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Luxman SQ-38u Tube Integrated Amplifier Review

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Luxman SQ-38u tube integrated amplifierThere are both objective and subjective traits that make a design a classic. Being a classic doesn’t mean it was the absolute best at what it did, or the most en-vogue, or the flashiest, or the most expensive. Sometimes a classic just happened to be the best, or fastest, or prettiest, but it’s something more than that. It has additional intangibles that make you think of it as a reference against which others are judged (whether good or bad). It is usually a combination of ergonomics, looks, performance, reliability and status that combine to make people say “that’s the way it should be done.”

My views on audio are going to be different from most. I’ve worked on it, listened to it, researched it, restored it, built it, and started over again. I’ve been exposed to a lot of bad ideas with good execution, and good ideas with bad execution. Just because something is ‘everywhere’ doesn’t make it a classic. There are a lot of GE Washers and Dryers, but that just means they are sold all over, are affordable, and are easy to use. For instance, I don’t consider the Dynaco ST70 a classic: the input/phase-splitter circuitry sucked. Similar design issues limit the PAS, and it has nothing to do with the tone controls, mono blend, balance control, or filters. Even when you take away the extra “stuff”, like the tone controls, it was still a very compromised circuit with junky parts. To make good sound, you have to rework the circuit, or get rid of it for a better circuit, and replace the atrocious parts. So, is it really a classic? By the way, if you want to hear an exceptional ST70 board, the best I have heard is the K&K board.

So, you may be asking: “what then do you consider classic audio?” Take the MX110 tuner/preamp from McIntosh. It has a good tuner, good preamp, good parts quality, good reliability, and good looks. The performance of each section was above average, and all the bells and whistles were cutting edge at the time. It is easy to use: You don’t need a manual to figure it out. Its flexibility allows it to integrate into many systems. A stock MX110 makes an excellent front end for anyone who has access to good radio; not me, unfortunately. I think a clue about the McIntosh and other classic pieces is that most buyers want them as close to stock as possible. Were there better tuners? Yes. Were there better preamps? Yes. But, I don’t think you’ll find too many packages as well rounded as the MX110, especially with stock parts. For substantially better sound, you would have to have two pieces, instead of one, and would pay a good bit more.

Other components I consider classics are Vandersteen’s 2, Shure’s Supertrack cartridges, SME V, McIntosh 225, 240 and 275 (along with the mono versions), Eico HF60/HF59 /HF89/HF87, etc…, Marantz 7 and 8, Thorens TD124, AR ES1, Technics SP10mkII, plus others that had “it”. I’m not saying they are “best”. But for some, they are ideal.

The 38 Generations

Most American hi-fi enthusiasts are a little oblivious to the classic high end equipment from Europe and Asia, and I’m no exception. Along the same lines as the AT33, DL103, the long tradition of Japanese integrated amps were relatively unknown in the US. Its various iterations rarely made their way over here, where audiophiles were on a more acerbic or “purist” path. A path that saw an absolute abandonment of adequate inputs, stereo-mono switching, gain plus balance, multiple outputs, tone controls, tone filters and reliability. It got to a point where most preamps had 3 line and 1 phono input, no monitor functions (loops), no tone considerations, no balance control, no mono switch, one set of outputs, questionable reliability and poor value. What they became is a top-fuel dragster of audio—no concessions to practicality, and not terribly useful when “problems” are thrown its way, as in most recordings made. The Japanese, especially, have always tried to make their systems accommodate as many sources and recordings as possible, with the idea that there are few, if any, perfect recordings, perfect room acoustics or perfect transducers.

“Johnny, what can you make out of this?”

“This? Why, I can make a hat or a brooch or a pterodactyl…”

-Airplane!

A full featured integrated amp like the Luxman SQ-38u comes with enough bells and whistles to keep most pragmatic audiophiles well-pleased. Besides tone controls, it offers the capability to integrate into a larger AV system for those who want to have an all-inclusive audio-visual experience. It can operate as an amp for the AV system with flick of a switch. It can integrate into an actively-crossed-over, multi-amped system, by using the built-in loop, while the SQ-38u’s amp functions as the mid or high frequency amp, or bass amp for that matter.

The unit has enough phono-stage flexibility to work with virtually all cartridges. The unit’s step-up transformers can be set at high gain, medium gain, or off. It has the tone controls, filters and mono switching I alluded to, which helps it make the most of worn-out and/or noisy records, not to mention those that just sound slightly ugly. The only thing missing is selectable turnover (like the Citation I) and a tape-head input. Both options would significantly complicate matters, and add expense, and not be too useful for most audiophiles, so what they have here is enough flexibility for the vast majority.

Here is a more complete list from the importer’s website:

· Separate switch on the front panel, allows the SQ-38u to be easily integrated into a home theater system. This separates the preamplifier section from the amplifier. Allowing one to take the output of a Home Theater Processor directly to the amplifier, bypassing the on-board preamplifier completely. Could also be used with a room correction device.

· Phono stage with selectable MM, MC low output (2.5 ohm) or MC high output (40 ohm). MC duties are handled by an on-board step-up transformer. With up to 63dB of gain available, should easily handle low output MC cartridges.

· Mono switch

· Subsonic Filter, to remove rumble from LP playback

· Tone Controls, easily engaged or defeated at the press of a switch.

· High quality headphone output on the front panel.

· Five inputs as well as a Tape Loop.

· Two pairs of selectable speaker outputs

· Conservatively rated at 30 wpc x 2, using Electro Harmonix EL34 output tubes

· Illuminated volume control, so that its setting can easily be seen across the room.

· Circuitry: Driver: Mullard circuit; output: UL connection

· Recording input and output: REC output, monitor

· Speaker Outputs: A, B (independent switching, with simultaneous output)

· Remote Control Functions: Volume up / down, mute

The fit and finish, and overall appearance of the unit remind me of earlier pieces. The quality is very much like that of the best from the ‘50s and ‘60s. It has a hand-rubbed all wood case, that is at least the equal to those from McIntosh. The satin front panel reminds me of the Marantz 7. It feels heavy, heavier than most golden-age tube integrated amps, and much better put-together. It makes the Dynaco SCA35 feel like a paperweight. The solid build-quality makes those old tube amps feel loose or flimsy. It’s like comparing a SME V and SME 3009: The feel of the two are completely different. That’s not a comment on sound quality, but purely of feel, fit and finish.

As with the best sounding units of the golden-age, the phase-splitter/driver is the Mullard circuit and the output transformers are Ultralinear. The amp section is similar to an Eico HF89. What was very interesting was driving an HF89, using the Luxman as the preamp. The big difference between the two amps is that the HF89 uses “fixed bias” instead of “cathode bias”. That means you have to regularly adjust the Eico, or risk the possibility of it going up in smoke. In terms of performance, I was surprised by the results: The bass of the Luxman amp was deeper and more powerful than the HF89. It’s hard to explain: the output transformers of the Eico are appreciably larger. It’s a technical question for the designer. In addition, the Eico was completely rebuilt, though I don’t know if the feedback or roll-off networks were changed. On the other hand, the midrange seemed prettier with the old Eico, probably comes down to the sound of the transformers, or the Chinese 12au7 versus the RCA 6sn7. If I had to make a choice, I would have gone with the Luxman’s built-in amp, which is really saying something about the Luxman.

I reckon the most significant difference between the units from the ‘60s, and the SQ-38u, is the remote control, and the presence of what looked like active voltage regulation – transistor stuff. The possible use of active voltage regulation might account for why the Luxman was quieter than classic pieces I’ve used, including the ones that were completely rebuilt. I suppose the inclusion of switching, to allow integration into an AV system, is something new, but it’s not new technology. They could have done the same thing in the ‘20s.

What the SQ-38u is then, is a prototypical old-style tube integrated-amp, built with modern parts, voltage regulation, with better fit and finish, and with a remote control. Take those modern touches away, swap in NOS tubes for the Chinese tubes, add dust and scratches, and you wouldn’t know it’s a new product. I think that’s what Luxman is going for. It’s meant to be a classic tube product, but with subtle improvements.

The rest of the system included: the Alpha Line Source speakers from Danny Richie (97 db/watt at 4 ohms), my usual Denon dp80, SME V combo, with Haniwa and Shure V15iii cartridges; plus some different transistor phono stages for comparison.

“It Slices, it dices, it makes Julienne Fries…”

Ron Popeil never had a product as nice as this, but I am sure he would appreciate all that it can do. Its versatility is one big reason I enjoyed using it, and it’s a combination of versatility and fidelity I haven’t heard before. As a youngster exploring my parent’s record collection, I quickly discovered that some records needed a treble cut, or a bass boost, or a switch to mono, etc… I was around music a lot as a child and tried to get the stereo to sound as good as the concerts I heard. That usually meant lots of power and more bass. Later, as I got into more audiophile equipment, many of my favorite records were rendered unlistenable. Every improvement in transparency would eliminate more records until I was left with a system that sounded bad with 85% of the records I owned. What the Luxman does is make those “bad sounding” records, the ones with noise or bad mastering, sound better. The tone controls, filters and mono switch can ameliorate a host of vinyl and mastering ills. A side benefit is that it will help with many of today’s pop music CDs, which sound bright and aggressive.

Using the Luxman’s tone controls took some getting used to. The bass control was a warmth control; the treble control was an air control. These aren’t the ham-fisted tone controls that found their way into the super-receivers of the ‘70s and ‘80s. With bright recordings, the treble control did help some, but I found that adding a few decibels of bass warmth did more to palliate bad mastering than did reducing treble. Using these controls didn’t screw up the phase like the old fashioned ones did. Think of adding a pinch of salt to your chocolate: too much ruins it, too little and it tastes bland; just the right amount of salt makes chocolate come alive. The same thing can be said for adding cayenne pepper to chocolate, which is like adding midbass warmth. With the Luxman, I never heard the distortion that plagued 99% of tone controls in the past. In total, along with the other switches and controls, slightly veil the sound. Most tone controls did more harm than good. For those of you who have studied a number of schematics, you would probably know there are many ways of implementing tone controls, and some are much better than others. I guess Luxman has chosen a circuit that doesn’t damage the sound.

The proof of whether the Luxman is a success is with less stellar-sounding records and CDs. The Luxman begs you to pull out favorite disks, especially guilty pleasures. With old mono jazz records, like my thrashed 10” Prestige, original Blue Notes and other early records, the record noise was objectionable on a purist system. The combination of a healthy treble cut (9 o’clock position), bass boost (1 o’clock) and mono (switched from stereo to mono), made most of these records sound wonderful. In absolute terms, they still suck compared to the best that Chad at Acoustic Sounds can source but, when you smooth over the bumps and bruises, your brain can concentrate on the music. Your mind somehow factors out a lot of the noise. I don’t pretend to know psychoacoustics, but there is something of a threshold where noise is no longer objectionable. Of course, this varies greatly from person to person. The Luxman allows your brain to do the job of interpreting noises and tones into music.

The flip side of having the tone controls is that the Luxman doesn’t sound as transparent and open as some purist designs. That was obvious from the start, and I expected it. Audiophile spectaculars were less spectacular. The extra parts in the signal path add subtle amounts of veiling and noise that make the sound-stage both shallower and narrower. Is it “bad”? No, it’s not bad! If you’ve heard rebuilt Dynaco, McIntosh, or Eico, to name a few, then think of that “golden” sound. The Luxman has much better clarity, and less “romanticism.” Somehow, the designers have been able to reduce the noise and distortion of these added parts to a much lower level than I thought possible, especially when you compare it to components from the ‘50s and ‘60s.

I am of the opinion that this particular piece has been voiced with digital. It made my cheap digital sources really sing. All the junk in the treble is subtly re-organized into something that resembles real tones from real instruments. I was able to listen to my CD collection, which is mostly pop, longer than with any preamp/amp combo or integrated amp that I can remember. If you are strictly a digital listener, this piece might cast new insights on your music for you. The speakers it was driving were brutally honest of high frequency distortion, and the Luxman is definitely doing something good with digital.

The only area that didn’t completely thrill me was the phono section. Against the suggestions of the manual and importer, I tried some different tubes and the sound did improve, but I did not have time to swap in dozens of different 12ax7 to find the set that was just right. The 12ax7 is a rather vexing tube: It has such high plate resistance and low transconductance, that it generates much more noise than a 6SL7 or 12AT7, which offer less gain, but also much less noise/veiling. Something else about the 12ax7 is that the sound changes dramatically from one brand to another. Even sample to sample from one production run can have different sound. I don’t know if you could swap in a 12at7 with high output cartridges. It might be a bad move, and I didn’t do it; it won’t blow anything up, but it might really suck. One tube choice that did make big strides in the right direction was some NOS GE JAN 5751’s, which have a gain of 70, instead of the 100 for the 12ax7, which is why the 12ax7 is used so often: lots of gain. Other possibilities are the ecc803 (frame grid version), which sounds quite different from the traditional 12ax7.

Using the Luxman’s phono stage with my low output moving coil was something of a Jekyll and Hyde experience. The built in step-up transformers had two gain options, with the highest gain option being the best load for the cartridge, but the resulting sound got harsh on loud recordings. I might anticipate this with cartridges like the Haniwa and its stable-mates from MySonic and AirTight. These cartridge lines manage medium-ish output from very few windings. For best tonal response, very low impedance loading is necessary. Unfortunately, the low impedance input of a step-up transformer has the most gain, and I got the very distinct impression that the Haniwa was causing the phono stage to distort because there was simply too much signal coming into the tubes. When I set the phono stage at the medium gain setting (less gain from the transformer), the sound was cleaner, but the magic of the Haniwa was missing in action. It went from exciting and occasionally scary to slightly boring. For me, this wasn’t a good combination of cartridge and phono stage.

Not wanting to give up, but not having an old fashioned low output moving coil, I went to the tried-and-true Shure V15III (era 3). What a difference it made! The overload distortion, or what I thought was overload distortion, was gone. In its place was a more relaxed sound that was slightly warm and forgiving. There was some detail lost compared to the Haniwa, but the overall sound was much better. Funny thing is, I bet you’ll find more V15s, compared to tweaky moving coils, connected to the AirTight in Japan. You’ll also probably find way more JBLs than 6’ tall line-sources. It made me pine for a pair of classic JBL or EV speakers, just to hear an all “classic” system. By the way, the Shure V15III is most definitely a classic. I prefer its sound to the last version produced, the Vxmr, which gave up too much warmth in exchange for detail.

Depending on your cartridge, and your patience with tube selection, plus deep pockets for high quality NOS tubes, you may love the phono stage. For my system, it lacked clarity, imaging and slam that I can get from budget priced FET phono stages. There will be others who prefer the Luxman phono stage. It can be very good, but I just didn’t have the right combination for it to work.

Not having decent headphones, I did not use the headphone provision. Not having an AV setup, I didn’t experiment with its integration into a large multimedia system. Neither are priorities of mine. I would surmise that the performance of the Luxman would be satisfactory as a headphone amp. As a stand-alone amp? Keep reading.

The overall sound of the amplifier section, which is the best thing about the SQ-38u, was pretty amazing for a traditional Ultralinear output stage. It had much better frequency extension, lower distortion, and much lower noise levels than any Dynaco, Heath, Eico or Scott piece I’ve used. The only amp that might beat it is a McIntosh, which doesn’t even use an Ultralinear output circuit, not to mention classic McIntosh amps which have some annoying flaws. The output section of the SQ-38u, which doesn’t sport particularly huge output transformers, sounded like a much, much bigger amp. The dynamics were darn good, as were rhythm, sound-staging and tonal balance. All in all, the amp in the Luxman is the strength of the package. It deserves to be offered as a stand-alone product. I’m not particularly fond of soft and mushy single-ended amps, and the combination of push-pull muscle and Ultralinear output transformer makes an amp that is both clean, compared to the “mushy” sound of single-ended, and sufficiently powerful. (A marked exception being the Harmonix Reimyo PAT-777, which I found to be extraordinarily dynamic, extended, and balanced sounding for an SET amp. –Ed.) I found the limits of the amp when it was asked to drive large, complex speakers. Pushed too hard and things compressed, the sound-stage collapse and the bass went away. To be honest though, the 97dB/watt, 4 ohm load does not tell the whole truth about the Alpha Line Source speakers. They have a treble and a bass filter network to cut some peaks in the frequency response. The result is that a lot of power is wasted in these bleeder networks, and the damping factor of the amp gets shot to hell. It’s why single-ended amps sound good with single driver speakers.

A more appropriate speaker load was a pair of Mark Audio Alpair 10 drivers in a transmission line enclosure. It was a full-range driver in an efficient box, which allowed the Luxman to come into its own. It played with gusto, vigor and authority. I imagine that this is more like the speaker system this Luxman would find in Japan. Over here in The States, our larger rooms and more power-hungry speakers can put too much burden on any amp. I would be careful about the choice of speakers with the Luxman. It won’t have a chance to drive Maggies, or Vandersteen 3s at anywhere near “real” levels.

Not all things to All People, but Enough for Many

When it comes down to the overall impression of the Luxman, it is this: It is a versatile player that can be remarkably good under the right circumstances. More so than most components, the Luxman needs the right associated listener, one who needs flexibility not found in the majority of today’s high-end offerings. When the room and speaker were reasonable, it had good sound-staging, good rhythm and low levels of noise. Given a modest sized room, there is enough power to drive less efficient speakers with real world music.

If it were a car, I’d ask if this is a “daily driver”. There are plenty of exotic cars that can be driven when the sun is at a certain position, the barometric pressure and humidity are just right, and it’s 75.3 degrees (F, not C). The Luxman is not that kind of piece. It’s more like a Mini Cooper or Fiat 500, which doesn’t fit every need, but do have a large market. The Luxman is attractive, built well, sounds good, seems reliable, is very flexible, plays well with others (like your home theater), features adjustment that should be more commonly available, and is likely to last a very long time and hold good resale value. Speaking of build quality, it’s made in Japan, which is still a selling point. It’s much like being Swiss or German made, though the South Koreans are definitely climbing Mount Deming.

So who is it for? Who needs a piece like this? Primarily, it’s for the music lover. Do you still listen to disks that sound like crap? Good for you! You can consider this integrated amp a near ideal piece for someone more interested in musical pleasure than ultra-fi purity. It makes your record collection bigger. It takes the edge off of pop music.

I don’t have a complete list of classic audio pieces because I regularly change my mind about these things, kind of like my answer to “what is your favorite piece of music?” However, the Luxman should have a place on my list with the likes of the Shure V15 and Thorens TD124. It’s not the ultimate at doing any particular thing, but its flexibility and ease of ownership make it a first class product. Unlike the DL103 and the Klipsch corner horn, to name two, the SQ38u has less of a definite personality. It doesn’t completely rule out thousands of tonearms like the DL103, or eliminate millions of rooms like the corner horn. It doesn’t have any particular distortion that overlays the music the way the DL103 or Klipsch does. Because of its flexibility and forgiving nature, the Luxman should be considered by many thousands of listeners and audiophiles.

Now that it’s gone, I miss it. I still like hyper-fi equipment, but there are too many times when hyper-fi is a musical dead end. To quote Arthur Conley: Do you like good music? If so, put the Luxman on your list.

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One Response to Luxman SQ-38u Tube Integrated Amplifier Review


  1. Don Wheat says:

    Good review. It will be my choice on my new system, a Thorens TD240, pair of Polk RTiA9s and a 1000+ old LPs I haven’t listened to for 20 years. Thanks.

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