Krell KAS amplifier hum

Is there a "conditioner" I can use to minimize/eliminate the mechanical hum

Beautiful amps BTW.

There is no conditioner I know of that can take idle current plus music playing current into MBLS’s of a pair of KAS Krell monoblocks and not be near it’s limit.

If your hearing hum through the speakers.
KAS Monoblocks can give hum by their very nature of being mono blocks, they should BOTH be plugged into the same heavy duty mains outlet to stop any earth loops through the house wiring.

Also use some "earth cheater plugs" on the preamp and source/s so they get the earth from the Krells through the interconnects, this way you stop any more earth loops through the house wiring.

Cheers George

georgehifi Said:

If your hearing hum through the speakers.
KAS Monoblocks can give hum by their very nature of being mono blocks, they should BOTH be plugged into the same heavy duty mains outlet to stop any earth loops through the house wiring.

jg2077 OP41 posts12-11-2019 5:54pmUpdate, I unplugged the 6m long XLR from each amp. Then, I powered on both amps. There was no hum at all.

@georgehifi ,
Yes I do realize the test above isolated the two amps from one another therein breaking the connection of the two amp’s power supply’s interactions (circuit ground/signal ground) but probably more importantly the two amp’s dedicated safety equipment grounding conductors.
Also worth mentioning is how did the designer of the Krell KAS amplifier connect the circuit ground/signal ground to the chassis of the amp where the AC mains safety equipment ground is bonded, connected to.



georgehifi Said:

Also use some "earth cheater plugs" on the preamp and source/s so they get the earth from the Krells through the interconnects, this way you stop any more earth loops through the house wiring.

Exactly.

Though there may be other factors at play. Process of elimination. The OP has to start somewhere. If we are assuming the hum is caused by a ground loop, imo, we need to isolate the 120V 15 amp wall outlet convenience outlet branch circuit safety equipment grounding conductor from the equation.

Why I picked the 15 amp convenience outlet circuit is because to me it has the highest probability for causing the ground loop hum.

Factors to consider?
Total length of the branch circuit wiring from the electrical panel to the wall outlet.
How many outlet boxes are in the run.
How were the equipment grounding conductors spliced together. (Wiring method used)
What other electrical loads are connected to the branch circuit. Possible small leakage currents from the hot line to equipment grounding conductor that may produced/caused by a connected load/s.


@ jg2077

ground cheater

https://www.homedepot.com/p/Commercial-Electric-15-Amp-Single-Outlet-Grounding-Adapter-Gray-U-09/203...

Put a piece of tape on the bottom side of the ground tab/lug, or over the outlet cover metal support screw, so it can not touch, contact, the equipment grounded receptacle metal screw that supports the outlet cover plate.

georgehifi6,400 posts

12-12-2019 12:32am


Also use some "earth cheater plugs" on the preamp and source/s so they get the earth from the Krells through the interconnects, this way you stop any more earth loops through the house wiring.

Use of ground cheaters for testing purposes only.

ICs signal grounds/small wires should never be used for safety equipment grounding conductors. In the event of a ground fault event not only could the ICs be damaged but worse yet audio equipment itself. Also worth mentioning in well designed audio equipment the circuit ground/signal ground is not connected directly (hard wired) to the chassis of the equipment where the safety equipment grounding conductor is bonded, connected. In many cases a small wattage low resistance resistor is used in series with the connection to connect the circuit ground/signal ground to the chassis.


Jim

You could try the Ebtech HumX, but you might need two.

Thank you all for taking the time.  After my first failed attempt last night, I decided to plug all "in" and listen to music instead :-)

Tonight, I will try what has been recommended.  Something else I forgot to mention; I have a cable line and box in this room.  The cable line runs parallel to the XLR (they do not touch) and is also plugged into the same 15A outlet the power distributor is plugged into...

with kind regards,
Jose