Communal thoughts on Hiwatt brilliant channel improvements

[luthierwnc]

Hi all and thanks for looking.  This is an amp I've been working on for a while and you have seen before as I got it running.  The normal channel sounds great.  The brilliant channel is thin and weedy -- considerably weaker than the normal at the same volume setting.  Run together they sound fine.  The OD sounds good after being tamed.

The schematic is attached.  It is identical to the Triwatt schemo out there on the first gain stages except the plate voltages on V1 are lower on the brilliant channel than the original.  They're identical to the Hiwatt DR504 except those plates are in the low 200's.

Right now I'm considering dropping the plate resistor and bumping the coupling cap up, but that just gets me closer to the perfectly acceptable normal channel.  So ... I thought I'd throw this in the ring and see if anyone has some ideas to make it more interesting. 

Mods: Bridge rectifier rather than full-wave, power tube plates are more like 422vdc -- other voltages are close to the schematic.  I used the Traynor (donor) choke rather than the 1k resistor.  All NOS Mullard glass.  The OD section has been reworked thanks to PDF64's excellent suggestion to keep the stages separate.

Thanks for your interest, Skip

 

[thetragichero]

my thoughts come from building marshall-style amps: increase c2 to 4n7 or 10nf (heck maybe even 22nf), add a bright cap to vr1 (220-1000pf maybe?), add a treble peaker cap to r9 (470pf is the marshall value... 1nf or 2n2 can sound great in some builds). i pretty much always play 4-input amps with the channels jumped so keep that in mind if jumping the channels isn't your intention

[luthierwnc]

Thanks.  I'm approaching this from a Marshall point-of-view too, although this amp is fundamentally cleaner.  I'm looking at the 1987 schematic now.
Yes, the switch at the jacks is designed to essentially jump the channels in the middle position.  I have to use either the high or low input for both, though. sh