Static building on phono

[Jason]

I recently picked up a brand-new Marantz turntable with the built-in preamplifier, the non-preamp version was backordered, I'm getting a consistent build up of static when I play a record that makes the sound inaudible. I'm running the turntable into a Sunfire theater grand, then pushing the signal to a cinema grand five channel amp and two Lumley tube amps.

Driving 2 klipsch THX and 2 Cerwin d9.

I tried numerous methods of grounding, but my home has knob and tube electric which is ungrounded.

Is grounding the problem?


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[Jason]

Just adding in that I have the turntable grounded directly to the ground spike outside my house, the preamplifier is not grounded because of the knob and tube electric, and all other audio sources seem fine.


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[Jason]

Please help!


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[audio.bill]

I've given some thought to your problem, but didn't post any response since I have no experience or knowledge of knob and tube electrical wiring. The only suggestion I can come up with would be to try running a ground wire between your connected turntable ground and your preamp so that they share a common ground. If the preamp doesn't have a ground connection point you can usually connect it to a chassis screw. Again since I have no experience with knob and tube wiring I cannot assume any responsibility if you try this and it causes any problem, so please proceed at your own risk (standard disclaimer.) When you stated that you have tried numerous methods of grounding what specifically have you tried? Good luck resolving this issue!

[MikeCh]

Try a different turntable and see if the problem remains. That will help narrow the issue for troubleshooting.

[Jason]

Thank you for the replies! I tried grounding the turntable to the Sunfire preamplifier that has a grounding post, but I don't believe knob and tube has a ground wire, so the preamplifier is plugging into a wall socket with only a positive and neutral, I believe that's how knob and tube works. In a modern system, I believe there is a positive, a neutral, and a ground. Basically, I think my wall socket is on grounded because of the knob and tube, so I don't think grounding the turntable on the preamplifier will do anything. Regardless, I tried it and still get static.

I then ran a wire from the preamplifier, outside I'm grounded it against my electrical service conduit, the static got worse.

I immediately removed it, then extend the wire to a grounding post on the side of my house where other electrical systems seem to be grounded, no change, more static.

The only thing that seems to help is when I clean the record with cleaning fluid and the cleaning pad, but the static comes back after a few minutes.

I don't have another turntable to try, nor do I wish to contact an electrician just yet to put in the ground, many of them don't like working on knob and tube.


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[MikeCh]

To test temporarily, take a finely stranded piece of wire of say, 24 gauge size and ground one end to your common ground point (the real ground that you say you have). Strip back an inch or two of insulation from the other end and splay the inner conductors into a fan (imagine a very fine bristle artists paint brush). Clip most all strands but leave a few remaining. Tape the wire to your plinth and arrange / place the exposed conductors so they drag / touch along the outer rim of the turntable platter itself. Play a record and see if things change regarding static build up with the newly affixed drain wire.

If it does resolve the problem, you can go about finding a neater solution to ground the platter but doing a little test like the above will at least tell you if it's necessary or not.

[Jason]

Very interesting, I'll definitely give that a try. Would a fine speaker wire be appropriate for that test?


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[MikeCh]

Sure, just use 3 or 4 strands of the inner copper conductor of one wire that maybe contains 50 or more actual strands. For the test you're just trying to create a drain path without adding any appreciable "drag" on the platter, hence the 3 or 4 tiny conductors touching the platter rather than 50 or more that are contained in the insulated wire as a whole.

[Jason]

Did not work, still a tremendous amount of static


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[MikeCh]

Is the "static" you're hearing translated to actual static cling when you remove the record from the platter? The kind of static I assumed you have and hence the drain wire idea above could address static-cling. However, if you're not getting this kind of static, but simply static noise without the cling, then I would investigate the cartridge itself. Confirm its alignment and health and that it doesn't have a big blob of crap on it causing the noise.

[Jason]

It's not the kind a static with minor crackling in the background from what I would perceive as a dirty record or a dirty needle. It's essentially distortion that grows and makes my speakers reverberate to the point I need to shut down the preamp, and it only happens with the turntable source. All other sources sound crystal-clear. I just want about ordering a new turntable and I'm returning the old one, it's the new Marantz tt42, maybe it's just a bad turntable


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[audio.bill]

Jason, what you described in your latest post sounds more like acoustic feedback than a static problem. Acoustic feedback usually results in a low frequency howling sound which grows in intensity forcing you to lower the volume. It generally only affects analog playback and is the result of bass energy from the speakers and room being fed back through the phono pickup which causes it to swell in intensity. If that is what you're experiencing it is usually addressed by better isolation of the turntable, and sometimes a wall mount table shelf works best.

[Jason]

I have the turntable in a salamander synergy unit on a turntable shelf, 6 feet from any of the speakers. The room is 20 x 20.

What I be correct in saying if I get the same distortion with headphones, then it's not because of feedback, but a turntable problem?


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[audio.bill]

Yes, if you get the same distortion on headphones (with the speakers off) then the problem is not acoustic feedback. Since it's only with your analog source it has to be a turntable specific issue which could include the arm, cartridge, and/or a related grounding issue. Trying another sample of the same Marantz table will determine if you have a defective one, but if the problem persists you still won't know exactly what the root cause of the problem is. Have you tried running the table without the ground wire attached to your outdoor ground spike? Some setups may perform better without the ground wire connected, which is a floating ground. Not sure about that with your house wiring though. This type of issue can be very frustrating, I feel your pain!

[slowgeezr]

Jason, I suggest rechecking cartridge connections. Also, if available, try a different cartridge to compare. Another thought, is the bearing lubricated? Everyone else already suggested the main possibilities. Good luck!

[Jason]

I wanted to Marantz TT 42 without the preamplifier installed, should have it next week. I'll connect back to the phono input of my Sunfire, but I'll swap cartridges when the other one arrives and check bearings as best I can.

Thank you for all the input, I'm still thinking it's the knob and tube electrical that's causing problems, but I'll take all your advice and give you guys an update next week. Thank you again for all the input and suggestions, along with the education!


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[Dr Morbius]

Just wondered if you grounded your TT, amp and anything else you use to the ground bar outside?

[Dr Morbius]

Ho boy, I just noticed it's almost 3 years since your last note. Hope you got it fixed by now!