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Old 10th December 2007, 09:34 AM   #1
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Default E-MU 0404 USB Modification?

I just buy E-MU0404 USB, for measurement purpose. In standard form, this sound card is quite good, all noise are below 120dB.

What modification can be done to this unit, to get better measurement properties? In loop back FFT, there seems some frequencies are rising.

The opamps are NE5532 and NJM2068. Is it OK to replace those dual opamps with OPA2134?
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Old 11th August 2009, 02:08 AM   #2
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Default Re: E-MU 0404 USB Modification?

Quote:
Originally posted by lumanauw
I just buy E-MU0404 USB, for measurement purpose. In standard form, this sound card is quite good, all noise are below 120dB.

What modification can be done to this unit, to get better measurement properties? In loop back FFT, there seems some frequencies are rising.

The opamps are NE5532 and NJM2068. Is it OK to replace those dual opamps with OPA2134?
I've heard using a linear 5v PSU insead of the bundled wall wart gives notable improvements, and I've also heard that replacing some of the op-amps with 4562's improves things even further. I only ordered a 0404usb today, so I may try this out when it arrrives.
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Old 11th August 2009, 02:18 AM   #3
cuibono is offline cuibono  United States
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The 0404 usb has some of the lowest noise floors and distortion figures of any soundcard - like -110dB to -120dB. I can't imagine why anyone would need quieter? My guess is that the ground paths are probably as important or more than different opamps, and very difficult to change. A linear PSU might help too, but once again, this thing is already very very clean - that's why I've got one too.

The only change I'd like to see is the damb SPDIF be made available to all applications!
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Old 12th August 2009, 05:04 PM   #4
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Quote:
Originally posted by cuibono
The 0404 usb has some of the lowest noise floors and distortion figures of any soundcard - like -110dB to -120dB. I can't imagine why anyone would need quieter? My guess is that the ground paths are probably as important or more than different opamps, and very difficult to change. A linear PSU might help too, but once again, this thing is already very very clean - that's why I've got one too.

The only change I'd like to see is the damb SPDIF be made available to all applications!
Well mine still hasn't arrived, but by the sounds of it, changing the op-amps isn't really worth the hassle.

Some people over at head-fi have said that the headphone out has more gain when using a different (higher current) PSU, which may mean the existing PSU is a little underspecced... It does seem a little optimistic that the whole unit can use less than 5W so much in there like DAC, ADC, pre-amp, headphone amp, etc... So I think the first thing I'm going to try is another PSU.

As for the SPDIF, so you mean not all applications can output SPDIF?
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Old 12th August 2009, 05:08 PM   #5
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Quote:
Originally posted by MikeHunt79

Well mine still hasn't arrived, but by the sounds of it, changing the op-amps isn't really worth the hassle.

Some people over at head-fi have said that the headphone out has more gain when using a different (higher current) PSU, which may mean the existing PSU is a little underspecced... It does seem a little optimistic that the whole unit can use less than 5W so much in there like DAC, ADC, pre-amp, headphone amp, etc... So I think the first thing I'm going to try is another PSU.

As for the SPDIF, so you mean not all applications can output SPDIF?

If the gain depends on the supply current capacity (or the supply voltage for that matter) this is a spectacularly incompetent unit. Which it isn't, far from that. I would completely disregard that supply comment as Full Of It.

Do you realize that 5W at +5V (or less) is 1 Amp? Sounds like overkill already to me.

jd
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Old 12th August 2009, 05:46 PM   #6
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Quote:
Originally posted by janneman
Do you realize that 5W at +5V (or less) is 1 Amp? Sounds like overkill already to me.

jd
Apparently the stock PSU is around 800mA, I'm not really sure how much power these things use but it's just something I've seen on another forum... I guess there's no beating personal experience, so when mine arrives I'm going to see for myself if a PSU makes a difference as I have more than 1 5v PSU, especially to the headphone output.
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Old 12th August 2009, 06:30 PM   #7
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Quote:
Originally posted by MikeHunt79

Apparently the stock PSU is around 800mA, I'm not really sure how much power these things use but it's just something I've seen on another forum... I guess there's no beating personal experience, so when mine arrives I'm going to see for myself if a PSU makes a difference as I have more than 1 5v PSU, especially to the headphone output.

I have an 0404, I'll see if I can measure current consumption, just for the heck of it...

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Old 12th August 2009, 08:36 PM   #8
Tolu is offline Tolu  Germany
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One guy recommended an old Zip drive PS. It should audibly superior to the standard one.
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Old 12th August 2009, 08:52 PM   #9
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Quote:
Originally posted by janneman



I have an 0404, I'll see if I can measure current consumption, just for the heck of it...

jd
Thanks, if possible could you measure if it uses any extra power with headphones plugged in... I imagine it will make very little difference, but I'd be interested nonetheless.
Quote:
Originally posted by Tolu
One guy recommended an old Zip drive PS. It should audibly superior to the standard one.
I actually have a Zip drive PS somewhere, I cut the plug off but if I can find another I'll give it a go.
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Old 27th September 2009, 05:11 PM   #10
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Quick introduction: I recently sold my Emu 1212M (modded: I bridged the coupling caps, replaced others in the analog section with blackgates) and now have the Emu 0404 USB. It sounds ok for the price (or compared to decent CD players like Marantz CD67), but I don't like it as much as the modded 1212M. The 0404 can sound a bit harsh at times (especially symbals on drums and vocals sometimes have a bit too much energy in the "s" region and have a bit of a "sharp" quality). I know this sounds weird because the frequency response and other specs are quite flawless but to my ears, this sort of sounds like the original 1212M. The modding brought "life" to the sound and maybe the 0404 is just an unpolished diamond...

I'm hoping you guys can help me out a bit in trying to squeeze more out of this little gem. The 0404 uses AK4396 as the da-converter and I'm sure many of you have heard the buzz around this one (many regard the AK chips as the best converters and the 4396 is definately from the higher end of AK chips).

So, let me give you a short tour.

On the left side of the potentiometer is the da-chip (half visible). On the right side of the chip are the R+, R-, L+, L- rails going in to the 4 capacitors. After the capacitors are two JRC 2068 opamps. On the left side of the caps is the headphone stuff (let's not go there).
Click the image to open in full size.

On the right side of the potentiometer the output stage continues. Two 5532 opamps next. The big plastic thingies are the balanced outputs.
Click the image to open in full size.

So what I've done so far? I replaced the four caps (coupling?) with Elna Silnic II as I had some in my drawer. Did the sound change? Don't know. At first I couldn't hear a difference but after keeping the unit on for 24h I got the feeling that maybe the sound is not as harsh but then again, maybe it's just my brain playing tricks on me.

What would you guys/gals suggest I could try next? Can you find muting transistors I could remove or any idea if I could bridge the coupling caps etc? I have Auricaps in the input of my amp so DC is not a big concern.

For reference:
AK4396 datasheet (last pages include reference circuitry and I believe it's very close to what the Emu has)
Some nice photos of the Emu 0404 USB PCB
Lots of PCB pics
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