AVA SS or Manley tubes for Jubilee clones?

[LarryC]

Dean said: Too much gain

Not sure I follow this. I have to rebalance after the switch, then I listen.

I think Dean is right, and I recall discussing this at length. This sounds like a gain matching issue, and certainly not grounding or the other usual suspects trotted forth when supposedly quiet amps are being accused of being "noisy." Chasing grounding problems when your only dealing with hiss, not buzzes and hum, usually doesn't work.

The first thing l'd ask is, can you turn down the gain on the amplifiers? Perhaps the manufacturer designed it to have high gain, not a good idea with horns.

The other possible reason is too much gain in the preamp or processor in the circuitry following the volume control. Short of redesigning the pre, turning down the amplifier gain might be a solution here, too.

I have tried to prevent gain problems in my equipment over the years, by choosing amps and preamps with low gain. My current preamp has only 11 db or less gain in the line stage, which follows the volume control. This works for me.

Edited February 6, 2014 by LarryC

[bracurrie]

Dean said: Too much gain

Not sure I follow this. I have to rebalance after the switch, then I listen.

I think Dean is right, and I recall discussing this at length. This sounds like a gain matching issue, and certainly not grounding or the other usual suspects trotted forth when supposedly quiet amps are being accused of being "noisy." Chasing grounding problems when your only dealing with hiss, not buzzes and hum, usually doesn't work.

The first thing l'd ask is, can you turn down the gain on the amplifiers? Perhaps the manufacturer designed it to have high gain, not a good idea with horns.

The other possible reason is too much gain in the preamp or processor in the circuitry following the volume control. Short of redesigning the pre, turning down the amplifier gain might be a solution here, too.

I have tried to prevent gain problems in my equipment over the years, by choosing amps and preamps with low gain. My current preamp has only 11 db or less gain in the line stage, which follows the volume control. This works for me.

LarryC - Thanks for jumping in here. The root of the problem is I have high sensitivity 16 ohm drivers mounted on great horns. I cannot adjust the gain on the amps without major surgery or tube changes. I did have a grounding issue that I isolated on and fixed and things are much better. My original issue was with my Manley GY50 and its a beast. We did increase feedback and reduced the gain with a tube switch. That plus an attenuator did the trick. My preamp is really a sound card attached to a computer. Its very quiet and I have the gain throttled way back.

You are very correct about watching gain.