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Turntable issue

I haven't had much luck finding an answer to this question so hopefully it's not something that's been asked a thousand times.

Yesterday I turn my preamp on, place a record on the player and I can hear every touch of the tonearm I make. It clicks when lifting it out of its resting position and when I screw or unscrew the record clamp this at is also very audible through my speakers. Also I'm now hearing a hum that was never present before.

I understand that the cartridge picks up vibrations and turns them to sound but this has never been something that was clearly audible before. I'v never heard siuns coming from my speakers when screwing the clamp on our off.

Thanks for any responses.

MMF 5.1SE
Project Tube Box S
jsouth72
jsouth72 OP
7 posts
 
Ground wire foing from the 5.1 to the tube box s is fine. No kinks and looks like it was taken straight from the box. RCA cables are signal cable silver ref phono cables. All connections are tight. All power cables are tight. I will try swapping cables first then try the ground wire from tonearm. Hopefully I have some time when I get home from work.

Thanks again fellas
swampwalker's avatar
swampwalker
5,138 posts
 
If there are separate tubes for the two channels, checking that off the troubleshooting list is as easy as swapping the tubes. If the circuit uses one triode of each tube for each channel, you'll need to try replacing each tube w a known good. FWIW, it sounds to me like an intermittent electrical connection somewhere. Ground or signal.
zd542
5,339 posts
 
I know your phonostage has 3 different gain settings. Try the lowest one. Not sure if that's your problem, but it's very easy to check.
lewm
13,108 posts
 
1. Both speakers or one of the two?
2. I doubt this is purely a grounding problem, although the hum problem might be separately related to grounding. Again, is the hum in both speakers or only one? And is it really "hum", defined as 60Hz or 120Hz tone, or is it "buzz", which sounds higher in pitch and is really a mixture of frequencies?
3. My thought on the fact that sounds made when you handle your tonearm are transduced into the speakers is perhaps a microphonic tube. Most likely culprit is the first tube (input) of the phono section. That's typically a 12AX7, and it supplies much of the gain of your phono stage. Check that there is good acoustic isolation between your tt and your phono stage or preamplifier.

Like someone else said, I would also say that if the problem is in one channel, then you can check hypotheses by swapping tubes from one side to the other.
jsouth72 OP
7 posts
 
Swapped the tubes out with a pair of reissued Mullards. Anyways mostly everything has gone away. When I tap the player I no longer hear it through my speaker, I cant hear the clamp being screwed...very slight hum when nothing is playing but only if I turn the volume up high.

Thanks again for all your help
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