Small Special Build...Sort of...

[jferris5]

I've been wanting to build a small special for some time now. I'm in love with the clean tone from the Bill Frisell video floating around on another Small Special build thread. However I also have a special place in my heart for the 18watt style amps since they were the first amps I started building over 10 years ago now. For the longest time I've wanted to build a big bottle version (6l6) but haven't gotten around to it yet.

Then I had an Idea to join these amps together in a 2 channel amp with the clean channel being based off the Small Special and the dirty channel being based off a superlite TMB. I drew up the attached schematic last night (rather quickly so good chance there are some mistakes).

What are your thoughts on this idea?

[tictac]

You've got way too much feedback on the 2nd stage clean channel. Personally I find local feedback kind of a "tone-killer" even in the Dumble type amps I find tone improves (and gain) when you remove the feedback circuit.

Some builders add a switch to turn feedback on and off. I did that and found I never used the feedback tone...

Dumbles use 22M or so and you've got 1M so you're really going to take a gain hit with that circuit as is....


TT

[jferris5]

Thanks for the feedback TicTac. I've never worked with LNFB before. My intent was to remove the feedback from the PI so the dirty channel wouldn't have nfb, but wanted to try and keep some on the small special side, I just wasn't sure how to approach it.

[pompeiisneaks]

Additionally if you look at how LNFB is done, it often uses a much smaller capacitor to focus the frequency range of the feedback. Dumble also used values like .002uF or .047uF instead of the full .1 uF you have. Your s will impact a lot larger range of frequencies, and make a more significant tonal change, instead of just adding headroom in a more targeted way. Of course, you may like it that way, the only way to know for sure is to try.

~Phil

[tictac]

Since you're looking for some drive why not build a D-lite ODS? The only extra work you'd have to do would be the relay for the channel switching... You've pretty much got everything else you'd need in your schematic...

TT