I have an E-MU 0202 USB. I do not know if the internals are similar to the 0404, but in the 0202 the +/- 15V opamps are powered from a DC-DC. Post-switcher filtering is skimpy as best, and there is a healthy RF residue in the output. I would worry a lot more about this than the 5V from the PC... besides, it sounds like crap.
Don't know about the EMU 0202 USB but the EMU 0404 USB is NOT powered from the PC USB port. The PC USB 5V are only used for detection so I doubt you will notice any difference.
The 0404 uses an external 5V supply rated at 2A and the standard switching one is crap. Noticeable improvement with a good linear PSU is reported.
The remaining internal DC-DC convertor noise is exactly what misterZu is addressing with his modifications described earlier in this thread (around page 13).
For best audio, you should completely eliminate the amplifier stage after the DAC chip. And replace it with something fancy of your own preference (transformers, tubes, discrete or even properly designed opamp buffer will improve sound).
Having said that, I am quite impressed with the sound quality out of the box. S-noises are a but harsh though. Still not found the time to try my Cinemag output transformers.... 🙁
The 0404 uses an external 5V supply rated at 2A and the standard switching one is crap. Noticeable improvement with a good linear PSU is reported.
The remaining internal DC-DC convertor noise is exactly what misterZu is addressing with his modifications described earlier in this thread (around page 13).
For best audio, you should completely eliminate the amplifier stage after the DAC chip. And replace it with something fancy of your own preference (transformers, tubes, discrete or even properly designed opamp buffer will improve sound).
Having said that, I am quite impressed with the sound quality out of the box. S-noises are a but harsh though. Still not found the time to try my Cinemag output transformers.... 🙁
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The audio improvement between a NUC and NAD D 3020 is no joke. The marketing as a jitter reducer might be though.
Stereophile sez:
While measuring the effect of the AudioQuest JitterBug didn't prove to be a complete snipe hunt, it also didn't reveal why using the JitterBug improved the sound—which it most certainly did.
Some day I will AB the plate goodbye noises. But I think it is safe to say it will do similar to the Jitterbug.
I would love someone to explain how it improves sound when USB is a digital stream, It does not attenuate any noise so please explain how it can alter the sound, this is a prime example of the emperors new clothes and how much scamming certain areas of audiophile products have fallen into. Under proper testing I bet no one hears a difference...
But again HOW, dosn't filter any noise, its digital data and to change that a DSP is needed so HOW....
But again HOW, dosn't filter any noise, its digital data and to change that a DSP is needed so HOW....
It has a common mode filter on the data lines, so maybe it eliminates some common mode noise. It also has a LC filter on power, so if the DAC is USB powered, why not.
The claim about jitter and packet errors is bogus, though. Packet errors cause very audible dropouts (and they almost never happen unless the cable is totally out of spec).
I'm rather unconvinced...
The claim about jitter and packet errors is bogus, though. Packet errors cause very audible dropouts (and they almost never happen unless the cable is totally out of spec).
I'm rather unconvinced...
When measured though it didn't do anything to noise and as I pointed out on the jitterbug thread if you want to remove noise you have to do a proper layout or the noise just couples back in...
But again how much noise is coming through, its always a generalisation that USB power is noisy but never any measurements and the computer noise gets through... Ha there are sound cards inside computers down in the silly figures so why would an external DAC suffer computer noise and how much effect does this computer generated noise have... on audibility, anyone any acess to real figures and testing... Nope its just another round of scaremongering and BS to sell a badly done product.....
Most USB interfaces have the Cm chokes on, not always populated but especially in PCs to get through EMC they are there already. VBUS and how its generated and controlled for each port is quite interesting, quite often a reg on the output and some current limiting....
But again how much noise is coming through, its always a generalisation that USB power is noisy but never any measurements and the computer noise gets through... Ha there are sound cards inside computers down in the silly figures so why would an external DAC suffer computer noise and how much effect does this computer generated noise have... on audibility, anyone any acess to real figures and testing... Nope its just another round of scaremongering and BS to sell a badly done product.....
Most USB interfaces have the Cm chokes on, not always populated but especially in PCs to get through EMC they are there already. VBUS and how its generated and controlled for each port is quite interesting, quite often a reg on the output and some current limiting....
I don't know how... but it is interesting to note that a USB isolator changes my DAC's THD from 0.00044 to .008. With that in mind it isn't a crazy idea that a USB filter could improve specs or sound qualty.
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The point I am making isn't about the isolator adding noise. It is that the USB bus quality is more than ones and zeroes. If you can add noise and see worse results, you can extrapolate that reducing noise could give better results.
All isolation methods (except fiber optics) create common mode noise... How this is handled will determine the result.
Why is everyone always ignoring common mode noise? With unbalanced audio interconnects, it is a huge factor! Dirty 5V from the PC can be cleaned up relatively easily, but common mode noise is mighty hard to get rid of!
Why is everyone always ignoring common mode noise? With unbalanced audio interconnects, it is a huge factor! Dirty 5V from the PC can be cleaned up relatively easily, but common mode noise is mighty hard to get rid of!
"but it is interesting to note that a USB isolator changes my DAC's THD from 0.00044 to .008. With that in mind it isn't a crazy idea that a USB filter could improve specs or sound qualty."
Until you have eliminated the effect of isolating the grounds, it is pure speculation. Do that first!
Until you have eliminated the effect of isolating the grounds, it is pure speculation. Do that first!
Not sure what you mean... PC and DAC are on the same power strip as of now.. may have made an impact for good but still worse than with no isolator
That not how digital signalling works, it works or it dosen't you cannot attribute analogue signal effects to digital signals, in fact the chokes are more likely to cause problems with the USB signals. It is a component that is badly designed thats sole purpose is to rip money of audiophiles who do not understand the interface.
Yes. The USB signal is not entirely differential. The end-of-packet (EOP) signal is both pins pulled low. CM chokes distort this. Wrong choice of choke will cause malfunctions.
As for your USB filter changing the DAC THD+N, I'd suggest either a change in common mode noise, or the DAC being powered from USB +5V through a regulator with inadequate PSRR and/or lack of passive HF filtering and/or crummy layout with dirty ground.
As for your USB filter changing the DAC THD+N, I'd suggest either a change in common mode noise, or the DAC being powered from USB +5V through a regulator with inadequate PSRR and/or lack of passive HF filtering and/or crummy layout with dirty ground.
Yes the communication is single ended but the data transfer is NOT... the problem is that lots of gear already has the common mode choke on the output to meet EMC regs. so adding another can cause (and does cause) issues.... They recommend its removal when certain storage devices are used... As I have said its another un-necessary scam audiophile product....
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Hello! My problem isn't in modification of the sound card, frankly speaking. I want to fix it, because broke it one day. USB port detached of circuit board, so I tried to attach it back. As I have no much experience I spoiled the places where to attach USB port on the board. Could you help and draw the schematics to understand how every pin of usb is connected to the board? May be some master will be able to connect the port necessary to the elements of the board. I will be so grateful for help.
Headphone stage opamps
I am thinking about replacing opamps in the headphone section. Will probably use the OPA1612 to replace the NJM2068 in the first stage but don't know what to use to replace the JRC2114 to drive the headphones.
Maybe the RC4580? Please suggest 🙂
I am thinking about replacing opamps in the headphone section. Will probably use the OPA1612 to replace the NJM2068 in the first stage but don't know what to use to replace the JRC2114 to drive the headphones.
Maybe the RC4580? Please suggest 🙂
People, could you please restore the pictures here, on a first post.
I would like to repare my e-mu0404 and these are will be usefull. 48V disapeared. pity.
Thank you
I would like to repare my e-mu0404 and these are will be usefull. 48V disapeared. pity.
Thank you
Hello everyone, im having a problem with my EMU-0404 USB, since i bought it brand new, when it powered up it took about 20 sec with only the LED power on, then all other LEDs started to blinking and lasted about 10 sec until it powered up fine, in time this power on process was taking more and more time until last time i had to wait about 5min for all LEDs stop blinking, now it doesn't boot up, after turning on it stays with all LEDs blinking for hours... I will really appreciate any help!
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