Motu M4 Audio Interface Review

[bennetng]

Why Motu, why >_<

Thanks for the correction, I had no idea.

EDIT: Any idea what's causing the rise in ultrasonics? Would've at least thought such a deep filter decimates properly, but it seems to lay off for later frequencies as hinted by the THD vs FR. Another inherent chip flaw of earlier chips or?

This?

But that's a 90kHz BW measurement, so probably noise instead of correlated distortion. Modulators of earlier chips probably working in a lower frequency so the analog filter is not fast enough to suppress this noise as good as the newer ones.

 

[Blumlein 88]

Here is a spectrogram where a slow sweep from 2 hz to 96 khz was fed into an ADC sampling at 48 khz. You can see there is aliasing all the way above 24 khz. Now this was a -1 dbFS signal so normally you won't have such at high frequencies. The thin blue line lies at -90 dbFS. And if the input level is lower this aliasing is lower as well.

Now play this back on a DAC and the DAC's filter will reduce it further. Beyond the transition band of 20-24 khz it is effectively gone so low in level it will be even with a lazy DAC filter.

Also not all filters act this way some alias a bit above 24 khz and then you have none. This one is a bit odd.

 

[maty]

The M2 outputs have volume control with the big knob.

I need glasses

1 x potentiometer • monitor vol
1 x potentiometer • phone vol

Thank you!

 

[3125b]

Curious about how the Scarlett Solo gen3 would fare against the Motu M2 now

Badly. The headphone out is barely useable (worse than PC onboard sound), the mic input isn`t too bad, the DAC (line out) is just about audibly transparent.
It`s doesn`t cost much, but it`s not very good. It`s more a comparison to the cheap Behringer interfaces.

 

[MRC01]

The answer is kinda sorta. This review details the limited functionality with various linux kernals.
https://panther.kapsi.fi/posts/2020-02-02_motu_m4
Working with ASIO is something I wish linux would fix. I'd use no other OS if they could do that.

When one sets the device bit depth & sample rate from their Windows app, does the unit keep those settings until they are changed or the unit is powered off?
If it keeps them until they are changed, even if powered off, then one could configure it on a Windows box, then plug it into a Linux box for recording.
If it keeps them until powered off, then one configure it by running the Windows app in VirtualBox, then switch the USB device to the Linux host for recording.

Even better would be switches on the unit itself to set the bit rate & depth. Then no software app needed. Just plug in the USB and mics, and run on any OS.

 

[Atanasi]

When one sets the device bit depth & sample rate from their Windows app, does the unit keep those settings until they are changed or the unit is powered off?
If it keeps them until they are changed, even if powered off, then one could configure it on a Windows box, then plug it into a Linux box for recording.
If it keeps them until powered off, then one configure it by running the Windows app in VirtualBox, then switch the USB device to the Linux host for recording.

Even better would be switches on the unit itself to set the bit rate & depth. Then no software app needed. Just plug in the USB and mics, and run on any OS.

I guess you can specify the sample rate and bit depth on Linux when you open the device with Jack, which serves the purpose of ASIO.

 

[Pluto]

there was a lot of cycling of recordings through analogue

Ahhh.... Analogue. The universal sample rate converter.

 

[thefsb]

Looks like a decent home studio unit for the PC and web broadcasting.

It is. It's very practical with a number of neat features.

The preamps are quiet enough at full gain to use low output mics directly, e.g. I usually have it turned up all the way when using my AKG D880.

Meters are very clear and allow a quick glance to check levels.

Indicators for when direct monitors are engaged are very clear. Same for the phantom power buttons.

The ASIO provides loopback interfaces that mix the inputs and outputs, which are great for video streaming stuff. For example, my music teacher only gives video lessons (because of the plague) and he can hear my mic and instruments plugged into the M4 and my computer audio, e.g. DAW output or Youtube audio.

Headphone amp is plenty loud enough for me with Sennheiser HD 58x.

Phantom powers the preamp for my SM35 headset condenser just fine. There was significant and annoying noise when I used this with the Focusrite Scarlett (that died when I powered it up with 110VAC -- oops).

 

[thefsb]

BTW: Remember to keep phantom power turned off when not using it. At least one reviewer found increased noise when it's on and you're not drawing any current.

 

[thefsb]

Yes

Preamps are pretty quiet in this unit. So how about connecting the TT cartridge to the M4 (make sure phantom is turned off) and apply RIAA in digital?

 

[PuX]

if someone in the US can send in a E-MU 0404 USB for review, please do - it would be nice to compare how far the industry has come in the last 15 years or so.

I believe it was sold for ~$250 originally and was considered the best in class.

I have one but I live in a different country so shipping would be pricey.

 

[CerealKiller]

This is Excelent news! and might as well replace my current desktop dacs DX3pro and D10 since performance is pretty much on par.

Thanks Amirm as always for your fantastic work, do you know if "monitor" outs are equal performance to line out? Will level be the same and as high as 5V?

Thank you very much. And cheers to all the woderfull ASR comunity.

 

[CerealKiller]

I almost ended up buying the M4 instead of my Topping DX7s - and I kinda regret not doing it. The low power headphone out turned me off, but as it is right now I only use high sensitivity headphones anyway.

I've already seen measurements, so the review is nothing surprising, but it just reaffirms that for the price the M4/M2 are impossible to beat in audio interface realm(correct me if I'm wrong).

Also, it might just be me, but I love the industrial design of the units.

Why not take line out signal from RCAs and feed it to som budget but good HP amp line JDS Atom ? *edit* just checked motus site, rca ar +9dbu so arround 2.2volts maybe? It is not clear in documentation if line outs both RCA and TRS are fixed or variable volume, manual just says "mimic monitor conection outputs"

 

[LTig]

Preamps are pretty quiet in this unit. So how about connecting the TT cartridge to the M4 (make sure phantom is turned off) and apply RIAA in digital?

Depends on the pickup and the input impedance of M4. MC pickups work fine with 100 to 1000 Ohm input impedance, MM pickups need 47 kOhm and very low input capacitance.

Actually I tried this with my RME ADI-2 PRO fs. I connected my MC pickup (0.65 mV rated output) to the RME set to +4 dBU = 1.2V which is a factor of close to 2000 lower sensitivity (it has no internal preamp). I recorded a song, amplified it a bit in Audacity, applied a RIAA EQ and then normalized its amplitude again. You could here noise/hiss until the music started to play which masked it. I was very impressed how much the RME could extract from this tiny signal. I'm sure that with some 30-40 dB gain before the RME (or the M4) one could record any song and process it afterwards without any loss due to noise.

 

[Blumlein 88]

Preamps are pretty quiet in this unit. So how about connecting the TT cartridge to the M4 (make sure phantom is turned off) and apply RIAA in digital?

Yes that works. But it isn't the 47 kohm loading for MM cartridges. Will work better for an MC.

 

[Blumlein 88]

if someone in the US can send in a E-MU 0404 USB for review, please do - it would be nice to compare how far the industry has come in the last 15 years or so.

I believe it was sold for ~$250 originally and was considered the best in class.

I have one but I live in a different country so shipping would be pricey.

You can look at Archimago's site. That used to be what he used.

http://archimago.blogspot.com/2016/07/measurements-focusrite-forte-usb-audio.html

Here he compares the Emu 0404 to a Focusrite Forte which replaced the EMU until he purchased the RME. Measurements of both devices.

Here he compares measurements of the Forte, EMU, and RME.
http://archimago.blogspot.com/2018/09/measurements-rme-adi-2-pro-fs-adc.html

 

[Robin L]

Given the limited dynamic range and high distortion of vinyl, why use hi-res?

I record 44.1//24 bits. Makes normalizing and click removing work out better.

 

[f1shb0n3]

Worth mentioning is that the volume knobs on the Motu M2/M4 feel amazing and super-precise. I was relieved to confirm that it has a good DAC so I don't need to get something else and lose those that fine volume knob.

 

[boXem]

Worth mentioning is that the volume knobs on the Motu M2/M4 feel amazing and super-precise. I was relieved to confirm that it has a good DAC so I don't need to get something else and lose those that fine volume knob.

Super-precise is not exactly how I would define them. On my M2, lack of line out volume setup accuracy is clearly the weak point.

 

[Wmu]

You know the Scarlett gear, at least the better ones, seem to be craftily made on the edge of inaudibility. Meaning some of them are good enough you'll likely hear no difference vs better gear or it will be a tiny very slight one heard only rarely. To me that is pretty good for low cost entry level gear. They did make a couple particular versions not quite that good. But mostly Scarletts are that good.

The M2 and M4 appear to be even better and nothing wrong with a little gilding the lily. MOTU doesn't yet have anything comparably priced to the Scarlett 18i20 with 8 microphone preamps. But maybe in the near future they'll have an M8 or something like that.

Check out the 8pre-es. It's a fantastic interface. I've been using it for 6 months and it's a phenomenal value. If I recall correctly, the specs are also better than the Scarlett. We actually bought the Motu to replace an earlier Scarlett 18i20. The motu blows it away although the Scarlett was a gen 2 and their gen 3 stuff is much better, so I know it's not a fair comparison since I wasn't able to test the latest Scarlett against the Motu, but I can say I'm really happy with the Motu.