Feedback

[dmraco]

I just put some new pickups in an old guitar.  The layout is 2 humbuckers, a three way toggle,1 tone and 1 volume.

When playing the bridge pickup, I get a feedback I have never had before with ANY guitar.  Sounds likee a mic feeding back.  It only happens at high gain and with the volume up ll the way. 

Thoughts??

 

[Cagey]

If it's a covered pickup, it may be the cover. That's why so many guys tore those things off starting in the '70s. If it's not covered, it's loose windings. The thing isn't potted properly, if at all. If you like the sound of it otherwise, you can pot it yourself following instructions like you can find here.

 

[dmraco]

If it's a covered pickup, it may be the cover. That's why so many guys tore those things off starting in the '70s. If it's not covered, it's loose windings. The thing isn't potted properly, if at all. If you like the sound of it otherwise, you can pot it yourself following instructions like you can find here.

it is covered.  i will check out the pot...I mean WAX.

 

[Cagey]

If you haven't yet, go read the article at the link before you do too much. It's educational as well as instructional. Some pickups don't come apart as easily as others, and some not at all. In all cases, it's fairly easy to wreck one or both windings if you don't handle them carefully.

 

[Super Turbo Deluxe Custom]

@ Cagey, I was under the impression a shielded covered bridge pickup cut the highs ever so slightly.  The look of the uncovered bridge pickup and covered neck pickup was so the bridge pickup would be brighter.

 

[Cagey]

@ Cagey, I was under the impression a shielded covered bridge pickup cut the highs ever so slightly.  The look of the uncovered bridge pickup and covered neck pickup was so the bridge pickup would be brighter.

Covers cutting highs is a real thing, but it is slight and the loss of highs from eddy currents in the cover is nowhere near as pronounced as the loss from the comb filter effect of having two coils sensing different points along the string, as occurs with the traditional Seth Lover "humbucking" pickup design. But, since the loss is there, every little bit you can do to bring them back helps.

It's part of what made Seymour Duncan's "Hot Rails" pickup so popular. You got the noise elimination from the CMNR (Common Mode Noise Rejection) made possible by reverse-wound coils wired in series with reverse polarity poles, the even response of a blade vs. rod pole piece, and the close proximity of the coils that reduced the comb filter effect, all of which combined to provide quiet, toneful high-output while still having a wide frequency response that wasn't missing so much high end, presence and clarity. Still not perfect, but a great compromise.

 

[Super Turbo Deluxe Custom]

So, are bridge pickup cover removal mods done to get back highs or eliminate feedback?

 

[Cagey]

Both. Although, not all covered pickups feed back so one might not be as tempted to tear into the things for the small sonic improvement removing the things brings.

It used to be quite common years ago, but I don't know that the phenomena occurs that often any more outside of really low-end gear. My niece had it happen with some Gibson pups a few years ago, but she was loathe to lose the covers so she just did the re-potting thing and it cleared the problem right up. Plus, you don't see pickups covered as much any more, so there's no reason to think about it. The only pickups I have covers on are a pair of EMGs and a new Gibson that looked like it was built by a kindergartner and so needed some covering up. Oh, and I covered my Roadhouse pickup for aesthetic purposes on the Tele it's installed in, but it's a plastic cover so it's sonically and magnetically transparent. Of course, all the single coils are covered, but those are also plastic so it doesn't matter.

 

[Super Turbo Deluxe Custom]

When I see 2 humbuckers on a guitar, a covered neck and uncovered bridge, especially when they're matched sets of the same construction (both being equally prone to the same feedback concerns), I assume it's to make the bright pickup brighter.

 

[Cagey]

When I see 2 humbuckers on a guitar, a covered neck and uncovered bridge, especially when they're matched sets of the same construction (both being equally prone to the same feedback concerns), I assume it's to make the bright pickup brighter.

That may be the intent, although I'd question its effectiveness. It's more of a desperate last-ditch effort that doesn't cost any money. The bridge pickup is usually has more winds on it to increase output to compensate for the reduced string movement at that position, so it's going to have less high-end anyway. Again, every little bit helps, so you do what you can.

 

[Dan025]

on one had the covers have some effect on the highs. but is a small incremental change because the metal is so thin. i think there were some charts posted somewhere some years back showing gibson tests of covered and uncovered and it was a minimal difference. hardly noticeable. but every little bit helps in some cases. in the end you would be better off changing strings to a lighter gauge.

 

[stubhead]

It's been a long time since I've run across an amplification chain that didn't have "enough" high end. Are you trying to kill mosquitoes or something?

 

[Cagey]

I don't see anybody complaining about the amp chain here. You're right in that few of them present any hardship in that area, although it is possible. One of my brothers has a Marshall TSL-601 combo with a Marshall 112 bottom that's pretty dark. Could be the speakers, though. Not sure what's in there - he's constantly shuffling things around in the search for the Holy Grail of amps.

 

[stubhead]

It's just that "more highs" gets to be held up as one of those Holy Grail type "achievements" like "sustain" that isn't really the exact equivalent of "sounding good." If you can seriously plug your guitar into your amp, turn the amp's gain volume, treble and master volume all up to "10" and there's "not enough treble" sure, your amp and/or guitar could use some work but in the vast majority of modern setups, that combination above is going to make for WAY too much treble. If you want to "stand out from the mix" turn UP; but remember to ask yourself "what is the mix going to sound like?" if everyone in the band is trying to avoid sounding like "the mix."

 

[Cagey]

I understand what you're saying and I agree with you, I just don't see where it fits into the context of this thread.

We did talk a bit about frequency response, but only to mention that there's a minor difference between covered/uncovered pickups, with emphasis on the "minor". As in "minimal" or "insignificant". At least, in practice. Some folk's imaginations may run wild, but that's true of just about anything having to do with "tone" in relation to guitars. I mean, some guys think the chemical composition of their paint makes a difference. Then again, some guys think there's an invisible rabbit or a batch of horny virgins on the "dark" side of the moon. How do you argue with that?

And no fair using facts.

 

[bagman67]

It's just that "more highs" gets to be held up as one of those Holy Grail type "achievements" like "sustain" that isn't really the exact equivalent of "sounding good." If you can seriously plug your guitar into your amp, turn the amp's gain volume, treble and master volume all up to "10" and there's "not enough treble" sure, your amp and/or guitar could use some work but in the vast majority of modern setups, that combination above is going to make for WAY too much treble. If you want to "stand out from the mix" turn UP; but remember to ask yourself "what is the mix going to sound like?" if everyone in the band is trying to avoid sounding like "the mix."

A propos of this, I recall attending a Larry Carlton show during his first tour after his gunshot wound, back in '88 or '89.  Leo Kottke opened - it was an oddball bill.  Anyway, after the first number, he polled the audience for some (pardon the expression) feedback on how the mix sounded, and expressly suggested that the treble end of the mix might be too harsh.  He was right - the edge at the top end was a little much - and it was gratifying that he took the audience's comfort into account like that.  Of course, there was only one guitarist in the band, and Carlton is a consummate pro.  Get a gang of drunks at a blooz jam, banging out Mustang Sally yet again, and you won't have any such luck.

And Cagey, since when is thread derailment worth even commenting on around here?  *grin*

 

[Cagey]

And Cagey, since when is thread derailment worth even commenting on around here?  *grin*

Hehe! Yeah, I know. But, Stubby's always fun to draw out. It's too bad he's so hit-and-run.

 

[dmraco]

For an update, the issue seems to have resolved.  It only feedbacks when using my sons ORANGE amp.  The guitar does not feed back on my other amp (mesa) nor does any guitar feedback on the Orange. Odd.