NSFW What's up with the buffers in cornish designs?

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lrgaraujo

Well-known member
Motivated by the new aion traces, a question has emerged.

If I'm not horribly mistaken (wouldn't be the first time), the buffers in those Cornish designs are bootstrapped emitter followers. I know this allows for higher input impedances, but is it worth the extra effort for a guitar pedal?

Thanks!
 
Not if the results of every bloody Cornish pedal I have ever built is the result! With or without the buffer, every one I have tried sounds incredibly average. Muddy and congested. Not my thing at all. I guess I'm not rock star enough. 🤪
 
lrgaraujo said:
Motivated by the new aion traces, a question has emerged.

If I'm not horribly mistaken (wouldn't be the first time), the buffers in those Cornish designs are bootstrapped emitter followers. I know this allows for higher input impedances, but is it worth the extra effort for a guitar pedal?

Thanks!
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I ask myself the same question every time I think about building one.
 
He has a very specific design philosophy about buffers. I think it’s possible that, back in the day, tone suck from very long cables was a real pita and he certainly solved that problem with output buffers. To some extent I don’t think he’s totally wrong: I have definitely experienced issues with modern built unbuffered pedals, things like the tone changes if you turn a delay (typically buffered) on after a drive which is caused by the drive having high output impedance and tone sucking when the delay is off and then the delay “fixing” that when on. That can cause serious problems for touring musicians, which is definitely the audience (I’m not one of them!).
 
giovanni said:
He has a very specific design philosophy about buffers. I think it’s possible that, back in the day, tone suck from very long cables was a real pita and he certainly solved that problem with output buffers. To some extent I don’t think he’s totally wrong: I have definitely experienced issues with modern built unbuffered pedals, things like the tone changes if you turn a delay (typically buffered) on after a drive which is caused by the drive having high output impedance and tone sucking when the delay is off and then the delay “fixing” that when on. That can cause serious problems for touring musicians, which is definitely the audience (I’m not one of them!).
Click to expand...
I'm not opposed to buffers at all! My question is related to the complexity of the buffers used. What could be the benefits of a bootstrapped emitter follower versus an opamp, for example
 
JTEX said:
None whatsoever, except maybe cost, depending on the op-amp.
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Yeah the cornish buffer costs pennies compared to an op amp buffer or even a jfet one. The trade off is obviously board space and the time it takes to assemble more components which both also heave real costs.

I’ve always been kind of impressed with high input impedence BJT designs because of how cheap they are. You could even get much more complicated than cornish’s bootstrapped emitter follower if you wanted, here’s some from Douglas Self:

Design B practically lives on my breadboard but is obviously overkill

IMG_4740.png
 
The only good thing about building Cornish pedals is knowing you didn’t pay full $700+ on reverb for the real deal. I had my eye on some Cornish stuff when I started out building and nothing has disappointed more. Same complaints as everyone else. Muddy and underwhelming.
 
Here's my latest attempt at designing the ideal buffer:

1200px-Op-Amp_Unity-Gain_Buffer.svg.png
To make it as good as it gets with a guitar input, use OPA205 (if the cost is acceptable to you). Any other opamp would either draw more power for nothing, make more noise, or both.

There. Now you know my biggest secret :)
 
Big Monk said:
...extremely rugged, tour grade construction, etc.
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I realize they're known for their "impeccable" build quality, but I must say, I'm not feeling it.

Plain paper labels, severely oversized, gooped / spray painted / hand etched PCBs, zip ties, and more offboard wiring than a 1950's telephone exchange... Better hope they're rugged because no one in their right mind is going to want to repair one.

They make my skin crawl to be honest... I really dread working with them and the goop is the least of my concerns. :ROFLMAO:
 
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