Crackling noise from the left tweeter - how I solved it

[ppataki]

I want to share my experience here so that if any other ASR folks run into this issue they could hopefully solve it faster than I did.....

I got a new Focusrite Scarlett 18i20 4th Gen audio interface (unbelievable Black Friday deal (30% off) that I could not miss)
I hooked it up all nicely - big smile on my face, now I have 26 channels!

But then I realized that there is a weird crackling noise coming from the left tweeter only..... pretty loud, it is totally audible in the MLP and it sounded like power supply 'leakage'
I have fully balanced connections but nevertheless as a start, I scrutinized all my cables: unplug, disassemble, multimeter check, re-assemble....... no change, noise is still there
Next step: maybe one of the new Topping B100 amps driving the tweeters kicked the bucket....no, both the amps were functioning properly, noise is still there
After scratching my head for a while I noticed that the noise was gone if I disconnected my 3e Audio A7 Mono amps (driving two subs) from the Scarlett
Strange.....

Based on that new discovery, as a final idea I literally moved all my gear from my IKEA Besta and scrutinized ALL the cables, connections, etc.

After spending approx. net 6 hours in total discovering the issue I noticed that the power cable going into the external PSU of one of the A7 Mono units was a tad bit loose in its socket....
That loose power cable connection somehow made the PSU noise get into one of my tweeters..... I have no idea how.....
But indeed that was the root cause - after re-plugging that cable firmly to its place the noise was totally gone

I think I must have aged at least 1 year while figuring this out......

I hope this will help others if ever you have PSU noise getting into your speakers

 

[jamescarter1982]

good to know, i hate these problems that seem to have no logical cause .
if I plug my powered monitors into one circuit in the house I get a mad ground loop hum unbelievably loud . if I plug an extension in from another circuit its fine . bit worrying as ive just rewired the house .
by the way they're are locking iec connectors to stop this kind of problem . or what I use for my powertools is called speakon. you can unplug and plug in powered on components without pops coming through the speakers apparently

 

[AnalogSteph]

if I plug my powered monitors into one circuit in the house I get a mad ground loop hum unbelievably loud . if I plug an extension in from another circuit its fine . bit worrying as ive just rewired the house .

Did you check whether PE, live and neutral are all exactly what they should be on the circuit in question? Perhaps the PE is not hooked up or something. Anything more problematic should normally trigger the GFCI in short order.