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Super Noisy Phono Pre--Help?

I have a Fosgate Signature Pre. I feed it with a Lyra MC cartridge mounted on an SME V arm. Until last week, all was bliss. Then the preamp started producing a random popping sound and a motor sound like there was poor electric motor plugged into the same outlet. I thought it was a tube, but swapping out tubes didn't change it. I took it to my local service department. They cleaned and resoldered some of the connections. Now the popping sound is gone, but the constant motor sound persists. The motor sound goes away if I disconnect my turntable. I can influence the sound by moving my interconnects around. I cannot change it by relocating my preamp. It seems like it might be some sort of interference, but I can't understand why it has shown up all the sudden after a couple of years of perfect sound. Suggestions, please. Could there be something wrong with my interconnects or my cartridge?
jmmorford
lostbears's avatar
lostbears
538 posts
 

Have you tried plugging it into another outlet? Maybe with an extension cord from another room. I also have a Fosgate V1 and it is very quite.

I had an intermittent hum in my tube preamp. I could not figure out what it was. It would come and go sometime after hours of listening. It turn out that it was the light in the dining room. We had replace the bulb with a compact florescent. Every time the light was on there was a hum in my preamp. Since the dining room is not visible from the room my stereo is in it took me a while to figure it out. We have now gotten rid of all the compact florescence in the house.

Does anyone know what the actual differences are between the Fosgate V1 and V2?
bpoletti
1,554 posts
 
Unplug your cartridge leads and report back how much noise was present.
oregonpapa's avatar
oregonpapa
4,867 posts
 
Could be an errant IC cable. Try swapping cables. Sounds like it could possibly be a ground problem to me.
almarg's avatar
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almarg
9,670 posts
 
Then the preamp started producing a random popping sound and a motor sound like there was poor electric motor plugged into the same outlet. I thought it was a tube, but swapping out tubes didn't change it. I took it to my local service department. They cleaned and resoldered some of the connections. Now the popping sound is gone, but the constant motor sound persists. The motor sound goes away if I disconnect my turntable.
I would not assume that the phono stage necessarily has anything to do with the problem. You didn't mention what turntable you have, but a possibility that occurs to me is that a capacitor associated with the AC wiring within the turntable has become leaky or otherwise defective. And it could be that the cleaning and resoldering that was done on the phono stage had nothing to do with the elimination of the popping sounds. Perhaps they just went away, probably temporarily if my theory is correct, as a result of the turntable being unpowered for some period of time, allowing the capacitor to temporarily recover to some degree.

Just a guess, but a possibility to consider. Good luck. Regards,
-- Al
tablejockey
3,936 posts
 
Lostbears, when it was on the market I believe it's mentioned power supply enhancements for even quieter performance along with replacing the blue LED's under the tubes to a shade that blends with the glow of the tubes.
Never was a fan of the blue LED, reminds me of cheesy made in China gear. I've been tempted to unplug the blue front display.
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