The 24h birthday present challenge...
So I had 24 hours to come up with a present for a friends birthday, he likes to play with synths.
The challenge was, can't order any parts, no time for that, so it had to be done from bits and pieces I got sitting around.
I decided to build a mono synth pre amp based on a 12V tube saturation amp I build for myself, it's 2 triode stages from a 12au7 running on 12V ... it adds about 20dB of gain and the more gain you apply the more harmonics it generates .
It has a Lundahl 1527 as output transformer for balanced output, input is unbalanced 100K.
When turned off (relay bypass) it will act as a balancing box with only the transformer in the signal path.
The pushbutton provides a non latching bypass to compare to the treated signal for dialing in the unit, on power off it's just a balancing box.
The box was given to me from someone cleaning his attic, tube was pulled from an old TV set, transformer was also given to me from a broadcast teardown job... I once ordered a set of these knobs from China and I received a box full of them, like 10x the amount I had ordered...
I think it's pretty cool ... it sounds nice.