Replace the vol pot or the tone pot to reduce brightness?

Longboarder

Longboarder

New member
Need some help here

Just ordered a PG pup for the bridge on my Epi dot and will also replace one of the pots from 500k to 250k. Thought replacing the vol pot (is easier) would reduce my brightness and do the trick, but was reading some threads that say changing the vol pot will not change the tone specially all full volume THAT I NEED TO REPLACE THE TONE POT INSTEAD. Has anyone actually done this?

PS All this pot talk is confusing me
 
Re: Replace the vol pot or the tone pot to reduce brightness?

Whoever you were talking to has it backwards. The volume pot changes the tone at full volume. 250k will have less highs than 500k. The tone pot doesn't make very much difference when it's set at full though.
 
Re: Replace the vol pot or the tone pot to reduce brightness?

GuitarStv said:
Whoever you were talking to has it backwards. The volume pot changes the tone at full volume. 250k will have less highs than 500k. The tone pot doesn't make very much difference when it's set at full though.
Click to expand...

I take it then that replacing the vol pot to 250k will reduce my brightness at ANY volume?
 
Re: Replace the vol pot or the tone pot to reduce brightness?

Longboarder said:
I take it then that replacing the vol pot to 250k will reduce my brightness at ANY volume?
Click to expand...

Yes, but only at the very highest frequencies. If you want to block out the high/high mids you might be better off trying new tone caps and using your tone control a bit.
 
Re: Replace the vol pot or the tone pot to reduce brightness?

I disagree. They work together. The high frequencies path to ground is the two pots in paralell, while the lower frequencies path to ground is the volume pot. Changing the relative balance of the volume pot to the combined pots will affect the ammount of HF rolloff.

Also, smaller volume pot is like but not exactly the same as turning down the volume on a larger pot. Smaller values will give some high frequency rolloff like turning the volume down does, but the inline resistance changes too.

A smaller tone pot is exactly like turning down a larger tone pot. Turn your existing 500k tone pot until it reads 250k and that is exactly what the guitar will sound like when the new 250k pot is maxed.
 
Re: Replace the vol pot or the tone pot to reduce brightness?

Chocol8 said:
I disagree. They work together. The high frequencies path to ground is the two pots in paralell, while the lower frequencies path to ground is the volume pot. Changing the relative balance of the volume pot to the combined pots will affect the ammount of HF rolloff.

Also, smaller volume pot is like but not exactly the same as turning down the volume on a larger pot. Smaller values will give some high frequency rolloff like turning the volume down does, but the inline resistance changes too.

A smaller tone pot is exactly like turning down a larger tone pot. Turn your existing 500k tone pot until it reads 250k and that is exactly what the guitar will sound like when the new 250k pot is maxed.
Click to expand...

I'm sorry, but I believe that's not quite right. Putting a lower value pot in the volume position (eg: a 250k instead of a 500k) will make the tone darker. Try it in a guitar that only has a vol pot, no tone pot. It is not dependant on having two pots in parallel. The high frequency loss is more dependant on the value of the vol pot (when wide open) and the capacitor + tone pot (when rolled off).
 
Re: Replace the vol pot or the tone pot to reduce brightness?

GuitarDoc said:
I'm sorry, but I believe that's not quite right. Putting a lower value pot in the volume position (eg: a 250k instead of a 500k) will make the tone darker. Try it in a guitar that only has a vol pot, no tone pot. It is not dependant on having two pots in parallel. The high frequency loss is more dependant on the value of the vol pot (when wide open) and the capacitor + tone pot (when rolled off).
Click to expand...

Read what I wrote carefully: "Smaller values will give some high frequency rolloff" which we both agree is true. But, changing either one will influence the tone. They both influence the tone on their own and they interact with each other. The advice that says its the tone pot or its the volume pot are wrong, it is both pots.
 
Re: Replace the vol pot or the tone pot to reduce brightness?

The way I understand it, a dimed 500K volume pot is brighter than a dimed 250K volume pot because there is more resistance to ground with the 500K pot.

And putting a 500K volume pot at the 250K position is not the same as a dimed 250K pot. In that situation, the resistance to ground would be the same...but the 500K-pot-set-on-250K has more resistance to the output, so it will be darker.

Two things are happening as you turn up a volume pot:

1) resistance to ground is increasing
2) resistance to output is decreasing

Just throwing that out there....
 
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Re: Replace the vol pot or the tone pot to reduce brightness?

Chocol8 said:
Read what I wrote carefully: "Smaller values will give some high frequency rolloff" which we both agree is true. But, changing either one will influence the tone. They both influence the tone on their own and they interact with each other. The advice that says its the tone pot or its the volume pot are wrong, it is both pots.
Click to expand...

Actually, I did read what you wrote...carefully. If YOU read what I wrote, you will see that I was responding to your statement..."They work together. The high frequencies path to ground is the two pots in paralell (sic)".

Your previous post said that the tone was a factor of both pots in parallel. That's why I responded about a guitar with only a vol pot.

I also would say that changing a vol pot from 500k to 250k does not affect the volume the same as turning the 500k pot down to 250k resistance. I think Chad's explanation is more correct...you have to consider the resistance to input as well as the resistance to output/ground. Otherwise, putting 250k pots in would reduce your volume by about half. And that does not happen.
 
Re: Replace the vol pot or the tone pot to reduce brightness?

I don't need to argue with you but what I said was true, there is a parallel path to ground and it is a major influence on the tone even if it is not the only thing in play. I also mentioned the inline resistance is different when turning down a larger volume pot. That is not a factor with the tone pot in normal wire schemes.

Changing EITHER pot will change the tone, changing both will change the tone, removing either or both will change the tone.
 
Re: Replace the vol pot or the tone pot to reduce brightness?

Just one more question...

Chocol8 said:
The high frequencies path to ground is the two pots in paralell
Click to expand...
So you're saying that if you roll off either the vol or the tone pot, the highs are shunted to ground and the tone becomes darker/less treble?

while the lower frequencies path to ground is the volume pot
Click to expand...
.
Then as you roll off the vol you shunt the low frequencies to ground and the tone becomes brighter?

Since this isn't what actually happens, what you are saying is very confusing. I guess I don't understand what you are saying.
 
Re: Replace the vol pot or the tone pot to reduce brightness?

How do you tell what pots are in the guitar?
 
Re: Replace the vol pot or the tone pot to reduce brightness?

Ask the manufacturer [only reliable if the guitar hasn't been modified by it's previous owner] or pop open the control cavity and either test it with a ohmmeter or read the value off the back of the pot if it hasn't been soldered over.
 
Re: Replace the vol pot or the tone pot to reduce brightness?

GuitarDoc said:
.
Then as you roll off the vol you shunt the low frequencies to ground and the tone becomes brighter?

Since this isn't what actually happens, what you are saying is very confusing. I guess I don't understand what you are saying.
Click to expand...

As you roll off the volume you are rolling of all frequencies PLUS you are altering the LP filter crated by the tone pot and cap. How you wire (modern? 50's?) will determine what happens. The circuit is not as simple and straight forward as it looks. You won't understand exactly what is happening with a basic knowledge of circuits and passive filters.

To keep it simple the two pots are always interactive. The guys at Gibson and Fender in the 50's knew what they were doing. They did not change the pots independently. You will note that Fender used 250K pots for both volume and tone on brighter single coil guitar. Gibson used 500K for both in darker humbucker guitars. After more than 5 decades neither has deviated from that. I am not saying you can't or shouldn't change one or the other, tone is subjective and we all want something a little different. That said, if you don't understand the circuit and you don't want to buy a bunch of parts for trial and error testing, it is probably best to follow tried and true designs. I personally would recommend you keep the pots fairly matched. Smaller to warm up, larger to brighten.
 
Re: Replace the vol pot or the tone pot to reduce brightness?

I didn't take enough time to fully explain my first two posts, so let me try now:

The volume pot in a guitar circuit acts as a voltage divider . . . so the pickups electrically "see" the same load from it no matter what position it's in. This means that taking a 500k volume pot and turning it to 250 will still sound different (brighter) than taking a 250k volume pot and leaving it on full.

Since the tone pot acts like a relatively linear high pass filter, taking a 500k tone pot and turning to 250k will be exactly the same sound as a 250k tone pot full up.

The upshot of all this:
- Replacing the volume pot with a lower value will decrease the peaky highs from your guitar and make it sound less focused on certain higher frequencies. This sounds darker in a different way than just lowering the tone pot . . .
- Replacing the tone pot with a lower value will act like turning your tone knob down a little bit. It gets darker, but in a different way (try rolling back your tone control a bit and you'll hear what this sounds like). To me, this is a useless mod . . . if you wanted a lower tone value, it's easier to just manually lower the tone pot than replace it completely.
- Tweaking the tone capacitor to different values will change the way that the tone roll-off sounds.

There's some cool information about this here:
http://emarsk.wordpress.com/
http://www.thegearpage.net/board/archive/index.php/t-848294.html

If this is off base, let me know please . . .
 
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Re: Replace the vol pot or the tone pot to reduce brightness?

GuitarStv said:
I didn't take enough time to fully explain my first two posts, so let me try now:

The volume pot in a guitar circuit acts as a voltage divider . . . so the pickups electrically "see" the same load from it no matter what position it's in. This means that taking a 500k volume pot and turning it to 250 will still sound different (brighter) than taking a 250k volume pot and leaving it on full.

Since the tone pot acts like a relatively linear high pass filter, taking a 500k tone pot and turning to 250k will be exactly the same sound as a 250k tone pot full up.

The upshot of all this:
- Replacing the volume pot with a lower value will decrease the peaky highs from your guitar and make it sound less focused on certain higher frequencies. This sounds darker in a different way than just lowering the tone pot . . .
- Replacing the tone pot with a lower value will act like turning your tone knob down a little bit. It gets darker, but in a different way (try rolling back your tone control a bit and you'll hear what this sounds like). To me, this is a useless mod . . . if you wanted a lower tone value, it's easier to just manually lower the tone pot than replace it completely.
- Tweaking the tone capacitor to different values will change the way that the tone roll-off sounds.

There's some cool information about this here:
http://emarsk.wordpress.com/
http://www.thegearpage.net/board/archive/index.php/t-848294.html

If this is off base, let me know please . . .
Click to expand...

Very nice....well done
 
Re: Replace the vol pot or the tone pot to reduce brightness?

GuitarStv said:
I didn't take enough time to fully explain my first two posts, so let me try now:

The volume pot in a guitar circuit acts as a voltage divider . . . so the pickups electrically "see" the same load from it no matter what position it's in. This means that taking a 500k volume pot and turning it to 250 will still sound different (brighter) than taking a 250k volume pot and leaving it on full.

Since the tone pot acts like a relatively linear high pass filter, taking a 500k tone pot and turning to 250k will be exactly the same sound as a 250k tone pot full up.

The upshot of all this:
- Replacing the volume pot with a lower value will decrease the peaky highs from your guitar and make it sound less focused on certain higher frequencies. This sounds darker in a different way than just lowering the tone pot . . .
- Replacing the tone pot with a lower value will act like turning your tone knob down a little bit. It gets darker, but in a different way (try rolling back your tone control a bit and you'll hear what this sounds like). To me, this is a useless mod . . . if you wanted a lower tone value, it's easier to just manually lower the tone pot than replace it completely.
- Tweaking the tone capacitor to different values will change the way that the tone roll-off sounds.

There's some cool information about this here:
http://emarsk.wordpress.com/
http://www.thegearpage.net/board/archive/index.php/t-848294.html

If this is off base, let me know please . . .
Click to expand...

To clarify, with a volume pot, the pickups see the same load...and that load is continually being split between the output and ground.

Wouldn't a dimed 250K pot be brighter than a 500K-pot-set-to-250K? Resistance to ground would be the same in that situation, but the 500K-pot-set-to-250K would have 250K resistance to the output vs the 250K pot would have no resistance to output, so the latter should be brighter.

As far as replacing a tone pot with a lower value being a useless mod, with that logic, shouldn't every guitar have 1meg (or larger) tone pots? At what point is too much, too much? It's a matter of subjective trial and error. If a person NEVER sets their tone pot all the way up, then it might be wise to move to a lower value. An added benefit would be a more spread out taper.
 
Re: Replace the vol pot or the tone pot to reduce brightness?

Chad said:
Wouldn't a dimed 250K pot be brighter than a 500K-pot-set-to-250K? Resistance to ground would be the same in that situation, but the 500K-pot-set-to-250K would have 250K resistance to the output vs the 250K pot would have no resistance to output, so the latter should be brighter.
Click to expand...

I have no measurements for this (and haven't done any A/B comparisons) so I couldn't tell you one way or another. It'll definitely have a different resonant peak though. I CAN tell you with certainty that a 500k volume pot full up sounds tons brighter than a 250k one full up. And that turning back a 500k volume pot does not sound like a 250k volume pot full on.

Chad said:
As far as replacing a tone pot with a lower value being a useless mod, with that logic, shouldn't every guitar have 1meg (or larger) tone pots? At what point is too much, too much? It's a matter of subjective trial and error. If a person NEVER sets their tone pot all the way up, then it might be wise to move to a lower value. An added benefit would be a more spread out taper.
Click to expand...

True enough.

I just figured it would likely not be the change that he wanted . . . most people who are unsatisfied with their guitar tone play with the tone controls first, so I figure that he would have mentioned it in the post if his dream guitar tone was 50% on the tone knob.
 
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Re: Replace the vol pot or the tone pot to reduce brightness?

As far as using mismatched pot values, Jackson used a 500K volume pot and 250K tone pot in my SL1T (JB in the bridge & Classic Stacks in the middle and neck). I really like that combo. Takes a little edge off of the JB, but not too much.

As a matter of fact, I just bought a Charvel Pro-Mod which has a JB & Classic Stack Plus pickups in the middle and neck. It came with only a 500K volume pot. I opted to install an RC network with a 270K (closest I had to 250K) resistor and .047 cap. This replicates the sound I get with both volume and tone dimed on my SL1T.
 
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