Motu M4 Audio Interface Review

[DJBonoBobo]

If the RME ADI-2 Pro had a mic preamp I would have bought instead of the ADI-2 DAC FS while using the M2 for mic purposes.

Me too, but after using TotalMix for a while i´m getting very fond of it. ADI-2 Pro with 48V, TotalMix and at least 8 output-channels would be perfect...
I used the ADI-2 DAC with the M4 and now ADI-2 + UCX II. Overkill, i know, but i just hate it when devices don´t work how i want them to.
If the M2/M4 work in your system, they are absolutely fine, of course.

 

[stemfencer]

Me too, but after using TotalMix for a while i´m getting very fond of it. ADI-2 Pro with 48V, TotalMix and at least 8 output-channels would be perfect...
I used the ADI-2 DAC with the M4 and now ADI-2 + UCX II. Overkill, i know, but i just hate it when devices don´t work how i want them to.
If the M2/M4 work in your system, they are absolutely fine, of course.

Any chance you could give some feedback (objective or subjective) about the headphone out of the API-2 vs UCX II onboard?

Reason for asking this is exactly the use case I'm weighing up, getting an M4 and adding on external headphone amp (e.g. Topping A90) and perhaps external mic preamp, compared to just dropping the coin and getting UCX II. While these units are for mixing/recording, really hope I can get "audiophile" listening out of it without an external amp.

 

[DJBonoBobo]

Any chance you could give some feedback (objective or subjective) about the headphone out of the API-2 vs UCX II onboard?

I don´t think i am able to tell the difference between the ADI 2 and the UCX II in a normal scenario. Just yesterday i began testing the headphone output of the UCX II, and it works well with all of my three headphones (s. signature). For my needs it has more than enough power and headroom even in "Low" mode and even for the Aeon 2. The main differences are the features (ADI has "extreme power" which i don´t need, dedicated IEM out, 5+2 bands of EQ, dynamic loudness, different filters, IR remote...). I am testing now if the 3 bands of eq of the UCX II are enough for me. I am not a "golden ear" though and did not try to really compare with level matching and such. I simply trust the UCX II sounds neutral and don´t have found a reason not to.

Edit: As far as i know, the UCX II´s headphone output is not built as a competitor to a dedicated headphone amp like the ADI 2 or the A90, but the question is, who really needs this. As far as i understand, the ADI 2 should be much more advanced than the UCX II, but as i wrote i don´t think it makes a difference to me. Still testing though and may continue using the ADI 2 for the peace of mind. Undecided yet.

 

[stemfencer]

I don´t think i am able to tell the difference between the ADI 2 and the UCX II in a normal scenario. Just yesterday i began testing the headphone output of the UCX II, and it works well with all of my three headphones (s. signature). For my needs it has more than enough power and headroom even in "Low" mode and even for the Aeon 2. The main differences are the features (ADI has "extreme power" which i don´t need, dedicated IEM out, 5+2 bands of EQ, dynamic loudness, different filters, IR remote...). I am testing now if the 3 bands of eq of the UCX II are enough for me. I am not a "golden ear" though and did not try to really compare with level matching and such. I simply trust the UCX II sounds neutral and don´t have found a reason not to.

Thank you, appreciate it. And cheers for letting us side track this thread a bit, now back to the M4

 

[VNN77]

Hello guys I just got my setup done at home including a Motu M4, DT 990s(250ohm), and a Shure SM57 mic.
From what I understand I have this new Rev2 version which states Made in China. I got the 2.00 Firmware version.
I've been reading around and most people are saying that they keep their headphone volume at 60-70% cuz it gets really loud, but for me, I keep it at 100% on the headphone knob, and is not really that loud like it could cause hearing damage. Everyone is saying that the M4 has enough juice to fully power the 250ohm 990s to 100+db.
With my mic, a hissing sound pops up after around 12-1am on the gain knob which really disturbs me cuz it's really audible and forces me to use low gain and almost shout while talking into it.
Any thoughts?

 

[Trell]

Hello guys I just got my setup done at home including a Motu M4, DT 990s(250ohm), and a Shure SM57 mic.
From what I understand I have this new Rev2 version which states Made in China. I got the 2.00 Firmware version.
I've been reading around and most people are saying that they keep their headphone volume at 60-70% cuz it gets really loud, but for me, I keep it at 100% on the headphone knob, and is not really that loud like it could cause hearing damage. Everyone is saying that the M4 has enough juice to fully power the 250ohm 990s to 100+db.
With my mic, a hissing sound pops up after around 12-1am on the gain knob which really disturbs me cuz it's really audible and forces me to use low gain and almost shout while talking into it.
Any thoughts?

I've the Motu M2 that I used as headphone amp for my Beyerdynamics DT880 Edition 250 Ohm as well as for my condenser mics, this on Windows.

I found the M2 headphone output a little weak for some of the content I listened to as that was mastered at a lower level so not enough gain possible. I'm now using the RME ADI-2 DAC fs for this.

I'm still using the M2 for my mics (mostly video calls) and I've not noticed any bothersome hiss at 13/14 o'clock. There are several reviews for the first revisions on youtube where you can here comparisons of noise levels with other audio interfaces.

A few things you could verify:

* The volume should be not digitally reduced on your PC/Mac.
* The recording level should be 100% in your PC/Mac and you adjust level on your M4.
* Disable various "auto-level" in the software you use. Note that on Windows 10 the "Game Mode" and/or "XBox Game Bar" changes the mic level made made my life miserable on Microsoft Teams until I turned it off.

 

[VNN77]

I've the Motu M2 that I used as headphone amp for my Beyerdynamics DT880 Edition 250 Ohm as well as for my condenser mics, this on Windows.

I found the M2 headphone output a little weak for some of the content I listened to as that was mastered at a lower level so not enough gain possible. I'm now using the RME ADI-2 DAC fs for this.

I'm still using the M2 for my mics (mostly video calls) and I've not noticed any bothersome hiss at 13/14 o'clock. There are several reviews for the first revisions on youtube where you can here comparisons of noise levels with other audio interfaces.

A few things you could verify:

* The volume should be not digitally reduced on your PC/Mac.
* The recording level should be 100% in your PC/Mac and you adjust level on your M4.
* Disable various "auto-level" in the software you use. Note that on Windows 10 the "Game Mode" and/or "XBox Game Bar" changes the mic level made made my life miserable on Microsoft Teams until I turned it off.

I figured out that the hissing is actually some kind of interference that the mic is catching from my computer because its sitting right next to my case. When I move it always from it disappears and goes back to normal. For example, when I have the gain on 100% the In LED is jumping a little bit without speaking to the mic but I think that is normal.

 

[Trell]

I figured out that the hissing is actually some kind of interference that the mic is catching from my computer because its sitting right next to my case. When I move it always from it disappears and goes back to normal. For example, when I have the gain on 100% the In LED is jumping a little bit without speaking to the mic but I think that is normal.

Good that you found the source of the noise you experienced. As for the LED moving a little at 100% gain could be other noise in the room it is picking up and is to be expected, but you could try record the noise and play it back to check what it is.

 

[Saikou]

Also, opamps (except headphone) are just OPA1678s now? The first rev also had some 4580s I think.

Do you happen to know more about this? Are these inferior headphone amps? I always thought the headphone amp that came with the M2/M4 was adequate enough. Curious if this means now it has a awful amp for that usecase.

 

[phoenixdogfan]

I bought this unit strictly to use it as an A to D converter. In the review it mentions that gain should be set to 18 Dbu to achieve optimum performance. How exactly do I do that? Do I just turn it up until it hits the clipping indicator, and then back it off a hair?

 

[mdsimon2]

I bought this unit strictly to use it as an A to D converter. In the review it mentions that gain should be set to 18 Dbu to achieve optimum performance. How exactly do I do that? Do I just turn it up until it hits the clipping indicator, and then back it off a hair?

What is the maximum voltage from your source? The review is simply stating a level of 18 dBu (6.15 V) was used for the dynamic range measurement for the line input and does not refer to any specific setting on the M4.

In general what you describe will give you the best signal to noise ratio. You want to use the line input (not the mic input) and feed it a signal with a maximum level of 6.15 V.

Michael

 

[AnalogSteph]

I would also like to mention that between the ADC digital filter periodic passband ripple (common to all AK55xx ADCs, their filters kinda stink) and slightly uneven distortion performance, the ~5 dB gain in dynamic range over a good CS4272 job (e.g. Focusrite gen3 or Tascam US-2x2HR) may not be worth it. It's definitely not clear-cut, unlike the DAC side. Unless dynamic range is an overriding concern, "old faithful" would generally have my vote in the recording department.

I'm hoping for the ESS ADCs to gain some traction, with manufacturers actually making good use of their filter choices (give users some options ffs, not everyone is out for minimum latency all the time - rant over). PCM4220 and PCM4202/4 are a good choice for SQ as well and not totally uncommon in the wild (e.g. Audient iD22, iD14 MkI). AK4621 can be good unless the short group delay filter option is engaged, likewise the AK5397 which had a very good sharp rolloff filter and a good minimum phase option.

Do you happen to know more about this? Are these inferior headphone amps?

I explicitly wrote "(except headphone)" in case you didn't notice. I'm pretty sure nothing has changed in that department.

 

[okMX]

Noob question here,

instead of the headphone OUT, I would like to use the balanced output 3 & 4 for my headphones. I thought that I would need an adapter which has 2x TRS (with 2 black rings) to TRS Female, but I can only find this cable:

https://www.thomann.de/gb/pro_snake_tpy_2003_bpp.htm?ref=cg_cg_3_14_n_0


I thought I would need stereo for both male jacks but that adapter doesn't seem to exist? If I want a balanced connection with my active speakers, I also have to use TRS for every single side, sorry I don't get it.
So is my linked adapter the right one or am I completely wrong? Would it make any difference in volume or quality if I would use the same adapter but for the RCA? Which one would you take?

https://www.thomann.de/gb/pro_snake_tpy_2003_sbrr.htm?ref=cg_cg_11_14_n

Sorry for the (probably) stupid question and thank you!

 

[AnalogSteph]

instead of the headphone OUT, I would like to use the balanced output 3 & 4 for my headphones.

Why exactly? What is the problem you are actually trying to solve like that?

As you have noticed, 2x TRS has too many connections for one TRS plug. A 4.4 mm Pentaconn would fit the bill, but your cans don't seem to have balanced wiring.

Would it make any difference in volume or quality if I would use the same adapter but for the RCA? Which one would you take?

https://www.thomann.de/gb/pro_snake_tpy_2003_sbrr.htm?ref=cg_cg_11_14_n

Well, at least that one would work - sort of. Output impedance would still be 50 or 100 ohms with whatever effect that has on the frequency response of your particular headphones, and the opamp may not be very happy driving lower-impedance headphone loads in particular. That's still not any worse than the dedicated headphone outputs in some other interfaces, but is it particularly great, no.

You can always get a little headphone amplifier to plug into there, of course. The usual suspects are a bit harder to get here on the old continent, but there are a few good options around the 150€ mark at least. (Portable amps can be had for far less but unless they can be charged and used at the same time this generally is not the most practical solution.)

 

[Saikou]

I explicitly wrote "(except headphone)" in case you didn't notice. I'm pretty sure nothing has changed in that department.

Oh, my mistake, I completely misread that.

Guess I'll have to wait and see once my unit gets here to see if it's a new revision or an old one. (I'm getting the M2, though, not the M4)

 

[JeffGB]

Noob question here,

instead of the headphone OUT, I would like to use the balanced output 3 & 4 for my headphones. I thought that I would need an adapter which has 2x TRS (with 2 black rings) to TRS Female, but I can only find this cable:

https://www.thomann.de/gb/pro_snake_tpy_2003_bpp.htm?ref=cg_cg_3_14_n_0
View attachment 151760View attachment 151763

I thought I would need stereo for both male jacks but that adapter doesn't seem to exist? If I want a balanced connection with my active speakers, I also have to use TRS for every single side, sorry I don't get it.
So is my linked adapter the right one or am I completely wrong? Would it make any difference in volume or quality if I would use the same adapter but for the RCA? Which one would you take?

https://www.thomann.de/gb/pro_snake_tpy_2003_sbrr.htm?ref=cg_cg_11_14_n

Sorry for the (probably) stupid question and thank you!

Please do not use the adapter in this image! It will short one of the balanced outputs and the MOTU M4 is direct coupled on those outputs. You would get no advantage at all from that connection and you could damage the MOTU. The single ended outputs on the MOTU are from the balanced outputs being properly summed with an opamp to an RCA jack. In addition the M4's headphone output has an output impedance of approx .02 ohms vs 100 or so on the line outputs. If you need additional headphone power I would recommend adding an external HP amp connected to either the RCA or balanced outputs (depending on whether the amp is balanced or single-ended).

 

[VNN77]

Why exactly? What is the problem you are actually trying to solve like that?

I was wondering if i should do the same thing, seems like the headphone amp is not powerful enough to fully drive my DT 990s, still the loudness enough for daily usage, i just wanted to hear it to peak loudness, one that can damage hearing.

 

[AnalogSteph]

I take it your Beyers also have the plain 1/4" TRS jack? Expected unbalanced line-out level on the M4 is +10 dBu (6 dB less than balanced level), which actually is less than the +12.5 dBu on the headphone out... and then you still lose a dB and change in the output impedance. So it's a completely pointless exercise AFAICT.

 

[okMX]

Thank you for the information guys!
I have 3 devices, pair of active speakers (balanced OUT 1&2), AKG 712 (headphone OUT) and the AKG 371 (RCA OUT 3&4).
I wanted to use the 712 with the normal headphone out and the 371 with the 3 & 4 output. Additionally, I want to use Equalizer APO with the 371 so it would be super convenient if I could just click in Windows on the 3&4 output and the Equalizer Profile gets loaded automatically.

So from what I get, I shouldn't use the balanced OUT (with the adapter) because it could destroy my device.
I could use the RCA out and the linked cable but it is not as powerful as the headphone out?

 

[JeffGB]

That's correct. The XLR outputs have a higher voltage capability than the single-ended RCA outputs but that does not equate to power for a headphone, which is low impedance. If you connect a good HPA, like a Schiit Heresy, it will usually have a gain switch (usually it's 0 voltage gain, and then a setting or two for higher voltage output) and this will allow you to make it louder, with low distortion, if maximum volume is your goal.