I'm stuck: Passive 25k volume + 500k tone, what happens?

[Silverburst]

Hi everyone,

I'm new to the forum since I'm diving into pickups and guitar electronics. But I'm already stuck with the following problem:

I've got this guitar in my hands that has been fiddled with.

it is a HH 3 switch 1 tone 1 volume passive situation with a 25k (not 250 indeed) volume + 500k tone, and turning the tone know has no effect whatsover. I was breaking my head over this, but I starting to think that is totally logical.

25k's are supposed to be for active elements, whereas 250-500-1M are supposed to be for passives.

Can someone confirm my phenomenon (the tone pot not having any effect) and/or explain ? Would be a great help.

Thanks!

 

[GoldenVulture]

Re: I'm stuck: Passive 25k volume + 500k tone, what happens?

Your right about 25K being used for actives usually. If the tone is wired correctly it should work.

 

[AlexR]

Re: I'm stuck: Passive 25k volume + 500k tone, what happens?

The tone should still work a bit its true. There would be a bit less range than normal, as a 25k vol pot would tame a lot of highs just in itself.

Check the grounding first and foremost.

 

[Silverburst]

Re: I'm stuck: Passive 25k volume + 500k tone, what happens?

Thanks for the inputs!

Checked the wiring over and over again. I just followed the typical seymour duncan sheet I find online for exactly the HH 3 switch vol/tone config. Not much about the tone pot wiring.

At first I tried with a higher cap value, than it has a clear effect to quite muffled, but it al happens on the last 5% of the pot. It is a B500k linear so for tone, it should affect very gradually I'd think. With the original cap I dont hear a thing. I measured the tone cap and it goes indeed very lineair from 0 to 500k.

 

[AlexR]

Re: I'm stuck: Passive 25k volume + 500k tone, what happens?

Most of my tone controls seem to do most of their work in the last few numbers on the dial, but as the 25k vol might be robbing the top end that the cap would normally be rolling off.

 

[Edgecrusher]

Re: I'm stuck: Passive 25k volume + 500k tone, what happens?

What pickups are you using and why do you have a 25k volume pot?

 

[Silverburst]

Re: I'm stuck: Passive 25k volume + 500k tone, what happens?

It is a guitar a friend bought, but the previous owner did all kinds of crazy stuff with it. I do setups, but am still a beginner when it comes to electronics on guitars. It does play nice now, it is a recent Kramer Vanguard.

So it came with these pots installed. Initially the neck pickup, tone pot and switch weren't even wired, so I promised I was going to take a look at that as well. Now I want to get to the bottom of this, understand it and fix it it is like solving a little mystery and trying to figure out what happened here.

Neck: So kind of Ephiphone humbucker, passive, 4 wire
Bridge: Duncan SH4, passive, 4 wire

Thanks !

 

[swissmountain]

Re: I'm stuck: Passive 25k volume + 500k tone, what happens?

25k loads a passive pickup too much, resulting in a very dull tone. And a 500k linear pot works almost like an on-off switch, as you found out.

I would get two 500k log pots for volume and tone. If the SH-4 sounds too sharp with the 500k volume you can use resistors to bring the load down.

 

[swissmountain]

Re: I'm stuck: Passive 25k volume + 500k tone, what happens?

double post, sorry

 

[Silverburst]

Re: I'm stuck: Passive 25k volume + 500k tone, what happens?

oh... I thought linear was good for tone as you want a nice progression of the filtering, and in deed a log pot to match volume awareness of the human ear.

So you think the 25k which loads the pickup already too much leaves almost nothing for the 500k + cap to have any effect ? With the stronger cap to magnify the possible too subtle effect that might be going in with the original cap, it indeed feels almost like an on off effect at the end of the sweep.

 

[GuitarDoc]

Re: I'm stuck: Passive 25k volume + 500k tone, what happens?

At least replace that 25k vol pot with a 250k or 500k audio/log pot before worrying about what the tone pot is or isn't doing.

It's like...."I know the battery in my car is dead, but I'm concerned about my radio, it doesn't work. Could it be wired wrong, is a fuse blown, is the radio just bad?"

Fix the most obvious problem first then worry about the next problem (if there even is one).

Isn't that obvious?!

 

[Silverburst]

Re: I'm stuck: Passive 25k volume + 500k tone, what happens?

yes of course it is obvious, but it is not my guitar and I don't have spare pots lying around. So I just wanted to get some certainty before buying any hardware. Not that pots are expensive, but anyway, just thinking/learning before I do.

 

[jeremy]

Re: I'm stuck: Passive 25k volume + 500k tone, what happens?

im also guessing the 25k pot is messing everything up, fix that before you spend more time on anything else. not having tried a passive pup with that value volume control i dont know what to expect so trouble shooting will be difficult. $5 and you can wire in the new pot and then see how things behave

 

[Silverburst]

Re: I'm stuck: Passive 25k volume + 500k tone, what happens?

So I swapped the 25k pot with the 1M pot I had lying around and the duncan in the bridge gives lot more beef now. The tone pot has clearly more effect now as well, although not tremendously.