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(re) Review of Sound Devices MixPre-3 II Multichannel Recorder Review - Advanced mode

Rja4000

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This is a complementary review of Sound Devices MixPre-3 II digital audio recorder and mixer.

_32A7298_Nik-1.jpg


@amirm has done a first review (you may find it here), but it appears he measured the device in "Basic" mode only.
This mode has some strong limitations.
One of those being that the limiters (there are several layers of them) are always active.

I will now have a look at the Advanced mode.

I rented the device for the week-end (45€) to measure it.


Ergonomy

One thing you may not realize immediately when looking at a photo of the device is how tiny it actually is.
Look at it on top of the RME UCX II.
The UCX II is half 19" rack width.

The device itself feels solid and quite heavy for its size.
A rubber-like coating prevents it to slip from any surface.
Critical knobs and commands are easy to recognize by touch.
The metal protrubation to the level knobs allows you to immediately sense the knob position in the dark.
Level knobs also have a ring that illuminates in Green or red, according to the input signal level.
You have a retracting 1/4" screw on top, to lock the device below a camera's tripod mounting hole.
And the hexagonal Alen key is included and attached to the MixPre rear.

Of course, the touch display is very small, and you need small fingers to operate it.


Navigating through all the options in the different menus is a different topic, though.
You need to really dig deep to find what you're looking for.

Also, the power switch is very small and hard to locate without looking.

Overall, this device's handling ergonomy is a mixed bag of quite well thought through controls... and messy ones.


Measurements

Given the limited time I had the device at hand, I decided to focus on Microphone input only.
This device is mainly a field recorder, so this is naturally its main focus point.
I also measured the Headphones output power, which is also of interest for field recording use.


Measurements were performed with my RME ADI-2/4 Pro SE, at various output levels, and with or without a Shure A15AS attenuator.
I use Virtins MultiInstrument 3.9.9.3 as a measurement software.
Noise and distortion measurements below are all for 20Hz-20kHz bandwidth.
EIN is measured with a 150ohm resistor at approx. 20°C.

As the device was rented, I didn't upgrade the firmware.
The firmware was 7.16 (build 3266)



I've setup Advanced mode.
This then gives me access to critical settings:
So I've set it up for 48kHz 32 bits float, limiters off.
I downloaded the ASIO driver and here we go.


ADC and Microphone input

Let's start with 2 measurements that summarize the 2 main saling points for this device


EIN at max Gain

Sound Devices MixPre-3 II EIN 76dB gain.png


This is a good value in general.
For a tiny portable device, it's exceptional.


Dynamic range at min gain

Sound Devices MixPre-3 II Mic 1 6dB gain DR -60dBFS_crop..png


Waow !
Yes, that's an actual analog measurement
That's unsee, isn't it ?
(Actually, it matches specifications.)

And what is REALLY unseen is that it looks like both EIN and Dynamic range figures remain the same whatever the gain setting.

Well, there is a catch. Read on.


Signal path

I measured by sending the input signal to the USB interface "Pre fader".
You may see the path on this block diagram (source)

Sound Devices MixPre-3 II Signal path.png


Let's zoom a bit on the input section

1702553953387.png


Now a word of explanation:

Usually, a Mic preamp interface has an analog preamp stage followed by the ADC.
And the analog preamp stage has a variable gain.

In this case, we see the ADC followed by a digital Trim (called "Gain" on the device screen). So it's not an analog gain.
This device is also using, per channel, multiple Mic Preamps and multiple ADC stages.
Their digital signal outputs are then combined in the digital domain, to mimic one single extra-wide dynamic range input.

Note that the exact number of Preamp and ADC stages is not documented, but given the measurement results here, I guess we have 2 preamp stages, each with its corresponding ADC.


You may see some hint of that if you vary the level:

Sound Devices MixPre-3 II Mic 1 6dB gain SNR Chart.png


At some point (around 78 mVrms input for a pure sine wave), you may see the SNR dropping abruptly.
This is where the device switches from one stage to another.

It is to be noted that this doesn't seem to be linked to 32 bits float operation: the device does the same in 24 bits.


32 bits float

So what's the benefit of 32 bits float ?

The benefit is that you may record above 0dBFS.
With an integer coding, your recording can't go above 0dBFS (dBFS=dB Full Scale)
With a float encoding, there is no such limit.

The big benefit is that you may push the level digitally, to allow proper level for monitoring through headphones, as an example, without any risk of saturation of the recording.
So this really allows to take full benefit of the dual stage preamp and ADC.

To operate the device, you just set the "gain" to the minimum value (6dB) and you forget it.
There is no need, like with most other Microphone preamps, to tune the gain to optimize noise and headroom.

Looks magic, doesn't it ?

Here is a plot of DR in 24 vs 32 bits (and the DR of the RME UCX II, which follows a "normal" pattern, for reference) for different "gain" levels

DR24 vs DR32 vs UCX II.png



Input sensitivity range
So you have actually 2 sensitivities to remind: 78mV (-20dBu) for the first preamp stage, and 4.1V (14.6dBu) for the second stage.


SINAD dashboard at 4V, min gain

Well, all is not pink, unfortunately, and here start the bad news

Sound Devices MixPre-3 II Mic 1 6dB gain SINAD 4V_crop_New.png


As you can see above, the distortion is quite high (and mostly composed of odd harmonics).
Sure, that's almost matching the specs: 0,005% is 86dB SINAD (-86dB THD+N), but that's not very brilliant.


Worse: given the way this device works, you'll find similar level of distortion at low to medium level: just below 78mV, when you reach the maximum level for the first stage, you'll see similar distortion level.
But if we go over 78mV, we see distortion decreasing.

2023-12-12 18_17_11-Chart_.png

Look at the THD+N plot vs level, where you see the SNR drop, but also the THD increase when you approach the upper limit of the first stage, and the drop when switching to the second stage.
(From this plot, I couldn't identify any additional lower level step that would indicate a third stage is at play)

Also, we see a heavy saturation close to full scale.
This is actually the analog stage saturating for level >14.4dBu (-0.2dBFS at 6dB "gain")
Why Sound Devices didn't set the level 0.2dB lower to avoid this is beyond me !
This is just unacceptable, on an engineering point of view. (Even if, in practice, this isn't likely to have any effect. You don't record at 0dBFS)


IMD is doing the same

Sound Devices MixPre-3 II IMD Chart.png


This is NOT GOOD.

OK, it's true that noise is more audible than distortion. But we're touching the level of distortion of your best microphones here.
So why to spend $x000(or more) per microphone to kill its performance by plugging it to a preamp with the same or worse distortion level ?

Note that above values are matching Amir's measurements


Frequency response

Sound Devices MixPre-3 II Mic 1 6dB gain FR 96kHz.png

(There are some measurement artifacts here, especially just below 20kHz, due to the impossibility to synchroize perfectly the clock of the DAC with the clock of the ADC. Don't worry about those.)

Also not good: the Frequency response gives me a strange 0.7dB boost at low frequencies.
I double checked everything and couldn't find where this comes from.

This may be due to firmware, as Amir's measurements seem normal on that front.


Multitone 32

Sound Devices MixPre-3 II MT above threshold_crop.png


We see the same emphasis on low frequencies.
MT is not very clean.

This is just above the Preamp stage switching.
If we have a look just below, things get much worse:

Sound Devices MixPre-3 II MT below threshold_crop.png



Limiter measurement

I also measured the limiter on the Mic input
I measured both the level and the THD.


Sound Devices MixPre-3 II Limiter.png


As one can see, the limiter doesn't prevent saturation above 4V.
Which is to be expected, since it looks to be working in the digital domain.

HPF measurement

There are also several High Pass Filter settings available.
Again, they are working in the digital domain, so won't prevent analog or ADC stage saturation due to plosives, wind or a shock.

Sound Devices MixPre-3 II HPF.png


Headphones amp measurements

Amir did test power with the limiters in place.
Here is a measurement with limiters set to "off".

Note that I couldn't have the DAC section working, so I fed the device from the Microphone inputs.
For power, this shouldn't make a difference, though.

I measured at 300 ohm and at 32 ohm.


Sound Devices MixPre-3 II Headphones out.png


Max power at 300 ohm was approx 18mW
At 32 ohm, distortion raises quickly. I stopped at 1%, where I could read 150mW.

The "hump" behavior at 300 ohm is likely due to the Mic preamp switching range.



Bottom line

As we already said about ergonomics, we have a mixed result.
The double stage architecture, combined with the capability to record in 32 bit float gives a lot of freedom for field recording.
The preamp noise performance is also pretty good.

Unfortunately, the ADC performance is not in line with those good results. The device performance is pretty poor on that aspect.
Also, the frequency response anomaly is just un-acceptable for a device of that price and pretentions. (That might be a firmware issue, though)

Personally, I wouldn't purchase this device for critical field recording.
I'd rather go with a more classic design, which will give better overall performance and more flexibility for a similar or lower price.

Your mileage may differ, though
 
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Bergante

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It would be interesting to see the measurements in 24 bit mode. After all 32 bit is a hack that lets you mostly disregard the input gain. I am not surprised that some artifacts appear in this situation. But, how well does it emulate a first generation device which is more "classic" and does not support 24 bit?

Now I see that the block diagram doesn't tell the whole story. The manufacturer says that the input HPFs and limiters are hybrid with an analog and a digital part.

Regarding the headphones output... Didn't you create a headphone preset assigning USB "inputs" to headphone output channels directly? I don't have my recorder (first version MixPre-3, no 32 bit stuff) here but it was possible I think.
 
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Rja4000

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It would be interesting to see the measurements in 24 bit mode. After all 32 bit is a hack that lets you mostly disregard the input gain. I am not surprised that some artifacts appear in this situation. But, how well does it emulate a first generation device which is more "classic" and does not support 24 bit?
The analog and ADC stages seem to behave identically in both 24 and 32 bits.
I measured the exact same figures, which can't be by chance.

Now I see that the block diagram doesn't tell the whole story. The manufacturer says that the input HPFs and limiters are hybrid with an analog and a digital part.
Yes, I've read that. I have no clue what that could mean.
What I do know for sure is that the limiter doesn't prevent saturation at top level.
(That's also in their specs: max level 14dBu with or without limiter).

Regarding the headphones output... Didn't you create a headphone preset assigning USB "inputs" to headphone output channels directly? I don't have my recorder (first version MixPre-3, no 32 bit stuff) here but it was possible I think.
Sorry, I didn't.
I don't think that would change the power result, though.
 

Bergante

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The analog and ADC stages seem to behave identically in both 24 and 32 bits.
I measured the exact same figures, which can't be by chance.
Unfortunately that part of the block diagram is rather opaque. The implementation details for the 32 bit sampling are proprietary I guess and probably each manufacturer uses a different variation. Maybe there is a patent filing, I think Zaxcom has their "Neverclip" design patented.

In the first generation MixPres I think the only "trickery" was to sample each channel with two A/D converters so that you can reduce noise a bit (the sum of correlated signals is greater than the sum of uncorrelated signals). I deduced that by looking at the internal photos posted on the FCC database.

Yes, I've read that. I have no clue what that could mean.
What I do know for sure is that the limiter doesn't prevent saturation at top level.
(That's also in their specs: max level 14dBu with or without limiter).
Well, I guess they took a pragmatic approach. Maybe the lowest frequency filtering stage are analog and they add a subsequent digital domain filtering for higher frequencies. After all the main purpose of those filters in a field recorder is to prevent low frequency rumble caused by wind or handling.

Sorry, I didn't.
I don't think that would change the power result, though.

You are probably right but I am not sure whether the 32 bit path is end to end, I mean, from A/D to headphone output. If it's not, fader positions (remember these units are mixer/recorders) might clip. If you assign pre fader inputs (be them microphone or line inputs or USB channels) you will make sure there is no additional fader effect and only the headphones output knob will affect levels.
 

Bergante

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I measured headphones power with mic 1 > Left and level 0dB
Ahh ok :)

Anyway if you are curious you can try to set up headphone routing. If you touch the headphone icon (screen top left) you get a menu where you can edit headphone presets. And the routing configuration works like the line output routing, you can select pre/post fader sources.

That said, these recorders pack a punch. If you use high efficiency headphones you can literally destroy your hearing listening at loud volumes. Or my ears are too delicate, who knows! ;)
 
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Rja4000

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Ahh ok :)

Anyway if you are curious you can try to set up headphone routing. If you touch the headphone icon (screen top left) you get a menu where you can edit headphone presets. And the routing configuration works like the line output routing, you can select pre/post fader sources.
I don't have the device anymore.
That said, these recorders pack a punch. If you use high efficiency headphones you can literally destroy your hearing listening at loud volumes. Or my ears are too delicate, who knows! ;)
That is clear.
150mW is plenty.
This is similar power than the UCX II (see here) and I know for a fact that's good enough for me.
 
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Rja4000

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Frequency response

Sound Devices MixPre-3 II Mic 1 6dB gain FR 96kHz.png


Also not good: the Frequency response gives me a strange 0.7dB boost at low frequencies.
I double checked everything and couldn't find where this comes from.
I think this boost is a secundary effect of a permanent slow-slope HPF in the analog domain.
We see the level decreasing with frequency below 20Hz.
That's probably why Sound Devices writes that HPF is a combination of analog and digital domain filters.
 
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Rja4000

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Thanks for doing the additional testing for us.
My pleasure :)
Very interesting device.
Indeed.

@Julian Krause also reviewed on his YouTube a similar device, the Zoom UAC-232.
The Zoom is much cheaper, and its preamps are less performant, but it's using similar technology.

Also, ASR member @signalpath (which is better known as John La Grou, from Millennia-audio) explained recently that this kind of technology is likely to be included in DAC and ADC circuits (/chips?) themselves in a near future.
 
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Rja4000

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What would be the distorsion figures with increased sample rates at 96 KHz or even 192 KHz ?
192kHz only works for recording.
USB interface is limited to 96kHz.

Therefore, I couldn't perform my full THD vs frequency measurement (which requires 90kHz Bandwidth to be aligned with Amir's standard measurement).

But look at the Multitone 32 plots: you'll then have a better idea of the total distortion (HD + IMD) in audible range.
Just below the stage switch threshold, the high frequencies are quite impacted with various types of distortion.

This is in line with Amir's own (48kHz) THD vs frequency plot.

Sound Devices MixPre-3 Audio Recorder Interface SD Card THD vs frequency Measurement.png
 
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MC_RME

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Very nice and informative review!

Regarding the headphone out: I agree that the difference between this and UCX II is not big at 32 Ohms. But it is at higher impedances: 150 mW to 18 mW, that is 8 times the power. Technically it means that our headphone stage is current limited while theirs is voltage limited. Makes sense for a battery driven, portable device.
 
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Rja4000

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I agree that the difference between this and UCX II is not big at 32 Ohms. But it is at higher impedances: 150 mW to 18 mW, that is 8 times the power
Yes, I agree.
The UCX II delivers much more power at 300 ohm.

2022-07-22 18_52_35-Chart (1).png


Personally, I only use low impedance headphones, so my experience is solely based on that.
But for people using higher impedance, insensitive, headphones, that could make a big difference.
 

Bruno

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This is a complementary review of Sound Devices MixPre-3 II digital audio recorder and mixer.

View attachment 334171

@amirm has done a first review (you may find it here), but it appears he measured the device in "Basic" mode only.
This mode has some strong limitations.
One of those being that the limiters (there are several layers of them) are always active.

I will now have a look at the Advanced mode.

I rented the device for the week-end (45€) to measure it.


Ergonomy

One thing you may not realize immediately when looking at a photo of the device is how tiny it actually is.
Look at it on top of the RME UCX II.
The UCX II is half 19" rack width.

The device itself feels solid and quite heavy for its size.
A rubber-like coating prevents it to slip from any surface.
Critical knobs and commands are easy to recognize by touch.
The metal protrubation to the level knobs allows you to immediately sense the knob position in the dark.
Level knobs also have a ring that illuminates in Green or red, according to the input signal level.
You have a retracting 1/4" screw on top, to lock the device below a camera's tripod mounting hole.
And the hexagonal Alen key is included and attached to the MixPre rear.

Of course, the touch display is very small, and you need small fingers to operate it.


Navigating through all the options in the different menus is a different topic, though.
You need to really dig deep to find what you're looking for.

Also, the power switch is very small and hard to locate without looking.

Overall, this device's handling ergonomy is a mixed bag of quite well thought through controls... and messy ones.


Measurements

Given the limited time I had the device at hand, I decided to focus on Microphone input only.
This device is mainly a field recorder, so this is naturally its main focus point.
I also measured the Headphones output power, which is also of interest for field recording use.


Measurements were performed with my RME ADI-2/4 Pro SE, at various output levels, and with or without a Shure A15AS attenuator.
I use Virtins MultiInstrument 3.9.9.3 as a measurement software.
Noise and distortion measurements below are all for 20Hz-20kHz bandwidth.

As the device was rented, I didn't upgrade the firmware.
The firmware was 7.16 (build 3266)



I've setup Advanced mode.
This then gives me access to critical settings:
So I've set it up for 48kHz 32 bits float, limiters off.
I downloaded the ASIO driver and here we go.


ADC and Microphone input

Let's start with 2 measurements that summarize the 2 main saling points for this device


EIN at max Gain

View attachment 334173

This is a good value in general.
For a tiny portable device, it's exceptional.


Dynamic range at min gain

View attachment 334174

Waow !
Yes, that's an actual analog measurement
That's unsee, isn't it ?
(Actually, it matches specifications.)

And what is REALLY unseen is that it looks like both EIN and Dynamic range figures remain the same whatever the gain setting.

Well, there is a catch. Read on.


Signal path

I measured by sending the input signal to the USB interface "Pre fader".
You may see the path on this block diagram (source)

View attachment 334177

Let's zoom a bit on the input section

View attachment 334178

Now a word of explanation:

Usually, a Mic preamp interface has an analog preamp stage followed by the ADC.
And the analog preamp stage has a variable gain.

In this case, we see the ADC followed by a digital Trim (called "Gain" on the device screen). So it's not an analog gain.
This device is also using, per channel, multiple Mic Preamps and multiple ADC stages.
Their digital signal outputs are then combined in the digital domain, to mimic one single extra-wide dynamic range input.

Note that the exact number of Preamp and ADC stages is not documented, but given the measurement results here, I guess we have 2 preamp stages, each with its corresponding ADC.


You may see some hint of that if you vary the level:

View attachment 334184

At some point (around 78 mVrms input for a pure sine wave), you may see the SNR dropping abruptly.
This is where the device switches from one stage to another.

It is to be noted that this doesn't seem to be linked to 32 bits float operation: the device does the same in 24 bits.


32 bits float

So what's the benefit of 32 bits float ?

The benefit is that you may record above 0dBFS.
With an integer coding, your recording can't go above 0dBFS (dBFS=dB Full Scale)
With a float encoding, there is no such limit.

The big benefit is that you may push the level digitally, to allow proper level for monitoring through headphones, as an example, without any risk of saturation of the recording.
So this really allows to take full benefit of the dual stage preamp and ADC.

To operate the device, you just set the "gain" to the minimum value (6dB) and you forget it.
There is no need, like with most other Microphone preamps, to tune the gain to optimize noise and headroom.

Looks magic, doesn't it ?

Here is a plot of DR in 24 vs 32 bits (and the DR of the RME UCX II, which follows a "normal" pattern, for reference) for different "gain" levels

View attachment 334175


Input sensitivity range
So you have actually 2 sensitivities to remind: 78mV (-20dBu) for the first preamp stage, and 4.1V (14.6dBu) for the second stage.


SINAD dashboard at 4V, min gain

Well, all is not pink, unfortunately, and here start the bad news

View attachment 334202

As you can see above, the distortion is quite high (and mostly composed of odd harmonics).
Sure, that's almost matching the specs: 0,005% is 86dB SINAD (-86dB THD+N), but that's not very brilliant.


Worse: given the way this device works, you'll find similar level of distortion at low to medium level: just below 78mV, when you reach the maximum level for the first stage, you'll see similar distortion level.
But if we go over 78mV, we see distortion decreasing.

View attachment 334186
Look at the THD+N plot vs level, where you see the SNR drop, but also the THD increase when you approach the upper limit of the first stage, and the drop when switching to the second stage.
(From this plot, I couldn't identify any additional lower level step that would indicate a third stage is at play)

Also, we see a heavy saturation close to full scale.
This is actually the analog stage saturating for level >14.4dBu (-0.2dBFS at 6dB "gain")
Why Sound Devices didn't set the level 0.2dB lower to avoid this is beyond me !
This is just unacceptable, on an engineering point of view. (Even if, in practice, this isn't likely to have any effect. You don't record at 0dBFS)


IMD is doing the same

View attachment 334188

This is NOT GOOD.

OK, it's true that noise is more audible than distortion. But we're touching the level of distortion of your best microphones here.
So why to spend $x000(or more) per microphone to kill its performance by plugging it to a preamp with the same or worse distortion level ?

Note that above values are matching Amir's measurements


Frequency response

View attachment 334189
(There are some measurement artifacts here, especially just below 20kHz, due to the impossibility to synchroize perfectly the clock of the DAC with the clock of the ADC. Don't worry about those.)

Also not good: the Frequency response gives me a strange 0.7dB boost at low frequencies.
I double checked everything and couldn't find where this comes from.

This may be due to firmware, as Amir's measurements seem normal on that front.


Multitone 32

View attachment 334194

We see the same emphasis on low frequencies.
MT is not very clean.

This is just above the Preamp stage switching.
If we have a look just below, things get much worse:

View attachment 334195


Limiter measurement

I also measured the limiter on the Mic input
I measured both the level and the THD.


View attachment 334197

As one can see, the limiter doesn't prevent saturation above 4V.
Which is to be expected, since it looks to be working in the digital domain.

HPF measurement

There are also several High Pass Filter settings available.
Again, they are working in the digital domain, so won't prevent analog or ADC stage saturation due to plosives, wind or a shock.

View attachment 334198

Headphones amp measurements

Amir did test power with the limiters in place.
Here is a measurement with limiters set to "off".

Note that I couldn't have the DAC section working, so I fed the device from the Microphone inputs.
For power, this shouldn't make a difference, though.

I measured at 300 ohm and at 32 ohm.


View attachment 334196

Max power at 300 ohm was approx 18mW
At 32 ohm, distortion raises quickly. I stopped at 1%, where I could read 150mW.

The "hump" behavior at 300 ohm is likely due to the Mic preamp switching range.



Bottom line

As we already said about ergonomics, we have a mixed result.
The double stage architecture, combined with the capability to record in 32 bit float gives a lot of freedom for field recording.
The preamp noise performance is also pretty good.

Unfortunately, the ADC performance is not in line with those good results. The device performance is pretty poor on that aspect.
Also, the frequency response anomaly is just un-acceptable for a device of that price and pretentions. (That might be a firmware issue, though)

Personally, I wouldn't purchase this device for critical field recording.
I'd rather go with a more classic design, which will give better overall performance and more flexibility for a similar or lower price.

Your mileage may differ, though
First and foremost thank you very much to You and to @amirm for providing these thorough and informative reviews.
However I'd respectfully add some personal (and I stress personal) considerations.

In the case of this type of gear I wouldn't give too much importance to neither THD/SINAD nor the headphone output for some reasons, namely:

- I belong to a generation whose HI-FI systems were deemed good if they sported a THD of 0,05%. Measured 0,005% THD is one order of magnitude better. Besides, I took an online audio test here: https://www.audiocheck.net/testtones_thdFull.php. It came out that with my current ears and gear I can't tell 0.05 from 0.01%, so it's evident that 0.005% is not an issue, at least not for me.

- This is not an Hi-FI piece but a prosumer field recorder and should be evaluated as such. The main issue here is not THD but noise. Noise is the main concern of field recordists. There's at least one reference page that lists available field recorders according to their Equivalent Input Noise levels here: https://www.avisoft.com/recorder-tests/
THD is not even mentioned because with available modern gear it's not a concern.

- Purchases are to be proportionally made. As said earlier this is prosumer gear and one's not going to spend $x000 for mics unless she prefers to spend more for a good set of mics now and plans to buy a better field recorder later. Pros do not stop at this level of gear but scale up. The legend himself Gordon Hempton relies upon an older but better Sound Devices 722 https://www.creativefieldrecording.com/2016/09/07/a-month-of-field-recordists-gordon-hempton/

- One should not lose sight of the use of the resulting files. Where do field recording files mainly end?
1) Entertainment industry i.e. sonic libraries meant for cinema and games
2) Biologic research and animal calls guides
3) Recreational use (yes, some of us have the funny habit of collecting sonic postcards of the places they visit other than photos)

In all three of the above cases the importance of distortion is negligible, at least with the current available gear.
In the first case we're talking about background noises. I can't imagine an audiophile trying to focus on the background noise instead of looking at the film and however it's done with higher level pro gear.
In 2) we're talking about animals population computing, localization telling one call from another and teaching beginners how to tell an animal from another. Again, absolute fidelity is not so much of an issue here. What matters here is the conveyed information.
As to 3) we're talking about preserving memories. What matters is the content and the emotions it brings back, not the accuracy.

As for the headphone output, the idea is expressed at the best by Ken Rockwell in his own review of the Sony MD7506 (which are commonly judged next to crap if evaluated with the same criteria used for Hi-Fi stuff) https://www.kenrockwell.com/audio/sony/mdr-7506.htm :

[...] for field use to be sure that your audio is clear, that you have no noise or rumble and that no one is cursing quietly in the background. The MDR-7506 are the best and most abuse-proof headphones there are for making sure you got good audio while you are still recording it. [...]

[...] The MDR-7506 are optimized for professional monitoring, meaning optimized to help professionals hear what's wrong with a recording while they can still do something about it.

The MDR-7506 are superb compared to any headphones at any price for letting us hear any noise, clicks, pops, inappropriate under-the-breath language or distortion while we're still on the set.[...]

Sure Mr. Rockwell's reviews are more colorful than accurate and are to be taken with a grain of salt, but what he says about the headphones can be safely assumed for the SD's headphones output too. This latter is not meant to listening to music but to be sure that there aren't any unintended items sneaking into the recording.
 
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Rja4000

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First and foremost thank you very much to You and to @amirm for providing these thorough and informative reviews.
Welcome :)
In the case of this type of gear I wouldn't give too much importance to neither THD/SINAD nor the headphone output for some reasons, namely:

- I belong to a generation whose HI-FI systems were deemed good if they sported a THD of 0,05%. Measured 0,005% THD is one order of magnitude better. Besides, I took an online audio test here: https://www.audiocheck.net/testtones_thdFull.php. It came out that with my current ears and gear I can't tell 0.05 from 0.01%, so it's evident that 0.005% is not an issue, at least not for me.
If you read on this site, you'll see that SINAD is less of a goal in itself than an indicator of good engineering, predicting a lack of any issue and full transparency.
Which is what we try to evaluate here with those reviews.

Of course, in some area, there might be some compromises needed. But in 2023, we see no need for such bad ADC performance. Because doing it right costs basically nothing.

Of course, we see even less excuse for this on a device costing 1k USD.

- Noise is the main concern of field recordists.
If you read above, that's what I say.
I highlight the good noise performance as a key saling point.

But, again, that's not an excuse.
There are way cheaper interfaces out there that perform "perfectly" for noise AND for everything else, so why to accept less here?
Sure, everyone is making his/her choices, but, at least, one may now do an informed decision.

- One should not lose sight of the use of the resulting files.
I think there are 2 main uses:
- Video sound recording. This will, of course, give better results than in board prosumer camera mic inputs.

- Field recording
I'm member of a group for classical music recording and I see quite a few users of those devices there. And some are using it with DPA 4006 and other Schoeps high end microphones.
Those people deserve better.

Of course, there may be more uses.
As for the headphone output, too.
(...)
This latter is not meant to listening to music but to be sure that there aren't any unintended items sneaking into the recording.
I measured headphones power, because, from my experience, being able to drive your headphones loud enough is important in the field.
Performance is good enough for low impedance headphones, but may be short if you intend to use high impedance ones.
Which may be important to know (and can't be guessed from the published specs).


My goal doing this review was to bring objective evaluation of this device's performance.

This is sometimes seen as a threat by some people, but there is actually no threat in bringing more information.


Audio quality is a quest that starts at the source, IMO. So, yes, the pro hardware vendors should also aim at increasing the quality of their devices.
Some do it right. They deserve recognition and praise.
Some could do better, and we should highlight the weak points to promote improvement.
 
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Bruno

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Welcome :)

If you read on this site, you'll see that SINAD is less of a goal in itself than an indicator of good engineering, predicting a lack of any issue and full transparency.
Which is what we try to evaluate here with those reviews.

Of course, in some area, there might be some compromises needed. But in 2023, we see no need for such bad ADC performance. Because doing it right costs basically nothing.

Of course, we see even less excuse for this on a device costing 1k USD.


If you read above, that's what I say.
I highlight the good noise performance as a key saling point.

But, again, that's not an excuse.
There are way cheaper interfaces out there that perform "perfectly" for noise AND for everything else, so why to accept less here?
Sure, everyone is making his/her choices, but, at least, one may now do an informed decision.


I think there are 2 main uses:
- Video sound recording. This will, of course, give better results than in board prosumer camera mic inputs.

- Field recording
I'm member of a group for classical music recording and I see quite a few users of those devices there. And some are using it with DPA 4006 and other Schoeps high end microphones.
Those people deserve better.

Of course, there may be more uses.

I measured headphones power, because, from my experience, being able to drive your headphones loud enough is important in the field.
Performance is good enough for low impedance headphones, but may be short if you intend to use high impedance ones.
Which may be important to know (and can't be guessed from the published specs).


My goal doing this review was to bring objective evaluation of this device's performance.

This is sometimes seen as a threat by some people, but there is actually no threat in bringing more information.


Audio quality is a quest that starts at the source, IMO. So, yes, the pro hardware vendors should also aim at increasing the quality of their devices.
Some do it right. They deserve recognition and praise.
Some could do better, and we should highlight the weak points to promote improvement.
Thank you very much for further clarifying Your point of view, truly appreciated :)
 

Bergante

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I'm member of a group for classical music recording and I see quite a few users of those devices there. And some are using it with DPA 4006 and other Schoeps high end microphones.
Those people deserve better.
The main selling point of those microphones as far as I know is off axis response. That is really important for classical music recording.
 
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