EMU 0404USB: 1/4 TS vs. Stereo Output - an underrated difference
Feb 7, 2008 at 2:35 AM Post #16 of 49
FYI... I got my 1/4" TS to RCA cable from Blue Jeans Cable. Was about $43 and built to last, and it was super easy to do business with BJC. I got the extra shielded cable (because I was fearing RF interference), so it is a bit stiff.
 
Feb 7, 2008 at 2:35 AM Post #17 of 49
Quote:

Originally Posted by Cankin /img/forum/go_quote.gif
I've read that, a true balanced DAC must have dual differential output from the chip itself, not just wired with XLR(or TRS) connectors.

Does 0404USB have true balanced output from the AK chip??


The E-MU spec is not explicit in that regard under "Analog Line Outputs" at E-MU Systems - Established 1971 - Emulator X2, Proteus X2, Digital Audio Systems, USB Audio/MIDI Interfaces, USB MIDI Controllers

Type: balanced, AC-coupled, 2-pole low-pass differential filter
D/A converter: AK4396
Level (auto detect):
- Professional: +12dBV max (balanced)
- Consumer: +6dBV max (unbalanced)

The AKM datasheet for the AK4396 does state......

".....The AK4396 has full differential SCF outputs, removing the need for AC coupling capacitors...."

......but the 0404 USB has AC coupling capacitors. The AK pinout diagram shows hot and cold pins for both analog output channels.

Guess we need someone who really knows what to look for to trace that out!

EDIT: Looking toward the back of that datasheet pdf, it appears that all of the suggested output circuitry terminates in an unbalanced signal.......something tells me that the actual topology ends up being an unbalanced signal from that point, sent to a balanced line driver....which I've been told is typical for a lot of pro gear. The inputs and outputs are designed to accept a balanced input and drive a balanced line, but that's primarily due to distances and to provide common mode rejection.
 
Feb 7, 2008 at 2:54 AM Post #18 of 49
Quote:

Originally Posted by Cankin /img/forum/go_quote.gif
I've read that, a true balanced DAC must have dual differential output from the chip itself, not just wired with XLR(or TRS) connectors.

Does 0404USB have true balanced output from the AK chip??


Yes, it is true balanced and the AKM chip has 2 channels, and also 2 outputs per channel.

EDIT: Actually, i have no confirmation whether EMU uses both channels of the AKM chip, so correct me if im wrong. However, i do know this chip does have 2 differential outputs per channel, which equals to 2 DAC per channel. Whether the EMU utilizes both channels of the AKM chip is something I cant confirm, but i dont see why they wouldnt utilize to the fullest potential of this chip.
 
Feb 7, 2008 at 4:07 AM Post #20 of 49
Quote:

Originally Posted by penguindude /img/forum/go_quote.gif
Yes, it is true balanced and the AKM chip has 2 channels, and also 2 outputs per channel.

EDIT: Actually, i have no confirmation whether EMU uses both channels of the AKM chip, so correct me if im wrong. However, i do know this chip does have 2 differential outputs per channel, which equals to 2 DAC per channel. Whether the EMU utilizes both channels of the AKM chip is something I cant confirm, but i dont see why they wouldnt utilize to the fullest potential of this chip.


I'm far from an expert, but a perusal of DAC datasheets shows that differential outputs are pretty much the norm on the newer chips....and that those outputs typically feed an output filter stage that also accomplishes the conversion to single-ended output. I haven't yet seen a DAC chip datasheet that depicts a suggested balanced analog output design.
 
Feb 7, 2008 at 3:05 PM Post #23 of 49
Quote:

Originally Posted by joe_cool /img/forum/go_quote.gif
See page 20 for AKM4393

http://www.asahi-kasei.co.jp/akm/en/...k4393_f02e.pdf


Thanks for finding that one. It appears that the output stage that I referred to for the AK4396 is essentially the same as the one for the AK4393 (and is typical of many others shown for DAC chips in datasheets), only without the intermediate connections to the XLR for a balanced connection!

I now realize that I could have missed that same feature on some other datasheets....I was quickly scanning through them, and was concentrating on the far right side where all of them seem to depict a single-ended output.
 
Feb 7, 2008 at 6:46 PM Post #27 of 49
Quote:

Originally Posted by maarek99 /img/forum/go_quote.gif
Hmm, no difference for me. You really need to use the same cables (with a plugin to get them to fit) for the comparison to be true.


Just curious, what amp are you using?
 
Feb 7, 2008 at 8:49 PM Post #28 of 49
Can anyone recommend any cheap RCA to 1/4 adapters that still have decent quality? I'd rather not have to pay $4 for each one.

I did find these, but I dunno if they'd be any different from other brands.
 
Feb 7, 2008 at 9:03 PM Post #29 of 49
For curiosity here in Finland it seems too hard to find an adapter TS->RCA so I'm afraid I have to buy such things from Germany with quite noticeable shippings. Those little Radioshack adapters would be perfect but I can't find any around eastern Finland.
Edit: the german ones ain't too great either:
153179.jpg

I have some IC's from the same manufacturer and they are not very good. The
 
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