help with audio resesrch d76

The D 76 is pretty old school, i have a D 75a that I bought new back in the mid-70's. It is not bloated sounding, but it doesn't have the resolution in the midrange that their later amps did. I don't know the D 90 at all. There is a database of all ARC models on line that will give you the basic specs, prices and model upgrades. Any amp of this vintage is going to need some attention unless someone has already re-capped and retubed it and gone over it, so that might be a consideration as well. The newer one might sound better, but they made some bombs, too, so I can't help you on sonics of a comparison. (I still have my D 75a, which I keep largely for sentimental reasons, I have maintained it over the years, all the original packing, warranty card, etc). Tube amps have come quite a long way, i'm not sure I'd put any of the old ARC stuff into the super collectible category of highly sought-after early tube amps. Interested to see what others have to say.

The D-76 and D-90b are terrific amplifiers. I have owned both and liked them equally well. However, it is important they are operating properly and the tubes are sorted and matched for these amplifiers. Audio Research is your best bet for tubes even though they are somewhat expensive. Without proper adjustments and properly selected tubes you will never know the full potential of these amplifiers. I guess if I had to choose between the two I would choose the later amplifier.

I like the D-76 a lot. I'm working on a D-90B right now. Both are great but the D-76 with new caps actually sounds better then when it was new as all the poor twist lock lytic caps get replaced with current technology filter caps. The D-90B uses different output tubes as well. The B version utilized 5881/6L6's vs. the D-76's 6550's as well as a servo circuit which is somewhat audible. Also for reliability reasons, the white relay in the D-90B should be removed as the audio can hum for a few seconds after the relay closes. Some people find that objectionable.

I own both....very similar driver circuits. The reason ARC came out with the D-90 is that Mr. Johnson's favorite sounding tube was the 6l6 (personal communication) That is one of the reasons he used the 6L6 in the ARC/Dynaco ST70-C mod. He told me his ARC guys always pushed the higher power 6550. Tube brands have a larger effect on sound than the different circuits. Mr. Johnson liked the GE 6550 in the 76/a and GE 6l6 in the 90B. The JJ 6l6 and the mesa boogie STR440 sound similar to the GE 6l6. The 90B set up correctly has the power to "float" an orchestra...as HP use to say. The 76 is gorgeous sounding especially in the midrange...but the 90b has BALLS!! ;)