isolation on a shoestring
Oct 20, 2008 at 3:40 AM Thread Starter Post #1 of 8

Halbyrd

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Hi all, been a while since I've posted here. I've done some poking around in the Computer Audio forum, but haven't found any good info on cheap (<$100) DAC boxes. I'm looking for something that takes TOSLINK or SPDIF input, and outputs to 1/8" or 1/4" stereo mini. Any thoughts?

Edit: I should probably mention, I'm going to be using this to drive Senn HD 280s and HD 495s (not the best, i know, but they were $30 at CompUSA). I'm currently running the inbuilt Realtek HD Audio card on my motherboard, but can put in my Chaintek AV-710 if needed.
 
Oct 20, 2008 at 5:58 AM Post #2 of 8

TopPop

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What about something like this?
 
Oct 20, 2008 at 9:47 AM Post #4 of 8

Halbyrd

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A USB DAC would introduce extra processor load on the system, I'm trying to avoid that. The main purpose of this is to electrically isolate the headphones from the main system, to hopefully get rid of the noise of HDD seeks, chassis fan speed changes, and (I kid you not) the occasional overheard CB radio transmission. Towards that end, I should probably specify TOSLINK input, as SPDIF doesn't break the electrical connection.
 
Oct 20, 2008 at 2:31 PM Post #5 of 8

sgrossklass

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As the very first step, mute all the inputs for playback. If that does not get rid of the unwanted noises, either you have a crappy power supply (never hurts to have a good-quality one) or the board manufacturer messed up either the HDAudio implementation or grounding layout.

With just headphones connected (i.e. no external ground loop in play), you normally should not be hearing such noises. Chances are, as long as it'd not the PSU, any half-decent sound card would get rid of the problem.
 
Oct 20, 2008 at 3:01 PM Post #6 of 8

Quaddy

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i would go with a usb to spdif box, the added processor load is nominal and could be negated by disabling your native optical out (BIOS or alike) and disabling any un-used usb host/hubs, as this most likely derives or pulls from USB anyway

the trends (lite or full=headphone out) is known for good electrical isolation which i can attest to which you can power from mains for better sound and 'less load' on the host system
 
Jul 28, 2010 at 12:05 PM Post #8 of 8

esdk

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Hi Halbyrd,
 
I have done the same research as you have done - trying to avoid the ground loop between PC and Sound Amplifier:
 
What I found was that the SPDIF and the optical SPDIF called toslink both do not support more than 2 channels in comercial amplifiers. So that was a nogo for me as I wanted 7.1 stereo surroundsound.
 
Another way is to use HDMI as that standard extents the SPDIF to multiple channels (I believe up to 32pcs), but my soundcard (Graphic card) does not support stereo surround - that might just be until drivers are updated, but for now - that was a nogo.
 
So in Marts 2010, I developed a USB isolation device - having both analog devices (ADUM 4160 usb isolating chip) and an isolated powersupply all in a sporty little USB stick enclosure. So now I have a perfect sound setup with 7.1 surround sound and no problems with ground loops. :)
 
I am now selling that solution at http://electronics-shop.dk/usb-isolator and keeping the price down to support as many as possible with the full experience of their surround sound system.
 
The device can also be used for programming in circuit chips - also to remove ground loops between circuit board and PC. First batch is almost sold - next batch we will produce in mid august.
 
 
Best Regards,
 
Soren
Electronics-shop.dk 
 

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