Flubby bass/Fender 5D3

[Diverted]

Hi all,

A while ago I built a point to point 5D3 circuit (paraphrase PI) for a friend of mine. He absolutely loves it apart from hitting bass notes at high volume.. it tends to get flubby/farty. I’ve done a few things that helped a bit but did not eliminate it. Any suggestions?

So far I:

1. Replaced both output tubes coupling caps with .015s
2. Replaced preamp bypass cap with 1uf.

https://el34world.com/charts/Schematics/files/Fender/Fender_deluxe_5d3_schem.pdf

Thanks,

Ted

[sluckey]

There are four .05µF coupling caps. Replace all four with .01µF caps.

There are three 25µF cathode bypass caps. Replace all three with smaller caps. I'd try 5µF or 1µF.

[Diverted]

Thank you Sluckey👍
Will report back.

[ac427v]

Cutting bass by changing caps might be the answer for your friend. But if he wants to keep bass frequencies only with less distortion,  you could try raising the headroom by increasing voltage. Using a 5AR4 or a 5V4 instead of a 5Y3 would increase voltage for the entire amp. Or changing one of the 10k dropping resistors in the power supply to something smaller--like 2k would increase voltage on the power tube screens and the preamp tube plates. The downside of increased headroom is that it increases headroom. That means less of the sweet distortion at middle volumes.