Smaart Help Please

[onemorestep]

Hey guys,



Over the past fews days I have been trying to get to grips with Smaart v6 by testing various aspects of sound systems and rooms. Although I do a lot of work around my local area I am yet to bump into any individual who is totally confident with the program to give me help.



Today I managed to do tests on a 300 cap. venue kitted out with a 4-way TurboSound Floodlight system. To test the system I used the following equipment:

Berhinger ECM8000 measurement microphone (all I could get my hands but I did manage to get my hands on a pro calibrator!)



Sony Vaio Laptop

Smaart v6

Lexicon Omega

Yamaha M7 (I know it would have been better to bypass the desk but using the M7 was only the way I could possibly patch everything correctly with the audio interface I was using)



For me the confusion begins when I then begin to analyse the results that I have captured. I have attached some screen shots and if there is any advice you guys can offer on how to best read the results it would be much appreciated.



Example 1

The first screen shot is of the sub and low mid crossovers and the phase between the two. Am I right in saying that the crossover happens at 190Hz and that they are about 120 degrees out of phase with one another? I know from reading about phase - which I am slowly getting my head around - that when two signals are 120 degrees out of phase either acoustically or electronically then this is part of the phase cycle known as cancelation.

The second jpg shows the magnitude results with all drivers on at once with a null in the response where the x-over point appears to be. Am I correct in saying this?



Example 2

Impulse responses are also another aspect of Smaart that is confusing. To do the IR test I am using the signal generator sweep within Smaart. I have great difficulty getting the IR to look anything like the ones that I have thus far in books, instead it looks like a massive block of noise and it is hard to see the RT60 of anything useful from the figure. I have attached a screen shot of the IR where you can see the setting I used.



I have read both the manual and several chapters of the brilliant Bob McCarthy book still I feel very confused.



Any help or advice would be much appreciated and I am sorry for the purely written post it has been a long day being exposed to pink noise and computer screens and it sure does make one tired!

 

[Tim McCulloch]

Re: Smaart Help Please

This doesn't look like a valid measurement but you already realized that. There are a number of possibilities for this, but start with your setup.



Do the loop-back test that's described in the ''Getting Started with Smaart'' tutorial. http://www.rationalacoustics.com/pages/New_Documentarium Scroll down to ''Smaart Reference Docs.'' Once you've got your measurement rig verified you can start measuring...



Measuring badly. I've done hundreds of bad measurements. There's no shame in that as long as you learn to recognize them on screen, and you will, eventually. One of the things that helps is the ''coherence trace'' in Smaart. If you see your phase trace get weird, the magnitude trace look like the stock market, take a look at the coherence. Where you see it take a dip you'll typically find it lining up with the phase/magnitude anomaly.



Measuring LF indoors is difficult. The relatively small space you're working in means reflections abound. This is another reason to run the coherence trace plus you'll be able to see the reflections in the impulse response.



I think the reason you're having trouble with the IR is your use of a swept wave. Use pink noise. Also, you can zoom the display to look at whatever slice of time interests you. Don't forget that the earliest impulse won't necessarily be a positive impulse. Trust me.

How are your sub/Floods crossovers/processing done?



Have fun, good luck.



Tim Mc