knob. Releasing the knob energizes the servo-lock which tends to pull the tuner to a nearby strong signal. Thus it could be called a 'hands-on' DXer.
"The styling seems low-key elegant with a champagne tinted face and dark rosewood cheekplates. It's also rather big at 19.88" wide, 13.5" deep and 3.25" high. Some factory specs: Practical sensitivity 9.8 dBf; S/N 50 dB; sensitivity 15.6 dBf mono, 34.7 dBf stereo; maximum S/N 88 dB mono, 83 dB stereo; THD: mono 0.025% wide, 0.10% narrow; stereo 0.035% wide, 0.30% narrow; stereo separation 60 dB wide; capture ratio 1.0 dB. RFM's subjective comments are, stock, good sounding, quiet, sensitive and easy to use. After extensive audio and power supply mods it's great-sounding (if the station is), very quiet, sensitive, and easy to use. The TU-900 is a really nice tuner - too bad it's so rare." The TU-900 is seen once or twice a year on eBay and usually sells for $125-250, but one in poor condition went for just $50 in 11/03 and a nice one fetched a very surprising $450 in 7/05.
DenonTU-1500RD (photo, owner's manual)
The TU-1500RD is a very common tuner with RDS capability and an optional remote control. Our contributor Girard, a DXer, reported: "The TU-1500RD is my DX tuner of choice these days. RF performance is wonderful, and changing the four IF filters for better selectivity is very easy. In wide mode it uses two of the filters, and in narrow mode it uses all four [two of which have a fairly narrow 180 kHz bandwidth - Editor]. It's not bad with the stock filters, but I modified mine by replacing all the filters with 150 kHz Muratas. In this configuration it's very close to being as selective as the Onkyo T9090II. What I like about the TU-1500RD is the sensitive and apparently low-noise front end. I've measured mine down to 0.5 microvolt for a usable (in DX terms) mono signal. The tuner handles my high-RF environment (less than five miles from two 100,000-watt FM stations) better than any tuner I've ever tested. I like this tuner so much that I sold my T-9090II. When you open the TU-1500RD it looks like a gutless wonder inside, because most of the components are surface-mounted on the 'underside' of the circuit board. There are very few components mounted on the 'top' of the circuit board. The tuner does not automatically switch from Narrow to Wide IF mode while tuning, but it does have selectable Auto/Manual tuning mode. I always run mine in manual because in auto it wants to scan to the next fairly strong signal it finds, which is annoying. In manual, it tunes normally in 100 kHz steps, but in manual mode it won't do stereo. [Could there be a problem with this one? - Editor] I think that's kind of odd, but it doesn't bother me for DX work. In either auto or manual, it retains whatever IF setting (wide or narrow) you've selected."
DXer Matt S. adds, "I too am pleased with the TU-1500RD, although I've not modified the filters. The audio quality is far superior to my Yamaha TX-900 but the .01 MHz tuning step on the Yamaha is very useful. I decided the best thing for me was to leave the Denon unmodified and use both tuners as conditions warrant. Having not used a 'regular' (read: unmodified) tuner in years, I can't really compare this unit to other unmodified tuners, but it does fine on adjacents if a signal is up. The real fun, of course, is the RDS display built in." Our contributor Alan M. says, "One of the great things about the TU-1500RD is the persistence of RDS station name. If you allocate a preset number to a 'blank' frequency and the ionosphere/meteor scatter brings in a distant station strongly enough, the station name will then forever be allocated to that preset! This is very different from other RDS tuners I've had which lose the station name as soon as the signal fades." Another DXer, Mike Bugaj, has a writeup on mods for the TU-1500RD, as well as a comparison to the Onkyo T-450RDS, on his website. But DXers Bill N. and Randy Z. complain that "the extended mute every time you change frequency, almost a full second," basically means that the TU-1500RD has to be DXed with in mono. Bill adds, "There is also next to nothing you can do to tweak that tuner as there just isn't much inside other than the big IC that has everything built into it, and the service manual isn't terribly helpful on what pins do what."
Our contributor Dan has more on the TU-1500RD: "The first thing that impressed me was the attractive design and somewhat intelligent layout. The buttons are a little on the small side but spaced far enough apart to be used without hitting two or more buttons at once. Using it for the first time was extremely easy with little surprise. The tuning knob works just like an analog tuner does, except in 'Auto' it will scan until it finds the next station. It doesn't change from narrow to wide mode automatically either, but will stay in either mode when searching. I noticed that the tuner was trying to lock onto even weak stations that barely had any signal that I normally don't listen to, but changing to 'manual' would bring in many cleanly. Sonically, nothing really jumped out at me, it was pleasant and non-fatiguing. Soundstage had very good depth, bass was very natural-sounding without being obnoxious or overly boomy, highs were a little laid back, but the detail and clarity is excellent. Overall, I'd say the sensitivity of this tuner seem to outweigh any sonic deficiencies there might be because you can hear more stations better than before, at least I can, and any sonic shortcomings are relatively small compared to other less sensitive tuners. The RDS can be a very nice feature, probably more suited for use in cars, but helpful when DXing. I think this would be a good tuner for someone who doesn't want to have to pay to have a vintage tuner upgraded and repaired - it just works well out of the box." The rack-mount version of the TU-1500RD is called the TU-1500RDP, with the "P" apparently standing for "professional" as with the Marantz ST-6000. The TU-1500RD usually sells for $110-160 on eBay, but as low as $75-90 and up to $200 or more are not uncommon. The record low is $42 in 9/09 for one with a remote.
Draco Micro/CPU 100
The Grafton, Wisconsin-based manufacturer of this unique Sherwood tuner also sold it under their own name for awhile after a falling-out with Sherwood. See Sherwood for a full writeup of the beast.
The Dynaco FM-3 is written up on our Tube Tuners page. It's worthy of mention that an unbuilt FM-3 kit sold for $468 in 8/09 on eBay.
Esotec ST-7 and Esotec ST-8 -
Listed under Marantz.
Eumig T-1000 (1980,
$795, front1, front2, left closeup, right closeup, back)
Eumig was an Austrian electronics company that was best known for their consumer movie cameras and projectors. Their other tuners, including the impressive-looking T-500, were probably sold only in Europe. The T-1000, which was sold worldwide but is still rare in the used market today, is a narrow black or silver rack mount-style tuner. It usually sells for $65-100 on eBay, with a low of $47 in 6/09. We're looking for more info on it. If you've used one, please post the details in our FMtuners group.
(1993, $1,395, ad, review and response)
The predecessor of the FT-1A, the FT-1 uses old-style circuit boards rather than the FT-1A's surface-mount technology. Our contributor Ed Hanlon says the FT-1 was made for Fanfare by B&K and was an upgraded version of their TS-108 tuner reviewed above. Our contributor John H. discussed the FT-1 vs. the Sansui TU-X1 in our FMtuners
group. For what it's worth, here's Sterophile's 1994 review of the FT-1. The FT-1 usually sells for $375-500 on eBay, but one went for $649 in 6/06.
Fanfare FT-1A (2000, $1,495, photo)
The FT-1A is a high-priced FM-only tuner that competed with Magnum Dynalab for those who would rather spend 3-5 times more on a new tuner than buy a better vintage one. Our panelist Jim was not a big fan of how the one Fanfare he tested sounded in comparison to many top tuners, as can be seen on our Shootouts page. But our panelist Eric thought that same FT-1A did a nice job pulling in the somewhat weak station he usually listened to, next to a stronger local, with good quieting. The FT-1A has only 3 filters to go with its 5 gangs, but one of them - the tuner's "secret weapon" - is a low-profile Murata filter coded SFE10.7HC, with a very narrow 110 kHz bandwidth. In stock form, the tuner is an excellent combination of adjacent channel selectivity and quieting - on the level of a Mac, Onkyo or Yamaha, and better for that purpose than any stock Kenwood or Sansui, including the TU-X1. But the FT-1A is waaaay overpriced when new, particularly considering the low cost of the parts inside. The FT-1A usually sells for $400-600 on eBay, with a bizarre record high of $1,276 in 9/06.
Fanfare FTA-100 (2003, $1,695)
The FTA-100 is cosmetically similar to the FT-1A. It's probably virtually the same inside, as well, with the addition of AM stereo. An FTA-100 sold for $815 on eBay in 5/04.
Fisher - See the Tube Tuners page for information on a number of Fisher tube tuners.
Fisher FM-2310 Studio Standard (1977, $250)
Our panelist Ray reports: "The Fisher 'Studio Standard' FM-2310 is an interesting FM/AM analog tuner, mostly due to its unique front face meter complement. Alongside the usual signal-strength and center-tuning meters is a switchable multipath/deviation meter. Since the meters are arrayed horizontally, they steal from the length available for the frequency dial, but it's not bad. The first thing to catch the eye when looking under the hood is a very clean layout and a varicap with 5 FM gangs. But, alas, like the SAE Two T3U, the FM-2310 only uses 4 of them. Obviously a casual count of gangs can misinform. The IF string is single bandwidth with four 280 kHz ceramic filters. These filters along with the LA1230 quadrature detector and LA3350 MPX ICs are factory socket-mounted! The de-emphasis time constant both calculates and measures at 64.8 µS and the frequency response measures -1.0 dB at 20 Hz, +0.95 dB from 2 kHz to 12 kHz and -0.35 dB at 15 kHz. Subjectively, I found it to be a good all-around tuner. The deviation meter is a really informative 'tattletale' on your received stations. It quickly shows the overdriven compressed signals and the better signals with wide-ranging dynamics, thus confirming what your ears are telling you. Yes, it was 'sparrow feed' as I paid $9.99 + shipping." Regarding that odd time constant, Ray's theory is that some lower-end tuners were intentionally given a compromise T.C. so as to be close in both the 50 µS and 75 µS markets. In addition to the FM-2310, other examples of this that he found are the Harman/Kardon TU615, Pioneer TX-6200 and Realistic TM-1000.
Our contributor Paul Baptista bought Ray's FM-2310 and offers his own report: "From the block diagram, here is a description of the circuit. Four-gang front end -> 2 filters -> LA1222 -> 2 filters -> LA1230 -> LA3350 MPX -> low-pass filter -> audio amplifier LA3122 with de-emphasis on the feedback loop (but Ray did his usual de-emphasis mod on this unit). This tuner features the rather rare FM deviation meter, which also doubles as a multipath meter at the toggle of a switch. My motivation for buying this unit was to get access to a FM deviation meter. It also includes signal-strength and center-tuning meters, so 3 needles to indicate 4 functions. The FM-2310 has fixed and variable outputs, with the variable output knob on the front panel. I did not spend any time on the AM side. It has FM blend and FM muting settings as well. The listed FM specs are:
Usable Sensitivity: Mono 1.7 µV/9.8 dBf; Stereo 4.3 µV/17.9 dBf
50 dB Quieting Sensitivity: Mono 2.5 µV/13.2 dBf; Stereo 34 µV/35.9 dBf
S/N Ratio: Mono 75 dB/Stereo 70 dB
Capture Ratio: 0.8 dB
Alternate Channel Selectivity (+/- 400 kHz): 75 dB
Image Response Ratio: 80 dB
Spurious Response Ratio: 100 dB
IF Response Ratio: 100 dB
AM Suppression Ratio: 65 dB
THD at 50 dB Quieting: Mono 0.3%/Stereo 0.4%
THD at 65 dBf (100 Hz, 1 kHz, 6 kHz): Mono 0.1%, 0.1%, 0.15%; Stereo 0.15%, 0.15%, 0.25%
Stereo Separation (100 Hz, 1 kHz, 6 kHz): 40 dB, 46 dB, 36 dB
Subcarrier product rejection (19 kHz/38 kHz): 60 dB/70 dB
"Listening impressions, keeping in minded that my unit was modified (power supply caps, diodes, signal coupling caps, corrected de-emphasis and changed to passive instead of in the feedback loop): The lower third of the audio band seems very good. I would use the word captivating. You are drawn in. The highs are not as detailed or extended as on my modified Sony, and the stereo width is not as wide, either. I think a remaining mod would be required to improve the top end and perhaps help in the stereo width as well: replace that output amp LA3122, which is a 14-pin DIP."
Our contributor Joe opened up his FM-2310: "I found that there are two circuit boards, one for the power supply (which includes the Deviation/Multipath circuitry) and one for the AM-FM IF MPX and audio circuits. Surprise, the FM IF ceramic filters are fitted into sockets from the manufacturer (Sanyo). This will make changing them very easy. The FM RF circuitry is in a separate shielded box along with the AM RF/Osc/Mixer tuning circuits. I compared this unit's FM RF and IF circuitry against the Fisher RS-1080 receiver which also has a Deviation/Multipath meter on its front panel. There is only one digit difference on the part number for the FM IF MPX board between the two. The RS-1080 receiver has a separate Deviation/Multipath detection board, but the components are identical between the two products. The FM-2310 has a 5-gang FM front end and the RS-1080 has a 5-gang FM front end, but it appears that one tuning gang of the FM-2310 is not used. The FM-2310 has single tuned circuits in its FM front end for RF amp input and output plus Mixer input and oscillator circuit. The RS-1080 has single tuned first RF amp input, double tuned first RF amp output, single tuned Mixer RF input plus single tuned Osc circuit. The FM 2310 has a single RF amp stage and Osc stage. The RS-1080 has a first RF amp and second RF amp and an Osc circuit with a buffered stage output to the Mixer.
"Right out of the box, the one thing that was immediately evident is that the IF detector stage is misaligned. When maximum signal strength is tuned, the center of channel meter is off to the high side of RF tuning. I will need to touch up the detector alignment. In comparing reception of my favorite station against my recently acquired Kenwood KT-9900, both seem to have the same level of signal strength indicated and the same degree of quieting. The Fisher tuner seems quite selective, likely due to its ceramic filters in the IF strip. Both have about equal MPX separation and good soundstage. The Fisher has higher bass response than the Kenwood, but neither unit has been modified in any way.
"My conclusion is that the Fisher FM-2310 is a respectable AM-FM tuner which is quite easy to modify. Both the top and bottom of the circuit boards are easy to access by removing the top and bottom covers of the tuner. The ceramic IF filters are all Murata 3-lead SFE 10.7 mHz units with red dots. The FM-2310 and the KT-9900 indicate the same exact levels of deviation on my favorite station and others tuned across the FM band. The overmodulated stations are easy to spot visually as well as having louder audio." The FM-2310 is scarce and usually sells for $30-60 on eBay.
Fisher FM-2421 Studio Standard (1978?)
Our panelist Ray reports: "The name 'Studio Standard' seems to cause the tuner shopper to move on, but this model turns out to have good performance and build quality. Call it the 'Studio Standard Sleeper.' The FM-2421 is equipped with a 4-gang varactor front end and wide/narrow IF bandwidths consisting of two or four CFs. The detector IC is an HA11225, the MPX IC an LA3380A and the AF amp an NJM4558. A few specs: Usable sensitivity, 9.8 dBf mono and 17.9 dBf stereo; 50 dB quieting @ 13.2 dBf mono and 35.9 dBf stereo; S/N is 75 dB mono and 70 dB stereo; alternate channel selectivity, narrow, is 70 dB; and THD stereo @ 65 dBf input is .1%, 1 kHz. A freshly aligned unit, tested for DXing, came up a little short of a Pioneer TX-9800 and a Hitachi FT-5500 MKII, and about equal to a Sansui TU-D99X. Those are all 5-gang tuners. Stock, the FM-2421 sounds good, with de-emphasis measuring at 70 µS. Modified with RFM's typical recipe, it sounds like all his other tuners. 8:-) The chassis is very solid and heavy with a massive power supply for a tuner. In fact, it has two shielded power transformers, one for main power and the second, unswitched, for memory backup. This tuner was available in either black or traditional Fisher champagne colors. It's of medium dimensions (3.5" tall), and has sensible ergonomics and a bright but no-nonsense dashboard. The eBay going rate has been $20-35 for this sleeper. That's a real bargain, sparrow feed for sure, and I like it." Since Ray's writeup appeared, many FM-2421s have sold for $40-60, but $20 or less is still possible.
Our contributor Tuck adds, "I picked up an FM-2421 last fall at a local tag sale. I nearly ignored it until I noticed that it had selectable FM IF bandwidths. I took it home and have been listening to it ever since. I wouldn't put it in the supertuner category by any means, but it is so much better than I have learned to expect from the Taiwan version of Fisher products. This is actually a quality piece. It is extremely quiet and clean and it looks as though the design engineers were given free rein to pull out all the stops without cost constraints. For instance, it has TWO power transformers, BOTH magnetically shielded. I have never seen that in any tuner that I have owned. There is none of the usual cost-cutting that you see in their other stuff. It is at least 20 years old (only six presets per mode) but it performs impressively." And our panelist Bob included the FM-2421 on his short list of digital tuners that get no respect: "A nice-looking tuner, especially in the black version. Reportedly made by Sanyo. Two IF bandwidths, 4 gangs, well-built with two shielded power transformers. This unit gets lost in the sea of cheap digital tuners, so usually sells for $50 and under."
GAS Charlie (photo)
Great American Sound ("GAS") was founded by James Bongiorno before Sumo was created and is best known as the manufacturer of the Ampzilla amplifier. To call the GAS Charlie tuner "the predecessor of the Sumo Charlie" may be oversimplifying the situation, because Bongiorno vehemently denied the GAS Charlie's existence other than as a prototype. ("The product was NEVER made. It didn't happen.") Frankly, we're not sure why anyone is so interested in this, but we'll play along....
By all accounts, the GAS Charlie tuner in our photos was created after Bongiorno left GAS, when Andrew Hefley controlled the company. Our contributor John V. says, "The tuner exists, the circuitry is all there inside the unit, a schematic does exist for the unit, and it is my recollection that a total of 3 or 4 were actually built, but remained in the Hefley family. I could be wrong about the total built but this is a conversation/correspondence I remember from 4 years ago or so. Since James B. states this was done after he left, I would err on the side of what was stated by the people that were there." However, our contributor Tim has a different story: "I was the assistant manager at Vicker's Audio in Chapel Hill, NC, from 1972 through 1979. We were one of the first GAS dealers in the Southeast and I distinctly remember Charlie the Tuner with a GAS logo on it. As I recall, it was the last new product we got from GAS before they went under and James Bongiorno resurfaced at Sumo. We carried the complete line of GAS products, from the enormous Godzilla amp to the Sleeping Beauty MC cartridges. Hell, I even have a complete set of the special Japanese audiophile records JB imported for a while and offered to his GAS dealers. And I remember selling GAS Charlies; I even took a GAS Charlie home to try out, but I returned it as I liked my Marantz 125 better for sound quality. There was a one-half of MSRP accommodation price on all GAS products and I would have bought a GAS Charlie if I thought it sounded better than my Marantz 125. I kept the 125. End of story. We even had literature with the GAS Charlie the Tuner shown on the literature. GAS never provided us slick brochures - JB used a foldout printed on newsprint in two colors and I don't think I have any left. We became a Sumo dealer after GAS folded, and we got the Sumo Charlies in, too, but we didn't think they looked as good - I distinctly remember the two meters on the GAS Charlie and I thought they made the GAS Charlie look better than the Sumo Charlie. However, we had sold all our GAS Charlies so we never had a chance to A/B a GAS Charlie vs. a Sumo Charlie."
If Tim's recollection is accurate, our GAS Charlie photos below may be of a different tuner than what his store sold. Our panelist Bob comments, "They certainly are commercial circuit boards, and commercial front and rear panels, but some of the internal fittings look a bit handmade or prototype. And there was no serial number. As for the design, it certainly looks similar to the later Charlie, especially the IF section with all those transformers. I also like the looks of the version with the big meters better."
And now (drum roll, please): Interior and back-panel photos of the GAS Charlie. The Chicago Sun-Times of April 25, 2009 is visible in two of the photos. Interior wide shot; interior closeup; RF section; back panel.
And still more fun. Two photos with the GAS Charlie above and on the right, and the Sumo Charlie below and on the left: Charlies 1, Charlies 2. Thanks to Ampzilla Joe and John V. for the GAS Charlie photos.
Here are some additional interior photos of the Sumo Charlie: interior wide shot; interior closeup; RF section photo 1, photo 2, labeled photo of RF section.
Please post in our FMtuners group if you have any information about any Grundig tuner. The top U.S. model in Grundig's Fine Arts line was the very rare T9000 (1988, $1,200) which we've seen on eBay only a few times in 18 years. Lower in the line was the equally rare T-903 (1988, $450). We won't try to provide a "typical" sale price range for either.
Grundig T7500 (1983?)
The T 7500 replaced the older ST 6000 (30 presets, battery backup) and retailed for approximately 800 DM in Germany (about $300 US).
It is not known whether it was ever sold in the U.S. Our contributor Stephan reports that it has three tuned front-end circuits (one before the preamp, two after) and an additional two in the LO, making it equivalent to a typical 4-gang tuner. There are four cascaded FM IF filters, sufficient for very good separation at 300 kHz and halfway decent separation at 200 kHz. The PLL demodulator uses a Philips TDA1576 chip (another of those is used for scan tuning and on-frequency recognition), and after a discrete birdie filter a TDA1578 serves as MPX. The AF amp consists of discrete transistors, and coupling caps are 1 µF before and 47µ:F after. Features include 15 presets that also store a 4-character alphanumeric note along with the mono and muting settings, if applicable, 25 kHz tuning steps on FM (with display to 10 kHz), a roughly logarithmic 8-LED signal strength meter, and adjustable output volume and scanning thresholds. Magazine reviewers liked its combination of good reception and sound with useful features at an excellent price point (it was compared to a Revox costing almost three times as much, possible a B261, and fared very well). Overall, Stephan calls the T 7500 "a tuner done right." There are some areas where cost-cutting shows, however, including only one IF bandwidth and no switchable attenuator. In a comparison with the Onkyo T-4650 (Euro version of the T-4500), Stephan found that the Onkyo is more selective in Narrow mode but the Grundig sounds better (somewhat warmer and with slightly better highs), and is somewhat more sensitive in mono. "Stereo sensitivity differs from the Onkyo insofar that the stereo decoder seems to apply some kind of blending when the signal level diminishes, until you get to the point where stereo is still being displayed but is no longer actually decoded." There is a also a Grundig ST 6500, virtually identical to the T 7500 but with a somewhat different case.
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