REW and Digidesign Interfaces

**PTRust** · **05-24-09, 04:30 AM**

I am not having much luck using my m-box as the audio interface. I'm currently running a 2.4 ghz Macbook/4 gig ram. It has pro-tools installed but I doubt its conflicting with it.

Is there anybody else out there having success with a similar setup?

**brucek** · **05-24-09, 06:48 AM**

Generally as long as your Mac has an Intel processor, you're OK, as REW only works on Intel Macs.

The problem with M-box is that it only uses ASIO drivers (I believe). REW requires the use of WDM drivers.

brucek

**PTRust** · **05-24-09, 11:43 AM**

More specifically it seems the problem is a feedback loop caused by an inability to mute the monitoring of the input signal. I don't have an answer. Any ideas?

**Barish** · **05-25-09, 04:57 PM**

I have tested a commercial studio's control room with success today using a Macbook Pro 2.4GHz (MB133B/A with OS X 10.5.6) and an M-Box Mini + PTLE 7.4.2. The trick is that you need to launch Pro Tools along with REW in order to control the M-Box, since the Digi drivers won't let you control the interface from System Preferences Sound Pane.

- Just launch PTLE and start a new session with two mono audio input tracks assigned to either of the inputs, and a stereo master fader, all set to 0dB. Mute the input tracks so that they don't relay what's at the input to the output, and then leave it as it is all throughout the test.

- Set the Output from REW settings panel to Java Audio Engine, and the Input to M-Box Mic Input.

- Connect the mic to the M-Box as usual and turn the direct monitoring knob full-clockwise to Input (opposite end of Mix).

- Calibrate the soundcard using the utility below the same panel and off you go.

Good luck.

B.

**PTRust** · **05-25-09, 05:35 PM**

Great answer, why didn't I think of that. Can't wait to try it.

Thanks!

**Barish** · **05-25-09, 06:40 PM**

No bother. The REW is free, and so is the supplementary advice

Quote:

brucek wrote:

The problem with M-box is that it only uses ASIO drivers (I believe). REW requires the use of WDM drivers.

brucek

FYI, there is no such thing as WDM for Macs. There's just Core Audio drivers. WDM is for Windows platforms. I even doubt that there is an ASIO driver protocol for OS X platform, cos I've never heard of it.

Digidesign products use Core Audio drivers in OS X.

Cheers.

B.

**brucek** · **05-25-09, 06:58 PM**

Great, thanks for the answers Barish. My Mac knowledge is about zero, so I always appreciate any Mac guy helping out.

brucek

**Barish** · **05-25-09, 07:12 PM**

My pleasure. Thanks for maintaining such a great board. It's very helpful and full of valuable information

Cheers.

B.

**Barish** · **05-27-09, 07:10 PM**

Tried the same setup again today. You don't even need to launch PTLE. Just adjust the settings in REW and on M-Box unit as above and carry on. The mic appears on the left channel on M-Box Mini.

B.

**PTRust** · **05-27-09, 09:17 PM**

I'm sorry I feel like an idiot here but I'm still getting a feedback loop. I opened up PTLE as per your instructions set the mbox's mix knob full clockwise and set the REW input/ouput settings as discussed but still getting a loop. In fact turning down the input signal knob does nothing.
Let me ask which out (L or R) are you connecting to which input (1 or 2).

**Barish** · **05-28-09, 01:46 AM**

Then make sure all the on-board mic in, line in and speaker outs are either muted, or at the minimum from the System Preferences Sound Panel when working, because in a few occasions I caught them working (and affecting the result) along with M-box Mini.

Other than that, it really is as simple as I've explained above. Put the mic in, press the phantom power button in, pad out, turn the direct monitoring knob to full right to All Input, go to settings, select Java Core Audio as Output and Digidesign M-Box as Input (default inputs, as there are no other inputs anyway), then select Left channel as "the" channel, untick the Left channel loopback calibration thingie (cos L channel is busy with the mic signal now), and check the I/O gain to -12dBFS/-18dBFS parity, then calibrate the SPL, then set the target level according to the speaker type and then click Measure and get the snapshot. I don't know what else to say.

B.

**PTRust** · **05-28-09, 12:26 PM**

Thanks, that's about as detailed as you can get. Do you run the calibrate function first by patching the output of the mbox into the input?

**brucek** · **05-28-09, 12:39 PM**

Quote:

Do you run the calibrate function first by patching the output of the mbox into the input?

You must do this first to obtain a soundcard calibration file.

brucek

**PTRust** · **05-28-09, 12:54 PM**

I figured that calibration was necessary but I guess my question is which outputs and inputs to use. Remember the mbox is not labeled L and R on the inputs but 1 and 2. I guess I can assume that input 1 (the only mic input) will be referred to as L in REW?

Because this is where I am experiencing the feedback loop. I haven't even gotten to hook a mic up to it yet.

Thanks for your patience!

**brucek** · **05-28-09, 01:07 PM**

Quote:

but I guess my question is which outputs and inputs to use

Like many higher end soundcards, a 1 and 2 are used in place of right and left. You have to establish which is which, since REW selects the channel to use with an R and L designation.

Make sure you don't check the "Use Left Channel as Calibration reference" box.

You may select either Right or Left channel to use for the calibration - it matters not. What does matter is that once you have created the soundcard calibration file, then the channel it was created on must be used for the mic and output to your system.

Quote:

I haven't even gotten to hook a mic up to it yet

As well you shouldn't until the soundcard calibration file is created and you confirm that the file is good by doing a measure of the loopback cable. It (of course) should now measure flat from 2-20000Hz because any inadequacies of the soundcard are compensated by the soundcard cal file.

Once you've accomplished that, it's a simple matter of removing the loopback cable and hook up your mic and system to do a measurement.

Set speaker type.
Run Check Levels.
Run Calibrate.
Set measure limits (i.e 0-200Hz for a sub , 0-20000 for full system)
Measure.

That's it.

brucek

**PTRust** · **05-28-09, 01:17 PM**

I appreciate it. Let me fool with it tonight and I'll let you know how it turns out.

Thanks again!

**PTRust** · **05-29-09, 12:51 PM**

Still having problems. I noticed that I'm not getting a clean sine wave. I patched the output of the mbox into my mixer and just ran the signal generator and realized that I'm getting a very modulated strange signal. This is not an overload problem as I adjusted levels to make sure I wasn't clipping anything.

**Barish** · **05-29-09, 03:04 PM**

Try selecting the MBox as default Audio In and Out device from System Preferences > Sound and then selecting Default device option in REW menu.

By the way I can confirm that the internal oscillator of the REW sends absolute garbage out of the right channel. The L signal is fine, but R signal is totally distorted.

I'm not sure if this is caused by an internal driver conflict or not, but whatever the signal type, be it Pink Noise or sweep, the R channel signal is not usable at all.

I've checked it both on my MBP + MBox mini system, and MacPro + HD Accel + 192I/O system. I could replicate the same symptoms on both systems.

Someone should let the developers know about this.

I could provide further evidence to track the fault if needed.

B.

**brucek** · **05-29-09, 03:38 PM**

Quote:

By the way I can confirm that the internal oscillator of the REW sends absolute garbage out of the right channel.

Thousands have used REW without having this problem, so it's a bit confusing that you have this trouble?

I'll inform the author of REW of your problem.

brucek

**Barish** · **05-29-09, 03:52 PM**

Thanks Bruce. What I'll do is, I'll record the outputs on another recorder over the weekend and post the files along with full setting snapshots and may be someone else can replicate it that way as well.

At first I thought perhaps it was something to do with my MBox but when I installed the REW onto the other MacPro + PTHD system the result was just the same.

PC versions might not have this problem, but Mac version seems to have it.

B.

**JohnM** · **05-29-09, 04:56 PM**

I guess it depends which Mac and which soundcard

I test on a Mac Mini using the onboard sound and an Edirol USB card, both channels are OK. Will be interesting to see the captured data.

**PTRust** · **05-29-09, 06:43 PM**

Posting a sound file of this is a good idea. I would like you to hear what I'm hearing also. I'm new to the board how would you suggest I do that?

**JohnM** · **05-30-09, 06:01 AM**

If you don't have a web account you can post files to you are welcome to email me the file at john_mulcahy@hotmail.com - 20MB limit for that. Just to repeat one thing though: there is a known issue with PowerPC-based Macs that results in incorrect byte ordering of the output signal, that problem does not occur with the earlier REW V3.11 (although that has its own limitations on the Mac).

**Barish** · **05-30-09, 06:11 AM**

Hi John, thanks for chiming in. No worries about the webspace. I have over 1TB of that with some 3Tb monthly BW or something so that should do. I also happen to own and administer Turkey's leading pro-audio forums at http://www.muziktek.net . I'm commuting at the moment, but I'll print and post the wave files immediately as soon as I get back to the studio. But if you'd like to have them unpublished I'd understand and comply with that too.

Cheers.

B.

**JohnM** · **05-30-09, 08:11 AM**

Posting the files would be great Barish, thanks.

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