Yes, another buffer question

[Bucksears]

Sorry, have to ask and the search I ran on the forums were specific to particular builds.
My query is more general: as most of my pedals are DIY and true-bypass, I'd like to incorporate buffers in some, if not half, of them (maybe alternating buffered-->true BP --> buffered, etc). What is a good clear/clean/transparent buffer that can be added when an effect is bypassed?

Simple JFET Buffer (SMD or IC)?
C-buffer?
Kliche Buffer?

Thanks!

 

[JTEX]

My favorite clean buffer is an OPA205 op amp wired as unity gain noninverting. Noise is as low as it needs to be for guitar (any lower would not make a real difference), while remarkably low power, and great with high Z sources.
The only way it could be improved is if it were rail-to-rail input capable (the output does swing rail-to-rail).

I've also used OPA196 where noise was somewhat less critical (bass). It's about on par with TL071 for noise, but rail-to-rail in and out, and far lower power. And its output is beefy enough to drive headphones directly if need be (not very hi-fi for this use, mind you).

,

 

[aquataur]

What is a good clear/clean/transparent buffer

Any buffer is clear/clean/transparent. MOSFET adds noise.

that can be added when an effect is bypassed?

I think you get this a** for elbow. The buffer it added to the front and is active as soon as you power the pedal up.
A good example can be seen in the AION Halo Deluxe. A small slider switch determines if you have a true bypass or a buffered bypass.
I do not recommend the exact double buffering method used there unrestricted. It serves extra purposes only Cornish knows, but it does not hurt.

Before settling on an OPA, check if it is sensitive to capacitive load. Attach a loose length (say, 1m) of cable and see if it is stable.
a +1 buffer (i.e. full feedback) is actually the most demanding configuration for an OPA. Look up some Pedal clone pages and see what OPAs they use for output buffers. Those are proven. Particularly the method using a "build-out" resistor to prevent oscillation.