Linear V Log ? 300K V 500K ?

[John Rutherford]

It's that time of year again for this old argument.

 

Not happy with Gibson's habit of using 300K Linear pots for volume on new models.

I went back to the tried and tested Gibson circuits of the 1960s and test fitted a 500K Log for volume on one of my

P90 Gibsons.

 

I must say the difference was rather marked, sound was brighter and the volume more controllable

from 1 to 10.

 

I've since fitted all 6 of my Gibsons with 500K Logs, and on the double pick-up SG Specials

the mixing of bridge and neck PUPs in the centre toggle position is more rewarding soundwise.

 

It's worth a try if you are unhappy with your SG sound.

[stein]

GOOD topic.

 

I don't know why the use of 300k linear for volume either. To be honest though, I haven't tried or compared. But it doesn't make sense.

 

Personally, I wasn't aware of linear being used in any guitars, I thought they were all audio taper or log. So, I never thought to even consider linear for a guitar.

 

I was always told that the "proper" pots for P-90's were 300k. However, when researching (years ago now), all I found for info on vintage Gibby's were 500k. And, sometimes, 250k.

 

I was in the habit of measuring, and what I discovered, nearly all 300k pots I measured came in around 350k to 390k or so, some over 400k. 500k pots on the other hand, measured 500k or less, sometimes down to around 400k. That was measuring anything I could get a hold of of various vintage (even if not actual "vintage" Gibby pots, but various NOS pots and a lot of new ones). Basically, it was common to have 300k pots that measured high to be the same as 500k pots that measured low.

 

I kinda developed a thoery that the reasom 300k became the "standard" spec for P-90 stuff was that it was the closest thing to what the origonals were, and that only 500k or 250k was common.

 

Sinse then, with more internet available, I think that's likely wrong. I don't find any real consistancy to it, while I don't see hard facts or info either. Best I can figure, Gibby chose values based more on the model of guitar, rather than the P-90 pup. I see consistancy in that most Jr's seem to be 500k volume and 250k tone.

 

My other "best guess" is that at the time of the humbucker being used, things seemed to standardize with 500k for everything.

 

And honestly, I STILL don't know for sure where the 300k spec for P-90's come from, or if it ever really was.

[John Rutherford]

The main beef is the use of Linear ones, it has little effect on volume from position 4 to 10.

That's the reason Logarithmic pots were invented.

 

They use them for Tone pots .

 

I agree about the crazy randomness of the pot resistance values.

The 250K one on my Melody Maker was 296K and a few 300K ones I ditched were down to 275K, bad quality control or what ?

[DiamondJig]

I really like the 300K linear. I find them very usable from 10 to 0. I don not like audio pots at all for volume. I just changed out the push/pull 500K audio on my LP trad pro for 300K linear. Don't know if I ever tried the 500K LOG pots.

[Snoopy]

Firstly, a LOG pot is the same as an Audio pot. The push/pull pots on Gibson guitars all seem to be 500k Audio taper pots. The non push pull pots are typically 300k Linear taper pots.

 

Audio taper pots are incorrect for the volume control on a guitar but linear taper push/pull pots are not readily available so they use Audio taper. On the audio taper nothing at all happens until the volume control is on at least 2 on the dial. This contrasts with the 300k linear taper (the correct type for a guitar volume) in which sound is apparent at 1 on the dial. Volume increases at the same amount for every number on the dial up to 10 which should be what one would expect a volume control to do right? I'll get back to that.

 

With and Audio taper pot as I said nothing happens till 2 and not much more happens at 3 or 4. You need to go up to about 6 to get an appreciable increase in volume over the initial level at position 2 on the dial. You will find that the volume increases very steeply with only a very short movement of the volume control from 6 to 7 or 8, and then up some more to 10. There is very little subtle control over the volume level when using this type of pot. It is most definitely the incorrect pot to use in this guitar volume control application.

 

You don't agree? Well you're welcome to be wrong, and welcome to like what is wrong and to use what is wrong and to buy what is wrong because big corporations sell things to you. Remember when I said that's how one would expect a volume control to behave, well imagine a large power amp for your stereo or PA setup. That volume knob doesn't behave like the guitar with an audio pot for a volume control scenario mentioned above.

 

When it comes to the passive filter that is the tone control you get a roll off of the treble frequencies above a cut off point which you can vary with the tone pot. In this case a smooth transition of tone is achieved using a logarithmic potentiometer.

 

I to bought some Gibson 300k linear pots to put into my Gibson Les Paul Traditional Pro as it was clearly WRONG!!! with it's audio taper push/pull pots.

 

 

So to sum up the guitar volume should be LINEAR taper and the guitar tone control should be LOG (Audio) taper. And this is precisely what Gibson uses in their guitar, except when they have to put in a push/pull volume control in which case it's not a readily available part so they incorrectly have to use an audio taper pot.

 

Note: The terms "wrong" is a matter of my opinion, however it is supported by my Electronics background and the evidence that you can hear just how wrong it is for yourself.

[John Rutherford]

These things, like many other are a matter of opinion rather than empirical fact [ Abbott and Costello, funny or crap ? you decide ]

 

500K LOG pots for Volume and Tone seemed to be OK for most P90 Gibbos since Angus Young was in short trousers.

 

Then in the last decade it changed to 300K LIN for volume for some financial rather than prosaic reason.

 

I changed all my new 2 PUP and single PUP P90 Gibsons to 500K Log all round and 50s wiring, they play fine.

[kaicho8888]

Firstly, a LOG pot is the same as an Audio pot. The push/pull pots on Gibson guitars all seem to be 500k Audio taper pots. The non push pull pots are typically 300k Linear taper pots.

 

Audio taper pots are incorrect for the volume control on a guitar but linear taper push/pull pots are not readily available so they use Audio taper. On the audio taper nothing at all happens until the volume control is on at least 2 on the dial. This contrasts with the 300k linear taper (the correct type for a guitar volume) in which sound is apparent at 1 on the dial. Volume increases at the same amount for every number on the dial up to 10 which should be what one would expect a volume control to do right? I'll get back to that.

 

With and Audio taper pot as I said nothing happens till 2 and not much more happens at 3 or 4. You need to go up to about 6 to get an appreciable increase in volume over the initial level at position 2 on the dial. You will find that the volume increases very steeply with only a very short movement of the volume control from 6 to 7 or 8, and then up some more to 10. There is very little subtle control over the volume level when using this type of pot. It is most definitely the incorrect pot to use in this guitar volume control application.

 

You don't agree? Well you're welcome to be wrong, and welcome to like what is wrong and to use what is wrong and to buy what is wrong because big corporations sell things to you. Remember when I said that's how one would expect a volume control to behave, well imagine a large power amp for your stereo or PA setup. That volume knob doesn't behave like the guitar with an audio pot for a volume control scenario mentioned above.

 

When it comes to the passive filter that is the tone control you get a roll off of the treble frequencies above a cut off point which you can vary with the tone pot. In this case a smooth transition of tone is achieved using a logarithmic potentiometer.

 

I to bought some Gibson 300k linear pots to put into my Gibson Les Paul Traditional Pro as it was clearly WRONG!!! with it's audio taper push/pull pots.

 

 

So to sum up the guitar volume should be LINEAR taper and the guitar tone control should be LOG (Audio) taper. And this is precisely what Gibson uses in their guitar, except when they have to put in a push/pull volume control in which case it's not a readily available part so they incorrectly have to use an audio taper pot.

 

Note: The terms "wrong" is a matter of my opinion, however it is supported by my Electronics background and the evidence that you can hear just how wrong it is for yourself.

 

 

Like you, I prefer linear taper for volume control since it affords more incremental control than a logarithmic potentiometer. But I've also gotten use to using the log pot on some of my LP's where it requires finer movements of the pot for volume control.

 

I don't consider "wrong" in either set ups...just what you prefer and what you are comfortable with to achieve making your music!

[TheTubeDude]

Hey Snoopy. I couldn't let your comment stand unchallenged. You must have skipped the chapter or class that could have explained to you

why logarithmic/audio pots were developed. Your explaination is inside-out and upside-down. A dis-service is done to those who might take

your mis-information as presented.

 

 

Firstly, a LOG pot is the same as an Audio pot. The push/pull pots on Gibson guitars all seem to be 500k Audio taper pots. The non push pull pots are typically 300k Linear taper pots.

 

Audio taper pots are incorrect for the volume control on a guitar but linear taper push/pull pots are not readily available so they use Audio taper. On the audio taper nothing at all happens until the volume control is on at least 2 on the dial. This contrasts with the 300k linear taper (the correct type for a guitar volume) in which sound is apparent at 1 on the dial. Volume increases at the same amount for every number on the dial up to 10 which should be what one would expect a volume control to do right? I'll get back to that.

 

With and Audio taper pot as I said nothing happens till 2 and not much more happens at 3 or 4. You need to go up to about 6 to get an appreciable increase in volume over the initial level at position 2 on the dial. You will find that the volume increases very steeply with only a very short movement of the volume control from 6 to 7 or 8, and then up some more to 10. There is very little subtle control over the volume level when using this type of pot. It is most definitely the incorrect pot to use in this guitar volume control application.

 

You don't agree? Well you're welcome to be wrong, and welcome to like what is wrong and to use what is wrong and to buy what is wrong because big corporations sell things to you. Remember when I said that's how one would expect a volume control to behave, well imagine a large power amp for your stereo or PA setup. That volume knob doesn't behave like the guitar with an audio pot for a volume control scenario mentioned above.

 

When it comes to the passive filter that is the tone control you get a roll off of the treble frequencies above a cut off point which you can vary with the tone pot. In this case a smooth transition of tone is achieved using a logarithmic potentiometer.

 

I to bought some Gibson 300k linear pots to put into my Gibson Les Paul Traditional Pro as it was clearly WRONG!!! with it's audio taper push/pull pots.

 

 

So to sum up the guitar volume should be LINEAR taper and the guitar tone control should be LOG (Audio) taper. And this is precisely what Gibson uses in their guitar, except when they have to put in a push/pull volume control in which case it's not a readily available part so they incorrectly have to use an audio taper pot.

 

Note: The terms "wrong" is a matter of my opinion, however it is supported by my Electronics background and the evidence that you can hear just how wrong it is for yourself.

[John Rutherford]

Hey Snoopy. I couldn't let your comment stand unchallenged. You must have skipped the chapter or class that could have explained to you

why logarithmic/audio pots were developed. Your explaination is inside-out and upside-down. A dis-service is done to those who might take

your mis-information as presented.

 

Yes, agreed.

 

In my experience Linear Pots give meagre volume adjustment from 3-10 this is in marked difference

to Log Pots which give a smooth and obvious increase in volume over the same range of 3-10.

 

There was little wrong with the tried and tested system of 500K Log Pots for Tone and Volume on Gibsons.