An A-Shopper Review


A Rediscovery Article

LUXMAN MQ68C Tube Amplifier:

A small amp that shines


      LUXMAN today is not typically associated with the manufacture of high end tube components. The company has been reticent in the United States. I have not heard any of its latest equipment rated in any of the high end audio journals. The last one was their tube hybrid integrated amp, the BRID LV105, which was rated class D by Stereophile in 1988. There was a time when Luxman's star was ascending indeed. This was in the late 1970's and early 1980's when the company unveiled an aggressive new line of tube components. It was the first time that a Japanese company entered the hallowed halls of the American high end market and competed with the best tube audio equipment manufacturers. (I understand that Luxman still manufactures on a very limited basis and for selective distribution tube components that are very expensive and very high quality. But these are not available in the U.S. market.)

      What was radical in their approach was the development of new tubes for their amps. This was in an era when tube usage was in fast decline. Using tubes of their design and produced for them by NEC, Luxman introduced the Lux MB3045 tube mono amps. These amps received encomium from the high end press. I had at one time possessed those beauties and remember enjoying many hours of listening pleasure.

      The MQ68C follows in the footsteps of the MB3045. Like the MB3045, the cage toggles a safety switch that turns off the power when you lift the cover. Both models utilize point to point wiring, triode outputs tubes (50C-A10 for the MQ68C and 8045G for the MB3045) and the same input complement of 6240G and 6267/EF86 tubes. The 50C-A10 output tube was likewise manufactured by NEC. There still are a number of 50C-A10 tubes out there though it does take some effort to locate them. Luxman recommends the 6CG7 as the substitute for the 6240G. This is in fact the tube that is being used in the unit under review.

Packaging

      The Luxman MQ68C with its slim rectangular box resembles most tube amps of its vintage. It's presentation is simple. In front there are the insignia and power-on orange led. On the top plate, two 50C-A10 tubes are positioned on each side with the power transformer in between. Behind them are the two output transformers and input tubes followed by the choke and high capacity/high voltage capacitors. At the back are the gold input RCA jacks, input level controls, fuse holder, speaker terminals, power-on switch and negative feedback switch.

      The fit and finish are first rate. The top plate is made of machined aluminum which provides a decorative touch to the brown color of both the cage and circuit housing. The MQ68C measures 15.75" x 6" x 6.5" (W/H/D), and weighs about 30 lbs.

      While biasing the unit, I had a chance to look at the innards of the amplifier. The MQ68C utilizes point to point wiring (a pleasant surprise) and high grade resistors and capacitors. Biasing the unit may appear challenging but is actually simple. After placing the amp on its side, unscrew the bottom plate, locate the four trimmers, measure the voltage at the two bias points and adjust the trimmers accordingly. A multimeter and small screwdriver are required. If you are unfamiliar with biasing procedures, I suggest you get someone to show you how. Beware, there are lethal voltages crisscrossing the cicruitry.

      The MQ68C is specified at 30 wpc at 8 Ohms. You will therefore need to partner this amp with logically sensitive speakers.

Listening Experience

      The unit under review was purchased by the Audio Shopper from a seller within its classified pages. I have had the unit for close to two months. I listened to the the MQ68C after duly checking the bias of the unit and using different setups. Most of the time however, I used it with the Audible Illusions Modulus 3 preamp, the JVC XL-Z1050 cd player, Pink Triangle turntable with MMT arm and Promethean cartridge, Promethean Bandpass interconnect, Inouye power conditioner, Kimber 8TC speaker cables, Sound Dynamics 300Ti, Rogers LS3/5a, and Linn Index speakers. I compared the unit with my in-house references, the Classe' Audio DR-9 amp and Quicksilver KT88 monos.

A Small Wonder

      The amp warms up quickly and reaches musical stability within less than an hour. In the beginning, it sounds edgy, lean, and hazy. Be patient and you will be rewarded. The MQ68C will metamorphose into a mellow and involving performer.

      It is amazing how one amp offers a different facet of the same musical source. Listening to the Luxman MQ68C is a case in point. One will immediately note what it is not. Firstly, it is not as full bodied as a classic tube amp. The Quicksilver KT88 is an exemplary representative of an excellent classic tube amp. Musical notes are rounded and mellow, and the highs are a bit softened. The MQ68C is different. There is more detail. It possesses a see through quality that lets one hear more of the nuances. Sometimes I would find myself saying "I did not use to hear that." The leading or receding notes are more clearly rendered. It has the translucence of a fine transistorized amp yet lacks its white and clinical edginess. This degree of detail comes with some reduction of overall bass tones. I remember when Audible Illusions first came out with their Modulus range, one reviewer had described it as sounding unlike tube preamps in that it offered the detail of its silicon counterparts. The MQ68C reminds me of that synopsis.

      Secondly, while the MQ68C is an involving and vivid performer, it lacks the impact and weight of other highly regarded amps. The Classe' I believe is a master of grip and control. It takes a firm hold of the speakers and plays complex orchestral music without any hesitation. There is effortless power. With the MQ68C, the rendition is less powerful and moving. No, it is not a function of volume. Even in lower volume, it does not portray the acoustic impact that muscular amps like the DR-9 are capable of or even to the degree that the Quicksilvers can deliver.

      Thirdly, I have always admired the soundstaging qualities of both the Quicksilver KT88 and the Classe' DR-9. Both are capable of carving a wide and deep portrayal of the musical event. Again, the MQ68C while coming intimately close is not both amp's peer. It's soundstage extends to the edge of the speakers, two feet back, and a half-foot upfront in a rectangular dimension. In this regard, it has more of a back of the speaker presentation.

      As one should have deduced by now, the MQ68C is not big on bass. It is not that bass is lacking. While one hears the notes rendered with delicacy, they lack the verve and wallop. On occasion the bass can sound both soft and loose. Even the Quicksilver produces better bass and, as you know, the Quickies do not excel in the low regions.

      So where does this small wonderful amp excel. Where does it make a critical difference. It's in the unobstrusive rendition of detail and nuance. Please note that it is not that this amp is more detailed. It is because of how it assembles and lays out the detail that makes it such a wonderful and unique amplifier. As I mentioned earlier, it's such a surprise to rediscover the LP's and CD's that one has been used to listening to. I get to appreciate and enjoy the music further.

Summing up

      The Luxman MQ68C with its 30 watts per side is by no means a powerhouse. It does not wallop like the behemoths nor will it rock your room. For that you will probably need a more substantial amp and a largess to pay for it. On the other hand, the MQ68C provides a delicacy and rendition of musical detail that is both surprising and addictive. It is surprising because it is unexpected of an amp its vintage. It is addictive in that one seeks to find its strength in other amps.

      When I purchased the MQ68C, it came with new tubes from Gold Aero. The previous owner, not having much experience with tube amp maintenance, had not rebiased the amp for seven or eight years. He then thought that the tubes needed replacing. On the contrary, I used the old output tubes and they still work well! The point is these tubes undoubtedly last for a very long time!

      The MQ68C is not often available in the used marketplace. On the rare occasion that you see one within the $500 range, go for it. Partner it with an efficient speaker system and appropriate electronics and you'll have a very musical combination. Three clefs for this newly rediscovered gem.

by Rome Castellanes

[Audio Shopper Home Page || For Sale Quickview || Wanted Quickview]

      For the time being, personal ads--those placed by end users and consumers on items purchased for personal enjoyment NOT for resale, profit or economic gain--will be accepted FREE of charge. Email your ads and comments to cdrome@cdrome.com, write to Audio Shopper, PO Box 702571, Dallas, TX 75370 USA or fax (972)307-9088.

Copyright © 1997 Audio Shopper. All rights reserved.