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Two Turntables and Hum Problems - Help Please

Hello.

I've got two vintage turntables and both are giving me fits with hum.

I have two separate audio systems. One turntable goes to my pre-amp and the other to my receiver. Each system has its own separate sub-woofer.

My pre-amp and my receiver are about 30 feet or so from the turntables. That's as close as I can get them. Obviously each ground wire is much shorter than 30 feet. What type of ground wire can (and should) I use to replace what I have now that is not working? Copper stranded? Copper solid wire? Silver-colored wire? Should the ground wire be coated in plastic or rubber or should it be raw?

I've seen some references to sub-woofers generating hum from turntables through ones' pre-amps or receivers. Any thoughts?

Thanks!
snazz123

Showing 2 responses by almarg

almarg's avatar
almarg
9,670 posts
 
In addition to the good comments above, another reason that a 30 foot run from turntable to phono stage is unreasonable is cable capacitance. With a moving magnet or other high output cartridge, sonics will be significantly degraded unless you use a cable having extremely low capacitance per unit length AND the cartridge is specified to work into high load capacitances. With a low output moving coil cartridge that may or may not be an issue, but the likelihood of noise problems will increase significantly.

Get a separate phono stage, as Stan and Elizabeth suggested.

Regards,
-- Al
almarg's avatar
almarg
9,670 posts
 
The gauge of the rca extension cables won't make any difference. What is important, in addition to shielding effectiveness (which is hard to predict) is (as I mentioned earlier) keeping cable capacitance as low as possible, particularly if you will be using moving magnet or other high output cartridges. I suggest Blue Jeans LC-1, which provides very low capacitance per unit length at a relatively low price.

For purposes of minimizing hum, the kind of grounding wire you use is not critical, as Elizabeth indicated above. I suggest initially experimenting with whatever is handy, or whatever you can get cheaply and conveniently at Home Depot, Radio Shack, etc.

If and when you eliminate the hum, however, you may then find that you are picking up radio signals or other interference. To address that kind of problem, the best type of ground wire would be a "braided ground strap." Google that term for further info, if necessary.

Regards,
-- Al
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