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

marksescon said:
I do not know but the answer I received was: ā€œThe omissions from the power supply will decrease the headroom, slow down the transient response, and generally be significantly noisier.ā€
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In other words, ā€œno, it doesnā€™t affect the sound, but I refuse to admit it.

Hereā€™s a bunch of magic word bullshit that doesnā€™t correlate with reality. Please donā€™t look into it any further.ā€
 
manfesto said:
In other words, ā€œno, it doesnā€™t affect the sound, but I refuse to admit it.

Hereā€™s a bunch of magic word bullshit that doesnā€™t correlate with reality. Please donā€™t look into it any further.ā€
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I donā€™t know about thatā€” I read on the Steve Hoffman Forums about the profound impact a $25k iec cable for a hifi system really makes the top end sparkle, and really brings out the analog properties of some $300 45rpm ā€œultradisc 1 stepā€ box set of some crummy SRV album or whatever
 
marksescon said:
I do not know but the answer I received was: ā€œThe omissions from the power supply will decrease the headroom, slow down the transient response, and generally be significantly noisier.ā€
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The working voltages are similar and I think we can feel fairly confident the power supply rails aren't buckling under the heavy load of a single TL072 based clean buffer.
 
Robert said:
The working voltages are similar and I think we can feel fairly confident the power supply rails aren't buckling under the heavy load of a single TL072 based clean buffer.
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Look, 18V is just *better* when it comes from a Rube Goldberg machine of rectifiers and regulators.

Theyā€™re fancier volts. Higher-headroom volts.
 
Let's say my bridge humbucker puts out about 0.4v on average and an op amp buffer is running just on 9v and biased at half that. Either side of the waveform would have to hit 4.5v to begin distorting, right? I don't think even hitting the strings hard would generate 1v at it's peak.
 
Robert said:
The working voltages are similar and I think we can feel fairly confident the power supply rails aren't buckling under the heavy load of a single TL072 based clean buffer.
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Yeah but what if you replaced the guitar with a 25Vpp sine wave from a function generator? Checkmate pedal nerds :cool:
 
cdwillis said:
Let's say my bridge humbucker puts out about 0.4v on average and an op amp buffer is running just on 9v and biased at half that. Either side of the waveform would have to hit 4.5v to begin distorting, right? I don't think even hitting the strings hard would generate 1v at it's peak.
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I've often seen brief 2v peaks on hot guitar/bass pickups when hit hard. Guitar straight to scope. Of course, just about any op amp buffer running off 9V should still handle them with ease. Especially one with R-R output.
 
Robert said:
[...} single TL072 based clean buffer.
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As usual, I am of the strong opinion that TL072 has no business being in a top notch guitar buffer in 2023. It's just too noisy at 18nV/sqrt(Hz) (same as the thermal noise of a 20k resistor). I would pick something with less than half that noise. And of course, it would also have to have very low current noise to do well with high impedance sources, so either JFET input or super beta bipolar (my new favorite). My best suggestions as a guitar buffer: OPA205/206/207, OPA145. Or, if you have all the money and want the quietest possible op amp that can handle high source Z, get an OPA827, or even two of them in parallel if you're nuts (I am, and I've done it).
 
giovanni said:
He has a very specific design philosophy about buffers. I think itā€™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 donā€™t think heā€™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 ā€œfixingā€ that when on. That can cause serious problems for touring musicians, which is definitely the audience (Iā€™m not one of them!).
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Tell me more... because I have a new DL4 mk2 and I hate it... Whenever I turn it on it adds an unwanted boost and a low mid thing... I have no clue how to make it stop, and I was so pissed at this brand new, $300 pedal that I threw it off my board and put my 20 year old original DL4 back on instead
 
ChrsGuit said:
Tell me more... because I have a new DL4 mk2 and I hate it... Whenever I turn it on it adds an unwanted boost and a low mid thing... I have no clue how to make it stop, and I was so pissed at this brand new, $300 pedal that I threw it off my board and put my 20 year old original DL4 back on instead
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The DL4mkII does have options for true-bypass and analog dry-through that might be worth trying
 
I have had similar experiences...

Things I feel a duty to post:

1. I have been to Cornwall and can attest that some of the pasties are amazing. Better than you might expect from the UK.

2. While I have never heard a Cornish pedal I like I hold no animosity towards either Mr Cornish, his family, or the people of Cornwall. The reasons I don't like his pedals are obviously my own stupid fault/lack of stadium gigs and very long cables.

3. While it can be irritating that the latest hip $500 pedal is simply a Timmy with two parts changed, sometimes changing a few parts in a Timmy can have an extraordinary effect on the sound. If someone (I'm looking at me specifically!) can take a Timmy circuit, change it around enough to get a significantly different and worthwhile sound from it, that's ok by me. I'm sure Paul Cochran didn't design Timmy in a vacuum. A Timmy is kinda what happens when you remove the transistor stages from each end of a Tubescreamer, add a bass pot and simplify the tone control. All of which sounds like a good idea to me.

Really, what matters to me is how good and useful something sounds. If it's affordable then all the better. If it's not I don't buy it. Sometimes as folks fascinated about how things work we lose sight of the original purpose - does it sound good and make me want to play more? If it does - great! If someone finds a way to change two parts in a pedal to make it suddenly sound amazingly different and better for you then that's fantastic!

I admit to being sceptical and disappointed by some new pedal when it is shown to be "merely" a modified whatever. But if it sounds better who cares? The whole reason I got into this hobby was to try and find a better sound for me. I couldn't get the sounds I wanted from what was available. And I still don't like any of the Cornish designs I have tried.

Man have things changed!
 
JTEX said:
As usual, I am of the strong opinion that TL072 has no business being in a top notch guitar buffer in 2023. It's just too noisy at 18nV/sqrt(Hz) (same as the thermal noise of a 20k resistor). I would pick something with less than half that noise. And of course, it would also have to have very low current noise to do well with high impedance sources, so either JFET input or super beta bipolar (my new favorite). My best suggestions as a guitar buffer: OPA205/206/207, OPA145. Or, if you have all the money and want the quietest possible op amp that can handle high source Z, get an OPA827, or even two of them in parallel if you're nuts (I am, and I've done it).
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Looking at the specs sheet of the tl072 I also came to that conclusion when I first started looking into buffers (not that I had the knowledge to really make such an assertive claim to other people - I still don't hahah). What's you're opinion on the TLE2072?

Edit: I double checked the datasheet for the TLE2072 and the noise is 11.6nV/sqrt typical, so it's better, but not quite at the level of the others you mentioned.
 
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mzy12 said:
What's you're opinion on the TLE2072?
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TLE2072 looks like an easy drop-in upgrade over TL072, but I find it stupidly expensive for what it is. If you're going to spend 10x the price of a TL072, then might as well get a much better OPA2205. Only downside (for some) is that it's SMD-only. SMD is not hard, though. Just get the right tools and embrace the damn thing, else you'll get trapped in the past.

Why do I insist on sub-10nV/sqrtwhatever input stages? A guitar pickup can easily have a DC resistance of 5k or less (some single coils and parallel wired humbuckers). The thermal noise of that 5k dictates the lowest achievable noise floor, and your op amp should be at least this quiet, or quieter.
 
Honestly, for me, SMD is fine even with moderately good, standard soldering tools. No need for an SMD soldering station, hot air gun or solder paste. As long as you have a relatively fine soldering iron tip available, I don't see why anyone can't give it a shot. Thanks for the info (y)
 
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