I just bought a Audio Research D-90.

NEWBEE,
Thanks for the info.What you said about the same tubes in differant amps having differant toneal quallity makes perfect sense.I had to hit myself in the head for being so dense.(By the way,please forgive my spelling.)Each tube is going to sound differant from one amp to another.I guess I did'nt think the ? though.I guess what I want to know is if one model of the tubes I mentioned has a better bass reproduction then the others.I'm looking at using this amp as a low end in a bi-amp set-up.(A.R.D-90)with a C.J.45-MV-a1 for the mids and highs.I've been into stereo's for over 30 years,but I'm very new to tubes. The C.J. is my first and the A.R.,my 2nd. So any input is a great help,Thank You,Bill

Bill - In response to your question ..."what I want to know is if one model of the tubes I mentioned has a better bass reproduction than the others?" I thought I answered that in my last post, but I'll try to put it in another way.

An amp designed around the use of a 6550 compared to an amp designed around a 6L6/5881 tube can and often will sound similar. In an amp designed around the use of 6550's but also allows the use of 6L6's will have the same differences only they will be more noticible. I described my perception of these probable differences in my third paragraph. Caveat, educated guesses perhaps, but they are just guesses!

Or, perhaps, are you just asking for a recommendation of which brand of tube to use in the ARC? As opposed to type? I do not know which of the models you have - does the model you have allow you to use either type of tube?

That is easy for 6550's - I would try SED 6550's first. I've used them for years and love their tone and ruggedness. They are often OEM tubes in ARC amps. If you want recommendations for 6L6's or 5881's, I can't help you. I've only used them in one amp and I never experimented. If your amp can use 6L6GC's though it is easy to recommend the SED 6L6GC, another excellent new production tube.

Hope that helps a bit more.....

Bump and old thread.. cd one use 7581A with D90? (Or other ARC power amps)