nasty ground loop noise??

[airgas1998]

i have a 2-part system where I mend my preamp with my ht avr via using aux(fixed) from my pre to my avr pre out fronts connection using standard RCA interconnects. Unfortunately this connection created a nasty hum like you here with a guitar and amp hookup. I know it's this connection as it's only there when I use this scenario for a ht bypass set-up. it appears to be coming from my preamp when i switch inputs from aux to another it's gone. any ideas on what to do?? I switched out the power cable to a non-ground 2prong and still nothing....

 

[NTK]

You can get one of these isolation transformers. Not cheap.

CI-2RR | Jensen Transformers

The unbalanced stereo design begins with gold RCA connectors to ensure optimal signal transfer. These are housed in a rugged steel enclosure that is fitted with screw-down flanges for easy installation in racks, under shelves or attached to cabinetry. The magic inside comes from two high...

www.jensen-transformers.com

 

[JayGilb]

i have a 2-part system where I mend my preamp with my ht avr via using aux(fixed) from my pre to my avr pre out fronts connection using standard RCA interconnects. Unfortunately this connection created a nasty hum like you here with a guitar and amp hookup. I know it's this connection as it's only there when I use this scenario for a ht bypass set-up. it appears to be coming from my preamp when i switch inputs from aux to another it's gone. any ideas on what to do?? I switched out the power cable to a non-ground 2prong and still nothing....

I might expect a very slight hum from a preamp out to an avr in connection, but not a nasty one.
Check your electrical connections and make sure that any non-polarized plugins are correctly oriented.
Try another rca interconnect. This one may have damage.
If available, try another input on the avr.

 

[airgas1998]

I might expect a very slight hum from a preamp out to an avr in connection, but not a nasty one.
Check your electrical connections and make sure that any non-polarized plugins are correctly oriented.
Try another rca interconnect. This one may have damage.
If available, try another input on the avr.

well, maybe "nasty" is the wrong word.... it's not audible when sound is coming out of the speakers just when there's a pause or a quiet passage. i can't use any other pre outs on the avr other than front l/r. Remember this is for a home theatre set-up...ill try another set of RCA's..

 

[JayGilb]

i can't use any other pre outs on the avr other than front l/r. Remember this is for a home theatre set-up...ill try another set of RCA's..

How is this connected ? Are you are connecting the output from your preamp to an input on your avr that is used to drive speakers ?

 

[airgas1998]

How is this connected ? Are you are connecting the output from your preamp to an input on your avr that is used to drive speakers ?

preamp aux input (rca) into my avr front l/r preouts(rca) my preamp has a "fixed volume" setting where all I have to do is turn it on and then my avr controls the volume of the 2 front channels...plus of course the other 3 channels plus sub...

 

[AnalogSteph]

The 2ch setup is earthed for sure, I think both the 2ch power amp and the DAC are IEC Class I.

Only takes one more earth in the entire HT setup for you to end up with a nice classic ground loop (and if it's just the sub).

Isolation transformers are made at varying levels of quality and price. A 10$ cheapie may not meet hi-fi standards. Always use directly at input if at all possible.

 

[airgas1998]

The 2ch setup is earthed for sure, I think both the 2ch power amp and the DAC are IEC Class I.

Only takes one more earth in the entire HT setup for you to end up with a nice classic ground loop (and if it's just the sub).

Isolation transformers are made at varying levels of quality and price. A 10$ cheapie may not meet hi-fi standards. Always use directly at input if at all possible.

yeah for some reason it's going through my aux RCA connection because if I simply disconnect one channel it's gone...and when I listen just with my 2ch gear and not select the aux input it's whisper quiet...or vice versa if I just turn on my avr there's nothing...any good iso trans available in the u.s and not snake oil crap??

 

[kongwee]

You can try your preamp to avr connected only and any unused device to disconnect even they are not powered on.

 

[Andysu]

do video of what the noise actually sounds like , so others may have better understanding . keep phone in horizontal landscape position as that then records in stereo . if have REW connect to source so can see the actual frequency of the noise ( that is what i would do ) then you know if a device or maybe the wiring somewhere as been incorrectly wired due to possible distraction and wired it incorrectly , it's easily done .