Anyone Know Where I should Look to Figure Out This Hum?


http://https//www.dropbox.com/s/faxmop972rok7i1/Noise.m4a?dl=0

I recently purchased a Lamm LP2. First couple days, silent. Now this. It's coming from both sides equally, turning up the volume makes it louder. It's not the cartridge. Noise still there when I unplug the turntable inputs from the phono preamp. It sure doesn't sound like a ground hum and since it's both channels I don't think it's going to be a bad tube . I have another set of tubes on the way but they won't be here until next week so I can't double check that. I swapped out the rectifier tube and that changed nothing. 

Help!
dhcod

Showing 10 responses by dhcod

Still using the cheater plug and have since heard from two Lamm owners that have had to float a ground for some reason and a few that haven't in old homes. It's all a mystery and yet it really doesn't matter. I would be hard pressed to imagine a better sounding phono preamp than the 2.1 that doesn't cost $25k. I will be making that upgrade from the LP2 at some point this year if all goes well. 
Thanks for the suggestion. Interesting but no. Coincidentally the fridge is broken and unplugged awaiting repair. No TVs on. I just unplugged the DVR and turned off everything else in the house and the noise is still there. The system is on a dedicated circuit.
Yeah, done all that. Swapped all the tubes now. It's definitely not a ground hum or related to a tube. Waiting to hear from Lamm.
Thanks so much for this confirmation. Now I just have to figure out how to get it repaired without shipping cross country. Can't find a schematic online so there may be no other option unless Lamm will provide one. Hopefully they'll respond soon.
I was wrong. It was a ground loop which was solved easily by the first thing I should have tried which was putting in a 2-prong adapter on the Lamm. Done. Noise gone. 
Well to be fair to Ralph, there may very well be something wrong. The hum is happening everywhere I hooked it up, including my neighbor the electrical engineer's bench. The solution my simply be covering up the problem, possibly something going wrong with the transformer since my neighbor testing most of the component. I'm emailing all the info to Lamm. I can be patient waiting for a response. Hopefully they will help me figure this out for the long term.
Lamm tech said they found the LP2 to be incompatible with older home wiring and the cheater plug is the fix. It's the best outcome for me, so I'm going with that explanation.
I’m not worried. Seller is a friend.

My wife is saying that our fridge problems started around the same time. Maybe it’s related to the fridge some how? Who knows. Maybe when the fridge is fixed on Friday the hum will come back and I"ll have to take the cheater plug off. That would be funny.

All I know is this phono preamp sounds incredible!