suitable power supply for dozen opamps?

[BV]

Products | Myrra , "electronic transformer", (switching PSU..) typ 47247. Connect about 330uH inductor in series with each ouptput pin (+15,-15,0V) and than 2 capacitors about 100-470u from +15 to 0V and from 0V to-15 (behind inductors). That´s all..

 

[giro1991]

Moo, not sure what you mean by 'short input of test',(you mean test amp, or, short the circuit in some way?)

Mik, definately not, as I said the 0-87hz section / band works without hum.

cheers for helping me out, i'm tempted to listen without hpf but I'd rather play safe..

 

[Mooly]

I missed a word out Yes, the amp.

Short the power amplifier input and there should be silence. Keeping it shorted, connect the filter to the amp (so you are really just connecting the grounds together now but with the input still shorted). It should still be silent. If not you have a grounding issue.

 

[giro1991]

Alright moo,
Shorting signal to ground does seem to eliminate the hum.

I put a stereo y-splitter at amp end, summing L+R into mono - then tested mono interconnect on both in/out jacks while shorted. both same result.

 

[Mooly]

So it sounds as though your hum is present on the feed from your circuit.

If you are very careful you could try connecting headphones to the output of the opamp circuit. Do you hear any hum/noise. Set it all up before you put the headphones on though... any pops and crackles could be deafeningly loud.

 

[giro1991]

Even better I recorded it.

At the very start psu is off then it's switched on - off- on
Zippyshare.com - noise (switched off then switched on).wav

When using the amp as aforementioned, the psu doesn't even need to be switched on for hum to occur...

The above wav isn't at output of op amp though i'll try again doing that.
Also,
I'll repeat process again and try shorting and upload the result.

cheers

 

[Mooly]

Its hard to tell from that file tbh.

Why do those kind of sites always seem to host malware.