Getting around the limitations of JavaSound on OS X - Page 8 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #71 of 171 Old 02-23-14, 03:28 PM
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Re: Getting around the limitations of JavaSound on OS X

Can I use an UMIK-1?
Easily? No, there are problems...

Can I use a FW interface?
Easily? No, there are problems...

Can I use Mavericks? Easily?
No, there are problems... (Apple doesn't sell previous versions of Mac OSX nor allows you to install it...)

In order to use REW with my Mac, I've bought so many useless things (UMIK the latest) that now I can say: "REW isn't for Mac users"

I think it is the sw which must be written according to the OS.
Not the other way...

P.S. I'd pay for a working version with Mac OSX.

Last edited by Esprit; 02-23-14 at 03:46 PM.
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post #72 of 171 Old 02-25-14, 07:09 PM
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Re: Getting around the limitations of JavaSound on OS X

I spoke to a world-class expert (Jim Johnston) about the garbage in front of the impulse and he said basically, no ifs, ands or buts, they have to fix it (they being FuzzMeasure). Since this garbage does not appear in FuzzMeasure's own display, it's probably not a problem for them, but then again, I don't think FuzzMeasure's display goes far enough back in negative time to be sure. JJ told me that the garbage is probably wraparound from the sweep and can cause all kinds of anomalies. And you can't get around it by windowing closet to the 0 as you don't know what other kinds of anomalies are occurring.

My solution: Sample in Acourate and export to REW. This works already, very well, I already tried it. Or, get another interface for my portable work :-(. Or, wait till John fixes the ASIO issue on the PC side. The Mac side will take a lot longer, if ever, for him to fix, sadly.

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post #73 of 171 Old 02-26-14, 10:00 AM
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Hi Bob, I am communicating with JohnPM and the head guy at MiniDSP, regarding the problems between Apple and Java and REW and MiniDSP.
There is a compounded impossible situation here. Apple are not doing Java, MiniDSP products are 48K natural, or only 48K in the case of the UMIK-1. There appears to be a reasonable chance of REW working with the UMIK-1 if it were changed to 44.1K. JohnPM is very helpful regarding REW, which is why I know about the association between the pre-image and distortion. There is only one real expert IMO. Perhaps if one considers the concept of pre-ringing in filters, it may become palatable to see action before zero? This is a normal REW graph of a measurement done in REW, not an import. Getting around the limitations of JavaSound on OS X-distortion.jpg

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Last edited by DanDan; 02-26-14 at 12:29 PM.
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post #74 of 171 Old 02-27-14, 08:05 AM
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Re: Expert

Dear DanDan:

While you're waiting for the developers of the MiniDSP to try to solve the Mac problems, why not install Bootcamp on your Mac and work in Windows? It takes me 1 minute total to switch operating systems on my SSD-equipped MacBook pro.

Now to go off-topic. Your image in dBFS shows something happening in front of the impulse but it is not the same phenomenon that I saw with the import from REW. That was NOT preringing or pre-echo of any form, and according to Jim Johnston, a respected world's expert on this topic, that was some form of wraparound distortion that should nullify the use of an import from REW.

Now in terms of interpreting your log scale impulse, those look to me like anomalies in the noise floor of your room contaminating the measurement in some way. It is not distortion caused by the sampling. I believe these echos are too far away from the impulse to be caused by pre-ringing in a filter. Attached are three pictures from my measurements in Studio A, which has a noise floor below 30 dBC. The linear is an extreme zoom to exagerrate any ringing or pre-impulse, and as you can see it still looks very well behaved. Those pre-rings are within 1 ms. of the start of the impulse while yours go back in the hundreds of milliseconds, which looks like an acoustical noise-related contamination issue to me. These are not imports either as I take measurements with REW directly using a Lynx Soundcard. I suggest you try averaging your impulses to reduce noise influence and see if that three-peak anomaly goes away. Or, if you are not taking the measurement at sufficient SPL, try taking it at a higher SPL to see what you get in front of your speaker impulse.

I also added a second log picture of the same impulse with as close to the identical zoom as in your image. The impulse starts at 908 actual milliseconds as due to the use of Acourate Convolver with FIR filters with a 65k long impulse there is nearly 1 second latency in my system!

If you disagree with my interpretations, we could both defer to our respective experts and agree to meet in a duel at high noon ;-).
Attached Thumbnails
Getting around the limitations of JavaSound on OS X-studio-lf-impulse-log.png  

Getting around the limitations of JavaSound on OS X-studio-lf-linear-zoom.png  

Getting around the limitations of JavaSound on OS X-stu-lf-log-zoom-out.png  


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Last edited by bobkatz; 02-27-14 at 09:12 AM.
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post #75 of 171 Old 02-27-14, 08:35 AM
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Re: Getting around the limitations of JavaSound on OS X

I'm a bit confused about the turn taken by the discussion as the REW docs state quite clearly that the images of the impulse before zero are distortion images.



(http://www.roomeqwizard.com/wizardhe...eresponse.html)

Returning somewhat to the topic of this thread, I run REW (and UMIK-1) regularly in Windows (7) under VMWare Fusion. I suppose that could be considered another approach to the OSX workaround, if you have a Windows license. I read there are various issues with Mavericks but have not explored them (and probably won't...!)
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post #76 of 171 Old 02-27-14, 09:19 AM
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Re: Getting around the limitations of JavaSound on OS X

In that case, HiFiZine, then I am mistaken about the anomalies which DanDan measured. I've learned something today! It also looks like the amplitude of the 2nd and additional harmonics is VERY LOW in my Studio A system! I've not seen anomalies like those ever in my Studio A pictures. I'll have to zoom in and look for them.

Regardless, I've decided not to trust the REW import that I got under expert advice. (see my previous post the other day).

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Last edited by bobkatz; 02-27-14 at 09:24 AM.
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post #77 of 171 Old 02-27-14, 09:30 AM
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Re: Getting around the limitations of JavaSound on OS X

Now we're getting down to something (still off topic). Approximately a year ago I switched from an analog-based subwoofer eq to a full DRC and digital crossover using Acourate convolver. In the previous measurement taken January 2013, I can see some small spikes in the negative time before the impulse (much less than in either DanDan's or PM's example picture). But since then I am using Acourate Convolver. The harmonic distortion measurements (using REW) have lowered by 15 dB between 20 and 200 Hz! Due to the use of a steep linear phase crossover keeping the woofer better within its operating range than any standard crossover. Probably that's why I have not seen any spikes in the impulse in negative time since that point.

If you would like to see some of my before-after Acourate Convolver measurements of the front speakers I can start another thread if you would like.

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post #78 of 171 Old 02-27-14, 11:42 AM
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Bob, I have bounced measurements back and forth between FM and REW extensively and for a long time.
The default behaviour of FM, not normalising and choosing 16Bit when exporting did show truncation in the resulting REW imports. That was about the extent of the problems I and many others looking carefully encountered.
This computer, my office iMac is on Mavericks and most of my online viewing and analysis are done here.
Due to your unease about the FM import I decided to test today. The expert to end all experts perhaps, the test....
I am using the onboard mic and speakers, which both REW and FM have always been happy with. I tried sweeps in both FM and REW and exported at 32 Bit, Normalised in FM and Not.
Without extensive and careful testing of each element there is no point in going in to any detail.
But from the immediate results I would not trust the Export and Import process at all right now. Certainly from FM to REW. Normalising seems to cause problems and the IR window seems to get included in the Export.

I don't think we will see a solution to the Apple Java issues any time soon, probably never, so the interface problems will remain. Seems like nothing other than a stereo USB will work for REW on a Mac.
I do believe that if the UMIK clock were changed to 44.! the Mac problems would go. I, and Apple it seems, do not regard 48K as a go to or norm for music.


DD

Last edited by DanDan; 02-27-14 at 01:50 PM.
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post #79 of 171 Old 02-27-14, 12:20 PM
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Re: Getting around the limitations of JavaSound on OS X

Quote:
HifiZine wrote: View Post
under VMWare Fusion.
Very interesting. Thanks
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post #80 of 171 Old 02-28-14, 07:00 AM
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Re: Experts

Guys, I have had complete success interchanging impulse responses between Acourate and REW and I do feel confident in that. The two programs go hand in hand. Acourate for the nitty gritty stuff and REW for the pretty stuff :-).

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