Derailment muddy low-end question

[Luthierwnc]

Hi;

I recently built a variant of a Derailment. It is a fun little amp but only with the bass control on "0". Years ago, I remember reading the notes on the Blueguitar that the coupling cap and grid leak resistor between the 2nd and 3rd stages were very touchy. Too much and the bass turns to mush. Too little and it loses its mojo. I've got .022's on the mid and bass stack. It uses a KT66 with about 375VDC on the plates.

Before I start randomly swapping out parts, does anyone have a recommendation on the values or cap types coming off V1b?

Thanks, Skip

[slajeune]

Hi,

which variant of the derailment did you build? For what it's worth, I find the derailment to be fairly bright, certainly not muddy (at least my build)!

On my build, I had to increase the .0022uF cap after stage 3 to a 0.0047uF cap to cut down on the brightness.

Which tubes are you using?

Cheers,
Stephane.

[Luthierwnc]

KT66

I tried an oil in paper .001 and changed the grid resistor to a 120k. I might hang a 500 puff cap across the .001. It is a pretty bright amp so I might end up going back to the original value and reducing the grid resistor even more.

sh

[kec]

KT66

What brand of tubes are you using.

[Luthierwnc]

Valve Arts in the power socket, Tung Sol reissue 12AX7 in the 1 hole and an EH 12AX7 in the 2 hole.