Phase Alignment - Smaart |
Post Reply | Page 12> |
Author | |
Grubbah
Old Croc Joined: 14 July 2011 Location: Portsmouth Status: Offline Points: 2014 |
Post Options
Thanks(0)
Posted: 25 March 2016 at 8:03pm |
I've been trying to phase align a mid cabinet to a low mid using the transfer function on Smaart. Got a couple of questions Do I align the phase traces to the processor xover point (in this case 250Hz) or to the point these cross on magnitude? (which seems to be about 290Hz!) Also is there a standard smoothing I should be using? Is there anything that looks particularly wrong? I was quite surprised how much more the box responds past the processors xover point! Could this be down to room reflection or cabinet resonance? I positioned the reference mic about 10 feet away, mic positioned at a 45 degree angle.
Edited by Grubbah - 25 March 2016 at 8:05pm |
|
toastyghost
The 10,000 Points Club Joined: 09 January 2007 Location: Manchester Status: Offline Points: 10920 |
Post Options
Thanks(0)
|
The acoustic crossover point should be where the two boxes -6dB points overlap, your filter choices will affect this and should be based around making that happen. Once you have that in place, you want the phase traces to overlap for a full octave either side of the acoustic crossover point for smooth summation. You may then end up with a small hump in response when you measure both channels running together, this can be EQ'd out on the input EQ of your processor to get it back to flat.
First point I'd mention though is that your measurement delay setting is way off, the traces should really be flat phase for at least one of the passbands. After that you save traces of each passband, and you want to delay the box with the gentler slope. A slope down from left to right means the signal is behind in time compared to your reference signal, a slope up from left to right means it is ahead of time. If they both slope the same way, you want to delay the one with the gentler slope to match the steeper sloped response. As a general rule I tend to use minimal smoothing, 1/48 or 1/24 at most, because I'd rather see the data for myself. I also tend to set the coherence blanking to 45%, anything below this and there's more noise than signal so the data is worthless. Here's an example from when I aligned one of Stable Audio's midtops for DSR in Glasgow. This has no smoothing on phase and 1/48 on magnitude: Edited by toastyghost - 25 March 2016 at 9:04pm |
|
Grubbah
Old Croc Joined: 14 July 2011 Location: Portsmouth Status: Offline Points: 2014 |
Post Options
Thanks(0)
|
Thanks Toasty, before I comment back and Im going to try my traces again etc so I can refer directly back
|
|
Shortrope
Young Croc Joined: 08 July 2013 Location: Ireland Status: Offline Points: 1232 |
Post Options
Thanks(0)
|
This is great!
Just what I've been reading up on to try and learn!! More info on the delay setting would be invaluable, layman's sterns? Sorry for the hijack. Edited by Shortrope - 29 March 2016 at 8:38pm |
|
My Tinnitus is coming along nicely!!
|
|
toastyghost
The 10,000 Points Club Joined: 09 January 2007 Location: Manchester Status: Offline Points: 10920 |
Post Options
Thanks(0)
|
The delay setting will vary depending on measurement conditions - distance to source, source type, soundcard/interface, etc etc.
You can often use SMAART's auto finder when doing midtops but it's pretty useless on subs because of the lack of useful data when measuring subs (low SnR ratio) and the fact that EVERY sub is stretched across a very broad period of time in it's usable passband. Your best bet for sub alignment is to start using tape measure or laser measure for subs, and then add on the processing delay of your soundcard, processor/LMS and if in use, mixing desk. Then tweak up or down using the manual controls until the trace looks reasonably flat - really it's a matter of setting something in the right ballpark and then sticking with it when you measure the other passbands so that the reference doesn't change. When doing midtops I would also strongly recommend going outdoors and putting the cab on its back, firing up into the sky, and then dangle the measurement mic above it at a reasonable distance - much easier to avoid reflections from buildings that way. |
|
Shortrope
Young Croc Joined: 08 July 2013 Location: Ireland Status: Offline Points: 1232 |
Post Options
Thanks(0)
|
Thanks a mill Toasty!!
|
|
My Tinnitus is coming along nicely!!
|
|
Timo Beckman
Registered User Joined: 09 August 2011 Location: Netherlands Status: Offline Points: 197 |
Post Options
Thanks(0)
|
I have some video's online regarding phase alignment if you're interested.
Some are measurement at the x-over output where you might find this one interesting: There are a lot more video's at my blog or Vimeo and more is to come in the future when i'm done with my seminar measurement room enjoy
|
|
The sound will be as good as the band play's
|
|
tthorsten
Registered User Joined: 22 April 2004 Location: Germany Status: Offline Points: 134 |
Post Options
Thanks(0)
|
www.satlive.audio - SATlive from Thomas Neumann could help also - try it
|
|
www.tb-audio.de LEVELchek www.levelcheck.de SPL tracking SATlive www.satlive.audio best Measurementsoftware for Live People DBlimits www.dblimits.com Isemcon EMX7510 measurment Microphon |
|
Abe The Babe
Registered User Joined: 16 September 2011 Location: Ireland Status: Offline Points: 336 |
Post Options
Thanks(0)
|
Hi Timo,
Your links are broken unfortunately.
|
|
There's a time and place for acoustical reflection.
|
|
cravings
Old Croc Joined: 30 January 2007 Location: Ireland Status: Offline Points: 7441 |
Post Options
Thanks(0)
|
Abe The Babe
Registered User Joined: 16 September 2011 Location: Ireland Status: Offline Points: 336 |
Post Options
Thanks(0)
|
Don't we all.
|
|
There's a time and place for acoustical reflection.
|
|
tthorsten
Registered User Joined: 22 April 2004 Location: Germany Status: Offline Points: 134 |
Post Options
Thanks(0)
|
Timealigin with SATlive
nice video
|
|
www.tb-audio.de LEVELchek www.levelcheck.de SPL tracking SATlive www.satlive.audio best Measurementsoftware for Live People DBlimits www.dblimits.com Isemcon EMX7510 measurment Microphon |
|
Post Reply | Page 12> |
Tweet |
Forum Jump | Forum Permissions You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum |