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Audio Research vt100mkll question

I wonder if someone has experince of this ??

Two questions really.

I've just bought a vt100 mkll and am running it with single ended input from the source , with-out the pins in the balanced input. It seems to work ok just wondered if there was any down side to this ?? Should it work at all ??

Also My amp has been re-valved with 6h30's instead of the original 6922s. Is this a good thing as the 6922's are a lot less current hungry than the 6h30's ?? Will it work properly ??

Over-all the amp is proving harsher than I expected on leading edge vocals and sounding a touch bright. (could the valve be causing this ??) I'm driving proac 3.8s . Bass is good and some things sound very, very good.

Any opinions would be appreciated.

Thanks for your time.
borg7x9
hi_hifi
120 posts
 
Well, a popular line of thinking is that the MkII with 6922s should be somewhat warmer/sweeter and less edgy (less definined, but more musical?) than the "white-ish/analytic" sounding MkIII. Whether that is because of the use of the 6922s vs 6H30s or whether that is because of other circuit design considerations in the all tube design of the MkII vs the hybrid design of the MkIII is something I can't say - but I'd think you'd want to hear the MkII with the 6922s to see it what is capable of and intended to do from an original design standpoint. Both the MkIII and the MkII should sound very good, but you might really like the MkII if you hear it as it was originally released with the 6922s.
9rw's avatar
9rw
318 posts
 
The VT100MKII is not designed to be used with the 6H30 tube. There's a good chance you've damaged the amp by using those tubes in that amp. Also, if memory serves me correctly, the MKII version added a toggle switch to go between RCA and XLR inputs. What you may have is the original version of that amp. In any case, what you are doing is highly ill advised. As Newbee suggests, call Leonard at ARC. He will no doubt be horrified.
evoneill
1 posts
 
You have a wonderful amp. I have owned everything and think the AR is the best. I don't agree that you have damaged the amp. Just call ARC and try the recommended tubes. Enjoy your teriffic system.
borg7x9 OP
91 posts
 
Thanks for your replies Guys,
I bought this amp on the weekend second hand. It came re-valved with 6h30's so not my doing. They have only been in there a couple of weeks so hopefully no damage has been done. I work in the Telco industry and there is someone here that I can borrow 8xmatched 6922's off and give them a go. Should be fun. However .....

Common sense tells me that this circuit should work best with the tubes for which it was designed. I just hope that no permanent damage has been done.

I think the Mklll not the Mk11 had the toggle balanced/single ended switch. see:- www.arcdb.ws/VT100/VT100.html

I'll give Leonard a call in the morning and see what he has to say.

Thanks for your excellent advice.

Myron.
hammertone_audio
16 posts
 
Just a word of wise. The VT100 Mk 2 requires a 2 stage bias set up. You must bias the 6922's prior to inserting the 6550's and then set up final bias. Leonard will be able to send you the biasing imformation which does not come with the original manual.
But all things said, congratulations on your purchase.
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