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A look inside Emu 0404 USB...

post #1 of 34
4/18/07 at 2:29pm
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post #2 of 34
4/18/07 at 2:33pm
Haha sweet. Thanks for the photos. I've been really interested in what the inside looks like. I almost bought one to find out myself.

Hmm, those opamps definitely need to be replaced. It could be an awesome source after modifications.
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post #3 of 34
4/18/07 at 2:52pm
Thread Starter 
I just bought this 0404 and will say that the sound is not bad at all, very quiet. I will be using it for headphone listening (Grado 80). I bought it because I wanted to use my laptop as source (mainly FLAC and APE) and because I wanted a volume control. I had heard that the DAC in this one is good. Then there is the opamp for the headphone out JRC 2114... I'm thinking about replacing it, but don't know with what...yet. The caps look like they need a replacing too...hehe. I'm looking for ideas on this one, what to mod and what to leave alone. Overall I'm very happy with it so far, but just think it could be made better.
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post #4 of 34
4/18/07 at 6:12pm
OK, who's going to volunteer to mod their EMU 0404 opamp and caps first?
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post #5 of 34
4/18/07 at 6:56pm
Awesome. Anyone see any potential mods?

How did you get the case open? I had some trouble and gave up for not wanting to break anything.
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post #6 of 34
4/20/07 at 11:45am
This might be the place to ask this:

Are the 1/4 TS outputs and the mini-jack output independent? I would like to route the big ones to my hi-fi and run the mini to a desktop speaker system. I do not need independent volume control or even switching. I simply do not want the presence of both connections having a deleterious effect on the SQ, so would hooking up both be akin to using a splitter or am I being a dunce here?
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post #7 of 34
4/20/07 at 2:44pm
Here is what the manual says, they are not independent of each other.

Main Outputs
The main outputs are normally connected to your monitoring system. The
signal is duplicated on a stereo 1/8ยจ jack for easy connection to desktop
stereo speakers.
Use TS unbalanced cables for consumer-level line signals and TRS balanced
cables for pro-level line signals. Balanced cables provide +6dB more output.
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post #8 of 34
4/20/07 at 4:36pm
Anybody see how the 0404 USB might step up the voltage from its supplied 5VDC wallwart to supply about 2.1 Vrms at the headphone output?

I measured that and posed the question of how that could be in this thread:

http://www.head-fi.org/forums/showthread.php?t=234398

and AMB replied that there might be a multiplier circuit in there.
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post #9 of 34
4/20/07 at 6:08pm
Thread Starter 
Opamp swap. I'm listening to the 0404 with OPA2604 on the headphone out. The pinouts on the 2114 and 2604 are the same so it was fairly easy to do (steady hand required...not much space). IMHO this is a better match with my Grado 80s.
Here are the spec sheets for the 2114 and the 2604...

http://thordk.homepage.dk/jrc2114.pdf

http://thordk.homepage.dk/opa2604.pdf
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post #10 of 34
4/22/07 at 5:14am
how about a opamp LM4562 replacement?
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post #11 of 34
4/22/07 at 3:58pm
hmm... anyone know what's the jrc 2068 in the first pic for? puzzled..
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post #12 of 34
4/28/07 at 6:18am
Quote:
Originally Posted by Thordk View Post
is it safe to remove the jrc 2068 from the pics?
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post #13 of 34
5/11/07 at 10:13am
has anyone tried any other op amp replacements?

Thordk can you say how the sound improved with the OPA2604?

Matt
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post #14 of 34
5/13/07 at 10:18pm
awesome

now i dont have take apart my roomates 0404

=)
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post #15 of 34
5/16/07 at 2:17pm
is there an unamped line out to use my own amp?
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