DS Sr. hum

When I connect DS Sr to my power amp (Krill Chorus 7200) using balanced then I don’t get any hum, but when I connect DS using RCA (Iconoclast) I get a annoying but mild background hum.

I hear this hum on my speakers.

DS Sr is connected using Iconoclast power cord to Furman Elite-15 PF i 13-Outlet Linear Filtering AC Power Source.

I just listened to 120hz hum and 60hz hum and feel its 60hz or less… but certainly not 120Hz.

I read few questions on the forum and there was a suggestion to use cheater plug.
Can someone explain why cheater plug helps get rid of the hum?
Also why RCA is causing the hum?

Is the Krell amp a fully balanced design?

With this combination, the iBias amplifiers may now deliver substantially more power while using a smaller footprint. Normally used in demanding, high-bandwidth video circuits, these transistors allow the design of gain stages with superb accuracy and very low distortion. The signal path is fully complementary and fully balanced from input to output. Independent complementary pre driver and driver stages for the positive and negative output transistors make the output stages extremely fast and linear. This unique circuit is impervious to low-impedance or reactive loads; it simply drives any loudspeaker with absolute confidence, achieving the very best possible sonic results.

Thats what the spec says. But I must confess… i don’t know enough about this.

Krell Chorus 7200 XD Multi-Channel Amplifier – Krell (krellhifi.com)

Then when using the SE Iconoclast cables you have a ground differential that is causing the hum. You will either have to use XLR cables or lift the ground on the Krell to put them on equal footing. Fremer ran into the same issue in his BHK 300 review using the non-balanced Dart preamp.

What does this mean and is this safe?

If you lift the ground on the DS which is also fully balanced instead of the Krell it would be safer as you are plugging the DS into the grounded Furman. If that works then you are o.k., but if you are plugging the Krell into the wall and have to use the cheater plug on it instead of the DS I wouldn’t be comfortable with it as a long term solution. Better to contact Bob and see if you can trade the Iconoclast cable in for a Balanced one or have it re-terminated.


Thanks for the help here Dawk!

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Fought this battle many times.

You ever consider taking these excellent solutions and rolling them up into a wiki?
Trying to hunt them down on the forum can be rather difficult. Maybe set-up a locked down thread, and open it for solutions to common questions. Be it stellar phono hum and noise, tube rolling in BHK 250/300, elimination of hum when utilizing single ended and balanced components, REL subwoofer combined with Stellar 300 hum elimination, etc… It would certainly serve the customer base.


Yeah, this is a good idea. The search in the forum is decent but not perfect. For someone new to the forum looking for a solution, it must be hard to find answers. I’ll look into doing something like this.

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It can be hard to find answers to questions. I suggest using Goggle in the format site:psaudio.com search terms. For example, site:psaudio.com s300 hum This gets you this.

I take this opportunity to again praise our members. They are lightening fast to respond to queries with near infinite patience. Often a seeker of knowledge would have an answer from other enthusiasts before he found it in a wiki. :slight_smile:


Works for me, how about for a new PSA customer unfamiliar with the Forum or Goggle search options?

A Wiki is a fine idea. I already “liked” your suggestion. :+1:

thanks a lot. This fixed the problem. Now the annoying hum is gone!

Glad it all worked out.