Guitar Shop Scam?

[TemjinStrife]

While I have no idea as to the effect on tone, what was said about EMGs and tapers with 250k/500k pots is definitely true.

Basically, what they mean about the pots acting as a switch, is that the taper is very extreme. At full-on, the pickups are on; however, nudge the pot a tiny bit and the volume will cut right out, essentially creating a switch. It's great for killswitch effects, but a bit annoying cause if the pot turns easily it can get shaken or knocked onstage and randomly mute your sound.

[Mike Sulzer]

While I have no idea as to the effect on tone, what was said about EMGs and tapers with 250k/500k pots is definitely true.

Basically, what they mean about the pots acting as a switch, is that the taper is very extreme. At full-on, the pickups are on; however, nudge the pot a tiny bit and the volume will cut right out, essentially creating a switch. It's great for killswitch effects, but a bit annoying cause if the pot turns easily it can get shaken or knocked onstage and randomly mute your sound.

Then there is something funny going on here. If the slider of the pot goes to the output jack which then runs to a standard high impedance (1 Meg ohm) load in the amp how could the pot behave in that way? On at least one model (RG-20) the slider appears to run back into the pickup. It could be internally loaded there, causing funny taper effects with high resistance pots. Other than that, it is hard to see how the taper could be affected.

[PhantomThief]

Hmm, guys, new issue has risen. The guy called me today and I went back to collect the guitar. He played both pickups, which both worked, and also demonstrated that when he removed the battery the pickup would not sound. However, there is something strange. The volume taper appears to be totally unaffected, acting as normal. But the pickup has the EMG logo on it and everything. I'm not sure if something weird is going on. The pickup certainly sounds pretty good though, boosting my distortion significantly.

[Mike Sulzer]

Hmm, guys, new issue has risen. The guy called me today and I went back to collect the guitar. He played both pickups, which both worked, and also demonstrated that when he removed the battery the pickup would not sound. However, there is something strange. The volume taper appears to be totally unaffected, acting as normal. But the pickup has the EMG logo on it and everything. I'm not sure if something weird is going on. The pickup certainly sounds pretty good though, boosting my distortion significantly.

That is exactly what should happen. If it is wired according to the EMG diagram for the 81, the slider goes to the output jack and off to your 1 megohm guitar amp input. Only if the amp impedance were much lower would the taper be affected.

[David Schwab]

EMG requires a 25K, Seymour Duncan requires a 125K and some others require a 50K pot. A 250K will work (as in produce audible sound) but your pickups will sound very poor. EMG pickups already sound shrill but a 250 or 500K pot would make them sound broken.

No it wont. The output impedance of an EMG is already very low, so the difference between a 25K and 250K is negligible. You will not hear any difference in tone, but the action of the pot will work a bit more like an on off switch. They might be ever so slightly louder with the 250K's.

Duncan uses 100K pots, and I've always found EMG's to sound better with 100K pots also. They seem punchier. Duncan preamps will work with either kind of pot, since they work with either passive pickups or active pickups.

I sold a customer some active pickups I made that normally use 25K pots. He was using it with a Basslines preamp, and he tried 250K pots because he had them (this was for pickup volume controls) and he said it was much fuller sounding with the 250K pots. Didn't make sense to me, but he's a good builder so I tried it on one of my basses, which has an EMG BTC preamp, and I couldn't hear any difference at all.

I have a guitar with two EMG pickups and 250K pots in it. Sounds fine, doesn't sound broken or shrill at all.

That being said, you should use 25 or 50K pots with EMG's, but nothing bad will happen if you use a larger value.

[MiKro]

PS if your tech has no clue about the pots, id be real careful about how he wires them in. You'll get a VERY nasty shock (i know of two deaths) if you ever play that guitar plugged into a amp running off dirty power (common), mis labelled power, or touch a mic that is out of phase and on a different circuit (very common) with miswired actives.

Hey Perry, want to explain this a little more...how are actives more prone to shock via mis wired pots than passives?

pete

oops. Reminder to self: Never post on two different forums, about guitar electronics, at the same time and jumping from one reply to the next, whilst answering the phone, and talking with the missus. Its liable to see me put my foot in my mouth!

Post editted here and on another forum

That was fun!!! It's okay Perry we all stick, foot in mouth, occasionaly. It's those that admit it, that are the real HEROES!

sincerely,

Mike

[ElRay]

I asked them a similar question once and got the "acts like a switch" response. It doesn't make sense to me.

Without knowing the specifics of the EMG internals, it sounds like a saturation issue. Between the values of 0 to 25k, you get a reasonably "linear" response. Once you pass 25k, the volume is pegged. So, on a 500k pot, you're looking at 1/20 of a rotation before you cross the 25k threshold. Add to that, the fact that perceived volume is logarithmic, hence volume pots are typically logarithmic, but the EMG circuit might need a linear pot. Switching from linear to log would make the threshold issue even worse.

A pot is just a voltage divider, and it should work as intended as long as it's impedance is large compared to the source impedance.

Depends. Without going too deep into the difference between current sources and voltage sources, this is true if you have a voltage source across the pot, and you're pulling your signal from the wiper. There are plenty of other ways to wire a pot.

Ray

[fookgub]

Without knowing the specifics of the EMG internals, it sounds like a saturation issue. Between the values of 0 to 25k, you get a reasonably "linear" response. Once you pass 25k, the volume is pegged. So, on a 500k pot, you're looking at 1/20 of a rotation before you cross the 25k threshold.

Huh? Saturation issue? A pot doesn't provide any gain, so what exactly is saturating? The preamp? It doesn't care what's going on with the pot as long as it can drive enough current into the load to maintain its output voltage. Are you implying that the output from the guitar depends only on the absolute resistance from wiper to ground on the volume pot? That's really not how these kind of circuits work.

Add to that, the fact that perceived volume is logarithmic, hence volume pots are typically logarithmic, but the EMG circuit might need a linear pot. Switching from linear to log would make the threshold issue even worse.

A pot is just a voltage divider, and it should work as intended as long as it's impedance is large compared to the source impedance.

Depends. Without going too deep into the difference between current sources and voltage sources, this is true if you have a voltage source across the pot, and you're pulling your signal from the wiper. There are plenty of other ways to wire a pot.

Feel free to get as deep with the difference between current sources and voltage sources as you desire, but I don't see the point. The preamp in EMG pickups is essentially a voltage source. They claim it has a output impedance of 2k ohms, which I assume is mostly resistive. They use audio taper pots, and the pots are wired exactly as you described above. Now, why should a larger value pot "act more like a switch"?

[westhemann]

I have just now seen this topic.I guess it is a bit late,but the thing is,like Rhoads implied(or flat out stated tongue in cheek)you should always use the set of electronics that comes with the EMG set.Any stereo jack will work for the battery disconnect(Ibanez includes a stereo jack on most,if not all of their guitars),but the tone and volume pots are the ones you should use to get the tone and performance EMG is famous for.

Doing anything else is just selling yourself and your pickups short.Plus,the pots they provide are EXTREMELY high quality...I have yet to ever have one get scratchy or have any sort of problem whatsoever in all the years I have used EMG...(10 years now?)

I just ordered a set of Duncan Live Wires though...my ears are growing weary of the same thing year after year...If I like them I may start using them.

[David Schwab]

I actually sent them an email to ask them what the effect on the tone would be, since all they said was that it would "act like a switch", but I got no reply from them. It's been... 4 days since I sent the email?

I asked them a similar question once and got the "acts like a switch" response. It doesn't make sense to me. A pot is just a voltage divider, and it should work as intended as long as it's impedance is large compared to the source impedance. I have an EMG equipped guitar (with 25k pots). I thought about trying some 500k pots to see if the "acts like a switch" statement is true, but I've never actually gotten around to it. I'm not saying it's not true, but I can't seem to figure out why it might be.

With audio taper pots, the volume comes up real quick when you use 500K pots with EMG's. It's not the end of the world though. As I said I have a frankenstein guitar that I slapped together real quick, and I used the 500K pots they were on the pickguard. I wanted to try out an old Overlend EMG mini humbucker I picked up. I stuck that and an SA at the neck. I haven't felt the need to change the pots, even though I have a whole box of 25K EMG pots.

So I would use the ones they supply, but they will work just fine with higher values.