Westbury W-20

[grapefruit]

Has anyone built the Westbury W-20 tube distortion? Does it sound any good?

It looks very similar to a lot of other tube overdrive/preamps, with the exception of the feedback diodes. Maybe some different sound could be gotten from this pedal by switching out the diodes and tweaking some other components...

Cheers,
Stew.


http://www.geofex.com/FX_images/westbury.gif

[tester]

I played a real one. It's not very good at all. Sorry.

[RaceDriver205]

Apparently the only acceptable tube distortion available for DIY is the shakatube. Every other tube stompbox ive heard clips of has sounded like complete #$%^. Don't buy into tube hype!

[rocket]

The westbury is just a normal tube preamp - I don't see any reason why it should be bad and if it is it should be as easy to tweak as all the other 10000 tube preamps.

Then on the other hand there is little reason to build the westbury and not a fender, marshall or whatever preamp you like.

If you use only the preamp you should consider this interesting posting on the effect of cathode followers at the ampage:

http://music-electronics-forum.com/showthread.php?t=1536&page=2

And be aware that it will always sound awful if you don't use a guitarspeaker or speakersim for recording, etc.

[Mark Hammer]

Take the 10uf cap and diode pair in series out of there completely and you have yourself a fairly "normal" tube amp front end.  I imagine it will sound better under those circumstances.

[aron]

You are right that it can be modded. I just meant the original I played sounded very bad to me.

Aron

[rocket]

oh - I missed the diode feedback because i concentrated on the power supply (if it's hv).

did they try to design a tube tubescreamer?

I think that one problem is that the diodes will load down the 2nd triode.

[Mark Hammer]

Well, it's an old drawing by RG.  He has made a few errors in some of those older drawings, though this one is simple enough that I somehow doubt the inclusion of drawing errors.  It may just be a bad design.  In any event, without that diode-cap thing, it becomes a very normal circuit and should sound no better or worse than any other tube amp input stage.

[grapefruit]

Thanks for all the reples. I'll have a look at various guitar amp preamp sections. Looking at some Mesa Boogie schematics I noticed that they used a three band tone control after the frist amp stage. For the high gain input he Mark 1 has two amp stages before the tone stack and two stages after. I might base my ciruit around this.

I want to build a tube circuit mainly to get more familiar with tube circuits, because I'm an electronics technician and work on a lot of SS power amps, but not tube amps. I think there'll be a growing demand in years to come for good valve amp techs here in Australia (unless DSP's get really good!) so I'd like to learn more about them.

But I also want it to sound nice. Does the Boogie Mk1 preamp seem like a good place to start?

Cheers,
Stew.