BF2S Forums Loud hum from my speakers

Freezer7Pro wrote:

Bertster7 wrote:

Freezer7Pro wrote:

What do you mean by that?

And are you sure that's the DAC that's in them? It's a bit expensive for the application.

That is the DAC they use. Well, it isn't actually a DAC, it's an audio processor that also performs the function of a DAC - but that's what most sound cards use these days anyway.

A bit expensive for the application? What do you mean? Having a decent audio processing chip is quite important for a set of speakers that have digital inputs.

Are you really sure that's what's in them? Do you have a source? Having a decent processor is indeed an important part of the chain, but seeing how Logitech went all out BOSE with the rest of the system, I don't see why they would use good parts anywhere else in it; there's a humongous bottleneck both in the amplifier and the speakers themselves.

Morpheus wrote:

Whoaah wrote:

Morpheus wrote:

Try plugging in everything to the same power strip? I know you said that everything is eventually run to the UPS, but that's really like saying every ground leads to the same earth... There could be stuff that makes all the grounds work individually, but not as a whole set.
...And what kind of digital out do you have? I though you said it was an optical out.....

I did plug it all into one power strip, even tried a different strip. As I noted I can unplug everything except the sound system and touch a ground wire to the pc chassis with everything disconnected from the pc except the speaker wires and produce a loud hum. I think there's something going on with the building ground. Maybe equipment some where leaking a small voltage to ground.

The optical connection is from my tv to the to the speakers. I have an open digital input on the speakers and a digital output on the sound card that is not being used.

Ok. Well, then you can try this:
http://www.sweetwater.com/store/detail/HumX/

It puts isolation on the ground, so I'd use it on a strip leading to your PC...

but you said other computers didn't have this hum issue?

And as far as the digital input, it depends on the format... you can't run AES/EBU into SPIDF and expect it work... although i suspect most consumer audio is SPIDF, i would double check the manuals.

Whoaah wrote:

Additional trouble shooting
Pull power cord on pc, speakers still hum.
Pulled sound card out of pc and plugged speakers in, no hum.
Put card back in pc and plugged in only the speaker cables, no hum.
Plugged in Ethernet, small hum.
Plugged in parallel cable to printer, louder hum.
Plugged monitor DVI cable in, very loud hum.
Unplugged Ethernet and parallel, still very loud.
Unplugged power cord to monitor, no hum.
Plugged power cord to pc in, loud hum.
Unplugged power to pc and took a piece of wire from the receptacle ground to the pc chassis, loud hum.

So any ground path to the pc makes this hum! Bad receptacle ground? A simple receptacle tester shows hot, neutral & ground is ok.

Note: Sound system has an ungrounded power cord.

What sort of cable can I use to go from the digital output 1/8” plug on the card to the RCA input on the Logitech sound system? Any cable with 1/8” plug on one end and RCA on the other? Will switching to this cable solve my problem?

Last edited by Freezer7Pro (2009-11-14 09:11:03)

Morpheus wrote:

Freezer:Overpriced it might seem, but do you have any other suggestions?

Whoaah: You could just ground lift the entire system...

I'd also try using a different outlet, you're right, the receptacle could be bad.

...Also, does it look like the audio power should be grounded? (as in, is there a pin missing in the plug, or is it a regular wall wort without ground?)

edit for clarification