Motu 8A Measurements

[Blumlein 88]

Considered yes, but from memory the Motu offered best performance on paper, was the right price and readily locally available. Luckily my "punt" payed off and its performance is excellent.

I think @Blumlein 88 has some of those interfaces he may be able to test in detail.

Yes I have three interfaces. I've posted some measures of a Focusrite 18i20 here.
https://audiosciencereview.com/forum/index.php?threads/focusrite-18i20-dac-measurements.2128/

Mine is a gen 1 unit, gen 2 units are similar using same chipsets only they work at 192 khz instead of only 96 khz.

I also have an Antelope Zen Tour and Focusrite Forte. The Forte is mainly the ADC/DAC chips and circuitry that is in the Focusrite Clarrett series. Both of those have better measured performance than the 18i20. In time I can post some measures of the other interfaces. I think if people were aware that generally prosumer or pro audio gear performs closer to spec than lots of consumer gear there would be wider use of it by audiophiles. The main thing lacking is remote control. Though many newer interfaces allow remote control via phone apps.

 

[March Audio]

I would be really interested in seeing these measurements.

 

[VanNeumann]

Yes I have three interfaces. I've posted some measures of a Focusrite 18i20 here.
https://audiosciencereview.com/forum/index.php?threads/focusrite-18i20-dac-measurements.2128/

Mine is a gen 1 unit, gen 2 units are similar using same chipsets only they work at 192 khz instead of only 96 khz.

I also have an Antelope Zen Tour and Focusrite Forte. The Forte is mainly the ADC/DAC chips and circuitry that is in the Focusrite Clarrett series. Both of those have better measured performance than the 18i20. In time I can post some measures of the other interfaces. I think if people were aware that generally prosumer or pro audio gear performs closer to spec than lots of consumer gear there would be wider use of it by audiophiles. The main thing lacking is remote control. Though many newer interfaces allow remote control via phone apps.

I too would like to see those measurements and how you setup you system with these other pro interfaces. I agree with you that the specs I have seen with Focusrite, Apogee, RME, Antelope, etc look very good and price/performance is among the best. Thanks.

 

[Sylex]

The MOTU 8A was a little out of my price range for a DAC so I picked up a MOTU Ultralite mk4. The bonus was this had 10 balanced outputs. I didn't noticed until it arrived that they are now putting the ESS Saber32 Ultra in these like the 8A. I opened the case up and it looks like it is using two ES9016S chips. One for the 8 line outs and one for the monitors outs.

 

[March Audio]

Now that's interesting. As you mention they have appear to have upgraded the Dac to the same as the 8A, however the paper spec states with the ultralite they have improved the thd + noise by 2dB over the 8A to 112 dB.

This now looks like the perfect interface for my dsp speakers. I actually need 10 channels to run the L, R subs and centre speaker. The centre is currently running off my AVR with a passive XO.

The ultralite A to D is not as good, but I'm not so concerned about that as it won't be used if I go fully dsp for the centre as well as L R.

I feel a purchase coming on........

Anyone want to buy an 8A?

 

[Blumlein 88]

Now that's interesting. As you mention they have appear to have upgraded the Dac to the same as the 8A, however the paper spec states with the ultralite they have improved the thd + noise by 2dB over the 8A to 112 dB.

This now looks like the perfect interface for my dsp speakers. I actually need 10 channels to run the L, R subs and centre speaker. The centre is currently running off my AVR with a passive XO.

The ultralite A to D is not as good, but I'm not so concerned about that as it won't be used if I go fully dsp for the centre as well as L R.

I feel a purchase coming on........

Anyone want to buy an 8A?

Don't tempt me. I have more interfaces than I need, but I liked that Motu. The one your considering looks good too. Seems like it should have had USB 3 however.

 

[March Audio]

Well if you are tempted Im sure we can come to a very agreeable arrangement

The Ultralite solves my 10 channel requirement very conveniently so I am going to go ahead with it. I think USB2 is probably a sensible cost saving measure, you don't really require usb 3 for this many channels

 

[jtwrace]

I have an 8A too that I'll probably be selling.

 

[March Audio]

Some updated 8A measurements with new Virtins Multi Instrument Pro Software.

Shows the performance of the 8A to be right up there. @amirm Can you add this into your database?

IMD well....


SINAD is in between Benchmark and Auralic at 112dB.

IMD

 

[ofrappier]

Hi,

Just received my MOTU 8A today.

The routing software is very good, and the sound..... good, very better than the internal DAC of my DDJ-1000.

I use now the motu 8A to drive my active speakers and subwoofer

 

[badboygolf16v]

You sure get a lot for your money: hardware, routing/mixing software and mobile control app. Looks like a great product.

 

[pos]

@BE718, thank you for these measurements!
I am considering buying a motu 24 Ao (same dacs as the 8A) for a similar purpose as yours (active crossover) on a dedicated linux machine (its is class compliant and reported to work!).
As I will be using fragile compression drivers I would like to be sure it is a reliable device.
Did you ever encounter problems or instabilities with your motu (on sampling frequency change, etc.), or pop/noises (even faint ones) when pluging/unpluging the device, or turning it on or off with the button or the power plug?...

As a follow-up, I have been testing a 24Ao today, and I must say I am a bit disappointed so far:

1. there is a turnoff noise with DC energy (meaning I cannot connect a compression driver directly, without a protection cap)
2. there are distinct noises on the outputs, not random (computer-like noises if you see what I mean) and quite audible at 2m with a 100dB/2.83V@1m woofer and a 26dB gain amplifier
3. these noises tend to reduce when audio is played, albeit I could not find a clear step: it seems to go and then come back.
4. these noises remain when no USB or ethernet cable is plugged.
5. changing sampling frequency takes a few seconds, even with the last firmware (probably due to the internal DSP processing re calibrating for the new sampling frequency)
6. the output trim settings are not really useful as they are done inside the DAC, meaning the 123dB(A) DNR becomes 111dB(A) when targeting a 8dBu max output level. Needless to say noises of points 1, 2, 3, 4 are not reduced by these trims.

I wonder if this particular unit might be faulty, but all output present the same noises, at any sampling frequency.
I also wonder if the motu 8A has the same issues (point 1, 2, 3, 4).

At this point I am not very interested in testing this unit further (linux configuration, toslink input, etc.)...

 

[March Audio]

Hi

Not my experience with the 8A, the switch off noise is a very minor click. My speakers aren't as sensetive, about 90bB, but same gain on the power amp and there is no significant noise. I can just get a bit of hiss if I shove the tweeter in my ear.

Maybe the 24 has a fundamentally different design around the dacs?

 

[pos]

In response to this discussion in another thead, I am posting a recording of the aforementioned noises, recorded with an iphone inside the horn of a JBL M2.
This is a 32 ohms compression driver with a 9dB lpad, connected to an unattenuated 26dB gain amplifier (hypex nc400, which has approx 25uV of residual noise). Balanced cables between the motu and amplifier (tried both the DB25 and phoenix outputs).

https://www.dropbox.com/s/b19h64uwabzmay7/motu 24Ao.m4a?dl=1

The noise stops when the motu is syncing to a different clock, and then comes back and varies depending on the signal, or with what look like internal events inside the unit.

 

[hiddentunnel]

In response to this discussion in another thead, I am posting a recording of the aforementioned noises, recorded with an iphone inside the horn of a JBL M2.
This is a 32 ohms compression driver with a 9dB lpad, connected to an unattenuated 26dB gain amplifier (hypex nc400, which has approx 25uV of residual noise). Balanced cables between the motu and amplifier (tried both the DB25 and phoenix outputs).

https://www.dropbox.com/s/b19h64uwabzmay7/motu 24Ao.m4a?dl=1

The noise stops when the motu is syncing to a different clock, and then comes back and varies depending on the signal, or with what look like internal events inside the unit.

Hmmm... yeah, I definitely do not have that noise present with mine... I just ran two of the outputs direct into my AD converter and turned up the gain plenty. All I have is a raising noise floor and a low frequency hum if turn the gain WAY up... no fluttering (although I do have a similar sound that my console sometimes picks up, but this is not due to the 24ao). Maybe a dysfunctional unit? Do all the channels do that?

 

[pos]

I have not tested all the channels, but several, and the situation is identical. I might be able to test another unit, I will keep this thread updated.

 

[hiddentunnel]

I have not tested all the channels, but several, and the situation is identical. I might be able to test another unit, I will keep this thread updated.

Sounds good! let me know if you would like me to post any loops of the noise on mine

 

[RayDunzl]

I am posting a recording of the aforementioned noises, recorded with an iphone inside the horn of a JBL M2.

Played back at about 15% normal speed it sounds a lot like this...

 

[JustIntonation]

IMD

View attachment 14343

This looks fantastic. Are you sure this is comparable to Amir's measurements? It almost looks too good to be true, below -10 to -15 it beats everything else tested?
Btw, what's the MOTU UltraLite mk4 AKM measurement? AKM seems to refer to an AKM DAC but the UltraLite mk4 is a Sabre DAC, I'm confused
(edit: Aah I see now there was an UltraLite mk4 before the Sabre version with AKM DACs? Reading an older manual now which says -101dB THD+N for the line outputs.)

One other thing that looks very handy is that the 8A and the UltraLite mk4 have a trim on their output. Quote from the manual:
"Analog trims All quarter-inch analog inputs and outputs can be trimmed. This allows them to support a variety of standards, including EBU-R68, SMPTE RP-155, +4dBu, -10dBV, 2vRMS, 1vRMS. The 8A’s quarter-inch analog inputs are equipped with high-quality, digitally controlled analog trim that provides a range from -96 to +22 dB in 1dB steps. Quarter-inch outputs can be trimmed in the DAC itself. Range is 24 dB. The headphone output provides full trim range from 0 dB to -∞ (-127). Trim controls are most easily accessed in the web app. See “Device tab” on page 12. Trim settings can also be accessed in the LCD menu. "
Since the default output is quite high, +20dBU which is about 7.75 Volt RMS this means that if we lower the digital signal we'll eat into these great specs. With the trim control it can be lowered (per individual output) in 1dB steps up untill -4dBU which is about 0.49 Volt RMS.
I was wondering if the trim control eats away at the specs as well or if it functions similar to an analogue attenuator (I suspect the first, that it is done through the ESS digital volume control of the chip itself?)

And one last quote from the manual to be aware of regarding connecting unbalanced cables perhaps worth mentioning here:
"Quarter-inch analog outputs are not cross-coupled. Therefore, when connecting them to an unbalanced input, use a TRS plug with the ring disconnected. Not floating the negative terminal will short it to the sleeve ground and cause distortion. "

 

[JustIntonation]

Now that's interesting. As you mention they have appear to have upgraded the Dac to the same as the 8A, however the paper spec states with the ultralite they have improved the thd + noise by 2dB over the 8A to 112 dB.

It may be that the 112dB spec of the UltraLite mk4 is of the stereo monitor outs where one ES9016S chip is used while the 8 line outputs have another single ES9018S chip to cover all 8 outputs.
Not expecting better performance from the Ultralite mk4 for the line outputs, just hoping they measure the same as the 8A but at a lower cost