Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: bnew63 on March 21, 2012, 12:40:25 pm

Title: parallel input
Post by: bnew63 on March 21, 2012, 12:40:25 pm

Whats the purpose of a parallel input.
I was thinking of building this 18watt lite,but have never seen a parallel input before.

Brian

Title: Re: parallel input
Post by: tubenit on March 21, 2012, 01:17:37 pm

Reportedly a paralleled 12A_7 tube produces about 30% more gain with a fatter tone and no increase in noise.

with respect, Tubenit

Title: Re: parallel input
Post by: John on March 21, 2012, 01:40:55 pm

Quote from: tubenit on March 21, 2012, 01:17:37 pm

Reportedly a paralleled 12A_7 tube produces about 30% more gain with a fatter tone and no increase in noise.

with respect, Tubenit

I had read the same thing, and tried it on my Webster re-build, and really like it. I'm actually running a 12aT7 input, into a 5879 pentode, then into the 6v6. Tone is great, sustain is great. The 12aX7 input was just too gainy, went to distortion much quicker than I wanted.

In fact, I think the paralleled input is supposed to have a noise reduction, IIRC.

Title: Re: parallel input
Post by: bnew63 on March 21, 2012, 02:28:26 pm

Thanks
I was drawn to this schematic because of the VVR and the el84 tubes(got a dozen good ones cheap)
After doing a 36 watt I decided an 18 is all that I need.

Brian