# REW and OS X



## JohnM (Apr 11, 2006)

The good folk at Genelec have spent some time trying to get REW V5 running under OS X with their GACT (Genelec Acoustic Calibration Tool) and found a way using an Aggregate Device. This is available in both Leopard and Snow Leopard and it is possible the solution may work for other devices, perhaps even Firewire cards (you never know your luck, perhaps someone with a Mac and a Firewire soundcard can try it out). 

Here are the details (screenshots from SnowLeopard). Note that step 6 (selecting 44.1k, 2ch/16 bit) is likely to be crucial for this to work.

1. Connect GACT to a USB port and close REW if it’s open.
2. Open Audio Midi Setup (/Applications/Utilities).








3. In SnowLeopard (10.6) press '+' from bottom left to add 'Aggregate Device'. In Leopard (10.5) open ‘Aggregate Device Editor’ from ‘Audio’ menu and press ‘+’ to add aggregate device. 








4. Select both USB Audio CODEC lines (IN / OUT) from Aggregate Device panel. Uncheck 'Resample' checkbox if selected. (_If using other audio devices you would select them here - JohnM_)








5. Right click 'Aggregate Device' and select 'Use this device for sound input'. Right click 'Aggregate Device' again and select 'Use this device for sound output'. You can rename the Aggregate Device to e.g. GACT.








6. Select each of the USB Audio CODEC input and output devices in the Aggregate Device and set their sample rate to 44100Hz and 2ch/16bit








7. Launch REW and open Preferences. Check that Default Device is selected from Output and Input Devices list. Set Sample Rate to 44.1kHz.

NOTE: IF YOU CONNECT GACT TO A DIFFERENT USB PORT, YOU MUST GO THROUGH THE SAME CONFIGURATION AGAIN. IT WOULD BE GOOD IDEA TO CONFIGURE ALL USB PORTS AT SAME TIME.

Thanks go to Ilkka for letting me know about this. Anyone that has a Mac and is having problems, let us know if this helps.


----------



## TCinGA (Feb 17, 2008)

I'm about to start making some REW measurements on a Mac Book Pro running Snow Leopard, and would like to add to this thread (or start a new one) trying the aggregate device work around and try this with an external firewire audio interface.

I have a Focusrite Saffire 24 audio interface. It has phantom powered mic inputs and should have a fine microphone preamp. I'd like to use the Behringer ECM 8000 microphone. 

Just a couple of questions to start then lots more going forward I'm sure.

First, Is the Behringer mic all I will need or will I also need a SPL Meter like the Radio Shack ? I read the getting started info but I wasnt sure if I will need both the MIC and the SPL Meter to make full range measurements.

Second, I've read about the issues of getting a firewire device to work on a Mac, am I trying to something here that has been tried before and just isnt going to work or is it worth a shot ?

My fall back is to just use the line inputs and outputs on the Mac Book Pro and the Radio Shack SPL and make measuremments to 3KHz.

This is my first attempt at making REW measurements and look forward to seeing some results.

Thanks


----------



## erikmichael (Aug 6, 2011)

I have a Mac with an mbox 2. This has not helped. I am unable to change the mbox 2 rate to 16 bit in the audio-midi setup window.


----------



## gdesbois (Nov 21, 2011)

Hi there, 
Trying to make REW5 work with my presonus firestudio mobile (firewire) and OSX snow, sadly it didn't work for me neither. Although I managed swap to 16bits after waiting a while.


----------



## JohnM (Apr 11, 2006)

Unfortunately Apple's Java runtime has a bug that prevents Java applications accessing the inputs of firewire-connected soundcards. They show no signs of planning to fix it, a fix may come when Oracle start providing a Java runtime for OS X.


----------



## mnib (Oct 11, 2012)

FYI, this technique made REW recognize my Behringer UFO202 (the USB adapter with the phono input option), which it wouldn't before. I'm running Mac OSX Lion (10.7.5) on a Mac Pro. yay


----------



## dexter (Oct 2, 2012)

Hey there, 
This hint worked great for me, (OSX 10.7.4, iMac Late 2009). Before that I was using REW on a Windows 7 VMWARE Virtual Machine. I use a firewire M-Audio 410 for the measurements, but as it was mentioned earlier, there is no way to open the inputs. The measurement are then with the Integrated iMac Audio Device. 

Once calibrated, the sound device performs fine, no glitches, no lag


Thanks for the tip mates, 
Enjoy you day!

x.


----------



## EarlK (Jan 1, 2010)

dexter said:


> Hey there,
> This hint worked great for me, (OSX 10.7.4, iMac Late 2009). Before that I was using REW on a Windows 7 VMWARE Virtual Machine. I use a firewire M-Audio 410 for the measurements, but as it was mentioned earlier, there is no way to open the inputs. The measurement are then with the Integrated iMac Audio Device.
> 
> Once calibrated, the sound device performs fine, no glitches, no lag
> ...


Hi Thanks,

FYI, your post reads somewhat ambiguously to me ( hopefully you'll clarify what you are doing ).

*Did you ?*

(i) Use the OSX(s) Aggregate Driver feature to simply get sound ( Into & Out of ) REW using your iMacs builtin soundcard . 
- If so , what are you using as a test mic ( pre-amp ), etc. ..
( If this is the audio device setup , I'm surprised since the builtin soundcard should have worked with REW without you having to create an Aggregate driver ! )

(ii) Use the OSX(s) Aggregate Driver feature to make a composite driver where the input is handled by your iMacs builtin soundcard & the output is handled by the M-Audio 410 Firewire . 
- If so, what's your test mic & pre-amp setup ?

(iii) The reverse configuration of choice (ii) ?

:sn:


----------



## dexter (Oct 2, 2012)

Hi again
My Setup in details : The preamp : very low noise and high gain battery powered DIY Opamp Pream. The design, with minor modifications : sound westhost com - project93
the opamps are changes, as so the voltage rail, and the gain resistors. There are some chokes added, to extra-filter the battery chemical noise (low, but still existing)

The mic - a simple high quality electret capsule in a cooper body, well shielded, low capacitance cable etc. 

I just made a loopback test with the internal soundcard. Actually it works. I need to say that I always did my measurements until now with my macBookPro 13, which do not have a line-in, so the need to use the FW410.
On the iMac, there is one, and in this example, the measurements are made on my Near field monitors : Dynaudio BM5A and my Sub, in order to correct some -14 db drop at 83hz and few rings in the lowmids. Now, after some experimenting all fits just fine : a simple test with a slow sine sweep 50-2k shows a solid centered stereo image. Starting at 500-750hz, my room has some acoustic panels and various treatments. 


True that


----------



## EarlK (Jan 1, 2010)

Okay , Thanks !

:sn:


----------



## geoffmallan (Apr 18, 2013)

Hi, 

This is my first post. 

I'm trying to calibrate REW with Loopback for the first time. I will be using a Klark Teknik spectrum analyser mic coupled with a Neve mic pre once calibrated and running REW on a MacPro running 10.7.5

Initially using the Mac built in sound card to no avail as the sine wave and sweep tone sound corrupted or there's a feedback loop (unlike any feedback loop I've ever heard) I then tried using a Prism ADA8XR as the output and the mac line in to negate any feedback but the corrupted sound files are still produced this time from the Prism.

I can only imagine there's an inherent compatibility problem with the Mac or maybe the soundcard input is fault?

If anyone has any thoughts?

Thanks in advance.

G


----------



## geoffmallan (Apr 18, 2013)

Me again,

I'm home now and tried the same initial loopback calibration, but this time with my macbook and its built in soundcard.

Can anyone shed some light on what it's showing? I'm not quite sure how the HF fluctuations occur within a soundcard?

Cheers


----------



## JohnM (Apr 11, 2006)

That looks fine, the wiggles at the top end are the shape of the soundcard DAC's oversampling filter and the roll-off at the bottom is the low frequency extension. Bear in mind the soundcard cal plot uses a very zoomed in vertical span, the whole plot only spans 6 dB.


----------

