Scratch TW Express Build Bad Idea for Relative Noob?

[Weathered]

How big a deal is it to make the change? I'm trying to find info on it. Is it a totally different transformer? I found some guy on the web, saying he built an amp with a switch that varies the bias.

If it's something easy to reverse, I don't mind doing it. I just don't want him to blow $500 on something that has to be completely redone if he doesn't like the sound.

The easiest place to start would be the tube data sheets. You will want to be sure that the PT you're using can supply proper heater current, and that you factor in any increased plate/screen current requirements. Any bias adjustments should be pretty easy, it's just a function of being sure that you can get the bias into the proper range, either by resistor or bias pot.

In terms of changing from one to the other, as long as the PT can handle it, you're likely looking at a low cost swap if he wants to move to EL34 or 6V6.

[The New Steve H]

I'll try to figure it out.

[PlinytheWelder]

I f he likes 6L6's, you can always try KT-77's... They will bias up like EL-34's and have more headroom and sound more like 6L6's to me..

An Express really isn't that hard to build with all the documentation to be found here. It's a fairly simple circuit and just needs attention to lead dress and other details.....