Tele bridge feedback on Express

[Cliff Schecht]

My MIM Tele recently got a new set of pickups. I managed to finagle a set of Strat SCN pickups that I bought for cheap into the Tele. The neck and middle pickup sound fine and dandy but the bridge pickup will become very microphonic at high gain. WIth the volume past about 70% the bridge breaks into a high pitch feedback that I can't dampen with my finger. When I roll back the volume and cut the gain a bit the feedback stops but the microphonics are still there (I can tap the bridge plate and get loud thuds).

I replaced the bridge pickup with a Seymour Duncan neck Hot Rails and it does the same thing. I really like this pickup in the bridge position (the bridge version is TOO HOT, the neck version works great in a bridge) but I can't get it to not squeal with the volume all of the way up. So both the SCN and the Hot Rails squeal..

I've heard of a few fixes, one being to anchor down the bridge at the neck side with a screw or two (they make bridges with three screws too) or to replace the ferrous chromed steel bridge plate with a brass version. I haven't tried the extra screws but some strategically placed tape under the bridge didn't seem to fix the problem. Shoving my finger into the bridge plate does dampen the squealing a bit when the amp is on the edge of feeding back, but it if I crank the volume then the squeal dominates.

FWIW the bridge didn't squeal with the stock Tele single coil. I didn't really like that pickup and the hum made it nearly unusable (the excess hum kills the Express's ability to sustain forever ). Again I'd like to make the Hot Rails usable without neutering the guitar too much.

Any help is of course appreciated guys, this is quite a pain as I love playing Tele's with the Express and just wanted to eliminate the hum..

[geetarpicker]

If the stock pickup didn't feedback it's probably that it was potted more effectively from the factory and/or it has a very tightly wound coil. Your replacement pickups were probably not potted or potted very well. That said these days some folks say potting pickups kills the tone, but in my experience (at least with the wax and techniques I've been using) I haven't noticed much loss of tone if any. Yes even my original '59 Les Paul has potted pickups... On my Strats I run Fralin pickups, but I've had to repot them even though they came potted already. A strat the bridge pickup can be the most tricky especially when running a steel plate on it. You might try mounting tricks to dampen it but in the end it's probably the coil and the only thing that will tighten it up is probably going to be a properly done wax potting job. Also check you guitar pot, if you have a higher than typical volume pot (like a 500k or 1 meg) you will have more high end potential and more difficulties with feedback. At the very least make sure you have a 250k volume pot in there before you mess with the pickups. That said a few years back I did have one Fralin bridge pickup that defied repeated potting efforts and still would feedback, though it had worked well for years. That was the only pickup I simply gave up on (my guess is it's coil was way too loose) and I had to buy a brand new pickup, which still needed a potting job but that one took to it ok.

If you want to try potting your own pickups be very careful, it can be very dangerous if you are not careful let alone you could kill a pickup. I made a little double broiler to melt the wax, basically a small soup can suspended by stiff wires in a larger coffee can. Then you add some water between the cans to basically dampen any hot spots from hitting the wax directly. I then heat the wax using this device on a small hotplate, use a thermometer to monitor it, and I only let the temperature get just hot enough to melt the wax but not a degree more. One other trick that works is once you dip the pickup in wax for a while quickly put it in the freezer right after you take it out of the wax bath. This will quickly skin over the wax and keep less of it from spilling out of the coil. Then after 10 minutes or so you can pull it out of the freezer and let it completely cool more slowly for a couple hours.

This is a good article on the subject, plus apparently you can send pickups to Fralin to have them potted:

http://www.stewmac.com/freeinfo/Electro ... ralin.html

[Reeltarded]

Not sure I am understanding

The bottom plate of the bridge pickup in a telecaster completes the bridge ground. The big brass plate is the instrument ground through the adjustment screws.

Otherwise, one must place a ground wire from the controls that terminates at a bridge plate screw or other niffty same idea.

I have used the JBjr and 59 tele pickups. I like Bill Lawrence, and Seymour Duncan wandering around back there in a vertical humbucker type. Still screams 'imma telle, bitches!'.

[Cliff Schecht]

Glen I don't think either of the pickups are microphonic. When they aren't installed in the Tele bridge they don't squeal or feedback at all. It's only when they are installed in the guitar and the bridge of the guitar screwed in. I've repotted the Seymour Duncan successfully in the past and it came out of the middle position in the same guitar where it never fed back. Neither pickup is microphonic when it isn't installed in the guitar. It's something about the bridge itself and the way it acts with humbuckers maybe that causes it to squeal. I think the way the bridge is held down (four screws on the saddle side of the bridge) and how the steel bridge interacts with the pickup that is the problem. I could be wrong here and I'm not against repotting the pickups but I don't think that's the solution. FWIW the stock pickup was not well potted..

Something I have heard that one can do is "pot" the bottom of the bridge (cover it in wax) so that it sits well dampened against the guitar. I might try this before ripping out the pickup to repot it. You can't repot the SCN pickup btw, it's permanently sealed because the designer (Bill Lawrence) held stringing manufacturing and quality control standards over Fender to make these pickups. Something about the way they are made requires them to be extremely well potted and sealed so that the coils don't break loose. Again I really don't think it's the pickup alone, it's that damned bridge!

Reel: I am not talking about the brass plate mounted to the bottom of your standard Tele pickup. I have Strat pickups in this Tele so there are no plates on the bottom of any of the pickups. I am talking about the bridge of the guitar and how it interacts with the bridge pickup. The whole bridge assembly with a pickup installed acts microphonic, not just the pickup itself.

[Reeltarded]

Yeah, Cliff. That is what happens when there is no ground from the bridge to the controls too.

The tele pickup completes that circuit with that brass bottom plate. Do you have an instrument ground run separately from the pickup then?

I have known that booboo the first time I ever installed a non-tele pickup in that hole.. without a separate ground..

(little voice slaps face: Oh What the Hell was I thinking!?)

[Cliff Schecht]

Yeah the bridge has its own ground and then the pickup has the ground and shield connected to the same spot inside the control cavity.

[geetarpicker]

Glen I don't think either of the pickups are microphonic.. .

It still could still be the pickup. In my experience the tele bridge assembly and the pickup copper plate (or steel plate added to the Fralin pickups) all make the pickup more prone to feedback. Even in a Gibson guitar something about the higher position of the bridge pickup up near the top of the pickup ring, and your hand above it can make the bridge pickup more touchy in this regard. I think it's like a microphone, where cupping it (like a rapper, ha) can make it more prone to squeal.

That all said, I've definately had pickups that seemed resistant to feedback OUT of the guitar but once installed had problems but I've almost always found in the end proper potting would cure most any pickup even in the bridge position. You might make sure IF the pickup has a metal plate that it's installed with a layer of wax (like Lindy Fralin mentions in that article) and even your bridge over the body might benefit from a tiny thin layer of wax between itself and the body.

I had a similar issue with the burstbuckers in my historic SG. The pickups were potted very well (coils untapped during the process) and even a second time with the covers on, but in the guitar the bridge pickup had this low frequency howl. I could dampen the howl by pushing on the pickup. The fix was to adjust the pickup and leave it, then remove the trim ring/pickup assembly and run a bead of silicone inside the trim ring to keep the pickup from vibrating. The neck pickup didn't have any issues as the pickup contacted the body routes there just enough to dampen it. Anyway that was an extreme case but I guess I like alot of gain at times!

Yes it could be the bridge assembly too. On my burst "back in the day" I noticed that when running WFO through a 100 watt Marshall super lead my bridge pickup would squeal even with full potting. It seemed that no matter how well I dampened the stings it would still howl. Oddly, I notice that with the strings removed it was OK, but it was because the bridge and tailpiece were then off the guitar. Turned out it was the stop tail piece and bridge which had enough magnetic qualities to cause troubles. In the end it was just too much to expect to play the guitar 6 feet from a 100 watt Super lead with it fully dimed. These days I just don't run as much high end or volume to have that sort of trouble, even with the Trainwrecks.

[badtweed]

I had this problem years ago with my 65 Tele's lead pickup squealing when
played through a blackface Super Reverb at higher levels.

I removed the bridge assembly plate and placed a layer of an index card between the bottom of the bridge plate and the face of the guitar body and the squealing problem was taken care of. Might help in your situation and is simple enough to try without too much drama. The paper had minimal impact on the tone.

[johnnyreece]

Yeah, the Callaham bridges have holes so you can screw the front of the bridge down if that's an issue. Suppose you could drill your own and hit the hardware store if you wanted to give it a shot.

Just to be clear - the pups that are howling DON'T have a brass/steel plate on the bottom, right?

[Cliff Schecht]

Thanks for the suggestions so far guys! I'm going to try a few of the easier fixes before I start trying out the fixes that require me to remove electronics or drill on the guitar.

Johnny: You are reading correctly, there is NOT a steel or brass plate attached to the bottom of the pickup. I've read about how Fralin attaches the bottom plates with wax to prevent squeal.

[johnnyreece]

Darn...that was my best idea. If the bottoms of the polepieces touch the brass plate, she can squeal like a banshee...

[jeff12]

HI,
Have you ever looked at the GE Smith Tele bridge. He modified his because of some of the same problems. You might take a look.

[sixstringer]

Pot it! Potting has fixed this in several Tele's I have (had). I have not noted any adverse change in tone. Wax potting is easy too. Be sure to agitate the PU while in the wax to get all the air out.

BTW, I just added a 4-way switch and a phase switch to a Tele and in doing so, had to cut the ground wire from the bridge PU to the brass plate. (like disconnecting the PU cover on a Tele neck PU). There was already a wire from under the bridge plate to ground, so no new ground wiring was required. It did no alter the bridge PU tone or output, but it worked perfectly in allowing the addition of the 4-way switching to the existing push/pull phase switch on the tone pot.

[Zippy]

HI,
Have you ever looked at the GE Smith Tele bridge. He modified his because of some of the same problems. You might take a look.

I had to look that up - here's a link:

http://thebridge-works.com/Fender-Telec ... 46207.aspx

[Cliff Schecht]

Thanks for bringing this up, I actually managed to solve the problem "well enough" without neutering my Tele too bad. I ended up drilling a couple of holes in the bridge around the pickup and ran in some fat screws to really sink the bridge into the body well. Good news is that in most cases this Tele doesn't have any feedback problems and is once again my main axe, bad news is it's still nearly unusable with a fully cranked Express. I say nearly because before I fastened the bridge plate securely to the body I couldn't get the squealing to stop with an Express and now it stops if I mute the strings hard enough. Like I said, still unusable but better .