60hz Hum! Don't we love it?

jaykeMURD

jaykeMURD

I sit on you.
I know I've grown awfully "happy" with the 60hz hum making itself present in my tracks. Of course, by "happy" I mean absolutely disgusted. ;)

Anyhow, here's a bit of the scenario.

SDC (mono) to PAiA TMP 1/4 out to RCA IN on my M-Audio Delta 1010LT.

I know I'm running an Unbalanced signal chain, which will eventually be changing, but for the time being I'd like to record without that flippin' horn in the back ground. I mean, I've heard some AC hum in other things before, but this is utterly sickening. It RUINS any and everything I record. I try to EQ it out, but those frequencies are important!

I can hook my DMP3 up the same way and experience NO hum whatsoever. So it's not bad interconnects or anything.
I'm thinking the Power Supply on the TMP may be the culprit (as in many cases is).

I thought I might have developed a ground loop, but I've tried moving the power plugs around, but to no avail.

What is going on!? :confused:
 
Yeah, try moving the ps as far as possible away.

It may also be the design of the Paia. An ungrounded design like that often grounds the chassis through the shield of the cable, which can make it very noisy. You could balance the outputs, or replace the metal jacks with plastic ones, or maybe make an adapter that connects the sleeve to the ring of a TRS connector instead of the normal way, and go into a balanced in.
 
boingoman said:
Yeah, try moving the ps as far as possible away.

It may also be the design of the Paia. An ungrounded design like that often grounds the chassis through the shield of the cable, which can make it very noisy. You could balance the outputs, or replace the metal jacks with plastic ones, or maybe make an adapter that connects the sleeve to the ring of a TRS connector instead of the normal way, and go into a balanced in.
Click to expand...

Thanks. However, if I use TRS on the PAIA, wouldn't that be defeated by the RCA INs on my Delta? Or would that fix the ground loop?

Perhaps there are tools/eqipment that would "lift" the ground, therefore eliminating the loop?
 
Did you build the paia? if so you may be able to answer a couple of questions. First is it using full wave rectification or a switching power supply or (cringe) half wave power supply?. Second you may be able to replace ( or add if lacking ) some filtering cap's and possibly a voltage regulator ( think lm317 as a start) and check all of your common grounding with a ohmeter less is better. If you didn't build this and you aren't comfortable with electricity then find someone who is. I know just enough to be dangerous so take what I say with some caution. I would hate to get someone else electrocuted! :eek: :eek:


Randy
 
Randy5235 said:
Did you build the paia? if so you may be able to answer a couple of questions. First is it using full wave rectification or a switching power supply or (cringe) half wave power supply?. Second you may be able to replace ( or add if lacking ) some filtering cap's and possibly a voltage regulator ( think lm317 as a start) and check all of your common grounding with a ohmeter less is better. If you didn't build this and you aren't comfortable with electricity then find someone who is. I know just enough to be dangerous so take what I say with some caution. I would hate to get someone else electrocuted! :eek: :eek:


Randy
Click to expand...

Yes, I built the Paia. I have no idea what kind of power supply it's using...
It's just a plain wall-wart going directly into the PCB. The plug itself says "Plug-In Class 2 Trans.". Also says:
INPUT: 120VAC 60hz 17W
OUTPUT: 12VAC 1A

I did think the power design was kinda....elementary. There seemed to be no sort of filtering, at least to my knowledge.
 
according to the schematics i have found ( havent built one myself) there is a fairly simple mod to change to a dc current for the filament heater instead of AC . that should help quiet it up some. ( not sure how much though but it looks simple enough and surely couldn't hurt) I am not an electrical engineer but that Power supply looks pretty crappy. Since you are currently sending basically mostly unfiltered power. Still trying to wrap my head around this PS. Im still learning so as stated before take my advice with a grain of salt ( that mod I recommend is in the actual schematic for your paia tmp though so it should definitely be safe) It also look to me as if it may be half wave rectified ( i could be completely wrong here and hope someone more experienced can confirm or deny) which if it is indeed the case is adding a fair amount of ripple to the power supply ( noise)

Randy
 
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