You want to talk with Chris Donnelly of Sundisk Studios in Flagstaff AZ. He knows about these amps - and yes, some of them did "blow up". I have the Quatre preamp, which is very good.
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These are very rare, and very special amps.
I first heard one circa 1980 when I was just getting into this hobby.
As I was in junior high school, the system was impossibly expensive and exotic - an Apt Holman preamp, Quatre Gain cell, Dahlquist speakers and a Thorens turntable with an Infinity black widow arm.
I searched forever to find one in mint condition for my collection, but havent really used it.
For future reference, it would be great to know who can service and/or upgrade them.
I purchased one in 1978 and had it upgraded to the QMI 300 when Quatre was purchased by them in 1980 IIRC. I ran it with Maggie II A & B's. It never blew up on me but I did hear the horror stories about it. Also, when it gave itself up to the audio ghost it liked to take the attached speakers with it. The problem has something to do with passing a 60 hz burst. They were limited to early manufactured units ann was fixed when the issue reared it's ugly head. One of the audio magazines gave it high praise and then retracked it when this issue first surfaced. It caused the company to decline and eventually to get purchased.
In 1992, I gave it away to my previous neighbor's son who was just getting interested in high end audio. Along with the QMI, I gifted him an Audionics BT2 preamp because the two seemed to have great synergy. Recently I visited with him and it was still in operation, but there was some noticeable mechanical hum coming from the transformer. It didn't pass through to the speakers and still sounded pretty good. Gain cell amps are one of those interesting designs. I will pass the repair person's name on to him so he can have it brought back to spec if it's cost effective.
Thanks all for your input. Being referred to Chris Donnelly at Sundisk Studios, he said there was another version (the 250c), but I wouldn't know it without looking at the circuit board. I'm going to take it to my local audio shop to have it checked out. Hopefully I'll have something good!
-LngBruno, did you say you knew of a repair person?
I have owned 4 gain cells over the years.
The GC 300 was the best sounding model and the best capable of driving speakers with difficult impedance properties. The next best was the DG250C. Quatre/QMI licensed the 250/300 designs and produced variations and made changes the designer did not sanction. In particular, the 500 I heard sounded terrible and these were prone to blow up.
Mechanical hum may be caused by the transformer mounts - grommets broke or bolts loosened up.
Some 300s were retrofitted into 250 chassis. These are more desirable than the flimsy chassis QMI used on the factory manufactured models.
Wow that name is truly a blast from the past. I had one in for service a long time ago. It was pretty well built. A lot of room under the cover. Unfortunately, I don't have a circuit diagram for it. I remember visiting Quatre and talking at length to the head of the company but for the life of me I can't remember his name. Big heavy set guy that's all I remember. The amp wasn't bad. That was around the time I was working for a company that made speakers for John Iverson in the San Fernando Valley while going to college. That was a trip!
my dg100 died after only a few years after buying it out the door of the factory in the San Fernando valley. The factory replaced the circuit boards with 250 models, and it has worked
since without any problems. Great bass no hum or vibration as mentioned earlier.
My question is what is the output impedance? I've run it into
B&W DM5's, both as a parallel pairs and singularly- 8 v's 4 ohms. As it is now "long in the tooth", I'm concerned about which configuration is healthier. BTW I also use an APT preamp.
I would be rather careful what you choose to connect to it as some of those amps were not particularly stable with all loads. They liked to blow up a lot. I would probably keep it between 4-8 ohms. No low or complex impedance i.e. no electrostats or ribbons. Resistive as opposed to capacitive.
Wow an Apt Holman Preamp. Make sure the Apt isn't outputting any DC. If I'm not mistaken, that was a AC (capacitor coupled) preamp.