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Need help finding a good ADC for speaker measurements

peniku8

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I'm looking for a stereo audio input device with digital gain controls for high accuracy/repeatability.
I recently bought a Topping D10b DAC as output device (118db SINAD from Amir's measurements) and I'd be very happy with a similar input device with two mic/line preamps for loudspeaker and electronics measurements.
I currently use an RME Fireface UC in my studio, but I wanna be a bit more flexible (mobile). The Fireface was also RMA'd once, which seemed to have a negative effect on its SINAD(?), so I'd like in upgrade in that regard, ideally in the range of the Topping DAC at 118db.

To sum it up: A stereo input device with mic pres and digital gain controls with a SINAD of 105db or better.

I've looked at the babyface, which looks alright, but obviously has many more features that I don't need, so I'd rather spend my money to improve the features that I do need. And I'd like to keep it under 500$, which seemed to be an impossible task while searching on my own, but maybe you guys have a good suggestion I haven't come across yet.

Edit: just in case that this product does not exist, what would be the cheapest alternative of any input device with digital mic gains? I'd bin electronics measurements for the time being and just go with a portable speaker measurement setup.
I'm using an EMX7150 btw. I also have a UMIK-2, which works great when I'm not after .5db accuracy, but I'd love to have a more accurate setup available.
 

DVDdoug

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I can't recommend an interface, but this seems like a dilemma
digital gain control...
...I also have a UMIK-2, which works great when I'm not after .5db accuracy
With variable gain you can calibrate as accurately as you like but you need something accurate to calibrate it with.
 
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peniku8

peniku8

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I can't recommend an interface, but this seems like a dilemma
With variable gain you can calibrate as accurately as you like but you need something accurate to calibrate it with.
I have an SPL calibrator, but I was talking about frequency response here. Not sure how accurate the UMIK is in that regard (especially in high frequencies, since it's larger than my isemcon, but the main problem with the UMIK is probably cable length (since it's a USB mic I can't just give it 10m of cable).
 

AnalogSteph

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Why do you need so much SINAD again?
Indeed. Dynamic range you might need, yes, but speakers in particular are so far away from the capabilities of modern electronics in terms of distortion that it's not even funny.

Digitally controllable gain typically places you in the midrange. The cheapest one I can name would be the cute little bus-powered Audient EVO 4 though, and that's actually not half-bad at all. @Julian Krause measured an input dynamic range of 115.7 dB(A) (which is actually excellent in its class), with decent enough levels of distortion of around -100 dB at 1 kHz (-1 dBFS in). FR is maybe 0.8 dB down at 20 Hz, with some of the typical AK55xx filter ripple (0.06 dB p-p) up top - it uses an AK5552. Typically for Audient, maximum sample rate is 96 kHz. None of all the possible negatives are going to concern you very much. It's not something you'd want to evaluate DAC performance with, but for throwing in the bag with a measurement mic it would be a hot contender for me. The inputs can handle +16 dBu maximum, too, so won't be clipped easily at all. You won't need super low EIN for a measurement mic but even that is at a good level (-128 dBu(A) and change).

Next more expensive is the Presonus Revelator io24, but it's Presonus, so I'm not holding out much hope for excellence there. Another Presonus, ioStation 24c, but that is a bit of a specialty thing. Spec wise I think it could be an AK4621 job... mic input dynamic range >107 dB(A) is OK, distortion <0.007% at min gain is kinda eh.

Another I might look at is a used Focusrite Forte, which at least in the 'States can often be picked up for a song. Archimago used to do his measurements with one. Spec for mic input SNR is 117 dB(A), max input level +12 dBu (plus 10 dB pad), gain range 0-75 dB, EIN -128 dBu. ADC AK5388 and DAC AK4413, apparently, so among the fancier 4-channel jobs you could get at the time. Gets somewhat toasty. The drivers have not been updated in forever (2012 or something), so perhaps they had some issues with this model. Mine will start to "hiccup" and reset after a while when just operated on bus power, while with its external power supply connected it's fine, so probably some sort of bad solder joint(s) somewhere. With the breakout cable and power supply it's a bit more cumbersome than the EVO 4 would be, but still portable I guess (more something for the desk).

Other than that, it's hard not to end up at least near the Babyface Pro price range... e.g. Arturia Audiofuse, Apogee Duet, both $599, so already past the limit and perhaps both a bit fancier than what you need, too. (On this side of the pond all three can be had for the same, so the RME is a better deal here.)

On a side note, this thread would have belonged here.
 
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abdo123

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Indeed. Dynamic range you might need, yes, but speakers in particular are so far away from the capabilities of modern electronics in terms of distortion that it's not even funny.

I don't even understand the need of Dynamic range. Aren't speakers measured at 2.83V?

The only reason i can think of is if you're testing some damping agents or meta-materials for a future speaker design. And even then, if you had to dig so deep for distortion / resonances does it even matter anymore?
 
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peniku8

peniku8

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Why do you need so much SINAD again?
two mic/line preamps for loudspeaker and electronics measurements
I measure amplifiers and other devices sometimes, so it would be nice to have a very clean input device with a SINAD similar to the Topping's, but that's not a must for now, which is why I've only mentioned speaker measurements in the title. I'm aware that even mediocre audio interfaces perform an order of magnitude better than even the best speakers in most cases.

@AnalogSteph thank you for the excellent suggestions, the EVO4 looks brilliant, especially at that price point! There seems to be a gap in the market, where we have nothing in the lower-mid price range. I've been looking at the Babyface, Duet and even the Twin X, but they all come with so many features which I don't need and they still don't quite deliver the performance I'd be hoping for to take reliable DAC&Amp measurements (for what they cost), which makes it easier to settle on a cheap alternative for speaker measurements only.
I've been browsing Thomann, but somehow missed the EVO. Maybe I filtered for 192khz interfaces, which I don't really need for speaker measurements, so 96k is just fine. It is indeed a strong contender for my use case, I will definitely put it on my list!
 
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