Need to recap my Classe Audio DR-8 Amps - need suggestions

I have two DR-9s and wholeheartedly agree with kacomess that these “authentic” Dave Reich-designed amps are special and worth the trouble to restore/prolong their lives.

I bought each from two different sellers. One was box-stock original and one had been “refurbished” by a prior owner a few years back using the Classe-supplied capacitor and power transistor kit. Although the “original” amp still works perfectly well with no signs of electrical issues, the refurbished DR-9 sounds much more open, lively, and detailed, eschewing the long-ago established reputation of the early Dave Reich class A/B amps as sounding dark, rolled off, laid back, etc. (which the original does in comparison to the refurbed one).

I attribute the sonic differences between the two to be more a result of the newer-spec power transistors (and possibly also different bias adjustment) than the replacement of the caps which appear to be identical between the two. Unfortunately, Dave Reich removed the markings on the original power transitions so it is impossible to discern what manufacturer and model they are. However, the newer power transistors that came with the Classe-supplied kit do have markings. They are Motorola. You can see pics of the inside of the refurbed DR-9 on my virtual system page.

kdross, I recommend you try to contact whomever you can muster at the “new Classe” with the hopes that they may still have documentation on the refurb kit component part numbers for your DR-8. It will be worth the effort and expense IMO.

BTW: avoid using the XLR inputs on these amps. The single-ended RCA inputs are vastly superior sonically.

Good luck kdross. I would appreciate it you would let me know if you have any luck with the new parent company as I would love to have my other DR-9 refurbished.

Dave

I talked to the Service Dept. at Classe' less than two years ago when they were still a part of B&W about obtaining a part for a TOTL CD player almost ten years newer than the DR-9's. They informed that not only did they not have parts but didn't even maintain parts lists for gear of that era. Their advice was to go through old reviews or look inside the unit and attempt to find part numbers and try to order equivalents from a supply house. So no help at all so I doubt another owner later would be of much help. I happened to find a veteran local tech who could identify the actual transport as a Phillips Pro from his work with commercial units and knew which part to replace. 

kdross Don’t listen to Kosst and waste big money on new caps, your amp are hardly used as you say.
Just take it to a good tech to get them re-formed, he knows not to power the amp, he’ll just use a big variac the bridge rectifiers and the supply caps, to re-form them first. Then after he’s re-formed them, he’ll do the same with the pcb board to re-form the smaller on board electro’s.
Parts cost = Zero, instead of at least $800 for all new caps, $1000 for good quality ones like you have now.
Labour cost = much less time hands on in total than replacing them all.

As you can see for just one amp you have 4 large red power supply caps and 5 smaller blue pcb electros. Double this for two amps. Those red ones for memory, I’m sure are Classe branded Nichicons at close to $100 each.
http://www.hifishock.org/galleries/electronics/classe/power-amplifier/dr-8-1-classe.jpg
This is very similar to the Classe DR25 I had to do.
http://img.usaudiomart.com/uploads/large/1304766-classe-audio-dr25-power-amplifier-excellent.jpg

Cheers George

This information is for Dave (dlcockrun).   The service manual for your DR-9 is located here:   https://www.hifiengine.com/manual_library/classe-audio/dr-9.shtml  The service manual identifies the transistors as MJ15024 and MJ15025.   As stated they were manufactured by Motorola, but now are manufactured by ON Fairchild.   All the other components are marked on the component as you stated.   I would find it highly likely that the preferred sound is not due to difference of transistor manufacturing, but in the transistor bias.   The procedure for adjustment is in the service manual.  Fairly straightforward;   however, be very careful with your probes, get a good clip lead on the emitter when powered down.   Do not use a normal DMM probe that can contact the rail voltage while on the emitter taking out the entire bank of transistors... unfortunately, I am talking from experience (smile).   You could even measure the bias of the preferred sounding amp to see if it matches the recommended bias of 18mV.    If this is not your forte, you likely could find someone locally to perform this function for you.  Just an idea.   One other note, the DR-9 manual (from provided link) is missing a page of the power output transistor section.   The drive section (shown) is what is adjusted is identical to the DR-10 (that service manual schematics are complete) and I find it likely that the power output section is also.