2. amps-preamps
  3. 1247577616

Bad Hum Coming Through Amp, What Happened?

I've been running a Primare I21 amp for over a year now, and have been quite happy with the fact that there is no audible hum that comes through the speakers at any volume output. Out of the blue a couple of weeks ago, a nasty hum has started to emit from the amp through the speakers, audible starting at 20-25% of the volume output and louder as the volume increases. I've changed AC receptacles to a Cryo Hubbell one, I've upgraded my power conditioner, and I've switched the stock power cable to a Magic Power cable (which makes the hum even louder).

I am only using 2 of the 4 inputs on the amp, CD and Line 1 (turntable). The hum only occurs on the inputs that have something plugged in to them, and the hum goes completely silent when switched to an input that doesn't have anything connected to it. I've tried rolling the other components to the other inputs (the hum followed the components), and have tried the upgrade power cable on both of the components (no change). The hum occurs whether the components are off, on, or in standby.

What happened here? How do I make this hum go away? It's driving me crazy! Is there something inside of the amp that can be replaced/upgraded to kill this problem? Thanks in advance!

I posted this in Misc Audio last night, sorry for the double post! I realize now this was a better spot for the question, and I can't seem to figure out how to delete my other post.
maha0098
magfan
1,583 posts
 
Longshot and maybe some help....long term.
Go to home multi-mart and get an outlet tester. Not one of the 'does it have voltage' types, but one which will show various hookup faults, including hot to neutral or ground reverse and various 'opens'.
They are cheap and should be in anyones parts box who has any work done on there power.
goldeneraguy
439 posts
 
Rtn1 and Almarg,I just want to be sure of the procedure in taping the ground post.When using a turntable do you connect
the grounding lead from the turntable to the grounding post on the preamp and then wrap the grounding post with Electrical tape.This is the first time I have heard of this method to eliminate hum.
almarg's avatar
Ag insider logo xs@2x
almarg
8,673 posts
 
Goldeneraguy -- No, don't use any tape at all on that connection. We were referring to power cords only (and isolating the safety ground of the ac wiring from the component's ac power connector), not to the ground connection between turntable and preamp. Defeating the connection of turntable ground wire to preamp ground post will most probably increase hum significantly.

Regards,
-- Al
rtn1
535 posts
 
On the AC IEC inlet located on the component, I tape the grounding prong to block its connection to the power cord. This is the same as adding a cheater plug at the opposite end of the power cord, or pulling the grounding prong out of the IEC.

I also have star grounding of all components from wires connected to the chasis, to the Tripoint Troy. Tripoint Troy is a RF/EMI filter that grounds everything through an outlet.
goldeneraguy
439 posts
 
Guys,Now I GOT IT. Thank you for that clarification.
Rtn1 I have interest in the Tripoint.Might be to expensive for me though.I spoke to Miguel shortly before RMAF but we have not spoken since.
Can I ask your thoughts on the TROY
More to discover