2. amps-preamps
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I want to give away my Audio Research D-52

I want to give away my Audio Research D-52 power amplifier.

It is pristine and has been sitting in its original shipping box for thirty years. My next-door neighbor gave it to me when he moved in the late 1980s. He used it for a couple of years to power two planar speakers. 

It has been sitting in my shop for all this time, so it has not been exposed to any temperature or humidity extremes. However, it has not been used. Yesterday I decided to power it up. I briefly thought about borrowing my friend's Variac, which I use when I repair other people's amps (especially their tube amps), but didn't bother. So instead, I planned to power it on for 2-3 seconds, turn it off, and then repeat a few times to re-form the capacitors.I attached a CD player and some 4-ohm speakers, powered it up, heard the expected small power surge and then, just as I was going to turn it off, I heard beautiful music, but before I could hit the off switch, the music stopped. I waited 30 seconds, turned it on again, but got no other signs of life, and the green power light on the front panel was not lit. There was no smell or any other sign of self destruction; it simply quit working.

I briefly looked inside and did not see any internal fuses. The external fuses all looked OK to me, although I didn't bother to bring out my multi-meter to test them.

I am not interested in this amplifier at all. My main system uses two Altec 604 speakers and they are so efficient, I can drive them with a transistor radio. I don't need this kind of power.

I don't have the time to troubleshoot it, and the caps (the most likely issue) are too exotic for me to tackle. 

If anyone wants it, all they need to do is pick it up (California central coast) or pay for shipping.

John Meyer
Carmel, CA

johnmeyer
degx1000
13 posts
 

This is my first post here, but go often to the asylum and Audiokarma. There is a thread in AudioAsylum on the D52B started August 15, 2018. It showed the amp rebuilt using Hypex UcD modules with SMPS power supply to replace mysterious and hard to identify circuitry.

I made this reply. I have a pair of D52B’s in the attic (ran them as mono.) Each blew up and burned out drivers in my Pro Ac Studio 1’s due to power module failure or whatever they called the thing that was encased in polymer. I read that was done to hide op-amps from the op-amp haters… I remember its having terrific bass but no depth and a bit of smearing.

I’m afraid your unit is probably worthless except to an ambitious rebuilder.

willcycle
46 posts
 

I would pay to have it shipped to me.

jasonbourne71's avatar
jasonbourne71
1,167 posts
 

Bad idea to encase parts of the circuitry in resin or epoxy! How stupid can the designers be! Something goes wrong and all you have is a door stop! I might have read a positive review of the D52 way back when in TAS. 

johnmeyer OP
2 posts
 
degx1000: Modding this with a SMPS would be a terrible idea. This amp's linear power supply and huge transformer is what provides the amazing performance.

 

willcycle:  If you are serious about getting this unit, PM me, give me your address, or at least give me the city and state, and I'll tell you what it will cost to ship. I don't know if FedEx or UPS will ship something this heavy, or whether I'll have to use a common carrier. Remember, while the unit did briefly work, it is being "given away" (in quotes, because you will have to pay $100+ for shipping) because it is not working at the moment.

My guess is that someone who has worked on these before will have an idea what to do. The fact that the green light is not on, and the fact that both channels were working and now both are not, gives me quite a bit of hope that there is some protection circuit that kicked in and that replacing that fuse, thermistor, or other crowbar circuit will get it working again.

 

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