# Sweep Mode Delay Issue, No usable results



## jordancolburn (Apr 17, 2011)

Thanks for any help you can give guys. I'm trying to use REW to compare the response of a traditional speaker, a plasma speaker, and a hardware line level crossover network for my senior design project. I have a good handle on how many of the features work, but sweep mode seems to act unusual for me.

When I start a sweep, the VU meter indicates the duration and number of sweeps i've selected. However, the audio playback of the sweeps occurs after a delay. The graph is usually on screen before I even hear the sweep. 

I'm using REW on OSx with a digidesign 003 interface, as well as the builtin mac mini soundcard. I have been able to get respectable looking graphs of the crossover network using the white noise generator and RTA feature, the issue for me just keeps reoccurring with the sweep measurements. Thanks for any help or insight you can provide!


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## jordancolburn (Apr 17, 2011)

Also just discovered that this same issue occurs for me in both versions 4 and 5.


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## JohnM (Apr 11, 2006)

Are you using the Mandolane M3DMixer?


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## jordancolburn (Apr 17, 2011)

No, Should I be? I downloaded mandolane but the readme says it only works on PPC macs and not intel based.

I keep trying to different configurations, but the main problem is still the same, when I run a measurement sweep, the test ends while the sweep is still occurring, or many times even before. 

Thanks again for the help.


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## JohnM (Apr 11, 2006)

jordancolburn said:


> No, Should I be? I downloaded mandolane but the readme says it only works on PPC macs and not intel based.


Yes. The readme says Intel and PPC Macs with JRE 1.5 or later.


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## jordancolburn (Apr 17, 2011)

Their website said that, but the readme said it would not function on intel macs. Maybe it just didn't get updated properly? Anyway, I took the .jar file and put it in my mac java extensions folder. I restarted for good measure but still can't choose the mandolane mixer in REW prefs.


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## JohnM (Apr 11, 2006)

It sounds like you have an old version of the package, it uses an installer these days. The Readme.txt file from the installer (V4.0) says:



> Platforms
> ---------
> Mandolane software is designed to run on Intel 32/64 bit and PPC Macintosh computers, running OS X 10.4 or later and using Java 1.5 or 1.6.
> It will not run on earlier versions of OS X or Java, but the free Plumstone plug-in is still available from our web site.


and the M3D_READ_ME.txt says


> System Requirements
> -------------------
> Any PPC or Intel Mac running OS X 10.4 (or later) and Java 1.5 (or later)


I run it on an Intel Mac Mini.


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## jordancolburn (Apr 17, 2011)

You're right, I was using the old version. The new version installs and works but has the same problem as every other soundcard selection. 

Even using "check levels" in preferences has about a second or two delay from when the display shows audio to when I can hear it. Same delay occurs after closing the dialouge, audio continues for a second or two.


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## jordancolburn (Apr 17, 2011)

Using RTA and the generator, I can see the log sweep through the signal, but the actual frequency I hear is about 2 seconds delayed from the frequency displayed on the generator. White noise also roughly shows my frequency response, but I would like to be able to use the log sweep option.


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## bui (Apr 14, 2011)

I had a similar problem on a Macbook Pro after installing Mandolane software (I previously did not have this delay problem). I then unselected it and just used the Default out and Line In (using the RS SPL mic).

Problem remained - test ends before measurement is done. On the RTA you can see the delay before the measurement starts.

I had to unistall Mandolane and reboot the Mac before I was able to make measurements again. 

Bottom line is that I never did get Mandolane M3DMixer to work.


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## JohnM (Apr 11, 2006)

Try reducing the playback buffer setting on the REW soundcard preferences.


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## bui (Apr 14, 2011)

JohnM said:


> Try reducing the playback buffer setting on the REW soundcard preferences.


I had tried reducing the record and playback buffer size to 32k. Didn't work either. I found that the Macbook internal sound card worked very well and had a very flat response so I just used that.

Separately - I have not been able to get the USB dual Pro to output a signal through the Pre monitor port although I can play music using iTunes through it. I wanted to use the Pre in order to use an external mike (EMM-6) instead of the RS SPL but in order to make measurements I wanted to calibrate it first - could not get the Pre to work. The receive side works fine. The reason I had tried the Mandalone sw was to get the Pre working.

Right now I am just using the RS SPL as the mic and the Macbook Line Out - works fine but as everyone has pointed out the RS mic has limited high freq response.

Any ideas regarding Pre?


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## paulspencer (May 11, 2007)

I'd suggest you do things differently. Ideally you want a calibrated mic + phantom power/mic pre, if that's an option for you at all. But in particular, I'd use Fuzz Measure which you can run in demo mode and still output results. It runs on the Mac and it's more suited for full range measurements. You need to set up your mic on a stand @ 1m and run gated measurements. You look at the impulse response and it shows reflections so that you can cut off the measurement "gate" before the first reflection arrives. Even better if you can find a quiet time and measure outdoors with both mic and speakers elevated, ideally to about 1.8m. Position so that the ground is the nearest boundary, then set the gate to eliminate the reflection off the ground.

I'm not sure if you can get Arta on Mac, but it also runs a demo mode and we used it in this GTG to measure a plasma as well as some waveguides.
http://redspade-audio.blogspot.com/2011/03/waveguide-gtg-2.html
Directivity plots were done in Arta.


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## c_bass (May 22, 2011)

Hello,

In first sorry for my bad english, i use google to translate.

Have you found a solution, I have the same problem with my macbook pro?


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## gymnos (Jul 3, 2011)

Same story here. MBP with Snow Leopard 10.6.7 and MOTU Traveler, Java 1.6.
I can't understand how the program creates a delay between left and right output channels...:dontknow: and then it stops to record even before sound has come out. Mandolane didn't help.


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