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

Schackmannen

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@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.
But if you don't hear any baseline noise (Edit: with no music playing of course!) then the voltage gain clearly isn't too high. The only thing the number of bits determines is the dynamic range, that's all. That's why I think it's unfortunate that it's often referred to as resolution (i.e higher amount of bits -> better resolution) which to me would imply that a higher amount of bits leads to more "detail" or whatever in the music, which simply is not true, it just gives you more available dynamic range. And you can test yourself how much dynamic range you actually need while listening to music, just play music through a player that lets you adjust the volume in dB, play at a level you would normally play and then instantly reduce the volume by say 60 dB. It will probably barely be audible until your ears have adjusted to the lower volume which takes a while. You can repeat this until you find which level of reduction is required for you to hear nothing directly after reducing the volume. I did this myself some time ago and IIRC I found that reducing the volume by -70 dB was enough for me to hear nothing at all, or just under 12 bits of dynamic range.
Sorry if this is off-topic @IVX
 
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Schackmannen

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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.

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.
Of course reducing the volume digitally reduces the SNR, I even said so in my first post. My point was that if you hear no noise with the volume turned all the way up, you won't hear it with the volume turned all the way down, and that loss of SNR doesn't matter, it just means you didn't need that much dynamic range in the first place. Obviously if you later amplify the signal you can hear noise but it makes no sense to do that, just reduce the gain in the later stage and compensate by reducing the volume less digitally.

And I have to disagree about analog volume control doing better, at least compared to the SOTA DACs we have now, since a lot of them have lower residual noise than the Benchmark LA4 preamp with the volume turned all the way down, for example.
 

trl

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Of course reducing the volume digitally reduces the SNR[...]
I have to disagree about analog volume control doing better, at least compared to the SOTA DACs we have now
I see a bit of contradiction here, but however, the analogue volume control will still improve SNR on lower volume for sure. I haven't tested nor heard SOTA DACs, but all DACs I have there is a fair audible hiss noise when I max out headamp's volume knob (ODAC v1 has the highest background noise here). This is probably why I can't put too much love in DAC/amp combos with digital volume control and this is why I love so much the pot-in-the-middle Objective2 and I'll always use it for IEMs in unity gain (it has lower background noise than the SMSL sp200 THX AAA 888).

It's a very good thing that Amir is testing the SNR for 50mV power output on combos and 5W SNR for speakers amp, so we can all understand how well the DUT is performing with sensitive headphones or speakers.
 

Schackmannen

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I see a bit of contradiction here, but however, the analogue volume control will still improve SNR on lower volume for sure. I haven't tested nor heard SOTA DACs, but all DACs I have there is a fair audible hiss noise when I max out headamp's volume knob (ODAC v1 has the highest background noise here). This is probably why I can't put too much love in DAC/amp combos with digital volume control and this is why I love so much the pot-in-the-middle Objective2 and I'll always use it for IEMs in unity gain (it has lower background noise than the SMSL sp200 THX AAA 888).

It's a very good thing that Amir is testing the SNR for 50mV power output on combos and 5W SNR for speakers amp, so we can all understand how well the DUT is performing with sensitive headphones or speakers.
But if an analog volume control has higher residual noise, even with the volume control turned all the way down on the lowest gain, than some of the SOTA DACs then I don't see how they would better preserve SNR on lower volume? I mean the top performer on the 50 mV SNR chart is the ADI-2 DACs IEM-port, which uses a digital volume control, might not be the most fair comparison since it's designed for low ouput and low noise, but still.
 

raanany

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But if you don't hear any baseline noise (Edit: with no music playing of course!) then the voltage gain clearly isn't too high. The only thing the number of bits determines is the dynamic range, that's all. That's why I think it's unfortunate that it's often referred to as resolution (i.e higher amount of bits -> better resolution) which to me would imply that a higher amount of bits leads to more "detail" or whatever in the music, which simply is not true, it just gives you more available dynamic range. And you can test yourself how much dynamic range you actually need while listening to music, just play music through a player that lets you adjust the volume in dB, play at a level you would normally play and then instantly reduce the volume by say 60 dB. It will probably barely be audible until your ears have adjusted to the lower volume which takes a while. You can repeat this until you find which level of reduction is required for you to hear nothing directly after reducing the volume. I did this myself some time ago and IIRC I found that reducing the volume by -70 dB was enough for me to hear nothing at all, or just under 12 bits of dynamic range.
Sorry if this is off-topic @IVX

@Schackmannen I don’t see where in this analysis you’re taking gain and the resulting quantization noise into account. Lets take an extreme example: Say I have an ideal DAC with zero residual noise but the total gain in my system forces me to use just the upper 4 bits of my signal then my LSB noise (quantization noise) is going to inflict SNR=4x6=24dB. I’m sure you’ll hear degradation. What am I missing in my calculation?

By the way, practically, with the Campfire Andromeda Gold’s sensitivity of 116 dB SPL/mW the admittedly low 3.5 uV residual noise of the E1DA 9038S is still going to give you 28dB SPL which is well above the hearing threshold.
 

trl

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That is exactly my point Ivan: a pot placed between gain-stage and output buffer will always lower the background noise on IEMs.
 

snowsurfer

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@IVX Great work with this item, I really think you're doing an excellent job. And now, to hijack the thread, when can we expect HiFiTOY? I know lots of us are really looking forward to it! Thanks!
 

raanany

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Of course reducing the volume digitally reduces the SNR, I even said so in my first post. My point was that if you hear no noise with the volume turned all the way up, you won't hear it with the volume turned all the way down, and that loss of SNR doesn't matter, it just means you didn't need that much dynamic range in the first place. Obviously if you later amplify the signal you can hear noise but it makes no sense to do that, just reduce the gain in the later stage and compensate by reducing the volume less digitally.

And I have to disagree about analog volume control doing better, at least compared to the SOTA DACs we have now, since a lot of them have lower residual noise than the Benchmark LA4 preamp with the volume turned all the way down, for example.

@Schackmannen You sir are right. Thank you for your patience and valuable input. It’s not every day that I learn something new. Sorry if I was stubborn and slow.
Yes, if the dac+amp noise floor is inaudible with your speakers then digital volume control is the best cleanest way. Unfortunately, with the andromeda, it will be audible. RME have a special low gain output for IEMs.

@IVX please please make the IEM mode use a lower gain setting in your next version.
 
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trl

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@IVX please please make the IEM mode use a lower gain setting in your next version.
An iFi Ear Buddy (20USD) will always be helpful to have it around, not only for E1DA, but for absolutely all headamps you might have at home/office. This will protect your ears for sure, also in regard with background noise, from Amir's chart with SNR @50mV E1DA (79USD) is the second combo DAC/headamp from the list with its 83dB, while the first one would be RME ADI2-DAC (1.150 USD) with 93dB (all the other DUTs are headamps, without DAC inside).

index.php
 

raanany

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An iFi Ear Buddy (20USD) will always be helpful to have it around, not only for E1DA, but for absolutely all headamps you might have at home/office. This will protect your ears for sure, also in regard with background noise, from Amir's chart with SNR @50mV E1DA (79USD) is the second combo DAC/headamp from the list with its 83dB, while the first one would be RME ADI2-DAC (1.150 USD) with 93dB (all the other DUTs are headamps, without DAC inside).

index.php

Thanks @trl but the iFi Ear Buddy has a too high output impedance. IEMs often have a very frequency dependant impedance (considerably lower in the bass region) so you must use a very low AMP output resistance (such as E1DA) if you wish to get a flat response.
 

trl

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Even it was not in IEM mode. So, I guess IEM mode will be good for most IEMs.
Don't think so, the IEM-mode is a digital attenuator for sure, not an analogue switch that changes the gain, so it will only protect hearing by lowering max. output voltage.
 

trl

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Thanks @trl but the iFi Ear Buddy has a too high output impedance. IEMs often have a very frequency dependant impedance (considerably lower in the bass region) so you must use a very low AMP output resistance (such as E1DA) if you wish to get a flat response.
You have Amir's measurements, so it is flat. Feel free to test it with 16 Ohms IEMs, I'm sure you'll be pleased.

If you're not happy with the 3 Ohms impedance of such adapter, then you can also DIY one with an even lower one, more details here: https://diyaudioheaven.wordpress.com/headphones/headphone-attenuation-adapter/
 
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Don't think so, the IEM-mode is a digital attenuator for sure, not an analogue switch that changes the gain, so it will only protect hearing by lowering max. output voltage.

In my memory, IVX said that after IEM mode on, hiss disappeared using IEM. If IEM mode is just a digital max volume limitation, was that possible?
 

mgmate

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Hi, Anybody can help me with this?

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). Or leaving it Auto.
...b) In Oversampling: Active, using a integer multiplier of the sampling rate Or leaving it deactivated.
2) In USB Audio:
...a) In Oversampling: Active, using an integer multiplier of the sampling rate Or leaving it deactivated.
3) In Volume:
...a) Volume Control: SW Volume control (that's for sure).

Regards!!
 

lxlx

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I'm using 9038s v2 on
  • Sennheiser HD600 (Sensitivity 97 dB, Impedance 300 Ohm)
  • Audiosense T800 IEM (Sensitivity 90 dB, Impedance 9.2 Ohm)
Volume level on HD600 in Mode2 performance between 80-100 (-5dB to allow EQ) where 100 is really really loud.
T800 in Mode4 IEM between 50-90 where 100 is unbearably loud.

I don't see a fail of the product for IEM.
And I was positively surprised about the performance mode on Hd600.
 
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raanany

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You have Amir's measurements, so it is flat. Feel free to test it with 16 Ohms IEMs, I'm sure you'll be pleased.

If you're not happy with the 3 Ohms impedance of such adapter, then you can also DIY one with an even lower one, more details here: https://diyaudioheaven.wordpress.com/headphones/headphone-attenuation-adapter/

@trl Thanks for the link. @amirm is assuming IEM impedance that doesn't change with frequency. The impedance of some IEMs (mine included) varied quite a lot depending on frequency. The impedance of the earphone and the output impedance of the AMP (+attenuator + wires) all act as a resistor voltage divider. The result is you'll get reduced bass. Campfire Andromeda Gold impedance is 3 ohm for low frequencies and it goes up to around 12 for treble. Do the math.
 
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