View Full Version : Why can I hear tapping on my RCAs??
01-29-2011, 12:39 PM
This personal confusion started when I rewired the tonearm in my sl-1210.
At first all seemed to have gone well but then I realized that my arm had gone seriously microphonic (even with the cart disconnected). I could even hear the wires moving inside the tube as I moved the arm. After a great deal of frustrating trouble shooting I decided to pull the whole thing apart and track the problem down from the headshell socket all the way back.
Result: I'm all the way back to just the RCA's and sure enough, a tap tap tap on the cable itself is coming trough the speakers.
I was under the apparently false impression that this should not be possible. How can insulated wire alone act like a mic.
Weirdest thing: My friend and I did this project together at the same time. Same table, same wire, I have this microphonc issue and he doesn't.
I think I'm going nuts here.
01-29-2011, 01:57 PM
what kind/type of cable are you using?
I assume you are talking about the phono cable from the tt to the phono pre/board?
01-29-2011, 02:11 PM
It's (gulp) Monster Interlink 250.
I had seen a posting of someone else's mod using this wire and they claimed to have good results. I happened to have some in a bag that came with a system I bought off of CL, so I used it.
Anyway, I'm currently halfway done putting it all back together. I wrapped the wire in the tube with teflon tape hoping that might help. I don't know.....
01-29-2011, 02:22 PM
If that does not fix the issue,,try using a pair of the IC's that come with dvd and cd players instead and see if you get an inprovement,,they are shielded,,if that works,I see some new IC's in your future.Good luck,,keep us posted.Oh,, do you have your tt grounded?
01-29-2011, 02:48 PM
I think you will find that George is right about the cables but there is another possibility, perhaps number two on the list. Is your turntable grounded to your phono preamp or receiver. (That needs to be done with most turntables). No or poor grounding usually causes hum BUT a failing return in the cable combined with lack of grounding might cause this. How does it sound when played? Weak and scratchy in one channel perhaps?
01-29-2011, 03:18 PM
try using a pair of the IC's that come with dvd and cd players instead and see if you get an inprovement
that is funny...:tongue:
Ok, all the soldering is done and.......
The tube is now silent!!!
I can tap on it to my heart's content and hear nothing.
I'm not sure if this is a result of fixing a bad solder joint or the tape but right now I don't care.
But, and you monster haters are going to love this, tapping on the RCAs is still causing a little poping noise. It seemed like good wire. (oxygen free copper, foil shielded, nice terminations) I guess I'll throw the stock wires back on for now.
01-30-2011, 09:38 AM
I got this interesting response from Coffee Phil over at Vinylengine.
Just thought I'd share it here.
"Cables can indeed act as microphones. Some polymers as well as ceramics have piezoelectric properties. You may remember the Pioneer HPM tweeters which operated on that very principle. I have seen some "high end" cables do this. I thought it was funny that they didn't check that out before selling the cables and hyping them as something great."
01-30-2011, 10:27 AM
thas why i said to try the cheapo cables,,they are shielded,,if it cures the ilness,,then an upgrade(cable) is in you future.Make sure the tt is grounded,usually to the pre,,,another trick is to solder some bradley resistors at the input ground to ground,, moves the noise to a different plane--old george wright tweak.
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01-31-2011, 09:35 AM
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