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Review and Measurements of E1DA 9038S BAL Portable DAC & Amp

raanany

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raanany
but anyway, the most ridiculous thing is MQA )) I always proud how mankind so much moved forward the last 30 years, at least in marketing tricks. Why the mp3 was so boringly introduced, and for free? Named as a robot's model "mp3" but not more allusive like "Master Quality Authenticated", being the same lossy compression? Marketing Science leading us somewhere what looks like hell.

Totally agree about MQA. It’s not master quality. I admit I can’t hear the difference but it’s far from being called lossless. Anyone with signal processing knowledge who learns the algorithm without going too deep into the details can tell that you’d be better off with simple untouched CD quality. They are pushing it so hard with help from self proclaimed “expert” journalists who swear it sounds better and back it up with bullshit technical terms. It drives me nuts. I’ll never join them again.
 

mgmate

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Hi,

I have received my 9038s unit, and trying to use it with Android UApp the volume does not work in Hw mode. If I put it in Sw mode I can not use Bit perfect.

What do I doing wrong?

What configuration should I use to have both: volume control and Bitperfect mode?

Regards and thanks in advance for your help!
 

IVX

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"Bitperfect" probably sounds too serious but it means exactly the same as HV volume mode and nothing more i.e. volume control on the DAC side. 9038S G2 has no volume control inside, so you can use only SW volume control on the USB host-streamer side. In a most cases, HW either SW volume control has the same affecting to the sound quality if SW implemented correctly and you not going to listen at -50dbfs SW volume slider position. In case if you bought 9038S to pair with high-sensitive IEM, and you have to listen to my DAC at such crazy low volume, you made a mistake.
 

raanany

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"Bitperfect" probably sounds too serious but it means exactly the same as HV volume mode and nothing more i.e. volume control on the DAC side. 9038S G2 has no volume control inside, so you can use only SW volume control on the USB host-streamer side. In a most cases, HW either SW volume control has the same affecting to the sound quality if SW implemented correctly and you not going to listen at -50dbfs SW volume slider position. In case if you bought 9038S to pair with high-sensitive IEM, and you have to listen to my DAC at such crazy low volume, you made a mistake.

@IVX I think you should put some warning in your aliexpress shop for this. I made the same mistake. I’m sure many people will do too. Another option is (in future revisions) to have the IEM mode use a lower gain (not just output power limit).
 

IVX

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9038S 540mW per channel @16ohm it is obviously targeted to big cans, right? Could anyone buy a 540hp engine for the scooter if there is 2hp enough to get 120km/h? My DACs are inexpensive and it easy to buy just for trying. By decision of fate, my products are expensive but are sold cheaply, however, not vice versa, as is usually the case in the audio industry ;)
 

raanany

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@IVX : "My DACs are inexpensive and it easy to buy just for trying" - I agree and I don't regret buying it.

However, I bought your DAC because of the very low output impedance which is required for the low (and frequency-dependant) impedance of IEMs and because of the SINAD @amirm measured.

Such a low DAC output impedance is not really required for big cans. right?

Also, you write in you shop: "IEM Mode, max volume limited at -15dbfs, LED is Off. In that mode 9038S ready for as low as 4ohm load."

This leaves the door open for people to make mistakes. I think you'll benefit from:

1. Closing this door. Write clearly that this DAC is practically unusable with IEMs.
2. In your next version make the IEM mode reduce voltage-gain by a lot. I'm guessing you'll need two modes of reference current to the DAC.
3. Add volume control. Opening iTunes/VLC or whatever you're using to play and moving a volume slider is not accessible. I have 50 windows open on my desktop while I work. I want to use the keyboard volume control.

I'll be very happy to buy such a new revision even if the cost is $500

I still think you rock :cool:

Cheers
 
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Schackmannen

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I've just quickly read the past few posts so I might be missing something but what's the problem exactly? Obviously if you use "bit-perfect" mode in any software player you'll lose the ability to control the volume in the software but is it really necessary to use it? Maybe there was a point years ago but I highly doubt any modern operating systems or software players are gonna have such a bad volume control to affect the sound, especially if you don't perform any re-sampling. And there seems to be a common misconception that digital volume control somehow is "lossy" because you lose resolution when reducing the volume digitally. While it's true that the SNR gets reduced by the same amount as you reduce the volume ("losing" resolution), it doesn't matter, if you didn't hear any noise with the volume turned all the way up, then you won't hear any even if you turn the volume way down. With a residual noise of about 3.5 uV the 9038s is just shy of the SOTA DACs, but as far as I'm aware, quieter than any other dongle out there so I'm not sure why you think that it's "practically unusable with IEMs". The only issue I could see is if the digital volume control doesn't have enough steps so it's hard to adjust the volume to the right level, but other than that I don't see any problem with using the 9038s with IEMs, just be careful so you don't accidentally play music with the volume at 0 dBFS.

To show that I'm not talking out of my ass (hopefully), here's a picture from RME's ADI-2 DAC manual. As you can see, digitally reducing a 24 bit signal by 60 dB and 96 dB doesn't change the noise floor at all, it just reduces the amplitude of the signal, without introducing any sign of distortion:
1579159911064.png

And for reference here's the manual: https://www.archiv.rme-audio.de/download/adi2dac_e.pdf They talk about digital volume control on page 63 and I highly recommend giving it a read even if you don't own any RME gear.
 

raanany

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I've just quickly read the past few posts so I might be missing something but what's the problem exactly? Obviously if you use "bit-perfect" mode in any software player you'll lose the ability to control the volume in the software but is it really necessary to use it? Maybe there was a point years ago but I highly doubt any modern operating systems or software players are gonna have such a bad volume control to affect the sound, especially if you don't perform any re-sampling. And there seems to be a common misconception that digital volume control somehow is "lossy" because you lose resolution when reducing the volume digitally. While it's true that the SNR gets reduced by the same amount as you reduce the volume ("losing" resolution), it doesn't matter, if you didn't hear any noise with the volume turned all the way up, then you won't hear any even if you turn the volume way down. With a residual noise of about 3.5 uV the 9038s is just shy of the SOTA DACs, but as far as I'm aware, quieter than any other dongle out there so I'm not sure why you think that it's "practically unusable with IEMs". The only issue I could see is if the digital volume control doesn't have enough steps so it's hard to adjust the volume to the right level, but other than that I don't see any problem with using the 9038s with IEMs, just be careful so you don't accidentally play music with the volume at 0 dBFS.

To show that I'm not talking out of my ass (hopefully), here's a picture from RME's ADI-2 DAC manual. As you can see, digitally reducing a 24 bit signal by 60 dB and 96 dB doesn't change the noise floor at all, it just reduces the amplitude of the signal, without introducing any sign of distortion:

And for reference here's the manual: https://www.archiv.rme-audio.de/download/adi2dac_e.pdf They talk about digital volume control on page 63 and I highly recommend giving it a read even if you don't own any RME gear.

@Schackmannen, thanks, that's interesting to learn.
You wrote: "if you didn't hear any noise with the volume turned all the way up, then you won't hear any even if you turn the volume way down."

I strongly disagree. It is usually in the quiet passages of music that a listener notices recording and instrumentation noise. Our brain simply can't notice low level noise when there's loud music playing but if you listen to music that has subtle quiet moments (such as classical music for instance) you'll notice background noise pretty easily. The saying that human hearing has 116dB of dynamic range is misleading. There are two ways of looking at a dynamic range, with and without gain control. Will you be able to notice 0dBSPL in a totally quiet environment? probably if your ears are good. Will you be able to withstand 116dBSPL, probably with some pain and ringing. Will you be able to hear somebody whisper while in a rock concert? No, you won't. The "Gain control" in your ear (which uses mechanical means) and the brains abilities won't let you.


You wrote: "I'm not sure why you think that it's "practically unusable with IEMs"."
It's not only me. Please see @IVX note above: "In case if you bought 9038S to pair with high-sensitive IEM, and you have to listen to my DAC at such crazy low volume, you made a mistake."

You wrote: "The only issue I could see is if the digital volume control doesn't have enough steps so it's hard to adjust the volume to the right level,"
That's exactly the problem.

My claim is that if you implement volume control by attenuating the analog output of the DAC before (buffering and) feeding it to the headphones you'll be able to retain most of the wonderful SNR you worked hard to achieve. This is limited to the attenuator's noise floor of course but it should be possible to have a much lower attenuator noise floor than that of the 32 bit main DAC.

The link to RME's document will probably be a very interesting read. Thank you for that.
 

PPP

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To show that I'm not talking out of my ass (hopefully), here's a picture from RME's ADI-2 DAC manual. As you can see, digitally reducing a 24 bit signal by 60 dB and 96 dB doesn't change the noise floor at all, it just reduces the amplitude of the signal, without introducing any sign of distortion:
View attachment 46045
And for reference here's the manual: https://www.archiv.rme-audio.de/download/adi2dac_e.pdf They talk about digital volume control on page 63 and I highly recommend giving it a read even if you don't own any RME gear.


The graph you show is only digital theoretical result. it is not a measurement of real world results. What it shows is the following: in the 24 bits test, even if you lower the volume to -96db, it's still >90db above the -190db noise floor. which seems fine for human ears.

in real world the noise floor will be much higher for a DAC (usually with SNR of ~120db). reducing the digital volume will definitely impair the SNR. For instance, if you turn down the volume to -96db, your SNR becomes 120-96=24db. if in later stage you amplify your signal, to normal hearing level, you will of course hear the noise very clearly.

Analog volume control (such as a relay controlled preamp) can do better, if designed properly.

In daily uses because you never turn the volume to -96db, so it's fine to use a digital volume control.
 

boXem

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The graph you show is only digital theoretical result. it is not a measurement of real world results. What it shows is the following: in the 24 bits test, even if you lower the volume to -96db, it's still >90db above the -190db noise floor. which seems fine for human ears.
Noise floor is not at -190dB. You need to take into account the FFT gain, here 54 dB. So you have a noise floor at about 135 dB, which corresponds to 24 bits dithered theoretical noise floor.
 

PPP

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Noise floor is not at -190dB. You need to take into account the FFT gain, here 54 dB. So you have a noise floor at about 135 dB, which corresponds to 24 bits dithered theoretical noise floor.
you're right.
 

raanany

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@Schackmannen, thanks, that's interesting to learn.
You wrote: "if you didn't hear any noise with the volume turned all the way up, then you won't hear any even if you turn the volume way down."

I strongly disagree. It is usually in the quiet passages of music that a listener notices recording and instrumentation noise. Our brain simply can't notice low level noise when there's loud music playing but if you listen to music that has subtle quiet moments (such as classical music for instance) you'll notice background noise pretty easily. The saying that human hearing has 116dB of dynamic range is misleading. There are two ways of looking at a dynamic range, with and without gain control. Will you be able to notice 0dBSPL in a totally quiet environment? probably if your ears are good. Will you be able to withstand 116dBSPL, probably with some pain and ringing. Will you be able to hear somebody whisper while in a rock concert? No, you won't. The "Gain control" in your ear (which uses mechanical means) and the brains abilities won't let you.


You wrote: "I'm not sure why you think that it's "practically unusable with IEMs"."
It's not only me. Please see @IVX note above: "In case if you bought 9038S to pair with high-sensitive IEM, and you have to listen to my DAC at such crazy low volume, you made a mistake."

You wrote: "The only issue I could see is if the digital volume control doesn't have enough steps so it's hard to adjust the volume to the right level,"
That's exactly the problem.

My claim is that if you implement volume control by attenuating the analog output of the DAC before (buffering and) feeding it to the headphones you'll be able to retain most of the wonderful SNR you worked hard to achieve. This is limited to the attenuator's noise floor of course but it should be possible to have a much lower attenuator noise floor than that of the 32 bit main DAC.

The link to RME's document will probably be a very interesting read. Thank you for that.


@Schackmannen I see now, you meant with the volume turned all the way up, not necessarily while the the music is playing. I agree with that. Sorry to have misunderstood you.
 

raanany

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@Schackmannen I see now, you meant with the volume turned all the way up, not necessarily while the the music is playing. I agree with that. Sorry to have misunderstood you.

@Schackmannen still, even if I don't hear the DAC's noise floor, I argue that if I need to set the digital volume to such a low setting (because the DAC's voltage gain is so high) that it leaves me with 8 bit audio then I'm doing something wrong. This IEM + DAC combination is a poor choice.
 

mgmate

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The problem with Android UAPP is that if you do not select bitperfect - to be able to select SW control Volume-, the original sample rate is lost (you can manually adjust it -more or less-, Frecuency -with upsample option but not maintaining it- and Bit Deep) ... but no original Frecuency (so conversion and then reducing original sound quality).

For sure the product roks because of the very high sound quality and price, but the real usability and expected sound quality (because of conversion not SW volume), at least for Android is reduced (also for comparison -bat not same quality nor high output-, almost all dongles handle HW volume).

The issue it could be even related with UAPP, that there is no option to select of "maintain sample rate" and "SW Volume control". That would be great as the sound would be barely modified, just to manage the volume, but this would be a workarround anyway.

Does anybody knows the best way to configure UAPP for this great dongle to handle the maximun sound quality as possible?, I understand but I am not confident enough that should be both:
1) In Audio HiRes:
...a) Controller audio format: select 24 bits or 32 bits (to minimize the SW volume control).
...b) In Oversampling: Active, using a integer multiplier of the sampling rate
2) In USB Audio:
...a) In Oversampling: Active, using an integer multiplier of the sampling rate
3) In Volume:
...a) Volume Control: SW Volume control

@IVX: Please, it would be great to have the G3 dongle with HW volume control (as considered in 9038D)

Regards,
 
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boXem

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Probably you mixing up the noise floor with dynamic range or SNR? 24bits resolution corresponds about -142db DR indeed but its noise floor rather -190db (at least at 20Hz) than -135db.
View attachment 46070
I agree that I introduced a confusion talking about noise floor for a DAC. You are right, I was thinking DR.
My understanding of the picture you show is that it is the result of the averaging (continuous aquisition) + FFT gain.
Since I forgot the math and I am too lazy to search for it, let's forget averaging.
The way I see the things: if we omit the front end noise, for one acquisition we have noise floor = FFT gain - ADC DR.
If the DUT has a noise below the ADC DR, noise is not seen.
If the DUT has a noise above the ADC DR, noise is seen. Again for one acquisition, DUT noise = FFT gain - displayed noise
 

boXem

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The noise floor is a self-declared term due to the "floor" there is really looks like a floor. It is not that case but when I don't know something, I simply checking the Wiki.
Agree on the self declared term. There seems to be 2 definitions pending people. Yours is one, the other being the lowest noise measurable by an acquisition system.
Anyhow, I initially just wanted to point out that the -190 dB was not directly correlated with 24 bits. Now I will stop hijacking the thread from your excellent product.
 
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