I don't have any personal experience with Krell amps humming, but a friend of mine says that he occasionally catches his amp humming "I Can't Get No Satisfaction"... (sorry, couldn't help myself).
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Do you have the Krell plugged into an AC conditioner? If so, try
plugging it directly into the wall. Krell amps, like a lot of amps,
do not like to be plugged into an AC Conditioner and will hum
if plugged into one. Next, do you have all your gear plugged into
a 15 amp circuit that is not dedicated for your system? If so, your
amplifier may be starved for juice or picking up a hum from another
appliance in your home, or even from a neighbor's home. Way to
solve that is with dedicated properly grounded circuits with Hospital Grade outlets for your audio/visual gear. Put your amp
on a separate 20 amp circuit and a separate circuit for the AC Conditioner. If your AC Conditioner is also an isolator, you can
plug the rest of your gear into it. After installing dedicated circuits
all humming is gone, my system is dead quiet, sonics are improved and no more humming.
As it is a 5 channel amp, are all of the 5 channels being used? If so, are they all being fed balanced XLR or single ended RCA's?
The amp comes with grounding pins to insert into the balanced inputs that are not being used.
Give us some answers to our questions, especially the cheater plug and we can troubleshoot the issues with you.
Cheater plug did nothing to change it. All gear is in one circuit, but have had Bryston, Pass Labs, Sunfire and B&K in same circuit in previous few days with no hum. Using RCA's as interconnects, can see no pins inserted in XLR's and none were in box, there is only the small silver piece at each xlr, that I'm assuming is somehow related to the connection. Don't have a dedicated circuit to put it on for now. All other gear is being run through line conditioner, have tried amp both straight into wwall and into conditioner. Odd new facts, the mnore interconnects run into the pre/pro the more hum, and when my subwoofer is connected and powered up, hum is almost 80db. Very strange, as I said I've had multiple amps on this circuit and configuration this week, and absoutely zero noise.
Your Krell is a theatre standard, I assume that's a mutli-channel amplifier. Does your Krell draw more juice than the other amplifiers you tried? And, do you have a powered sub-woofer?
Did you have a powered sub-woof plugged into the same circuit
when you tried the other amplifiers? Amplifiers and powered sub-
woofers draw a lot more juice than anything else in your system.
If your Amplifier draws more juice than the other amps you tried
and/or if you have a powered sub-woofer plugged in with the Krell, but you didn't with the other amplifiers, you don't have an apples to
apples comparison. It is curious that adding the Sub-woofer makes the hum worse.
You'll want to add a couple of dedicated circuits if your budget allows. I had humming problems and nothing worked until I installed dedicated circuits -- now it is stone silent -- no more humming of any kind. One other thing -- I did specify 10 gauge wire for the 20 amp circuits. Please write in and report after you get the pins and dedicated circuits -- I want to hear a success story!
Rob, I think the RCA center conductor is wired in parallel with pin 2, the shorting pins short pin 1 and 3. I think the small silver piece he is talking about is the cable release. Krell amps come from the factory with the pins in I think? If the amp was new then Krell screwed up or if it was used, the former owner was running it balanced and may have lost the pins. You can bend a small nail to use as a pin if you had to I would think.
Rather than bending a small nail go to the hardware store and purchase about a foot of #12 solid copper wire. Remove the plastic shield and using a pair of long nose pliers just bend yourself some shorting pins...be sure to run some 200grit sand paper over the ends to round them out and keep the inside of your xlr's scratch free. Wipe the sand grit off before inserting in the amp. If this does not work ship the amp back to Krell for a repair...in the last 12 years I have owned 7 Krell amps and have never had a single issue with noise or anything else.......Good luck