Luxman MQ-68c Tube Amplifier with Original Tubes
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Luxman MQ-68c Tube Amplifier with Original Tubes
479 South Broad Street
Glen Rock NJ 07452
The MQ68c is a 30-30W stereo tube amplifier made by the renowned Japanese audio company Luxman.
It was hand made in Japan from the highest quality materials of the time and benefits greatly from the quality of the transformers in particular, which contributes to the lush warm dynamic sound quality.
Luxman tube amps from this era are a rare find in the US. Most were sold overseas and kept in the Asian market. You can buy them from Japanese websites, but it will cost you an arm and a leg and may not be the correct voltage.
This amp has been well cared for and babied. It was part of a large collection that we just purchased from a local collector which included dozens of amplifiers, so you can imagine how little use it got.
The MQ68c was designed to run on proprietary Luxman/NEC 50CA10G tubes. This example is loaded with just that and the tubes are in great shape and test strong. I suspect there are many years left in them.
If you find another MQ86c out there it likely has been converted to work on common 6L6GL or KT88 tubes. There is a simple conversion available in case someday you don’t want to have to buy the much more expensive 50CA10G tubes. They are out there so if your pocketbook allows you can keep this original over time which is my suggestion and that of many other connoisseurs.
Overall physical condition is good but there are a few scratches or scuffs throughout.
On the back you will binding posts and RCA jacks. You will also find variable input adjustments for the audio signal.
The amplifier is in perfect working condition and the tubes test strong and clean. We ran the unit on our workbench to its full rated power and it measured clean.
It was also tested in our listening room for some time to ensure that what the test equipment reported translated to good quality audio.
This is a rare and beautiful unit (especially with the original output tubes) and is priced accordingly. No lowball offers please.
Here is a bit of a review I found online:
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.
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.