Princeton Reverb Scratch build blocking dist

[2pupwonder]

Still probably need to do the output coupling caps and maybe input bypass cap reduction to clean up the remainder.

[Adrien]

I will look into the reverb mod. Looks like would need an additional parallel filtering stage cap and some resistors.

You don't actually need another filter cap. I only added separate ones because the cap can I had forced all the grounds to be together and I wanted to separate them. Node "C" on the board is effectively unused, so it's "just" a matter of moving that long reverb transformer under-board connection from node B to C (easier said than done!), and changing the 18K resistor (R69 on Hoffman's schematic) to 12k to keep the downstream voltages similar. I would also suggest changing R32 (Reverb driver cathode resistor) to 1.5k and adding a grid stopper to the reverb driver as discussed in that other thread. Those changes should keep it from overdriving.

[2pupwonder]

So I changed V1a & V1b cathode resistor bypass caps to 4.7uf. This definitely improved things, but still getting the nasty Harley idle distortion at higher settings. I also played with the bias, running it a bit hotter, and trying a new set of JJ 6v6's. I needed a new tip for my solder iron to change the coupling caps, which i have now.

next steps are:
- Test with a different speaker.
- Change the power section coupling caps - I have several values to try. .01 - .022 & .047uf
- Retest with V2 pulled
- Try a 5U4 rectifier and see if lower voltages help
- Change Reverb power - changing the Node C dropping resistor to 12K
- Change R32 to 1.5K - wondering if I should adjust the bypass cap as well.
- Add a 10k grid stopper to V2

Other ideas are to add 33k and 470k resistors on the PI Grid, then bring a 470K resistor from between them to the PI tail. I already have a 470Kgrid stopper here, but that's with the 1M PI grid lead in place.

I am also having some issues with the trem motorboating when it's off and the depth is on 10. This might be lead dress, but has anyone else had this?

Thanks!
2P