Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: DummyLoad on May 29, 2012, 11:16:48 pm

Title: on the breadboard - single tone knob wreck.
Post by: DummyLoad on May 29, 2012, 11:16:48 pm

the wreck express is a decent amp as gain and layout execution are concerned, however, richard and i are of the same opinion about the tone stack - it sux. i grafted a modified james stack that i was experimenting with on the bogen ch30 i modded recently that pleased us both and what we have on the breadboard tonight.

i'm thinking of building it with 6AV6 pre-amp tubes with V4 splitting into 2 6AT6. - at the moment i'm using RCA 6SF5 cans and a pair of 6L6GC RCA black plate - tone nirvana. i may just build it in it's current configuration. with the amount of gain these wrecks have, i don't think a combo layout would work well - thinking a smallish marshall looking head maybe even a rack mount chassis.

lastly, some means to variably shave off bass with a rotary switch that switches the value of C2 might work out well.

schematic attached. thoughts?  less power? 6V6? etc...

 :icon_biggrin:  

--DL

EDIT: R26 has a ref des. duplicate - i'll fix it later... :-/

Title: Re: on the breadboard - single tone knob wreck.
Post by: John on May 30, 2012, 02:11:48 pm

DL, I'm interested in how that single knob tone works for you across a couple different amps. I like one knob myself. On my little SE the Big Muff "shift" works great. On this last one it is still okay but the "shift" is not as dramatic.

Which is why I'm asking. :smiley:

Title: Re: on the breadboard - single tone knob wreck.
Post by: DummyLoad on May 31, 2012, 08:26:39 pm

the single knob stack i'm using is simply a james stack with the bass control chopped off. shitty web based SIM says that the overall insertion loss is around -10 to -12dB, not quite as much loss as with fender/marshal TMB which are around -20dB.

 

Title: Re: on the breadboard - single tone knob wreck.
Post by: 38Super on June 03, 2012, 09:36:10 am

Quote from: DummyLoad on May 29, 2012, 11:16:48 pm

the wreck express is a decent amp as gain and layout execution are concerned, however, richard and i are of the same opinion about the tone stack - it sux.

One idea is to buffer the tone stack with the extra triode a la Bassman or TW rocket.  That will punch up the gain and give you some odd harmonic crunch.


rob

Title: Re: on the breadboard - single tone knob wreck.
Post by: tubenit on June 03, 2012, 09:55:44 am

I definitely would move the 47p snubbing cap AFTER the .047 coupling caps.  It does make a significant difference, IMO, allowing more transparency to the tone (after the coupling caps).  Before the coupling caps seems to just muffle the tone.


With respect, Tubenit