Treble bleed alternatives

[RedHouse]

The 9pF/ft for the Mogami cable is a "partial capacitance". It's the capacitance between the two cores, but you also have to take into account the capacitance between each core and the screening, which is listed as 54pF/ft.

Thanks, but that's 54 pF/ft from either conductor to the shield and 9.8 pF/ft between the two conductors.This could be significant in a Gibson type guitar on the path from vol pot to switch and to the jack. (You probably do want shielded cable on that path.)

It should be possible to use some of the lower pF/ft cable that Joe mentioned because it is protected inside a guitar.

Ah yes Steve, Mike, I just went and cut a 1ft piece and measured it, it measured 13pF between the two cores and 40pF core-to-shield. So plugging that into your favorite lowpass filter equation (40pF at 8.5K) you both still see a problem?

Got the same off a piece of "vintage" braid single conductor too BTW

[David Schwab]

Craig was a typical EE no disrespect intended, he was good and a ground breaker, helped get DIY effects into the mainstream and yes I read his columns and bought his book back in the 70's. But a good example of an EE that can use his ears is Tom Sholtz, he was able to find sound.

If I'm not mistaken, Craig is self taught, so he's not an EE. He got started as a musician, record producer/engineer and a writer. He got into electronics via music. Sholtz has a degree in Mechanical Engineering, not EE, and worked for Polaroid Corporation as a senior product design engineer, so he wasn't really involved with audio circuits.

Just because two smart people learned electronics to create audio circuits doesn't mean they don't have good ears. Anderton certainly created more guitar effects circuits that Sholtz did! Anderton is also a sound designer and has created sounds and samples used in a lot of products.

I think it's safe to assume both these guys got into electronics for the same reason I did... music! They were musicians before they started messing with circuits.

[Steve Conner]

So plugging that into your favorite lowpass filter equation (40pF at 8.5K) you both still see a problem?

You said you tested it in the real world and liked the results. So whatever's going on in theory, there's no problem. If it sounds good and it doesn't hurt or get you arrested, use it!

To my mind, if I wanted to calculate the effect, I'd want to know the self-capacitance of the pickup coil, so I could figure how far the extra capacitance would shift the resonant peak. But I don't see it making a huge difference.

[RedHouse]

You said you tested it in the real world and liked the results. So whatever's going on in theory, there's no problem. If it sounds good and it doesn't hurt or get you arrested, use it!

To my mind, if I wanted to calculate the effect, I'd want to know the self-capacitance of the pickup coil, so I could figure how far the extra capacitance would shift the resonant peak. But I don't see it making a huge difference.

Yes it works extreemely well.

But back to the question if you please, Steve, and Mike, do show me (us) how a <1ft piece of 40pF/ft wire is rolling off enough highs in the audio band of interest (at our impedance level) that we should be discussing it as a problem?

Sure if we were talking about an IF, RF, or Video or other band signals I would agree in a New York minute, but we're talking here about the audio band and a reduced part of that even.

I'm staying open minded though, convince me...

[RedHouse]

If I'm not mistaken, Craig is self taught, so he's not an EE. He got started as a musician, record producer/engineer and a writer. He got into electronics via music. Sholtz has a degree in Mechanical Engineering, not EE, and worked for Polaroid Corporation as a senior product design engineer, so he wasn't really involved with audio circuits.

Just because two smart people learned electronics to create audio circuits doesn't mean they don't have good ears. Anderton certainly created more guitar effects circuits that Sholtz did! Anderton is also a sound designer and has created sounds and samples used in a lot of products.

I think it's safe to assume both these guys got into electronics for the same reason I did... music! They were musicians before they started messing with circuits.

I was only going on recollection there, but I thought Craig mentioned his creditation in his magazine articles either in Guitar Player or Popular Electronics (maybe it was Electronic Musician?) but anyway it doesn't matter, and I do see on Official Boston Homepage that Tom is indeed an ME, my mistake. Never the less, there's a time and a place for everything and one has to use the ear with audio issues, not just the mind.

I got into both music and electronics at the same time so it was a natural. I recall one of my first projects besides canibalizing everything in site to learn how it was made, was a Fuzz box from an article in Popular Electronics maybe 1971 or so.

[Mike Sulzer]

@Mike Sulzer: Generic tube amps sound good because of a happy accident. Tubes are so musical-instrument-friendly by their nature that you can throw together a circuit from a Mullard handbook, plug a Strat into it and it'll sound good even though the designer has no clue what he's doing. They're almost little instrument parts in their own right, like the strings of a guitar or the reed in a saxophone.

But with solid-state devices you need an understanding of what makes tubes sound good, and how to emulate it. So maybe generic SS amps sound bad because they were designed by people who don't really understand tubes.

Exactly, but I would add "...who don't really understand tubes or solid state." And that is not a criticism, just a statement that understanding non-linear behavior is difficult, and manipulating the non-linear behavior of devices to get a particular sound is challenging. The "happy accident" allowed electric guitars to evolve from a curiosity into the dominant instrument in rock.

So the goal actually is not to make an SS amp that is just like a tube amp, but rather to understand what makes a tube amp good and then do better.

[Mike Sulzer]

But back to the question if you please, Steve, and Mike, do show me (us) how a <1ft piece of 40pF/ft wire is rolling off enough highs in the audio band of interest (at our impedance level) that we should be discussing it as a problem?

I never was trying to convince you of that. (You have heard of a straw man, right?)

In any case the part of the harness we were discussing (from the vol pot towards the jack) has a capacitance that just adds in with the guitar cable capacitance. The cable is dominant. A couple of feet (in something like a Gibson guitar) of that 54 pf/ft cable probably has an audible, if small, effect. It does shift the resonance by enough so that you could measure or hear it. I do not consider it a problem.

Possum might.

[RedHouse]

I never was trying to convince you of that. (You have heard of a straw man, right?)

In any case the part of the harness we were discussing (from the vol pot towards the jack) has a capacitance that just adds in with the guitar cable capacitance. The cable is dominant. A couple of feet (in something like a Gibson guitar) of that 54 pf/ft cable probably has an audible, if small, effect. It does shift the resonance by enough so that you could measure or hear it. I do not consider it a problem.

Possum might.

Ahh I see.

[Joe Gwinn]

It should be possible to use some of the lower pF/ft cable that Joe mentioned because it is protected inside a guitar.

Yes, but as has been mentioned, with full cavity shielding (such as with shield spray paint), one can use hookup wire and get very low capacitance. And better shielding, as it covers everything, not just the wiring.

[Mike Sulzer]

Yes, but as has been mentioned, with full cavity shielding (such as with shield spray paint), one can use hookup wire and get very low capacitance. And better shielding, as it covers everything, not just the wiring.

I agree, except for that switch I mentioned. And you really do not have to use shielded cable for the whole path, but you have to be practical at some level.

[David Schwab]

...was a Fuzz box from an article in Popular Electronics maybe 1971 or so.

I made one of those for the guitarist in one of my bands back in the early 80's.

I still have the article here on my computer.

[David Schwab]

In addition sometimes, as in the case of treble bleed, a player (not listener) can percieve the additional treble (or loss of bass if you will) as more "spank" or presence, or definition, and appreciate it as a good thing, which tends to allow one to play better because they get into the sound more, while on the other hand another the person in the room listening (not playing) might say it sounded better w/o the treble bleed based soley on it's sound w/o tactile feedback.

The main problem with the treble roll off is that many players turn down the guitar's volume to clean up an over driven amp. So you are expecting a clean bright tone, but instead you get a dull tone.

People started using the treble bleed caps because there was a problem that needed to be solved, not because they thought it looked good on paper.

If you are playing with a totally clean tone, then turning down will make it shrill, but that thin Tele tone has been used on many recordings. Sometimes you need a guitar tone that's thin and bright, just as you sometimes need a bass tone that has little top end.

Other times the treble roll off is just what you need, and is an effective tone shaping device. This is common on bass where you might back off the volume a slight bit to flatten the resonant peak and get a smoother tone, or on guitar where you want less distortion, but not a clean tone... just a softer tone.

We have all become accustomed to the idiosyncrasies of passive guitars. Like using the two volumes and the switch on a Gibson to act as a kill switch. If it works, it works.

[Joe Gwinn]

I agree, except for that switch I mentioned. And you really do not have to use shielded cable for the whole path, but you have to be practical at some level.

Switch? Wouldn't it be inside the shielded cavity?

[RedHouse]

...People started using the treble bleed caps because there was a problem that needed to be solved, not because they thought it looked good on paper...

?

[Mike Sulzer]

Switch? Wouldn't it be inside the shielded cavity?

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