Treble bleed alternatives

[Joe Gwinn]

This is just like the old "Neve" console thing, shunting the 47uF electrolytics that couple segments with 0.1uF poly's. EE's can't rationalize it with the math so they deny it's audible effect.

Well, maybe some audio EEs never heard of this effect and trick and math, but it is well known to the RF community, and all the capacitor manufacturers have application notes explaining the issue. Sells more capacitors.

[Mike Sulzer]

With the treble bleed in place connect a 20 foot cable, note the effect, then connect 1 foot cable, you will note the same tonal effect, which really puts a cramp in your point but again it's one of those rubber-meets-the-road things. That's the beauitiful thing about actually doing listening tests, and using the ears instead of the mind when it comes to sound and music related issues, one can tell if something works without needing any others explainations.

No cramp on my point. Of course the treble bleed circuit has an effect when you use either a 1 foot or a twenty foot cable. It bypasses highs around part of the vol pot resistance in either case. The point is that you do not need to counteract the high frequency loss from turning the volume part way down unless you have enough capacitance to cause the loss. A one foot cable does not have very much. A twenty foot cable has enough.

[David Schwab]

The point is that you do not need to counteract the high frequency loss from turning the volume part way down unless you have enough capacitance to cause the loss. A one foot cable does not have very much. A twenty foot cable has enough.

Proof of this is shown by placing a JFET buffer after your controls, but before the cable, such as in the typical Stratoblaster install. You now have no treble loss when turning down the controls, since the pickups and controls are isolated from the cable.

[Steve Conner]

Yes, and vintage weenies will tell you that this sounds terrible! :-/

[Mike Sulzer]

Yes, and vintage weenies will tell you that this sounds terrible! :-/

I might too, unless there is enough capacitance located at the input to the buffer to set the resonance at about the same frequency as my favorite cable does. Isolating the guitar from the cable capacitance is great because cables differ and cause change in response when using the volume control. But you still have to get it right to start with! Some people forget this.

David, thanks for pointing out the effect of a buffer.

[Mike Sulzer]

I prefer a decent 2 conductor with shield so the pickups can be phase adjusted in the control cavity. I'm currently using some decent Canare two conductor, which is like 3-5pF/Ft.

Would you provide me with a product number for that cable?

Thanks.

[Steve Conner]

Sorry, that information is classified

(They keep it in the same bunker as the other stuff from Roswell.)

[Glass Snuff]

Some will advise using a resistor/cap in parallel, but when you add that across pin2 and pin3 of the pot it alters the taper too much. Using the resistor/cap in series doesn't mess with the taper.

Well, most guitar players like the change in taper. It takes an audio taper pot closer to the taper of, say, an RS Superpot or the Centralab pots used in old LPs.

And as David noted, it restores the bass at lower volume settings. As soon as the resistive value of the 'upper' part of the volume pot exceeds the resistor in series, you've got a bass filter, not a treble bleed. A parallel resistor is the only way to get a circuit that works somewhat evenly at all volumes.

[frankfalbo]

The point is that you do not need to counteract the high frequency loss from turning the volume part (pot?) way down unless you have enough capacitance to cause the loss.

Okay this is where I'll jump in, but realize I'm not in major disagreement with any of the banter thrown about thus far. I'm more of the school that "everything makes a difference" AND "if it works for you, then its right." because this is more art than science, and the science should be slave to the art. But...it seems we're ignoring the effect of the resistive load on the pickup to ground. The flattening out of the resonant peak is often heard as a loss of brightness, since the pickup's resonant peak is generally in the "treble" region, give or take. Capacitance notwithstanding, remove all of the controls from the circuit and place a 250k resistor from hot to ground. What are you hearing? A loss in treble, or a flattening in the resonant peak? Cable capacitance is different, of course, and the treble bleed mod can be used to counteract both, whichever you consider the greater evil. I for one don't consider it bad, and most of my guitars have no treble bleed.

Proof of this is shown by placing a JFET buffer after your controls, but before the cable, such as in the typical Stratoblaster install. You now have no treble loss when turning down the controls, since the pickups and controls are isolated from the cable.

No, the effect of loading the pickups will still be audible. You would hear a difference between placing the buffer before the volume control (right after the pickup) vs. after the volume control. Maybe that's what you're trying to say and I'm missing it. (ignoring the fact that you'd have changed pot values after the buffer, etc.)

As for the 50's wiring, etc. Yes David and Steve, the difference is in the stacking of the loads, including the inherent pot values even when they're all the way up. Some EE's see it more modular, like "anywhere you put the _____ in the circuit the net effect at the output is the same." and it's not true.

[David Schwab]

Yes, and vintage weenies will tell you that this sounds terrible! :-/

I tried a buffer in my Tele and it was too harsh sounding. But you can fix that with resistors and caps. Also if you make the input impedance lower on the buffer it sounds more like a passive guitar.

[David Schwab]

No, the effect of loading the pickups will still be audible. You would hear a difference between placing the buffer before the volume control (right after the pickup) vs. after the volume control. Maybe that's what you're trying to say and I'm missing it. (ignoring the fact that you'd have changed pot values after the buffer, etc.)

Yes, that's correct. But you don't get the dulling effect when you turn down the pot. The tone stays even. But you do get some loading effects from the controls, which could be what you want. Sounds more natural to some than buffering the pickup.

I used the Stratoblaster as an example because it installs after the controls, at the output jack.

[Mike Sulzer]

But...it seems we're ignoring the effect of the resistive load on the pickup to ground.

You are right, of course; flattening the peak with a resistor is heard as a loss of treble. That is, after all, how the tone control works until you get pretty close to zero where the capacitor has an effect.

But the treble bleed circuit counteracts the effect of capacitance, not the resistance, that is, the input resistance of the amp. You can see that this is so because turning down the vol pot on the guitar increases the resistance across the pickup by just a bit (since it tends to isolate the pickup from the amp input resistance). Therefore it would tend to increase the treble, not reduce it as the capacitance does.

[Possum]

....

Actually there are very few factory made guitars with decent wiring harnesses, almost all of them can be improved on. You just have to try it or you will never believe it, theory holds no water in this case. If you prefer the plastic coated wire with the foil shield and thin tiny leads over vintage cloth wire, cut identical leads of each, say 2-3 feet long and use your Extech and read the capacitance of each, the vintage cloth/braid wire wins everytime. But there isn't ONE version of the vintage braid/cloth and they vary in capacitance from manufacturer to manufacturer. I have a custom made tele that cost a ton of money and the luthier wired it with that awful plastic crap and it really dulls the sparkle from the single coils alot. He used a complex switing deal so just don't have time to rewire the guitar from scratch.

Changing your guitar cord isn't going to help your wiring harness at all. You need to start at the source, guitar cords are secondary and much easier to change. I just got a George L cable today, so I'm not blind to guitar cords. Fender makes a cheapie low capacitance cord for about 25 bucks but the molded ends always fail, been through 3 of those so far and done with 'em.

[David Schwab]

If you prefer the plastic coated wire with the foil shield and thin tiny leads over vintage cloth wire, cut identical leads of each, say 2-3 feet long and use your Extech and read the capacitance of each, the vintage cloth/braid wire wins everytime.

If it's not shielded cable, you wont have capacitance issues. If the insulator between the shield and the hot is thicker, the capacitance should be lower.

Vintage cloth/braid wire loses if you need 4 conductor cables.

Craig Anderton did tests once and found that patch cords with molded plugs were lower in capacitance, which is not surprising if you think about it.

[Steve Conner]

Craig Anderton also used to do blind tests showing that people struggled to tell the difference between solid state and tube guitar amps. That would get him burnt at the stake here :-)

Guitar cord capacitance typically runs about 20-30pF per foot. I think George L's is 21pF. 5pF/ft is almost impossible, because the capacitance depends on the logarithm of the ratio between core and screen diameters. To get the capacitance down by a factor of 4, you have to make the centre core e^4 times, or about 54 times smaller.

Scope probe leads need very low cable capacitance, so they use a hair-thin steel wire in a foamed poly dielectric. The wire breaks easily and is a PITA to mend: you couldn't use it as guitar cord.