Denon TU-747 ($250, photo) search eBay
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.

Denon TU-767 (1985, $350, photo, closeup, user manual, service manual) search eBay
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!

Denon TU-800 (1988, $500, photo, brochure, front panel operation, owner's manual part 1, part 2, service manual part 1, part 2, schematic, parts) search eBay
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:

FEATURES:
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.

Auto Memory
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.

Preset Scan 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.

MPX-NR Switch
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.

Low-Impedance Output
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.

Denon TU-850 (1978, $480, photo, audio board, block diagram and specs) search eBay
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.