my P-90s hum too much

Kevincharles

Kevincharles

New member
im playing a tc-100(a double cut, thru-neck, semi-hollowbody telecaster:naughty:) with 2 seymour duncan P-90's.

i absolutely love the sound i get from it, but when i run my distortion above about 4, i get crazzzzy feedback. but not if i have both selected. any suggestions?
 
Re: my P-90s hum too much

Teach them to sing!
















Are you boosting when your running at 4.It seems your dropping the signal enough to not feedback when you've got both Pups running.Is it neccessary to run your pedal at 4?
 
Re: my P-90s hum too much

Maybe some sheilding? Is it just that guitar? It could be a microphonic tube in the amp as well...
 
Re: my P-90s hum too much

microphonic pickups...pot 'em if you want to keep them or check the polepiece screws, base, mount, etc and seed if anything is loose (sometimes polepieces are a little loose in the threads and can cause feedback).
 
Re: my P-90s hum too much

kevincharles, what's the situation with the cavities in your guitar and access to them re shielding? your guitar sounds very intersting, btw

re gates - under gain (talking hum on solid-bodies here, i believe the OP's feedback issues go further than this), when trying to gate un-shielded guitars with soapbars i've found that they're generally screaming too loud for the gate threshold and so you either still have the hum, or you lose heaps of your actual signal; that said, i have much to learn about gates though... i'm a gate 'n00b'
is there a known way around this without paying sh1tloads for a rackmount gate unit etc?

may be time to attempt my first full shielding job... the P60A could be a good option
 
Re: my P-90s hum too much

Make sure the baseplate is grounded.

Make sure the rest of the guitar is as shielded as possible.
 
Re: my P-90s hum too much

well, it has a tune-o-matic bridge, and its post is grounded.

how would i go about shielding it? is that the metallic foil/paint that covers the cavity walls? ive seen that working on a friends guitar. i dont know a whole lot about it though.
uOpt said:
Make sure the baseplate is grounded.

Make sure the rest of the guitar is as shielded as possible.
Click to expand...
 
Re: my P-90s hum too much

yep, that's the gist of it

do search on shielding, there's a site called guitarnuts (i think) that goes into it in detail... but, without actually looking your modelof tele up, i believe you'd just need to do your pup cavities and control cavity and then check some wiring stuff out. this will make more sense once you've read a bit about it ; ]
 
Re: my P-90s hum too much

I'm confused, is it hum/buzz, or squeal/feedback? Two different problems with two different causes.
 
Re: my P-90s hum too much

I meant make sure the baseplate of the pickup is grounded, not the bridge.
 
Re: my P-90s hum too much

and for all of you that care/know any different, i bought the guitar on consignment at a local shop and they told me it was a tc-100. but they were wrong, apparently its a tc-90.
 
Re: my P-90s hum too much

Bottom line is that P90's are just noisy pickups and you have to figure out a way to live with it. Pretty much everything you can think of that would reduce the noise unfortunately also 'reduces' the tone to varying degrees, even just shielding the cavities, so you have to pick the method that minimizes treble loss.

On the other hand, if the baseplate isn't grounded, that will give you far more noise than is acceptable even from a P90. Ground that thing.
 
Re: my P-90s hum too much

As other has said, your hum problem is a different can of worms from the feedback. For hum, ditto to everything re. shielding and grounding. Gibson came up with an interesting way to tackle p90 hum on their Blues Hawk. They used a third, "dummy pickup", which was just a coil wrapped around a pup bobbin without magnets. The wire is wound in the opposite direction from the real pickups for hum cancelation. If you google Blues Hawk, you can probably find the schematics.
 
Re: my P-90s hum too much

that dummy pickups idea sounds like a really good idea, but im guessing it lowers output. annd for my that isnt the best solution, i dont want to bore into the body. not on this guitar. but thanks!


ill look into muting the baseplate, and until then ill just use the mute on my wireless haha
 
Re: my P-90s hum too much

The dummy pickup idea is actually very old and well-known, except is was called "blind coils" (they cannot see the pickups since they have no magnets).

It was the "mother" of all the stacks, a stack is just a pickup with a blind coil right in the pickup. This it is only done for space reasons, the additional coil could as well live in the cavity. But people want 1 pickup and you can't sell blind coil systems that have a cavity coil.

The dummy coil adds it's electrical properties to the original coil. You can do it in parallel, then you get a thinner sound like a Strat notch position or in series which is what a humbucker does (it gets fatter with both coils on). So the sound is off by a mile unless you fiddle more.

The way to make blind coils work is to make both coils a little lighter so that the added resistance and capacitance drive the resonance frequency back to where it belongs. Usually you use thinner wire for these things.

Blind coil designs make more sense for P-90s that Strats because a P90 stack cannot get any good results, not nearly as close as a Strat stack. (due to the magnet and polepieces design).
 
Re: my P-90s hum too much

ok, just chewing on the p90s idea... if the blind coil is just the extra wire coil for hum-cancellation, if it were outside the p/up housing and didn't have magnets or poles how would it affect the p/ups characteristics?
i'm learning a lot off you btw uOpt, i appreciate it
 
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