ARC vt100mkiii Questions?


I brought one of these 2ndhand lately. The amp had both side boards inside replaced and only the transformers were old. So, it is not broken in. Well, I would like to get advice from other owners about its bass responds. It seems on some music esp. acoustic double bass, the bass is a bit soft and undefined but on others like big symphonies, it sounds quite right with good dynamics. But overall, the bass is not as tight as I would thought it is. I use JBL4425 and Haarbeths HL_5S so to think it is not the speaker’s faults. Does yours have very tight bass? What bias settings were yours set to, mine is set to 60. Thanks.
luna
Thanks guys for the reply. I was wrong about the bias was actually setted to 55! Too low. I set it to 60 and the bass seems to get better. Yes, it is rounded and not tight but full and quite musical.
I sure hope you are using power tubes from Audio Research.
At 60mA or higher those so-called Black Sable 6550Cs wont last you more than a few hundred hours.
User beware.
I set it to 60 and the bass seems to get better.
12-08-10: Luna
60? Not 65? If you do not have the owners manual you could call Leonard at ARC. He will tell you the proper setting.

Phone 763-577-9700
http://www.audioresearch.com/service.>http://www.audioresearch.com/service.html>http://www.audioresearch.com/service.

http://www.arcdb.ws/VT100/VT100.html
.
Yes, I knew it should be 65 but as johnsonwu said, the 6550 will last longer if set lower. That is also why the technican set them to 55mv.
Leonard is no longer at Audio Research. If the bass is a bit lacking, I would suggest your output tubes need to be replaced. I always tell customers if your buying a used tube amp don't expect the seller to re-tube it. My guess is your output tubes have come to the end of their life. You might also wish to talk to an authorized ARC service provider in your area so he can have a look at your amp to make sure it's functioning properly. I think the MK3 version of that amp is quite good. They normally don't have bass impact issues. BTW the proper setting is 65mV and I believe it says it on the circuit board right next to the resistor your supposed to measure across.