Getting him in my ARC PH3se phono pre


I use two isolation transformer to hook up all my equipment. 
One has the phono pre, TT motor (VPI Prime) and the speed controller equipment for the TT - 250w.  The other has the preamp, and amp - 1000w. 
I’m getting a hum when I turn up the volume when listing to audio through the TT. Here are the are the conditions it’s happening under:

1. Phono pre must be on for hum to occur. If turned off hum goes away. Obviously, so must amp and preamp Be turned at the same time to hear the hum. 2. Phono pre on, but TT motor off, hum is present. So no music playing. Btw motor is controlled by Eagle and Roadrunner. 3. Phono tubes are new and in good condition. 4. The Phono unit is an older unit, but when I had it connected to another system in another room I did not have a hum problem. 
Not sure where to go from here. Especially since I’m connected to isolation transformers. 
last_lemming

Showing 9 responses by mijostyn

Don't forget those RAM Labs tubes. They will lower your noise floor 10 dB!!
So, not location. Check the tonearm negative wires. After that it has to be the cartridge. I understand Soundsmith cartridges do not do this. You may also call Grado and ask if they have a solution to this problem. Ortofon and Clearaudio cartridges are also hum resistant. Again, the PH3 SE is a wonderful phono amp. If you only use one tonearm and do not mind soldering a couple of resistors in to change loading it is very hard to do better. You would have to spend over 10K. Take good care of it!!
Also, check your tonearm negative leads for continuity. Tonearm wires have broken. 
Not sure that means anything Last_lemming. If it is the vicinity the turntable is in the only way to determine that is to move the turntable, what a PITA. The Grado is notoriously sensitive to external fields maybe if you explained your misery to a local shop and promised to buy a new cartridge from them they would let you take a demo unit home to see if that fixes it. Yes, it could be the kitchen but are you going to move everything around to get off that wall?
The PH3 SE is a great phono amp and should be dead silent if loaded correctly. It is certainly a keeper. You would have to spend serious money to do better. RAM Labs SLN 6922's are a great upgrade.
If the hum goes away you have a cartridge problem. Is the turntable near anything else that might cause a hum?
woops, I see you have used the cheater plug. Remove the positive signal wires from the cartridge.
Last_Lemming, the Grado hum will get louder as the cartridge gets closer to the motor. I would start floating grounds starting with the Phono preamp.