Rational Acoustics



Funk-O-Meter
December 8th, 2011, 02:38 AM
Hey guys. First post here. Thanks in advance for the help.


So I'm trying to use SMAART's auto delay finder to align my tops to my subs by finding delay delta between the two but SMAART can't get a usable reading from the subs. I've seen people turn off the high pass filter and sweep a PEQ filter around the midrange of the subs to help SMAART find the time but that seems like it wouldn't give as accurate a result. Ive tried music and pink noise, midfield and ground place mic positions. I'm in a medium sized venue.

Can you help?


Think I'm going to try impulse response methods next.

Rasmus Rosenberg
December 8th, 2011, 04:01 AM
Hey guys. First post here. Thanks in advance for the help.


So I'm trying to use SMAART's auto delay finder to align my tops to my subs by finding delay delta between the two but SMAART can't get a usable reading from the subs. I've seen people turn off the high pass filter and sweep a PEQ filter around the midrange of the subs to help SMAART find the time but that seems like it wouldn't give as accurate a result. Ive tried music and pink noise, midfield and ground place mic positions. I'm in a medium sized venue.

Can you help?


Think I'm going to try impulse response methods next.

Hello,
Basic answer is don't use the auto delay finder. The auto delay finder has a hard time finding the "right time" for "sub" signals, for one because they are streched in time. Also it will lock on to the frequency with the most energy, and thats not always the one you want to use.

Instead use the phase trace. There are plenty of info on sub alignment and the phase trace, here on this forum and on other forums: the LAB, Varsity, Bob McCarthys blog, Timo Beckmans blog, Pepe's blog etc, a good video to get started on the phase trace is here:
http://www.youtube.com/watch?v=A9098KMP_Q8
Jamie put together a master example powerpoint on the phase trace linked to in this:
http://homepage.mac.com/soundscapes/PSW/MeasureForum/Phase_Trace_Jamie_Anderson.pdf

If you have the chance, take a class, what you get from them are priceless...

James Woods
December 9th, 2011, 03:06 PM
Hi,

I agree with Rasmus.

Keep in mind that all filters change the phase response. The guys who bypass the crossover or use a sweepable parametric filter to get a reading on the subs are really altering the normal sub phase trace, and are therefore not really getting the results that they want (they are not really aligning their system).

Jay Barracato
December 16th, 2011, 08:51 AM
Hello,
Basic answer is don't use the auto delay finder. The auto delay finder has a hard time finding the "right time" for "sub" signals, for one because they are streched in time. Also it will lock on to the frequency with the most energy, and thats not always the one you want to use.

Instead use the phase trace. There are plenty of info on sub alignment and the phase trace, here on this forum and on other forums: the LAB, Varsity, Bob McCarthys blog, Timo Beckmans blog, Pepe's blog etc, a good video to get started on the phase trace is here:
http://www.youtube.com/watch?v=A9098KMP_Q8
Jamie put together a master example powerpoint on the phase trace linked to in this:
http://homepage.mac.com/soundscapes/PSW/MeasureForum/Phase_Trace_Jamie_Anderson.pdf

If you have the chance, take a class, what you get from them are priceless...

I am on my phone, so I am not going to attempt it, but it might be worth describing the math to determine the delay from the slope of the phase.

Marcos Vinicios Jardim
June 8th, 2014, 12:34 PM
Hi!! So, how can I find delay to align my subs, because I run smaart and always the results are not right.

Johnny
June 11th, 2014, 11:23 AM
Hi Marco,

Please read the posts above. They include links to more information about sub timing, information that answers your exact question (which is basically the same question as the OP). Also, using the Search function on our forum will yield even more information about timing subs.