Tone Pots: Linear or Audio? Why?

[David Schwab]

I've always thought A=audio taper, B=logaritmic taper.

What do you mean when you say Linear taper? A or B?

I'm all ears!

Audio and log are the same thing.

The Secret Life of Pots

This compensating resistance taper is accurately called a "left hand logarithmic taper" but for historical reasons has been called an audio or log pot.

A is audio and B is linear in the US.

[Vihar]

I'm all ears!

No you're more like all tongues and zero knowledge.

[David Schwab]

No you're more like all tongues and zero knowledge.

I'm getting tired of your attitude. Find a less insulting tone to use here.

You don't know what he knows and what he doesn't know, so you can't quantify your remark.

[uvacom]

Yes, because you want half way to be half way.

Half way to what? A linear pot will attenuate the voltage by half at the halfway point, but the ear will perceive it to be about 69% as loud. If you want the halfway point to equal half the perceived volume, log taper is the way to go.

That said, that is not always the desired behavior of the pot, as you have mentioned, so a linear taper (or some other taper) might be more appropriate depending on usage.

[David Schwab]

Half way to what? A linear pot will attenuate the voltage by half at the halfway point, but the ear will perceive it to be about 69% as loud. If you want the halfway point to equal half the perceived volume, log taper is the way to go.

Look at a graphic EQ or active tone controls. They aren't set up like that. You have +/- 10dB or what ever. You can see the compressed range on the volume sliders, but the tone controls are linear. If it didn't work as expected, they wouldn't be making them that way.

But I accept that some people like log taper tone controls.

That said, that is not always the desired behavior of the pot, as you have mentioned, so a linear taper (or some other taper) might be more appropriate depending on usage.

I agree.

[David Schwab]

And as for the post that is no longer here... I actually got reports on it, which is why I came to see. The poster wasn't adding anything to the conversation. LtKojak didn't know something, big deal. The difference was a couple of people explained it to him. And someone didn't.

As far as my actions, I get tired of people who act like idiots. That comes with age, so I'm certainly not childish.

[LtKojak]

No you're more like all tongues and zero knowledge.

You really know how to make friends on the forum, Vihar!

[LtKojak]

Audio and log are the same thing.

The Secret Life of Pots



A is audio and B is linear in the US.

Ok, that's what I thought. I get my pots from Alpha, which are american made. At least here in Italy CTS pots cost more than double than Alpha and are not so easy to get either... most pots sold here are chinese-made... not a good thing!

I don't think I've used B pots... ever! Does it make me a bad guy...?

I don't remember anybody complaining either...

[David Schwab]

You really know how to make friends on the forum, Vihar!

Not to beat a dead horse... but go to his profile and look at all the posts by him. They all have a similar tone to them...

[uvacom]

Look at a graphic EQ or active tone controls. They aren't set up like that. You have +/- 10dB or what ever. You can see the compressed range on the volume sliders, but the tone controls are linear. If it didn't work as expected, they wouldn't be making them that way.

Graphic EQs sound lousy and cheap and don't give a musical response no matter what, so I think that's why taper doesn't matter. But I think those are also a case where you actually want a logarithmic response so a linear pot is appropriate. IMHO if we had really good tone controls in guitars, they would be VCFs, which would require exponential voltage control in order to provide usable control. But ironically the pot would still be linear, because no exponential taper pot has a precise enough slope to produce 1V/octave.

[David Schwab]

We wouldn't need a VCF... why voltage control? There's no need for it. They use VCF in analog synths because the whole system works on voltage control, including the oscillators.

So suppose you have a low pass filter installed with a frequency knob. How do you want the knob's taper? If the control goes from 500 Hz to 5KHz, you want the rotation of the knob to evenly distribute the cutoff frequency.

The thing you don't like about graphic EQ is the phase shift issues. It has nothing to do with the slider's taper. There are very good sounding EQs, and most of the recordings you listen two have probably gone through one in the mixing or mastering stage.

[maltone]

Mark Hammer...

Mark, can you please help me. I have a 2005 Gretsch Firebird with Alnico Filtertron pickups. I'm adding a hotter TV JONES Classic Plus Bridge: TV Jones Guitars and Pickups and a treble bleed mod on the Master Volume, and converting my tone switch - to a tone pot.

I took a look inside the back this morning, and the volume pots read:
037407 0506 CTS.

How do I find out if the pots are 500K or 250K. Because these are humbuckers, typically, Gretsch installs 500k pots.

What do these numbers refer to, and will they tell me anything? Much Thanks.

[billyz]

Do you have a Digital Multimeter? Sent to Ohms and measure the outside lugs. might need to disconnect the pickup first.

Most likely they are 500k. I recently installed a set of custom built TV jones pickups and I found 500k Audio worked the best for me. You can play with the treble bleed cap (tone control). I believe I ended up with .022, but I tried .047 and .01. Believe it or not the type of tone cap seemed to make a small difference in the smoothness of the tone rolloff. I preferred a polyester film cap, like mallory 150.

I have also used 250k A pots in a tele retrofit and that valued worked fine. Perhaps a small loss of highend and a little gain reduction, but hardly noticeable. Conversely 1 meg pots will give a little brighter tone and a little more output.

[maltone]

billyz... CTS Tone Pots...

Billy, thanks for your reply. I'm trying to keep things simple. In my case, I'm also option for the TV Jones Classic Plus Bridge pickup, which is rated at:

7.79k* DC Resistance, and 3.71 H Inductance (whatever that means, I'm a newbie).

But, I know what 7.8k sounds like in a bridge through a Marshall, compared to my current 4.6 rated bridge pickup - hence the change, I want more output and growl.

With regards to the pots, I need 500K, solid shaft, 3/8 inch pots. Where I'm a bit confused, is what to use for the volume pots. Someone has suggested a linear pot for a more even, and incremental increase or decrease in volume - basically, I want it to feel and sound as natural as possible. NOT that jump from quieter to LOUD all of a sudden. I like the idea of being able to roll down the volume incrementally.

I know Linear pots are more common for Tone, but couldn't I use 500K linear pots all around? Much thanks.

[maltone]

I forgot to ask you Billy, you mentioned

I preferred a polyester film cap, like mallory 150.

I've been asking about resistors and caps as well. This is what TV Jones uses on their treble bleed mod: https://tvjones.com/cgi-bin/commerce...03-015-0401-00

A .001 mf Vishay/Sprague orange drop cap, with a 1/4 watt, 150k carbon film resistor.

Would I benefit at all from using a different type of cap, like these? Vitamin T (Oil Filled)

Also, would metal film be better, (a 1% tolerance) compared to the 5% tolerance of a carbon film? Would it be noticeable in tone or clarity, noise reduction? Much thanks.