2. amps-preamps
  3. 1249244359

Can you lower gain requirements on tube amp?

I have a Cary Rocket 88R tube amp (30w tri/60w UL) that requires more gain then I'm used to to get to 'realistic' (ie louder) listening levels (90db+). I have a Promitheus Ref4 TVC passive that I love, but volume knobs at full throttle sometimes still isn't loud enough. I literally need it go to 11.

Specs on the TVC state -48db to 0. I'm curious if I can do something to the amp, ie roll different driver tubes or??.... to decrease the gain requirements? I've also contacted Nicholas at Promitheus to see if he can modify the gain, haven't heard back yet.

I will also state that my speakers are Usher 6381 rated at 87db/8 ohm. The Cary drives them well, but wondering if the speakers sensitivity relates to loudness (ie more sensitive speakers would generate more loudness at the same volume settings?)

I don't want to introduce a tubed buffer into the mix -- tried it and didn't like the sound. Want to work with what I have if possible. Thanks

FYI tubes in the Cary are:
kt-88 output
12BZ7 / 12AX7 / 12AY7 drivers (currently using 12BZ7)
EL-84 / 6BQ5 current source
tholt
tholt OP
547 posts
 
2 other things -- I like to run in triode over UL, though UL gives me a 2db boost. Also, does voltage into the TVC affect volume? ie if I had a source with higher output would it increase volume? My current cd player is rated at 2V, +/-3dB output.
newbee
4,751 posts
 
You can buy a different amp with lower input sensitivity. You can't change the Cary to get higher output other than the triode/UL option afforded. KT88's are high output tubes so rolling them won't make much or any difference.

You can buy an active pre-amp and get units with up to about 26db of gain which would be plenty.

You can get a CDP/DAC with high gain output (my Wadia had 2, 4 & 6db options).

Other than that about the only thing I can think of would be a possible problem with the passive set up, ie. using inappropriate IC's (too long or electrical values) but I doubt that this is your problem as that would be more frequency dependent than broadband unless they were really long!

But, FWIW, something just doesn't seem right to me about this 'problem'. It is almost as if something is damping your system down. With 87db speakers and 60wts you should be getting some very loud sounds even without pre-amp gain added. Are you using more than one pair of outputs from the 'preamp'? Some pre-s have two outputs which do no act independently of each other and create an additional load on the line out and can greatly reduce the pre-amp out put.

Anyway, that's all I know. Hope it helps a but.
rodman99999
5,988 posts
 
Your only option, if you want to continue using the equipment mentioned, is to up the output voltage of your source(which you didn't mention). Do you find that some of your recorded material provides adequate SPLs? There's a wide disparity in recording levels between various labels/engineers, and that will affect what reaches the Cary's inputs. The output of the Rocket 88 isn't really enough to drive an 87db system to what I'd consider high SPLs anyway. I owned one(tried it with a Placette Passive Linestage) and, if they could be easily converted to higher powered monoblocks: I'd have a pair.
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