Tweed 57

[Kipper4]

Has anyone built the tweed 57

Sounds good to me

http://revolutiondeux.blogspot.co.uk/2012/06/wampler-tweed-57.html

What did you think?

[chi_boy]

Has anyone built the tweed 57

Sounds good to me

http://revolutiondeux.blogspot.co.uk/2012/06/wampler-tweed-57.html

What did you think?

Built it and it sounds great, but the transistor matching is a real pain.  BW is pretty adamant that for the tone to be right, they have to be matched.  I have no idea what his real spec is for the transistors, but finding 6 that match is tough enough.

[Kipper4]

thanks for the tip Chi boy
I'll have a look and see how close mine are.
Do they hav to be exact or ball park?

[chi_boy]

I'm no expert, so all I can really do is tell you what worked for me.  I matched all of them as if I was matching for a phaser, but I had about 200 J201's to work with so it wasn't too tough.  Q1 and Q6 also wound up with different bias resistors than the Q2-Q5 pairs, FWIW. 

How close they need to be matched really depends on how you want to interpret the few words BW has shared on the topic.   He has said that they need to be matched so that the bias resistors are all the same value (except Q1 and Q6 I assume) and the resulting bias voltages fall in the 4.5v to 5.0 volt spec.  I have never found anything saying how close to perfectly matched the final voltages had to be.  From a manufacturing perspective there must be some broader tolerance that will still work just fine.  From my man cave DIY perspective, I went for the overkill and matched them so they biased to within 0.15 volt.  The result was very good and I don't have to worry about finding the upper end of the tolerance. 

[Kipper4]

Thanks for the detail Chi
Its appreciated. Copy and paste to word doc for future referance.
Its on the build list.

[Gus]

I wonder why it does not use one 202 instead of two 201s?

[Kipper4]

Are they 202 defunkt as well?
I didnt even know there was a 202
whats the differance Gus please?