Would you try testing the ADC performance with lower input level? -6db -9db something like that?
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Motu 624 Audio Interface Review
- Thread starter amirm
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OP
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That is in the IMD versus level graph.
Well, my personal interest in measuring gear is about that kind of device.No to all. I have the thing packed to send back. Speak if you must have those measurements and if so, please be specific.
Mic preamps, for sure, are of interest.
At least as much as line in.
Ideally, you want to simulate a 1mV 50 ohm microphone, with enough gain to reach near 0dBFS, and see what happens, in terms of noise, distortion, bandwidth, frequency response, linearity, max level, max and min gain.
Some interface have different ADC/DAC chips for different inputs/outputs. Some are performing better on mic preamp than on line.
I'm trying to do that myself.
As for headphone outs, the power is the most important, at various impedance.
I tried to use a closed-back 35 ohm Focal Elegia on a Yamaha digital mixer during a live event recently, and the level was not enough.
Had to use the RME ADI-2 Pro for that instead.
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Hi
My first interface like this was a Motu 828mkIII (first, firewire only, edition)
The problem to use the 828mkIII as a DAC is lack of automatic frequency switching.
If, say, you want to feed it with a streamer from Tidal or Qobuz, you'd end up changing the frequency manually on the interface between each track/ album.
I don't know if that's the case with this USB one, but that was a show stopper for that kind of use for me.
By the way, I also have a pair of 2408mkIII.
That was kind of SOTA back in time... in 2002/2003
I guess any trim output is purely digital, and it probably makes no difference where you set it.
Mic input front-panel Gain setting is most likely different though.
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Blumlein 88
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I can't say how it will work universally. With USB over ASIO when the playback software can use ASIO it should switch sample rate to match the playback software. Obviously this is with Windows. With Mac I think it will also switch over USB with most playback software.
Blumlein 88
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If you puzzle through the big users guide I linked up thread it has most of the info to figure out the answer to this question.
Did you try it with one of those interfaces?
I don't remember what the problem was exactly.
With syncing to external clock, this should work, but I remember there was a problem.
Probably I was using 2 different digital sources at that time?
I will remove the dust from the 828 and give it a try.
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+1 for the Mic measurement.
Blumlein 88
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Not with a Motu no. With other brands with ASIO yes. It does with some playback software, and not with others.
Strange, but there is no block diagram in the manual.
At least none where the mic gain is shown.
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I might give it a shot today... See if I can get something happening and see what the questions are. These are very capable boxes as you say.
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Interesting. What HT setup do you have in mind? I was thinking about the same, but couln't find a processor with at least 20 digital outs that does Auro 3D, DTS and Atmos.
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Thanks for the review.
Anyone looking to use one of these with linux should research the state of compatibility. I hope things have improved since I last checked. I'm assuming they're using a common interface on all their AVB products since the Ultralite and 8A seem to have similar problems.
MOTU publish the API for controlling their AVB interfaces over the network, so making a custom control interface should be pretty easy (kids at a code club level). Think linking volume on 6 channels of an active crossover for instance. Use this with an ESP32 and a shaft encoder and you can have a wifi remote with an actual volume knob.
Anyone looking to use one of these with linux should research the state of compatibility. I hope things have improved since I last checked. I'm assuming they're using a common interface on all their AVB products since the Ultralite and 8A seem to have similar problems.
MOTU publish the API for controlling their AVB interfaces over the network, so making a custom control interface should be pretty easy (kids at a code club level). Think linking volume on 6 channels of an active crossover for instance. Use this with an ESP32 and a shaft encoder and you can have a wifi remote with an actual volume knob.
Just to illlustrate somehow what I expect from Microphone input test:
Typical dynamic microphone output level is around 1mV/Pa at 50-150ohm (94dB SPL)
(Shure SM 58 or Audix OM 7)
So, first difficulty (to me, not to somebody owning an AudioPrecision device, I guess) is to have a test signal at around 1mV that is good enough for measurements.
If we go directly out of the DAC at +4dBu range, we have to dial down by 62dB
Remaining SINAD we can measure in loopback on the RME ADI-2 Pro fs is 53dB
Things become a bit better if I insert a Radial JDI Duplex DI mark 4 in the loop.
This DI is using Jensen transformers (I opened it to make sure).
The Radial allows XLR inputs, and that's how I use it.
We have still to dial down signal, but by 23dB or so. The rest is done by the DI
We have 58dB SINAD now.
Note that the output impedance of the DI is also much more in line with a Microphone output.
To improve things on the ADC side, we can average both inputs (possible with last firmware of RME ADI-2 Pro fs)
We reach 61dB SINAD for the loopback
That means that the limiting factor is the ADC, indeed.
What if we insert an old MacKie 1402 VLZ as a Preamp (Mic input, max gain, to insert out) ?
We see that the MacKie, beside its venerable age (1998!), is still going strong:
That's 74dB SINAD, or 13dB SINAD improvement
Again, the ADC is obviously the limiting factor at such low levels.
(If you don't average the 2 inputs, you get around 71dB SINAD)
And how does perform a true professional Preamp interface ?
Here one of the most used worldwide, Yamaha AD8HR, at max gain.
(There is a pretty good chance that the live CD you're listening to was recorded using those.)
The AD8HR includes its own ADC, so that's what we use as input.
SINAD is going down to 65dB.
That's an old interface now (2004?), so the ADC is not to today's standards.
But, still, beside this figure, this is a pretty good interface.
Remember, we are at 1mV.
All this is using some tricks to get a good-enough test signal.
Using an Audio Precision, I guess that would be easier.
Typical dynamic microphone output level is around 1mV/Pa at 50-150ohm (94dB SPL)
(Shure SM 58 or Audix OM 7)
So, first difficulty (to me, not to somebody owning an AudioPrecision device, I guess) is to have a test signal at around 1mV that is good enough for measurements.
If we go directly out of the DAC at +4dBu range, we have to dial down by 62dB
Remaining SINAD we can measure in loopback on the RME ADI-2 Pro fs is 53dB
Things become a bit better if I insert a Radial JDI Duplex DI mark 4 in the loop.
This DI is using Jensen transformers (I opened it to make sure).
The Radial allows XLR inputs, and that's how I use it.
We have still to dial down signal, but by 23dB or so. The rest is done by the DI
We have 58dB SINAD now.
Note that the output impedance of the DI is also much more in line with a Microphone output.
To improve things on the ADC side, we can average both inputs (possible with last firmware of RME ADI-2 Pro fs)
We reach 61dB SINAD for the loopback
That means that the limiting factor is the ADC, indeed.
What if we insert an old MacKie 1402 VLZ as a Preamp (Mic input, max gain, to insert out) ?
We see that the MacKie, beside its venerable age (1998!), is still going strong:
That's 74dB SINAD, or 13dB SINAD improvement
Again, the ADC is obviously the limiting factor at such low levels.
(If you don't average the 2 inputs, you get around 71dB SINAD)
And how does perform a true professional Preamp interface ?
Here one of the most used worldwide, Yamaha AD8HR, at max gain.
(There is a pretty good chance that the live CD you're listening to was recorded using those.)
The AD8HR includes its own ADC, so that's what we use as input.
SINAD is going down to 65dB.
That's an old interface now (2004?), so the ADC is not to today's standards.
But, still, beside this figure, this is a pretty good interface.
Remember, we are at 1mV.
All this is using some tricks to get a good-enough test signal.
Using an Audio Precision, I guess that would be easier.
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I'm thinking the same... Speakers everywhere...
It looks like these can be chained to give you complete control of up to dozens of channels in a mix/match in terms of analog/digital outs.
To do all that, it may need to be run through its pcie card (424?) and all components connected through firewire. That's not a big deal, but I want to see what it might be capable of through USB first.
Ideally I would run the output through the minidsp ddrc 88d. I know you can run two of them together for 16 channels...not sure if there's a limit, but that gives me Dirac because, why not...
Want to get 8 channels up and humming first, then figure out how to go from there...
Gotta find the cuemix software, and start getting further into the manual...
Added for completion:
Same test, with my old (<2008) Motu 828 Mk III (Firewire-only edition)
Mic input to SPDIF out, Max gain -5dB (above that, ADC is overloaded)
That's 6dB better than the Yamaha AD8HR, and about equal to MacKie + RME (without averaging the 2 inputs, of course)
Note: at that input level. I measured with higher level signal and the Yamaha is able to perform significantly better than the MOTU.
(We probably reach the limit of our test signal here, again.)
Same test, with my old (<2008) Motu 828 Mk III (Firewire-only edition)
Mic input to SPDIF out, Max gain -5dB (above that, ADC is overloaded)
That's 6dB better than the Yamaha AD8HR, and about equal to MacKie + RME (without averaging the 2 inputs, of course)
Note: at that input level. I measured with higher level signal and the Yamaha is able to perform significantly better than the MOTU.
(We probably reach the limit of our test signal here, again.)
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While testing mic preamps would be nice for those that use them, this is primarily a consumer site AFAIK so adding that may be a stretch. It is another interface to test and for really useful measurements requires a number of tests.
It would be nice to keep track of headphone output performance since it is relevant and is shown for a number of other devices. Not sure I'd unpack it to retest, but my thoughts for the future.
IMO - Don
It would be nice to keep track of headphone output performance since it is relevant and is shown for a number of other devices. Not sure I'd unpack it to retest, but my thoughts for the future.
IMO - Don
That's a fair point...
But how many here are also playing music and recording home?
I don't say we should start reviewing true pro devices (as for any pro tools, there are other factors than raw sound quality involved. Reliability, pro-world acceptance and integration come to mind), but testing this kind of amateur or semi-pro interface, including mic input, make sense to me.
A subset of tests (SINAD vs gain?) is probably enough to assess mic input quality, on top of the standard.
And there is enough of a market for those to lead to serious impact on price/quality, also for lambda consumer.
See the number of decent performing interfaces for a low price. Aren't they better options than Audiophooley DACs ?
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AndrewDavis
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I don't know how to read an ASR review to think without a panther to start me off
