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

[lrgaraujo]

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!

 

[HamishR]

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.

 

[Fama]

Muddy and congested. Not my thing at all. I guess I'm not rock star enough.

You must have that all wrong! It is not muddy and congested, it is warm and don't forget the buffer is Class A!

 

[Laundryroom David]

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!

I ask myself the same question every time I think about building one.

 

[giovanni]

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!).

 

[Laundryroom David]

Buffers are great and I think they almost always do make things better. I am not sure though that one needs so many components to make a competent buffer. I don’t enjoy complexity for its own sake and haven’t heard a Cornish pedal yet that convinced me the parts count was necessary.

 

[jesuscrisp]

Buffers are great and I think they almost always do make things better.

Bill Finnegan likes this post.

 

[Laundryroom David]

Bill Finnegan likes this post.

Well, I do agree with him on at least one thing!!

 

[lrgaraujo]

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!).

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]

What could be the benefits of a bootstrapped emitter follower versus an opamp, for example

None whatsoever, except maybe cost, depending on the op-amp.

 

[finebyfine]

None whatsoever, except maybe cost, depending on the op-amp.

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

 

[Laundryroom David]

 

[Feral Feline]

I absolutely LOVE pasty buffets by Cornish designs.

 

[drgonzo1969]

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.

 

[szukalski]

All you folks complaining about Cornish stuff aren’t running them through 100 ft cables playing at arena volume to 25,000 people.

 

[JTEX]

All you folks complaining about Cornish stuff aren’t running them through 100 ft cables playing at arena volume to 25,000 people.

That's also true about all of us not complaining about them, though, what's your point?

 

[Laundryroom David]

I don’t want to continue the suspense - though I am a David, I am not David Gilmour.

 

[Feral Feline]

Maybe you tire of this, but I don't...

 

[Big Monk]

What I usually find interesting about discussing Cornish pedals is this: It seems, almost invariably, that people in DIY talk about them in the same "mojo" realm as $1000 Fuzz pedals, etc.

Yet he was not, and still really is not, a household name when he designed them. And make no mistake, he designed his stuff the way he did for many purposes as stated above and elsewhere: Eliminating tone suck in pro rigs, extremely rugged, tour grade construction, etc.

And frankly, of course he makes them the same way because once a builder gets in a groove and the stuff works, why change it?

To me, the Cornish stuff represents Custom Builds made available for the laymen, so of course they don;t always work in bedroom rigs.

 

[JTEX]

Here's my latest attempt at designing the ideal buffer:


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