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Motu M4 Audio Interface Review

retroflex

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Quite curious - which graph or statement shows this? Always been confused on the gain level you should set for DACs or other upstream equipment.
You can see it on the plot with description "Unfortunately the IMD test relative to level [...]". The line for the Motu M4 keeps going down; compare that to the Razer Adapter line which has a lowest spot at around -15 dBFS (decibels relative to the full output scale). The plot only shows intermodulation distortion, but one would expect other kinds of distortion and SINAD to follow the same trend.

When Amir says the nominal voltage output is 5.2V - is that at the max volume? Since the SINAD tests run at output = 5.2V we should expect full volume doesn’t do any distortion.
He says that 5.2 V(rms) is more than the nominal balanced output of a DAC, which he considers to be 4 V(rms) if I'm not mistaken (I don't know if there is any official standard here). The review doesn't say that this is the maximum output, but I'm pretty sure it is. It's certainly a bit confusing that the manual claims that the maximum output is lower than this.

I read the manual but didn’t understand dBu to volts conversion. Seems like standard thing in audio to represent volts in dBu?
Just saying "volts" doesn't mean much when talking about an audio signal, since it's not clear if you're talking about peak voltage, peak-to-peak voltage, root-mean-square voltage, or something else. Similarly, talking about "decibels" on its own is meaningless, a decibel is always relative to some absolute quantity. Combine those two factors, and throw in some history, and you get the absolute mess that is the various types of decibel units used to describe sound.
 

robertzsun

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Thanks for the great info! I come from an EE background and it’s been tough to reconcile the audio terminology and techniques to classic analog design or signal processing - just have some stupid burning questions that are relatively bizarre.
 

CtheArgie

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I am sorry if I missed this but: If I want to connect an unbalanced RCA to the line input of a M4, which is the correct adaptor to use?
1. Female RCA-Male TS.
2. Female RCA-Male TRS.
3. Female RCA-XLR.
Thanks....
 

Lambda

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1. Female RCA-Male TS.
yes. this.

Just saying "volts" doesn't mean much when talking about an audio signal, since it's not clear if you're talking about peak voltage, peak-to-peak voltage, root-mean-square voltage,
root-mean-square voltage is actually equally unclear if you don't define the waveform at the same time.
 

Cadence

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The M2 / M4 were released in 2019. Could Motu release entirely new models of these entry-level interfaces, or do the new revisions practically exclude such a possibility?
 

Trell

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The M2 / M4 were released in 2019. Could Motu release entirely new models of these entry-level interfaces, or do the new revisions practically exclude such a possibility?

I would say unlikely, at least for the short term.
 

phoenixsong

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Probably depends on how much they are affected by the releases of the Arturia Minifuse, Universal Audio Volt and Audient id14Mkii interfaces since then
 

mightycicadalord

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Oh man, that audient id14mkii looks like a killer deal, is anyone else doing adat pre expansion for $300?

The volt, minifuse, and audient don't have real meters though, I don't think I can go back to having crappy segment LED metering.
 
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