Onkyo TX-NR656 & Audiosource Amp Three

[mkkelly75]

Hello, I have been searching for an answer to this but have had no luck finding one.  I recently bought a pair of Klipsch KSP 300s that had bad amps in them.  I decided to buy an Audiosource Amp Three and bypass the internal amps.  My plan was to run the subout from my Onkyo TX-NR656 to the Amp Three (this is only powering the sub, the high/mid of the speaker is run off of the fronts of the Onkyo).  With everything hooked up I only get a buzz through the Amp Three.  I have tested with another source (cellphone with adapter cable) and it works fine this way.  The sub out from the Onkyo also provides signal to other powered subs with no issue.

I can't imagine what the issue could be.  Do I need some other sort of signal processor/preamp between the sub out and the amp?  I am stuck at the moment.

Thanks for any help that can be provided.

[TRainH2O]

I am not familiar with the KSP-300. Is it totally self-powered or does the amp only power the sub?

[mkkelly75]

The internal amp only powers the sub portion.  I have bypassed the internal amp and with the Amp Three hooked up to another source it powers them fine.  Only when hooked up to the sub out from my Oknyo it is causing the buzzing ( low hum only, no signal coming through).  But that output send signal to other subs fine.

[TRainH2O]

Have you internally disconnected the Klipsch amp from the sub driver?

Have you verified that the Audiosource amp works independently from the Klipsch?

[mkkelly75]

Yes, I have bypassed the internal amp, the Amp Three it's going directly to the sub.  When using another source, the Amp powers the sub speaker fine.  When connected to the sub out on the Onkyo I only get a buzz/hum.

I have also hooked up to another pair of speakers with the alternative source and it works fine but same result when hooked up to the Onkyo sub out.

[TRainH2O]

Sounds like a ground loop issue. Is the Onyko and Audiosource amp plugged into the same outlet?

I'm no expert since I have never experienced this but try the same outlet. If that doesn't work try a 3-prong to 2 prong adapter on the amp.

If none of that works, you might try plugging the Onyko into one power circuit and the amp on a different one.

[mkkelly75]

Ground loop for the win!  Or maybe for the fail.  A 3 to 2 prong adapter fixed the issue!

[TRainH2O]

Good to hear that a part that you most likely already had, buried in a box of random stuff, fixed your issue.