Hummmm .... and I don't like it!

[TORB]

Hope I can some assistance please.

In my study I have a (new) PC hooked up to a Yamaha RX-367 Amp, and in the lounge I have a complete home theater set up. The lounge sound comes into the study sound via a long Toslink cable and that's working well.

In the study there is a Digital Coaxial Audio to Analog Stereo RCA Converter.
A Toslink comes out of the computer and into the converter. A coax (digital) comes out of the converter and into the Yamaha Amp.
A set of analogue cables out the other side of the converter and then goes into an analogue input of my amp in the lounge.

Until I got my new computer all worked well, but now not so good.

On the computer, in the Control Panel/Sound/Playback I have Realtek Digital Optical Output as the default device. In the Advanced Properties of this device, I have selected Dolby Digital Live (5.1 Surround) as the default format. That gives me good quality sound in the study.

The problem is that it also gives me "humming" in the speakers in the lounge. However, if I change the Default Format to 2 channel, 16 bit, 44100Hz, then the lounge speakers stop humming, but the quality of the sound in the study is very ordinary.

I am using KMPlayer, if that helps, and the lounge Amp is a Pioneer VSX-AX2AV-S.

Can someone please help with suggestions that will enable me to get rid of the hum in the lounge speakers, but still keep the good sound quality in the study.

 

[TLS Guy]

Hope I can some assistance please.

In my study I have a (new) PC hooked up to a Yamaha RX-367 Amp, and in the lounge I have a complete home theater set up. The lounge sound comes into the study sound via a long Toslink cable and that's working well.

In the study there is a Digital Coaxial Audio to Analog Stereo RCA Converter.
A Toslink comes out of the computer and into the converter. A coax (digital) comes out of the converter and into the Yamaha Amp.
A set of analogue cables out the other side of the converter and then goes into an analogue input of my amp in the lounge.

Until I got my new computer all worked well, but now not so good.

On the computer, in the Control Panel/Sound/Playback I have Realtek Digital Optical Output as the default device. In the Advanced Properties of this device, I have selected Dolby Digital Live (5.1 Surround) as the default format. That gives me good quality sound in the study.

The problem is that it also gives me "humming" in the speakers in the lounge. However, if I change the Default Format to 2 channel, 16 bit, 44100Hz, then the lounge speakers stop humming, but the quality of the sound in the study is very ordinary.

I am using KMPlayer, if that helps, and the lounge Amp is a Pioneer VSX-AX2AV-S.

Can someone please help with suggestions that will enable me to get rid of the hum in the lounge speakers, but still keep the good sound quality in the study.

Not enough, or the right info.

Somehow you have a ground loop. As I understand it, the only direct connection between your systems is an optical cable. However what about cable/sat/telephone hookups to the two systems?

Somewhere you have a potential between grounds.

 

[TORB]

Not enough, or the right info.

Somehow you have a ground loop. As I understand it, the only direct connection between your systems is an optical cable. However what about cable/sat/telephone hookups to the two systems?

Somewhere you have a potential between grounds.

Thanks. What other info is needed?

As far as it being a grounding issue, I don't think that is likely for a couple of reasons.

Firstly, the only 'outside' connection is a wireless internet connection and it still hums when it is unplugged.

Secondly, it has only started since I have got the new computer and all the other gear is the same. The only difference is the software driving the audio.

 

[avnetguy]

I gather the Digital Coaxial Audio to Analog Stereo RCA Converter is powered?

If so, try plugging it into a different circuit than the one the computer is on. I'm guessing it's on the same as the computer but try other ones even if it's not.

Steve

 

[TLS Guy]

Thanks. What other info is needed?

As far as it being a grounding issue, I don't think that is likely for a couple of reasons.

Firstly, the only 'outside' connection is a wireless internet connection and it still hums when it is unplugged.

Secondly, it has only started since I have got the new computer and all the other gear is the same. The only difference is the software driving the audio.

May be the computer has an internal ground loop. This is common. Computers make lousy audio sources, that is why I use an external DAC not part of the computer case.

Computers as a source of hum is common.

 

[TORB]

Thanks for the answers guys, but they fail to take into account one critical factor.

If the software is set on Dolby Digital Live it hums through the analogue connection in the lounge, but the study speakers are fine. And when I change the setting to but when I change the software settings to 2 channel, 16 bit, 44100Hz, then the lounge speakers stop humming.

That makes me think its software related.

 

[avnetguy]

Maybe I misled myself when I saw the word "Hummm" ... usually relates to a ground issue of some type.

So the "hum" issue only occurs when you play "Dolby Digital Live" through the converter to the lounge right?

The converter box probably only handles uncompressed 2 channel digital audio and selecting "Dolby Digital Live" causes the output to be in a dolby digital format that the converter can't handle.

Steve

 

[gpost3]

I don't think it is the computer. I have used computers all my life as audio source and never had humming problem. Maybe it is the audio interconnects?

 

[TLS Guy]

Thanks for the answers guys, but they fail to take into account one critical factor.

If the software is set on Dolby Digital Live it hums through the analogue connection in the lounge, but the study speakers are fine. And when I change the setting to but when I change the software settings to 2 channel, 16 bit, 44100Hz, then the lounge speakers stop humming.

That makes me think its software related.

This is a ground loop until proved otherwise.

We can't solve it at long range, because your system is too diffuse and complex.

You need to do the analysis and start lifting grounds. Start by lifting all grounds in the lounge system.

If this were the converter not up to the task there would be issues other than just hum I think.

You won't get any answers here, unless you read up on ground loops and how to prevent them. Then you have to do intelligent targeted interventions and post back here.

With further data from your experiments we have a better chance of helping you solve this.

 

[avnetguy]

If this were the converter not up to the task there would be issues other than just hum I think.

I agree, I would not normally guess an invalid digital signal to the converter would cause a "hum", just a techno-digital-garbage sound at best. The only reason I flagged it as a problem was the few I googled only handled 2 channel uncompressed digital audio.

Steve