[Traddad]

Um...are you answering the right post? I don't own (nor ever would) a monster cable. I write off monsters as the "Kleenex" of cables...All name with only mediocre quality.
Also...I'm not a cable freak...as long as it's a big enough gauge and made of quality materials and connectors, I'm good.
Now...back to the computer hum
It also only happens when the computer is on...so it is not cable interference.

 

[milkweg]

Yea, you asked the below and is what I was replying to but I see now you are asking specifically for optical to RCA adapter cable. I've never had to buy one but you don't need a new cable if you already have a coax cable as you can buy adapters that do the conversion.

"I'm using a USB DAC (powered by the computer) would Toslink do better? if so, what is a good, inexpensive Toslink > RCA DAC?"

If USB is causing a hum then by all means try an optical digital cable as it should solve your issue. I use optical cable from soundcard to my EMU 0404 USB instead of the USB port. But not because USB caused a hum, just because it requires no EMU drivers to be installed and it is more convenient for me. I have only ever experienced hum when using analog out of the soundcards to an amp and use ground loop isolators on my 2 PCs to fix it but you are getting it over USB and not analog so that is of no use to you.
Try the optical to coax adapter method. YMMV.

 

[ericj]

I'm not sure "RCA" really makes cables. In the sense that once upon a time there was a company called RCA that sold their consumer electronics division to a french company called Thomson Consumer Electronics a very long time ago, and a few years back Thomson sold the 'electronics accessories' division to Audiovox. Which is to say that Audiovox can use the RCA logo on their crappy products.

But that's beside the point. People who attended the denver meet know what cables i roll with.

Why do people think that keeping the sound levels maxed out is a good idea? It's a great way to introduce clipping. the ideal level may be closer to 80%. or even 60%, depending on the actual system's construction.

 

[milkweg]

Because it is digital we are talking about and not analog. When using digital you set your PC to max volume and use the hardware amp to control volume. If you don't it affects dynamic range negatively and causes no clipping because it is a digital signal being sent by the PC. And there is nothing wrong with an RCA made optical cable from Walmart. Sounds exactly the same as any other optical cable no matter the price.

 

[ph0rk]

If it is a PC, one test might be to selectively mute all the sliders in your sound mixer one by one to see if that kills it - I've heard a baseline hum from line in/mic in on a pc before.

Do you get the hum if you plug headphones directly into the pc?

 

[Traddad]

OK, here is what I've done so far.
Since the hum comes across to the amp only when the PC is turned on and connected to the amp (no hum when the PC is off or turned on and disconnected from the amp on the computer end) I started disconnecting peripherals; no change. The hum is still there and unchanged with all of the peripherals turned off.
Sorry Ph0rk, I cannot hook my headphones to my computer. I cut them out when I added the AV-710.
I added an AV-710 a year or so back and then decided to just go to a USB DAC because the sound card would "screech" every once in a while. When I hooked the sound card back up the hum was still there although different. I'm going to try a new USB cord next. Any other suggestions?
As for cords; the reason I mentioned RCA was because I would like a DAC with optic in and RCA outs to match up to my system.
Thanks, all

 

[Traddad]

I just switched USB cables, moved to a more isolated USB port on the front of the computer (away from other cables) moved the DAC away from the computer and routed the RCAs away from other cables and devices.....no change. Am I right in assuming that it is most probably coming from the computer and through the USB?

 

[Traddad]

Another Update. When I hook my MP3 player (via headphone out to a mini-to-RCA cable) to the wall cable connection (no DAC) there is no hum. This means that there is no issue in the RCA cable I have running from the DAC to the Amplifier.
This says to me it is either the DAC or the computer.(?) As soon as my daughter gets off the laptop I'll hook that up.

 

[ericj]

Quote:

Originally Posted by milkweg /img/forum/go_quote.gif Because it is digital we are talking about and not analog. When using digital you set your PC to max volume and use the hardware amp to control volume. If you don't it affects dynamic range negatively and causes no clipping because it is a digital signal being sent by the PC. And there is nothing wrong with an RCA made optical cable from Walmart. Sounds exactly the same as any other optical cable no matter the price.

When using digital, the fader chip that the mixer controls shouldn't enter into the question at all. if you're using digital out and one of those sliders does something to the volume level, something is wrong.

Which is not to say that muting them won't make the audio cut out. But everything between 1% and 100% should sound the same.

 

[Traddad]

Well, I just hooked my wife's lap top up (plugged in to AC) and played a CD through the DAC (only difference in the chain was the computer) and no hum. This lead me to believe that it was the computer.....then I plugged the laptop into the same power strip as the main computer and...the noise was there!
Looks like I'm going to run another power strip!

 

[Traddad]

Sorry about the travelogue but....I hooked the surge protector strip that the computer is on to a different outlet (the outlet that had no noise previously) and the noise was back!
Then I hooked the computer directly to the outlet and....no noise!
The surge protector? Just weird. Could someone suggest an "audiophile" surge protector? (smiley)

 

[ph0rk]

can you plug your dac into another computer, like a laptop, and try it?

 

[Traddad]

See post 25. Did that and as long as the laptop was plugged directly into the wall it was good. As soon as I plugged it into one of the surge protectors it started to hum.

 

[Andrew_WOT]

Just lift the ground on your amp with 2 to 3 prong adapter or get HumX. Both breaks the ground loop the latter one still keeps the earth thus safer. If your equipment has floating ground, afraid the only option is RCA ground loop breaker like one from Xitel.

 

[Traddad]

Quote:

Originally Posted by Andrew_WOT /img/forum/go_quote.gif Just lift the ground on your amp with 2 to 3 prong adapter or get HumX. Both breaks the ground loop the latter one still keeps the earth thus safer. If your equipment has floating ground, afraid the only option is RCA ground loop breaker like one from Xitel.

If it were a ground loop would it hum when plugged into a surge protector (nothing else plugged in) and not hum when plugged into the outlet that that the surge protector was plugged into? The only difference is the surge protector.