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81 Sunburst with squealing DiMarzios


thoro

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Hello,

I play an '81 Sunburst with very microphonic DiMarzios – they are so microphonic I can hardly play them with a real amp, I'm using a Helix and in-ear headphones most of the time.

You can turn the bobbin screws without using a screwdriver.

Oil City Pickups describe it very well here.

I thought about wax potting them but after reading this article I searched for "microphonic dimarzios bobbin screws" and some people write about fixing the screws with silicone rings or teflon tape. Oil City Pickups suggest putting clear nail polish around the junction of each of the pole screw.

What is your experience with these old DiMarzios? Is there a way to tame them without wax potting them?

Thanks

Thorsten

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Yes, this is definitely an issue with many of those early DiMarz, unfortunately. Two slug bobbins with these and the only thing holding those pole screws in place is the threaded baseplate! Ugh.

Nail polish lightly applied around the screw exit hole at the bottom can work - or not - depending on the pickup and its condition. Beyond that, a light wax potting with the pickup cooling off face down so that the wax builds up and solidifies in the pole screw holes should do the trick.

 

 

 

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If I may add, the Dimarzio bobbins are prone to warp when wax potted @ above 140 degrees, 20 minutes due to the type of plastic they used to manufacture there bobbins in that time period. Other Pickup manufactors, Gibson, Duncan, ^ Josh Gravelin Pickups^ , etc. can handle a proper Waxing to reduce micronic feedback, squeling.

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Thanks for your suggestions!

I already put some foam rubber into the cavities and tried rubber rings to tighten the screws a bit, this didn't help. 

I wax potted a pair of old DiMarzios from my '78 Kramer DMZ a few years ago and kept an eye on the temperature. It worked great and the squealing was gone. I just wondered if there are other ways to get rid of the squealing and think that so many users here must have the same problem with these old DiMarzios. And reading of wax potting there are so many people telling you that the pickups behaviour and tone will change... My Kramer DMZ still sounds nice but I think it's hard to compare the tone before/after without recordings.

JGravelin, how long would you keep the pickups in the wax for a light wax potting? I think I will do that.

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10 minutes or until the wax has mostly melted off on the bottom of the frame. Murkat is absolutely correct on those bobbins deforming easily if the wax is too hot so do check the temperature. 60C is safe.

Another option that I just thought of: electronics-grade silicone. You may be able to find it at a hardware store but if not, here's a link on Amazon. It's inexpensive, easy to apply, very sturdy once cured, and will definitely hold those screws steady. As used by DiMarzio, Carvin, and many others.

 

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Edit/Addendum: I can't believe I didn't think of silicone until now and I sort of feel like a dumbass about it but this post inspired new ideas so thank you Thoro. Because I've worked with this specific type of silicone enough over the years to know about it and know how it sets up when it's cured, if you want to resolve this problem and rock forth:

1. Back the screws out of the bobbin until they are hanging on at the last few threads.

2. Electronics-grade silicone. When you cut the application tip to apply, do so at a 90 degree angle- as flat and squared off as you can. Position directly over the entrance hole and squirt a moderate amount inside.

3. While the silicone is still in it's semi-liquid state, turn the screws back in and then go do something else for about 6 hours. Let the silicone cure and firm up.

At the end of this you'll have solidified the internal build, made the pole screws nice and snug, and the best part is that you can adjust the height to your pleasure because the silicone is pliable when it's dry. I know this will work exactly as I described even though I've not done it yet - trust me on this one! Non-invasive and completely reversible with no alterations to the important part of the original build. 

And if that doesn't resolve it, wax pot - solidify the mechanical parts. This silicone is completely stable at 140F/60C.

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@thoro, I’d try Josh’s suggestion first. I do hear a difference when I pot a pickup or play the same one unpotted. I bet the silicon method with fix your issue without altering the tone of that snarling Dimarzio.

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On 9/12/2020 at 3:05 PM, murkat said:

If I may add, the Dimarzio bobbins are prone to warp when wax potted @ above 140 degrees, 20 minutes due to the type of plastic they used to manufacture there bobbins in that time period.

Must be the Achilles heel of the super-secret petroleum derivative that made the double creme bobbins so trademark-worthy (and likely, the secret behind the Illudium PU-36 Space Modulator). 

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In the meantime I ordered electronics-grade silicone and last weekend I was ready to give it a try fixing the bobbin screws with it. I was going to record a short video before... to show how microphonic the pickups are. So I powered up my old Marshall JCM 800 in a small room and... no squealing.

What was happening? When I received the guitar a few years ago I set it up and took it to a rehearsal – and it was squealing like crazy. So I tried it with some foam rubber under the pickups and it didn't help. I changed the pickups and put the original DiMarzios aside. When I decided to reinsert them a few weeks ago I was putting some foam rubber under them again. But this time I used a very dense kind of rubber foam and I think this puts enough pressure to the screws to prevent them from vibrating.

I tried it adding an Ibanez Metal Charger for more gain and even with higher gain everything stays fine.

So I think I leave it as it is now and hope that the foam rubber doesn't wear out too fast. And if it does, I will use the silicone...

Thanks for your suggestions!

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