| Author |
Topic: Microphonic knee lever |
Brett Lanier
From:
Madison, TN
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Posted 19 Dec 2016 6:08 pm |
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I've been experiencing some crackling noises coming from my steel lately, especially when engaging RKR. So the other night I replaced the jack, lead and ground wires.
The crackling was still there so I put the guitar up on the bench with it plugged in and continued poking around. My only explanation is that the RR knee lever is microphonic. Just flicking it with my finger I can hear it through the speaker!
I connected a wire from the bell crank on that cross shaft to the grounds under the control panel and it took care of it... but is this something that happens? Should I hit it with the demagnetizer? |
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David Higginbotham
From:
Lake Charles, Louisiana, USA
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Posted 19 Dec 2016 6:27 pm
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I can't see how a mechanical part of the steel can become microphonic as there's no electrical current passing through it. Is it possible the a part of the knee lever linkage is touching the wires or input jack when you engage it?
Other than that you don't say whether you're using a single coil or humbucker. Single coils have a tendency to become microphonic over time because of loose windings and any body noise such as pedals and knees will cause the noise to amplify through the pickup. Does tapping anywhere on the guitar or legs cause the noise through the amp? If so, your pickup may be the issue. |
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Brett Lanier
From:
Madison, TN
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Posted 19 Dec 2016 6:49 pm
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| David Higginbotham wrote: |
Is it possible the a part of the knee lever linkage is touching the wires or input jack when you engage it?
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That's what I was thinking but I even had it plugged in with the jack off the endplate so I could move it far from the knee lever. The crackle was consistent either way. My other thought was that it's getting a charge from inside the pickup cavity. It's an old pull release so the fingers are pretty bulky and maybe they're hitting an exposed wire on the pickup.
The pickups are definitely suspect. Output is pretty weak. Luckily Todd Clinesmith is making me some that will be a good fit for such an old vibey guitar. My Macgyver grounding situation will do just fine for the next few weeks or so until the pickups come. What a weird thing though. |
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Michael Brebes
From:
Northridge CA
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Posted 20 Dec 2016 7:46 am
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You might want to take a digital multimeter and measure the resistance between the knee lever and ground. If there is not a good connection there it could be acting as a variable capacitor when you move it, similar to the noise that is sometimes picked up my moving your hand across a pickguard on a regular electric guitar (this happens on one of my Teles). Also make sure that your ground on your pickup is connected directly to the connector, not to the body of the steel. I ran into one steel that had the pickup grounded to the metal rails for the pedals while the crossrods had insulators so that the ground was iffy at best.
_________________
Michael Brebes
Instrument/amp/ pickup repair
MSA D10 Classic/Rickenbacher B6/
Dickerson MOTS/Dobro D32 Hawaiian/
Goldtone Paul Beard Reso
Mesa Boogie Studio Pre/Hafler 3000
RP1/MPX100 |
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Donny Hinson
From:
Glen Burnie, Md. U.S.A.
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Posted 20 Dec 2016 10:22 am
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I'd also check to see if there is any voltage present between the guitar frame and a good ground. An amp that's not properly grounded, or one that has a bad cap, can leak some voltage to the amp chassis or input, which will then be conducted to the guitar.
Of course, if the signal is very weak, it could just be an open pickup that's causing the problem. If the new pickup doesn't fix the problem, you could also just hook a very light spring from the lever to a grounded place on the guitar.
Strange problem.  |
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Jerry Roller
From:
Van Buren, Arkansas USA
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Posted 20 Dec 2016 9:56 pm
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It sure seems the lever or a pull rod is touching a wire or switch. The input jack is most likely located right at the RKR. On a push pull the RKR stop rod almost touches the wiring on control panel. It would be a very unique thing for a lever to be "microphonic". I wish I was an electronics guru but I am definitely not. What kind of guitar?
Jerry
_________________
http://www.littleoprey.org/ |
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Tim Marcus
From:
San Francisco, CA
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Posted 22 Dec 2016 11:33 am
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might be static electricity. You are in VT, where its very dry.
I know a guitar builder there who had static issues in the winter in the past. Spring comes with moisture, and presto! no more static!
I have had static like that here too in the winter, only once though. Just touching the faceplate of an amplifier made crackling sounds out of the speaker. The weather changed, and it went away.
_________________
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Milkmansound.com
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Rick Johnson
From:
Wheelwright, Ky USA
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Posted 23 Dec 2016 9:58 am
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I had that problem with a '74 LDG that
the previous owner had installed a
TruTone pickup in. I wrestled with it
for two months and I changed the input
jack with no luck so I decided to reverse
the wire on the input jack and it fixed it.
I didn't think the pickup would would work
if wired incorrectly but it did.
Sounds strange but it worked.
Rick
www.rickjohnsoncabinets.com |
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Tony Rankin
From:
Land O’ Lakes, FL
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Posted 23 Dec 2016 5:48 pm
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I had this problem once after installing a 710 pickup in an LDG. I called Bill Lawrence and he had me get a wire and touch one end to the ground of the output jack and the other to an end plate screw...then try the knee lever. An extra ground wire solved the problem...poor ground.
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Tony Rankin |
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Tommy Mc
From:
Middlesex VT
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Posted 27 Dec 2016 10:40 am
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| I don't see how a lever can be microphonic. My suspicion is that the proximity of the RKR to a microphonic pickup is more likely the issue. I'll bet having the pickup potted (or re-potted) would cure the problem. |
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Georg Sørtun
From:
Mandal, Agder, Norway
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Posted 27 Dec 2016 2:08 pm Re: Microphonic knee lever
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| Brett Lanier wrote: |
| I connected a wire from the bell crank on that cross shaft to the grounds under the control panel and it took care of it... but is this something that happens? |
Your description of "the fix" fits perfectly with "how to discharge/eliminate static build-up through common grounding". All conducting and semi-conducting parts, and most insulators, can be statically charged in isolation relative to anything else in the environment. Our "overly electrified surroundings" usually has plenty of electric fields that can cause static build-up in isolated parts - including our bodies, and if the air is dry enough those relative statics stay there until they are deliberately or accidentally drained off one way or another.
| Brett Lanier wrote: |
| Should I hit it with the demagnetizer? |
Won't do anything ... static and magnetic charges may have related causes - surrounding electrical fields, but magnetically charged parts won't cause crackling noises. |
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Carl Mesrobian
From:
Salem, Massachusetts, USA
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Posted 28 Dec 2016 8:30 pm
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Another vote for ESD!
_________________
--carl
"The better it gets, the fewer of us know it." Ray Brown |
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Brett Lanier
From:
Madison, TN
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Posted 28 Dec 2016 11:25 pm
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| Tommy Mc wrote: |
| My suspicion is that the proximity of the RKR to a microphonic pickup is more likely the issue. I'll bet having the pickup potted (or re-potted) would cure the problem. |
That sounds right to me. I put the new Stratospheric copy pickups in and it's all better. I had to take the guitar just about completely apart to get them in there but it was worth it. |
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Carl Mesrobian
From:
Salem, Massachusetts, USA
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Posted 29 Dec 2016 9:59 am
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Please remind me, What make is the guitar and what pickup?
_________________
--carl
"The better it gets, the fewer of us know it." Ray Brown |
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Brett Lanier
From:
Madison, TN
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Posted 29 Dec 2016 11:42 am
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It's an early 60's Marlen. The pickups were Marlen (opposing polarity on each magnet), but the new ones are Clinesmith.
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Carl Mesrobian
From:
Salem, Massachusetts, USA
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Posted 29 Dec 2016 1:49 pm
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Nice!
_________________
--carl
"The better it gets, the fewer of us know it." Ray Brown |
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