Which Mic & Set Up

[MickC]

Hi
I'm new to REW but I'm using it to understand the response in my home studio, with a view to adding treatment

I'm on a 2015 MacBook Pro, El Capitan with a Focusrite Clarett 8Pre audio interface, connected by Thunderbolt. The DAW I use is Studio One 3. Can you help with two questions please to get me up and running?

1) What measurement mic is recommended? I'd prefer to buy one with XLR as it could come in handy for recording purpose too. Behringer's ECM8000, Dayton Audio EMM-6 and the dbx RTA-M are all within my budget, and the comparisons done by Realtraps suggest they'd be as good as the much more expensive top end mics anyway (http://realtraps.com/art_microphones.htm), but is there any advantage for using one over the other with REW (for example, ease of calibration etc), or other more suitable mics I should look at?

2) Setting up the signal chain - I've see info about using line outs from the audio interface to connect back to the computer, but presumably the set up I have already (via Thunderbolt) makes that unnecessary? Where can I learn more about how to configure and set up according to the type of equipment I have?

Thanks for all your help!

Mick

 

[EarlK]

You may have limited choices when running a multi-input soundcard on a newer Mac OS.

I suspect ( if I correctly remember the contents of a recent Mac thread on INPUT FAILURE ) that your only real choice is a USB based mic ( when using a Mac-based SoundCard having more than 8 inputs ).

- Even with a USB type mic, you may still need to use your Macs on-board soundcard for output.

- Apparently, there's a compatibility problem between JavaMac ( the software engine that REW is built upon ) and the newer Mac OS's ( since I'm on a PC, I didn't 100% log the details into memory about this failure in Mac land ).

The UMIK-1 ( USB mic from dspAudio ) is quite popular, affordable and very usable ( & includes a calibration file ) .

OTOH, one can always buy a simple 2-chnl USB soundcard ( with mic pre-amps sporting XLR inputs ) and then use the test mic of your choice.



PS; See this thread!

 

[Matthew J Poes]

You may want to check a cross-spectrum calibrated mic. They send a calibration files for their mic against a Aso Pacific NIST traceable measurement mic designed for direct field use. You get both a 0 and 90 degree file.

The differences in mics isn't massive. The better mics have better high frequency performance. For acoustic measurement it isn't a huge issue.

I would stay away from the Behringer mics. A slew of bad mics has caused a number of folks to lose faith in their QC. With Cross-spectrum you are guaranteed a good mic. Consider it a next level of QC plus a calibration file. They sell calibrated Dayton and umiks. They have both the xlr and USB version.

The biggest problem with the USB mics is noise. Still you can get a noise floor measurement down into the 30-40 db range for most of the area that matters for acoustics as long as you use a 1 Meg FFT length. If you use a USB audio interface and the xlr Dayton mic the noise you can drop the noise floor about 10 DB more or more. Especially at high frequencies. For acoustic assessment this is helpful with decay measurements if your studio has a low noise floor. My theater has a noise floor at least as low as 25db so the USB mic with the long FFT length still sits well above the rooms actual noise floor.

 

[MickC]

You may want to check a cross-spectrum calibrated mic. They send a calibration files for their mic against a Aso Pacific NIST traceable measurement mic designed for direct field use. You get both a 0 and 90 degree file.

The differences in mics isn't massive. The better mics have better high frequency performance. For acoustic measurement it isn't a huge issue.

I would stay away from the Behringer mics. A slew of bad mics has caused a number of folks to lose faith in their QC. With Cross-spectrum you are guaranteed a good mic. Consider it a next level of QC plus a calibration file. They sell calibrated Dayton and umiks. They have both the xlr and USB version.

The biggest problem with the USB mics is noise. Still you can get a noise floor measurement down into the 30-40 db range for most of the area that matters for acoustics as long as you use a 1 Meg FFT length. If you use a USB audio interface and the xlr Dayton mic the noise you can drop the noise floor about 10 DB more or more. Especially at high frequencies. For acoustic assessment this is helpful with decay measurements if your studio has a low noise floor. My theater has a noise floor at least as low as 25db so the USB mic with the long FFT length still sits well above the rooms actual noise floor.

Thanks for this. Cross Spectrum are out of stock for both the EMM-6 and the UMIK-1. The UMIK-1 in particular seems hard to get in the UK - out of stock in every place I've looked.

But if an XLR mic helps me keep away from noise floor issues you described with a USB mic then that just leaves me with the possible compatibility problem described by EarlK above - do you know anything about this? can I use my Focusrite Clarett 8Pre with my MacBook Pro?

Thanks
Mick

 

[Matthew J Poes]

They are frequently out of stock. You just have to keep checking.

There are a lot of inexpensive 2 channel USB interfaces that combined with the mic might be good and still affordable. Behringer and Focusrite both have low cost options. You really don't need much to be better than the USB mics in quality. It won't impact measurements all that much but you will see it in noise related measurements.

I probably make too big a deal out of the noise floor. I often have to do transmission loss and NC measurements which requires a low noise floor. It bothers me a bit how bad the USB mics are as they are useless for that. For normal acoustic measurement they are fine, but I like to be able to see a solid 40-50db of dynamic range when looking at decay. With a normal 75db measurement level you are basically at the noise floor. I had been taught in shool to shoot for a 15db noisefloor headroom and that isn't possible at all anymore.

Point bring whatever you get will likely work fine. The problems really arise in special measurements and fringe use. Normal stuff, even RT60 is mostly fine.

 

[MickC]

Ok, so if I get a USB mic and connect directly to the MacBook USB port, and output the REW tones via my Thunderbolt interface, I should be good to go - have I got that right?