Text_Edifice wrote:ok so...
after a bit more thinking I'm going to try and build a design a bit like this
http://www.jensen-transformers.com/wp-c ... /as014.pdfBut with a different buffer stage (tl071, single 9v), ground lift to the xformer and phase reverse as per the radial and only one split.
I have some AWA 1:1 transformers (600:600) that I think will work ok post-buffer. Apparently EDCOR make suitable 10k and 15k 1:1 and I wonder if they'd work better. Will use what I have first I guess and see...
Opamp:
For high impedance guitar pickup the opa627 on +-9V is about the best choice as it has a bootstrapped front
end that has very low capacitance. They also sound very good. TL071 on a single supply is about the worst choice
but at the end of the day if you cant hear a difference... well the 627 is pretty expensive. Bottom line
put an opamp socket in so you can have a swapsy session.
Supplies:
+-9V is the best option and if you want to switch power with IP socket just use an isolated double switched IP
socket. Running +- supplies with a 627 or equivalent OPA will allow you to direct couple the opamp to transformer(s) and flick the OP coupling cap.
Transformers:
Personally I would want transparent transformers as I want my guitar sig to get to the amp as pure as possible -
However maybe you could have 1 x Nickel core and 1 x Steel core for options. I recommend Cinemag, they
will help you with the right choice. They are fantastic people to deal with, the transformers sound great and are
cheaper than Jensens for similar quality. Whatever transformers you use, put a 10k square wave through the unit
and look at OP. If it's ringing all over the shop snub it (with R//C) to get cleanest square wave.
Having said all of the above, you may find that a sigle supply 071, cap coupled to an Edcor tranny is fine for
you, it just depends how fussy you (and your ears) are.
T