noob:question before mic purchase

[robin]

Hi all. ive literally not learned anything about REW yet.. im still designing my soundsystem ( fullrange speakers and 10 inch subs with class D amps and a minidsp2x4HD.)

i will be diving into the world of REW very shortly!

in the meantime, i have a simple question.

is it possible to run a sweep for the room from REW, and record the result on an android smartphone with this mic:

http://www.daytonaudio.com/index.php/imm-6-idevice-calibrated-measurement-microphone.html

its a lot cheaper than a Umik and has great reviews online.

if its possible to record the result on the smartphone, then transfer the recording to REW for analysis, i will purchase this mic.

seems connecting it to a pc is problematic, hence the idea to record sweep on phone.

if not, ill look at other options.

thanks all.

 

[MasterLufier]

I don't know about import measurements from another software, but I'm sure, that design and tune loudspeaker system without good mic with calibration file and minimum 2x2 channels soundcard (first for mic and second for loopback) not good idea.

 

[robin]

well that mic has a calibration file.. i also read that the calibration file is compatible with REW.. i also have a 2x2 soundcard.. The only issue is the mic is designed for use with a smartphone/ipad, and requires the power source present on the 4th "ring" of the plug, which most soundcards do not provide, however phones do.

assuming the mic is calibrated, i cannot see any technical reason why a response curve recorded on the phone would not be basically the same as the response curve recorded on the computer.. so, as long as REW lets you import a wav file or similar of the room/speaker response, it should be fine.

however being a complete noob in active speaker systems and REW in particular, maybe im missing something.

 

[John Mulcahy]

I'm just completing some work on REW to allow import of sweep recordings made using an REW-generated sweep file (see screenshots below). I don't know, however, whether that combination of mic and phone would produce accurate recordings. Might well do, but I don't have any info about that.

 

[robin]

ok looks promising, although as i said, ive literally not started my REW journey yet, so im not 100% sure what im looking at.

however, even if it does not work, i think ive found a way to wire an adapter for powering this mic and using it with a pc. so im gonna buy it.. 20 quid for a calibrated microphone instead of 100 quid.. worth a try.

 

[MasterLufier]

OK, I don't tell you, that this mic is bad, but you can't organize loopback on smartphone or tab, and codec on this device have big distortion of all measure parameters. Good soundcard and bad mic, better than good mic and bad soundcard.

 

[robin]

ok, well its pretty obvious i dont understand the process well enough!

i assumed i could use the pc with REW to play the sweep over the speakers, and record the result uncompressed on the smartphone, no loopback necessary, using this calibrated mic, before transferring the wav file of the result to PC (REW) for analysis.. if the DAC in the phone is so bad as to ruin the result maybe its not a good idea after all!

if this is not possible maybe i will purchase the Umik after all.

 

[MasterLufier]

For tune and align you components of system, you need Transfer Function. Without loopback, you does not see difference between original signal and you system. You will cannot setup crossover and other filters, so you don't see absolute impulse position.

 

[John Mulcahy]

The acoustic timing reference option can be used when loopback is not possible (e.g. with USB mics), that was the motivation for adding it.

 

[MasterLufier]

The acoustic timing reference option can be used when loopback is not possible (e.g. with USB mics), that was the motivation for adding it.

Yes, is good idea, but I did not tested it (so my company have 64x64 channel audio interface, and loopback is not a problem for me) but i think this method can have problem on large and much reverberation rooms. Or I don't understand full mechanic?

 

[John Mulcahy]

The acoustic reference could come from a nearby speaker, but even in a large room it may well be OK - the signal is restricted to the tweeter range.

 

[MasterLufier]

Thanks. I will try this technique. It's interesting.