The New Krell- The PP 1050 and the hummmm

[bodiezaffa]

In another thread, I wrote about a hum that was emanating from the transformer of my brand new Krell 302e amplifier.
An AA member suggested that I try to connect the amp directly to the wall even though I was sure some DC was going through the lines back to the amp.
I did just that and the hum disappeared. However, and this is the strange part, when I plugged the amp back into the PP 1050, the hum reappeared.
I scrolled through the information panel on the PP and saw the “load” was between 30-35%. Remove the Krell plug and the load goes back to 0
Plugged into the PP 1050 is a laptop, external hard drive, 32” monitor and a NAD M51 DAC.
I am completely stumped as to why the PP is causing transformer to hum like that.
Any suggestions?

[Removed]

Depending on the vintage of your 1050 there was a revision done, PP installed a trim pot at the front of the unit located behind the front panel that took care of hum problems that occured from some amps being plugged into the PP units......

[bodiezaffa]

Thanks Jeff. Mine was purchased in 2009.

[Removed]

Take a flash light and shine it through the vents on the front and look in both corners, if your has the trim pot there easy to see.....if not call PP and see if there is anything they can do, most likely there will be nothing they can do as they have the new units out now and they don't have parts for older units.

[bodiezaffa]

Actually mine was purchased nov 2011 so the warranty should still be valid.

[bodiezaffa]

Looks like there's nothing wrong with the unit. The Krell is just too much for the 1050.
Here is the reply I received from PurePower.

Hi mark,

Your unit should have an adjustment pot located behind the front grill - lower left side. It can be tweaked to balance the current draw from the amp. This may help.

The 302 is quite a powerful amp with a large transformer. It can draw up to
3400 watts at peak with low impedance speakers. It is also possible that the
1050 just doesn't have the scale to be able to properly support it. If I were doing a power analysis for you today with the 302 I would recommend at least a
PP+ 2000 if not a PP+ 3000 depending on what you have in the rest of the
system (plasma, subs, etc.)

First thing though would be to check that current balance adjustment I
mentioned at the beginning.

Let me know how it goes.

Thanks,
Damian Janzen
PurePower Partners LLC