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Wish Variac reduction range

mixermang

New Member
to bring the 100 watt amps down to 25/10/5 watt range. also so you could severely starve a preamp model down to sputters when using them standalone
 

Rex

Legend!
Help me understand what you're asking for. There's already a range of Variac values available.
 

Rex

Legend!
variac reduction range that goes farther down than 50%, preferably down to 0%
I get what you're saying, but a Variac set to 50% is putting put 50% voltage, not 50% power. Below a certain voltage, tube circuits just stop functioning altogether.
 
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mixermang

New Member
Below a certain voltage, tube circuits just stop functioning altogether

That's the point, to bring the power low enough to introduce the pleasing intricacies. With variac parameter at ~65%, reducing the power tube grid bias parameter very far to the left brings everything down to crackles, at a certain point they just shut off. Variac parameter range lower than 50% you could leave grid bias parameter alone and still bring the whole amp down into that edge-of-bias break up range, preamp along with it.

Variac range down to 0% would also let you to starve the preamp sections down into that extra breakup range when using them without the power amp simulation, 50% variac doesn't seem to have a very drastic effect on preamp feel when using them with the power amp turned off. Maybe if you were able to starve the IIC+ preamp down to 10% variac nobody would be asking for a studio pre anymore, or if you were able to starve a high gain marshall preamp down to 15% variac, maybe it would scratch the ADA MP-1 itch. Rack preamp breakup always feels so soft compared to heads/combos
 

IronSean

Experienced
That's the point, to bring the power low enough to introduce the pleasing intricacies. With variac parameter at ~65%, reducing the power tube grid bias parameter very far to the left brings everything down to crackles, at a certain point they just shut off. Variac parameter range lower than 50% you could leave grid bias parameter alone and still bring the whole amp down into that edge-of-bias break up range, preamp along with it.

Variac range down to 0% would also let you to starve the preamp sections down into that extra breakup range when using them without the power amp simulation, 50% variac doesn't seem to have a very drastic effect on preamp feel when using them with the power amp turned off. Maybe if you were able to starve the IIC+ preamp down to 10% variac nobody would be asking for a studio pre anymore, or if you were able to starve a high gain marshall preamp down to 15% variac, maybe it would scratch the ADA MP-1 itch. Rack preamp breakup always feels so soft compared to heads/combos

I'm not sure why you think the solution to these preamps is the turning the Variac down to 10%, these preamps still ran at 120V, not at 12V. The B+ voltage on the Mesa Boogie Quad Preamp (couldn't find it labelled on the Studio Pre scematic) is still 450 V, so it's not like it's running really low power compared to a full head.

And Rex's point is that a real amp probably wouldn't work at 12V either which is why turning the variac down to 10% might be useless. However if it's still working at 50% (60V) then it does show the range could be expanded a little further.
 
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