2. analog
  3. 195213-5876

In need of a GOOD 3:1/4:1 passive input selector

I have two turntables and will be adding a 3rd to my main system. It will be used to screen records purchased from less than ideal locales (goodwill, garage sale, etc). I have a 4:1 passive ’preamp’ (sic) that I use with my primary turntables on my Bryston 1B-MC. The problem I hear is a audible low-frequency hum over the speakers at around 70 hz regardless of the input I select. Both tables are grounded. If I select one table over the other and connect directly to the back of the preamp, the hum goes away. This tells me that the selector i have is, well, a cheap POS.

Is there a solid 2:1 or 4:1 passive selector that filters out the hum?

(NOTE: worst case, I could create a filter that filters out the hum. but seeing as it is the 70hz and below region, I will cut-off some low frequency information.)

jcipale

Showing 1 response by dover

dover
2,353 posts
 

If your switching unit is a passive preamp, and if you are handy with a soldering iron, try bypassing the volume pot.

Hum could also be simply poor earthing arrangement.

You can also short any unused inputs with a "shorting plug" - put a resistor across the +- inside an RCA connector - this is better for eliminating noise intrusion than the "audiophile" shorting RCA's sold that are simply a dead short.

 

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