Motu M4 Audio Interface Review

[somebodyelse]

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?

It's unlikely to destroy the device - there's an expectation that someone will plug in an unbalanced TS connector - but it will often lead to increased distortion on the output while it's connected that way. Connecting headphones directly to line outputs just won't work well because the line outputs aren't designed to drive a low impedance load like headphones. Distortion will go up, and there will probably be variations in frequency response as the headphone impedance varies with frequency, interacting with the relatively high output impedance of the line outputs. You would be much better plugging the 371s into the headphone output, or getting a headphone amp to put between the 3&4 line outs and the headphones.

 

[okMX]

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.

It's unlikely to destroy the device - there's an expectation that someone will plug in an unbalanced TS connector - but it will often lead to increased distortion on the output while it's connected that way. Connecting headphones directly to line outputs just won't work well because the line outputs aren't designed to drive a low impedance load like headphones. Distortion will go up, and there will probably be variations in frequency response as the headphone impedance varies with frequency, interacting with the relatively high output impedance of the line outputs. You would be much better plugging the 371s into the headphone output, or getting a headphone amp to put between the 3&4 line outs and the headphones.

Thanks, I appreciate your explanations.

That's great to know, so if somebody uses a hard to drive headphone and buys a balanced HPA he can have a fully balanced DAC and HPA combo with the M4, which can be pretty neat.
Last question, regarding the RCA Out with adapter (without using a HPA) vs. Headphone Out:
- I'm using the AKG 371 which is (I think) pretty easy to drive
- how big would be the differences in max. volume?
- most important: is there a difference in audio quality, besides the volume, can I expect that one output sounds better than the other one?

 

[somebodyelse]

https://www.audiosciencereview.com/.../akg-k371-review-closed-back-headphone.19657/
The impedance is flatter than I expected, so there shouldn't be much frequency response variation. At 35-39R it's low though - line outputs are typically expected to drive impedances >100 times higher, and distort significantly more when used with low impedances like this. Power will be limited by how much current they can deliver into this load. As it's not an expected use case we haven't got measurements for either power output or distortion, so it's guesswork. Someone more familiar with the opamps used in the line output might be able to give a more informed guess. They are sensitive though, so perhaps you'll get away with it. Check whether the outputs are fixed or variable before you try it though - I have in the back of my mind that 1&2 have a volume control but 3&4 are fixed, but I could be thinking of a different interface.

 

[Grooved]

Last question, regarding the RCA Out with adapter (without using a HPA) vs. Headphone Out:
- I'm using the AKG 371 which is (I think) pretty easy to drive...

I have several headphones and DAC, and for example, I can't push the full volume on the headphones output of my Tone2 Pro with this K371, even if this DAC has a top power among "mobile DAC/headphones amp" but not among "desktop DAC/headphones amp", so I'm a bit surprise that you need to use it on a more powerful output

 

[okMX]

Check whether the outputs are fixed or variable before you try it though - I have in the back of my mind that 1&2 have a volume control but 3&4 are fixed, but I could be thinking of a different interface.

I think you were right, I wasn't able to output Windows sound on the output 3&4, so I don't know about the volume control. But my idea doesn't seem to work out. Still thanks.

I'm a bit surprise that you need to use it on a more powerful output

I don't need a more powerful output, I just wanted to map it on 3&4 to load automatically my Equalizer APO settings. But it's okay, I will find another solution for that.

Cheers

 

[Evgeniy]

Anyone tested, Motu M4 version 2 (with new USB chip) works with Android USB audio recorder pro ?

 

[Tks]

Anyone tested, Motu M4 version 2 (with new USB chip) works with Android USB audio recorder pro ?

There's a V2?

 

[sharpty]

There's a V2?

@hira posted about it a few pages back, #386

 

[Saikou]

These new internals look very similar to the internals inside the MOTU Ultralite Mk5 as seen in this video by Julian Krause

 

[Buckster]

Managed to order one finally - and thanks to ebay was discounted too

Arrives tomorrow be interested if v1 or v2

 

[xaviescacs]

I've bought a Behringer 204 and always regret a bit not having saved a little money for this one.

 

[Buckster]

I bought an Amazon warehouse SSL2+ first but unfortunately it seemed to have a fault so had to go back

M4 arrived today - seems to be a v2 according to Firmware reported by Motu driver

says Firmware version 2.00

sounds fantastic so far - quick question ref levels though please. I set my JBL 305 MKIs to +4 - volume at 9/10 (one click off max), and I'm using Monoprice TRS to XLR cables - which as far as I aware are balanced

I need a lot of gain on the Motu to get decent volume out - reasonable volume seems to be just above 12 o'clock and to start sounding loud needs +2 or more

this is in my DAW (Bitwig) or in Windows with volume set to max

which is fine just feel like I'm overdriving voltages somewhere - should I have set the JBLs to -10 please ?

many thanks

 

[phoenixsong]

I bought an Amazon warehouse SSL2+ first but unfortunately it seemed to have a fault so had to go back

M4 arrived today - seems to be a v2 according to Firmware reported by Motu driver

says Firmware version 2.00

sounds fantastic so far - quick question ref levels though please. I set my JBL 305 MKIs to +4 - volume at 9/10 (one click off max), and I'm using Monoprice TRS to XLR cables - which as far as I aware are balanced

I need a lot of gain on the Motu to get decent volume out - reasonable volume seems to be just above 12 o'clock and to start sounding loud needs +2 or more

this is in my DAW (Bitwig) or in Windows with volume set to max

which is fine just feel like I'm overdriving voltages somewhere - should I have set the JBLs to -10 please ?

many thanks

That is strange, the LSR30Xs that I have get crazy loud through even the unbalanced DACs I had in the past. I'm now using a Motu M2. What is the signal level that you are sending into your M4 through your pc?

 

[Blumlein 88]

I bought an Amazon warehouse SSL2+ first but unfortunately it seemed to have a fault so had to go back

M4 arrived today - seems to be a v2 according to Firmware reported by Motu driver

says Firmware version 2.00

sounds fantastic so far - quick question ref levels though please. I set my JBL 305 MKIs to +4 - volume at 9/10 (one click off max), and I'm using Monoprice TRS to XLR cables - which as far as I aware are balanced

I need a lot of gain on the Motu to get decent volume out - reasonable volume seems to be just above 12 o'clock and to start sounding loud needs +2 or more

this is in my DAW (Bitwig) or in Windows with volume set to max

which is fine just feel like I'm overdriving voltages somewhere - should I have set the JBLs to -10 please ?

many thanks

The -10 dbV setting will gain you about 12 db overall. So yes, switch to it.
That said, I would have expected the Motu to drive it as loud as you could wish on the other setting. The LSR does have a max input of about 8 volts that way so maybe the Motu doesn't quite reach that.

 

[Buckster]

Thanks very much for the replies - signal level from PC is max (in Windows desktop) and when using Bitwig well whatever gain for the track

I'll try -10 thankyou - 8 volts for max SPL does seem quite a lot for the JBLs - just to clarify I had plenty of volume just dial was way higher than I'd have expected. I'll experiment more

Overall very impressed with the MOTU sounds great

 

[sharpty]

just to clarify I had plenty of volume just dial was way higher than I'd have expected. I'll experiment more

Nothing wrong with using the full range of the dial, I'm not sure why you would want to, or expect to use 1/2 the range to begin with. Arguably it's better to keep the level higher at the source, than to add more gain (or less attenuation?) at the speaker.

I know it's not a direct comparison to working in a DAW with unprocessed tracks, but for playback thru Spotify etc. my LSR 305's are set to +4dBu and 7/10 on the rear volume control, I have a -4dB pad set using EQ APO (to avoid Windows CAudioLimiter), and I can easily drive the JBLs to audible distortion without maxing out the knob on the M4. Usually I have the M4 at 12-1 o'clock for near-field playback, but at 3 o'clock it's enough to fill my (relatively small) room.

Based on the manuals, the M4 should be capable of overdriving the input of the 305's when set to -10dBv, so I'd leave it at +4dBu unless you actually run out of range on the M4 dial for some reason. Just my 2c.

 

[Alchemist_]

Please tell me how the "INPUT MONITOR MIX" knob works.
1 If direct monitoring is off (MON button NOT on) does the "INPUT MONITOR MIX" knob adjust the volume balance between the inputs and USB?
2 If direct monitoring is on (MON button pressed), does the "INPUT MONITOR MIX" knob adjust the volume balance between the inputs and USB?

 

[phoenixsong]

Please tell me how the "INPUT MONITOR MIX" knob works.
1 If direct monitoring is off (MON button NOT on) does the "INPUT MONITOR MIX" knob adjust the volume balance between the inputs and USB?
2 If direct monitoring is on (MON button pressed), does the "INPUT MONITOR MIX" knob adjust the volume balance between the inputs and USB?

I don't think direct monitoring affects the sound or control of sound in any way

 

[Alchemist_]

I don't think direct monitoring affects the sound or control of sound in any way

They say. that the Input/Playback control only works if the MON button is enabled. A strange Motu solution in my opinion.

 

[Buckster]

Nothing wrong with using the full range of the dial, I'm not sure why you would want to, or expect to use 1/2 the range to begin with. Arguably it's better to keep the level higher at the source, than to add more gain (or less attenuation?) at the speaker.

I know it's not a direct comparison to working in a DAW with unprocessed tracks, but for playback thru Spotify etc. my LSR 305's are set to +4dBu and 7/10 on the rear volume control, I have a -4dB pad set using EQ APO (to avoid Windows CAudioLimiter), and I can easily drive the JBLs to audible distortion without maxing out the knob on the M4. Usually I have the M4 at 12-1 o'clock for near-field playback, but at 3 o'clock it's enough to fill my (relatively small) room.

Based on the manuals, the M4 should be capable of overdriving the input of the 305's when set to -10dBv, so I'd leave it at +4dBu unless you actually run out of range on the M4 dial for some reason. Just my 2c.

thankyou - makes sense - I've left at +4dB and am using the full range of the dial