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Measurements of RME ADI-2 DAC and Headphone Amp

daftcombo

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#22
"Better" when we talk about frequency response is the flattest possible. So the answer is already in the manual: Sharp and SD Sharp!;)

About RCA Vs XLR. It is the opposite. Amir first measured RCA out in the first review and then XLR (still, with the old AP) with slightly better results. But nothing audible, IMHO.
Thanks. About the filters, why do several exist if only one is good?
 

Tks

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#23
Thanks. About the filters, why do several exist if only one is good?
It's the AKM chip implementation/feature that is intrinsic to them all(the company provides this for whatever reason, I would take a pure guess in the dark that they had OEM's in mind that may have wanted to choose one and lock it away, but seems some makers are letting you mess with which filter you would like. The issue is, they're all sonically so close essentially, you need to be trained, and know what to look out for to notice any difference.

Personally, I can't notice a difference between any one of them, but then again I haven't really cranked up the volume in some recording studio booth with closed eyes and tried telling them apart.

 

daftcombo

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#25
It's the AKM chip implementation/feature that is intrinsic to them all(the company provides this for whatever reason, I would take a pure guess in the dark that they had OEM's in mind that may have wanted to choose one and lock it away, but seems some makers are letting you mess with which filter you would like. The issue is, they're all sonically so close essentially, you need to be trained, and know what to look out for to notice any difference.

Personally, I can't notice a difference between any one of them, but then again I haven't really cranked up the volume in some recording studio booth with closed eyes and tried telling them apart.

That's why I asked if Amir could try it, as he has trained ears.

If Sharp & SD Sharp are both good, which one of them is best?
 
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#26
That's why I asked if Amir could try it, as he has trained ears.

If Sharp & SD Sharp are both good, which one of them is best?
It may have some audible difference between Sharp and Slow considering the drop in HF. But...

...To be honest, I really don't think there is any kind of audible concern between both Sharp Filters (some may believe there is...). I stayed with the stock SD Sharp set out of the box and I'm happy with it.
 

Tks

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#27
Don't know if "best" is the proper question. It's like asking whether Defuse Field or Harman Target is best I would think. Hopefully you get your answer, I'd be interested to see how wrong I perhaps am about what I've stated.
 
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#28
Don't know if "best" is the proper question. It's like asking whether Defuse Field or Harman Target is best I would think. Hopefully you get your answer, I'd be interested to see how wrong I perhaps am about what I've stated.
Sure.;)
However, I'm still saying, strictly measurement-wise, "best" should be the flattest and straightest FR... So Sharp Filters.:cool:
 

MC_RME

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#29
Hi everyone,

I am sorry to say this upfront, but although reading here quite often I do not plan to post here often, as I am very busy with my own forum already ;)

Thanks Armir for checking the ADI-2 DAC again. There are two things I would like to comment on.

1. The Extreme Power headphone stage's THD should not rise until the clipping point. That had been verified/measured here with Pro and DAC before. The slow rise shown here in the 33 Ohms measurement might have been caused by the overload protection slowly kicking in, or a cable connection/adapter problem.

2. I know, point 1 is boring, point 2 is more interesting: The signal to noise ratio of phones and IEM output. The 1/4 inch output is measured with 85.x dB at a reference level of 50 mV, which equals -23.8 dBu. So the basic noise floor sits around -108.8 dBu. This number perfectly matches the value stated in the tech specs section of the manual:

Signal to Noise ratio (SNR) @ +7 dBu (which equals the Low Power setting): 116 dB RMS unweighted. 116 minus 7 = -109 dBu.

But the measured value of the IEM output is a bit too far off. It has a self noise of -118 dBu RMS unweighted. Referenced to 50 mV/-23.8 dBu the measured value should have been 94.2 dB, but measured was 'only' 90.7 dB, equalling -114.5 dBu. I know this sounds like a non-issue that far down there, but I would like to share my own experience on this topic. One of our testers with very sensitive ears was able to hear the self noise at -115 dBu in our first prototype with highly sensitive Andromeda in-ears, so I had to modify the IEM output stage again, and finally reached -118 dBu. He was satisfied then :)

But exploring those low levels I also learned about the limitations of the audio measurement systems. The AP's input can not measure lower than -118 dBu, that's its official spec (a bit covered as uV value). That means if you connect a unit that also produces noise at -118 dBu you already see a value of -116 dBu or worse on the AP (the noise adds up). To be able to measure 'deeper' you need to use a preamplifier (for example a microphone preamp) with a high gain setting (let's say 40 dB), to raise the IEM's output level far over the input noise of the AP. Then simply subtract 40 dB from the measurement result. This way the AP can measure noise down to around -130 dBu!

The second possible reason for the slightly off value might be hum and noise. This is an unbalanced connection and needs some attention to very low level noise, maybe checked before measurement by performing a FFT. One could argue that the unit must be free from all sorts of ground-loop interaction with the AP test setup, but IMHO that is not a fully valid argument as we talk about a headphone output - there usually is no connection to ground through other devices.

I hope that gives Armir an idea on how to improve his future measurements. I am pretty sure we will see more and more units reaching values that take the AP to the extreme.
 
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#30
Thanks MC for the contribution.

Ive been loving my RME since i bought it. I'd sort of forgotten about it, and thats a good thing - in the sense that I'm not worrying about my DAC being the weak link
 

daftcombo

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#33
This dac is probably the best bargain dac right now. The features and ability to tweak audio are incredible.
Call a 1099$ DAC + headphones amp + DSP a bargain, really?

Topping D10 (76$) + a pair of RCA cables (10$) + JDS Lab Atom (99$) + Foobar2000 with Convolver plugin (free) and you'll have the same sound quality.

Replace the D10 + Atom by a DX3Pro if you need a all-in-one.

Good product? Yes. Bargain? No. "Best bargain DAC"? No, rather "worst bargain" or "best expensive".
 

rmo

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#34
Call a 1099$ DAC + headphones amp + DSP a bargain, really?

Topping D10 (76$) + a pair of RCA cables (10$) + JDS Lab Atom (99$) + Foobar2000 with Convolver plugin (free) and you'll have the same sound quality.

Replace the D10 + Atom by a DX3Pro if you need a all-in-one.

Good product? Yes. Bargain? No. "Best bargain DAC"? No, rather "worst bargain" or "best expensive".
Bargain.
 

LTig

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#35
To be able to measure 'deeper' you need to use a preamplifier (for example a microphone preamp) with a high gain setting (let's say 40 dB), to raise the IEM's output level far over the input noise of the AP. Then simply subtract 40 dB from the measurement result. This way the AP can measure noise down to around -130 dBu!
Can you recommend such a preamplifier, possibly with a Hi-Z option? I'd like to use one with my ADI-2 PRO fs.
 

MC_RME

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#36
As all the sources that I had to measure so far were lower impedance ones I never needed to use something different than our own mic preamps. THD is of no concern here, and noise (EIN) is not so critical either.

BTW, the ADI-2 Pro's input stage uses 10 kOhm resistors to ground. You easily find them on the PCB and can replace them with 100 kOhm if you need a higher input impedance. It's used ilke this in several labs. Costumers are frightened by higher noise with no input cable attached, the XLR combo socket can not short the inputs, so we had to use 10 kOhm...
 

daftcombo

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#37
Hi @MC_RME and welcome,

Maybe you could cast some light on the use of different filters (Sharp, SD Sharp...). The documentation doesn't explain why one should use one filter rather than another and in which situation. Which one do you advise?
 

daftcombo

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#39
Last edited:

Veri

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#40
The choice of colours for fonts & background on this website is absolutely terrible.

Thanks though. Default setting on the ADi-2 Dac seems to be "SD Sharp". It is not linear phase, right?
The default filter is (minimum phase) Sharp short delay, because it has the lowest latency which is generally an important thing for studio/pro usage.

The other Sharp filter is linear phase which has the more accurate phase response. Whether this is by any means audible is questionable though.
 
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