E1DA 9038D Review (portable DAC & Amp)

[amirm]

@amirm FYI

-3 dB point is 315 Hz so well above mains.

 

[IVX]

amirm, Your PC HF noise isn't AC main 60Hz, there are from hundreds kHz and up to hundreds MHz, and 1uF at such frequencies is shorter than your USB cable(any 1uf MLCC has 10mOhm of ESR typically and 1-10MHz simply shorted by 1uF to the AP chassis, hence, to its GND wire, next few meters to your PC GND, and returns with USB cable back). Do you understand what advantages balanced inputs offer? What is the reason to switch from balanced XLR inputs to unbalanced BNC when you testing unbalanced DACs outputs? I offered a simple test a few days ago, try a battery-powered source to isolate your ground loop noise and see what AP will show. Just to make sure that your setup isn't correct.

 

[MC_RME]

So what cable did you built yourself to do so? I can think of a normal balanced cable with XLR male on one side, on the other side TS or RCA. Phase/Tip is connected to XLR pin 2(+), Ground to XLR pin 3 (-), and the shield is only connected to XLR pin 1, but not to the TS/RCA in any way. Right? Or is it the other way round, with shield and Ground shorted and connected to TS/RCA but not to pin 1 of the XLR?

 

[Veri]

On the one hand I know atomicbob guy on SBAF also measures using XLR inputs of the ADC using well shielded balanced-unbalanced cables. On the other hand I assume Amir uses the unbalanced-unbalanced connection to measure a more 'realistic' real-world connection of an unbalanced device connected over RCAs. If Amir has always measured that way, comparisons are fair; to now change the set-up to give a slight advantage and cleaner display of the unbalanced output will make comparisons to other devices more of an apples to oranges comparison, no?

 

[MC_RME]

Ok, I cannot be sure I just don't think a common mode noise voltage would result in much energy at 3x 1 kHz.

Read this: https://intona.eu/en/support/answer/1233

 

[MC_RME]

On the one hand I know atomicbob guy on SBAF also measures using XLR inputs of the ADC using well shielded balanced-unbalanced cables. On the other hand I assume Amir uses the unbalanced-unbalanced connection to measure a more 'realistic' real-world connection of an unbalanced device connected over RCAs. If Amir has always measured that way, comparisons are fair; to now change the set-up to give a slight advantage and cleaner display of the unbalanced output will make comparisons to other devices more of an apples to oranges comparison, no?

The point is that this is a headphone output. Not intended to be connected to anything other than a floating, earth-free headphone. Leakage currents etc that are caused by the measurement setup and influence the measurement result therefore do not represent the results from typical use cases.

 

[IVX]

If Amir has always measured that way, comparisons are fair

sure, if you use a DAC when lay in a grounded tub full of water, you have a slightly similar GND loop. Normally, you are well isolated from the GND, and doesn't matter grounded PC in use or battery-powered Android. Hence, the most realistic method of measurement is isolated USB source, or isolated AP, or correctly grounded entire setup. As a criterion of how far your AP+DUT setup from an ideal, you can compare that with a battery-powered USB source(Android) as a nearly ideal sample. Using the unbalanced input without isolation is the worst case ever.

 

[IVX]

MC_RME, my cables usually are XLR2crocodile_clip style.

 

[Veri]

The point is that this is a headphone output. Not intended to be connected to anything other than a floating, earth-free headphone. Leakage currents etc that are caused by the measurement setup and influence the measurement result therefore do not represent the results from typical use cases.

That is a good point. A differentiation could be made between that, and simple line-out as currently measured.

 

[staticV3]

There seems to be an error in this spreadsheet. On the top it says 'Meenova (15 cm)'. But the link goes to a no name cable. I found a 'Meenova'
version at this link:

https://www.aliexpress.com/item/100...g0o.detail.1000060.1.441a5ceevO3zr4&gps-id=pc

So which cable is the right one?

The one I linked in the spreadsheet is the one referenced in the results. It's also made by Meenova as per the logo on its plugs.

 

[MC_RME]

MC_RME, my cables usually are XLR2crocodile_clip style.

Come on Ivan, you can do better! Tell us interested readers how you handle ground in the transition from SE to Bal (I even gave specific examples).

 

[staticV3]

I'd assume it's Pin 2 -> Signal and Pin 1+3 -> GND

 

[IVX]

MC_RME, I'm serious, pure lab-style, look at my rig:

 

[capslock]

Read this: https://intona.eu/en/support/answer/1233

Interesting link, thanks!
- with isolator, all harmonics, even and odd, are well below the noise level we see without the isolator
- only the even harmonics seem to "float" on the added noise. HD2 peak is only half as high above noise as with isolator. HD4 go from not there or barely there to impressive peaks.

Why is that? RF rectification? Wouldn't that favor the odd harmonics?

 

[staticV3]

@IVX I think MC_RME was disappointed you didn't give them exact information on how you connect single-ended DAC/Amps to the XLR inputs of your analyzer.

 

[IVX]

I did that directly to the 3.5mm plug with 6mm PLB traces, as you can see on my pic, AP's chassis tied with one more croc-clip to the USB-C shield. That's it, that setup has minimal difference vs isolated Android.

 

[capslock]

Ivan, so in your own measurements and looking at typical performance, does the 9038D or the 9038SG3 do better on harmonics?

Sorry to ask this again. I think it got overlooked in the discussion of AP grounding.

 

[IVX]

Ivan, so in your own measurements and looking at typical performance, does the 9038D or the 9038SG3 do better on harmonics?

about the same but 9038D has a lower current + opa1622 has higher loop-gein, so it has less load/unload harmonics difference. The best samples have -135db 2nd and 3rd, worst about -123db. If I see really low-performance unit I offer it for a lower price on my Aliexpress shop(need to ask Sunny about such units for -30-50% discount). Also, I have some mistaken laser engraved units, they are 100.0% fine but I was sleepy and made like this:

 

[jannek]

These versions with special Laser engraving are only 9038D I suppose? Or also 9038SG3?

 

[IVX]

only 9038D so far.