Hot wired pickup louder than conventional wiring

mwmeci

Member
Messages
12
I had a pair of classic 57's I bought used that came out of an Es339 Gibson. Identical resistance.
I put one in an Epi Es339 and hot wired it so the volume and tone pots are out of the circuit. I always wanted to try this. I put the other one in a import Les Paul and wired it normally. The hot wired one is noticeably louder. It's also much brighter but I assume that has to do with the wood and construction of the different models. I didn't think the added impedance when going through the pot would affect the output. After all when the pot is on 10 it's essentially a dead short from the middle lug to ground, i.e. zero ohms.
Any thoughts?
 

Dave Weir

Gold Supporting Member
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1,523
Most pots have some resistance even at 10, and that will lower volume a bit, or for tone leave a bit of the cap in the circuit. You can get "No Load" pots that have much closer to zero resistance. I just checked one and it is rated at 500K but sweeps from about .478M to 1.2 ohms wide open. I'm guessing the .478M would be the same as 478K, which I think is within the normal tolerance for these things.
 
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StratoCraig

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3,219
After all when the pot is on 10 it's essentially a dead short from the middle lug to ground, i.e. zero ohms.

I think I must be having trouble understanding what you mean, because what you seem to have said is wrong. In typical electric guitar wiring (including Les Pauls), the volume and tone pots have maximum resistance between the middle lug and ground when they're on 10. So a 500K pot will be 500K in that situation, not zero or "a dead short".

I've never tried hooking up a guitar with no controls at all, but you know that a no-load tone pot on 10 makes the signal brighter than a normal pot because it removes itself from the circuit, right? You're basically doing that for both volume and tone, so the guitar gets louder and brighter.

I'm guessing the .478M would be the same as 478K, which I think is within the normal tolerance for these things.

Yes, .478M is the same as 478K. And yes, 478K is about -5%, which is well within the normal tolerance for pots.

You make electric guitars, but you aren't sure of the relationship between K and M and have to "guess"?
 

walterw

Platinum Supporting Member
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40,984
I put one in an Epi Es339 and hot wired it so the volume and tone pots are out of the circuit. I always wanted to try this. I put the other one in a import Les Paul and wired it normally. The hot wired one is noticeably louder.
regular pots even on "10" will trim a bit of high end and output, but the epi pots should be 500k so that loss should be minimal, just a slightly less edgy tone. even then you might not be able to notice unless it was wired to a switch so you could instantly compare.

you shouldn't have one be noticeably louder though; my suspicion is that there's a wiring problem with the LP copy that's choking the pickup more than it should, and/or you don't have the pickup distance to the strings absolutely identical.
 
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18,321
you make think that the signal wire being connected directly to the output on one side of the pot means nothing is interfering, but think about the other side of the pot, which is connected to ground.
you've only got 250 or 500k Ohms between the signal source & ground on that side.

before I dropped all the controls in my Rickenbacker, I wired it up direct & it was dead quiet as well as louder than after I put the V/V/T controls in
there was also just a bit of noise with the controls in & absolutely none w/o the controls
 

Dave Weir

Gold Supporting Member
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1,523
You make electric guitars, but you aren't sure of the relationship between K and M and have to "guess"?

I didn't feel like looking it up, and I wasn't sure, so I called it a guess. Maybe "assume" would have been a better word. I know pots are often rated in K (Thousand) Ohms, but my meter automatically switches scales and I wasn't certain "M" was million ohms. A lot of people in these forums will state as fact things they really don't understand, or state opinions as fact. I try to avoid that. Anyway, thanks for confirming. I don't install tone pots or volume pots on my guitars, so what do I know.

One thing I've always wonder about the discussions between 500k or 250k. If you want 250k, can't you just install a 500k and turn down to 250k? Just guessing again, but it seems like if it sweeps from 500,000 to 1, somewhere in there it was at 250,000. Maybe too close to 10 to be manageable?
 

StratoCraig

Member
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3,219
For a tone knob, yes, you can install a 500k pot and turn it down to about 7 (if it's an audio-taper pot, which is usually what you want for a tone control) and it will sound the same as a 250k pot on 10.

For a volume knob, no, because the volume pot is wired as a voltage divider (all three lugs are connected to something), whereas the tone control is wired as a rheostat (one side lug not connected to anything). This means the pickup always sees the full value of the volume pot, even if it's turned down, whereas the value of the volume pot seen by the pickup changes as you turn the tone knob up and down.

K and M are basic metric system prefixes. K, or kilo, is thousands, while M, or mega, is millions. K is actually supposed to be lowercase k, but people are sloppy about that. Fortunately capital K isn't used for anything in this system (except in computer science), so there's no confusion.

https://en.wikipedia.org/wiki/Metric_prefix
 
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vortexxxx

Member
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11,421
Pickups sound more dynamic if you wire them directly to the output. Some musicians are known for doing that.
 

Dave Weir

Gold Supporting Member
Messages
1,523
What would be the effect of having the output on the volume pot right off the input lug. Not work a t all or slightly louder at full volume, slightly brighter as you roll it off? Or something else?
What is the advantage of a 250K Volume Pot? It's just never as loud?
 

walterw

Platinum Supporting Member
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40,984
What would be the effect of having the output on the volume pot right off the input lug. Not work a t all
yep, the volume wouldn't work at all, it would be full blast no matter what.
What is the advantage of a 250K Volume Pot?
vs. a 500k? not quite as bright (good for fender style single coils, they sound too harsh and nasty at 500k) and a smoother sweep from off to full.
 

mwmeci

Member
Messages
12
I think I must be having trouble understanding what you mean, because what you seem to have said is wrong. In typical electric guitar wiring (including Les Pauls), the volume and tone pots have maximum resistance between the middle lug and ground when they're on 10. So a 500K pot will be 500K in that situation, not zero or "a dead short".
What I meant was, putting the pickup hot lead on the middle lug of the volume pot, which goes to the output jack tip or hot connection, I'm by passing the 500k ohms of the pot.
Is that correct?
 

StratoCraig

Member
Messages
3,219
Okay, I know you've got the hot wire from the pickup connected to the middle lug of the volume pot, but what else are the three pot lugs connected to? When you say "the pickup hot lead on the middle lug of the volume pot, which goes to the output jack tip", do you mean there is also a wire going from the middle lug of the volume pot straight to the output jack? Meaning you're trying to bypass the pot? If that's the case, then are the other two lugs of the pot connected to anything? The only way to get the pot completely out of the circuit is to make sure there is no path through the pot to the output jack.

Maybe a picture of your wiring would help so I can see all the connections.
 

mwmeci

Member
Messages
12
It's too hard to get the push pull pots out to take picture. I think the switch wire is also connected to the middle lug.
index.php
I can't figure out how to post an image. There's a PDF file in the link below.
http://forum.gibson.com/index.php?/topic/87329-es339-opened-up/
 

StratoCraig

Member
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3,219
I see the PDF. It doesn't look to me like the pickup is going to the middle lug of the volume pot. This looks like modern Gibson wiring, with the addition of coil-splitting switches. The hot wire from the pickup (in red) is going to the right-hand (in the drawing) lug, and continues from the middle lug to the pickup selector switch. So it's passing through the pot.
 

mwmeci

Member
Messages
12
the pickup (in red) is going to the right-hand (in the drawing) lug,
That's how I originally wired it, but the volume went from nothing to full volume from 0 to 2 on the volume knob. So I decided to have the neck pickup on without the controls.
Before I soldered it I used alligator clip type jumpers to try all the options an could never get the volume and tone pots to work correctly.
 

walterw

Platinum Supporting Member
Messages
40,984
What I meant was, putting the pickup hot lead on the middle lug of the volume pot, which goes to the output jack tip or hot connection, I'm by passing the 500k ohms of the pot.
Is that correct?
nope.

you still have the 500k between that center lug and ground, which still affects the sound.
 

mwmeci

Member
Messages
12
So, if I took the hot wire from the pickup and the wire to the switch off the middle lug of the pot and soldered them together the pot would be out of the circuit?
Long sentence!
 

walterw

Platinum Supporting Member
Messages
40,984
So, if I took the hot wire from the pickup and the wire to the switch off the middle lug of the pot and soldered them together the pot would be out of the circuit?
if you disconnected the pot entirely then yes it would be disconnected ;)
 




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