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[Kyle Gerhart]

Hey Guys Im hoping someone can shed some light on why I am getting the measurements Im getting from the rig I have to use for some upcoming dates. The subs are stacked side by side with the mains on top of them. The measurements where done 5' on axis with the subs @95dba

I am wondering why I am getting the dip around 50hz? Is it speaker related or processor related. The subs are 18" folded horns

Heres the basic info

Processor: DBX driverack 260
Subs: Cerwin Vega AC-36's (x4)
Amps: Cerwin Vega 2800's bridged mono ( 2800w @ 4ohms) two subs per amp.

Hp:30hz LR24
Lp:70hz LR24

I attached some screen shots of the smaart measurements i got.

[Kyle Gerhart]

[Ivan Beaver]

Hey Guys Im hoping someone can shed some light on why I am getting the measurements Im getting from the rig I have to use for some upcoming dates. The subs are stacked side by side with the mains on top of them. The measurements where done 5' on axis with the subs @95dba

I am wondering why I am getting the dip around 50hz? Is it speaker related or processor related. The subs are 18" folded horns

Heres the basic info

Processor: DBX driverack 260
Subs: Cerwin Vega AC-36's (x4)
Amps: Cerwin Vega 2800's bridged mono ( 2800w @ 4ohms) two subs per amp.

Hp:30hz LR24
Lp:70hz LR24

I attached some screen shots of the smaart measurements i got.

I would start with getting the phase correct.  It is wrapping WAAYYY to much.

Your delay is WAY off. 

[Art Welter]

The subs are stacked side by side with the mains on top of them. The measurements where done 5' on axis with the subs @95dba

I am wondering why I am getting the dip around 50hz? Is it speaker related or processor related.

Kyle,

It looks like a room problem. The only way it would be processor related is if you put in a deep narrow band  cut filter at 50 Hz, normally the CVs  have no "hole" there.

Try laying the mic on the ground, cabinets outside, at about two meters from the mouth, and at least 30 feet from any large objects like houses or cars. Test the cabinets one at a time,  short out any unused cabinets to keep them from affecting the sub under test's response.

Get the Smaart time alignment set correctly (it should be only around 13 ms for the folded horn + two meters distance) and you will be also able to look at the unwrapped phase response.

Art

[Kyle Gerhart]

Get the Smaart time alignment set correctly (it should be only around 13 ms for the folded horn + two meters distance) and you will be also able to look at the unwrapped phase response.

Art

Where would i set the settings for this? I noticed the delay times seemed weird, but they were weird for the mains as well. When I calculated the diffrence between the subs and the mains, and added the delay to the mains the full range system was in phase i believe.

I am fairly new with using smart for anything other than a fancy RTA.

[Tim McCulloch]

Where would i set the settings for this? I noticed the delay times seemed weird, but they were weird for the mains as well. When I calculated the diffrence between the subs and the mains, and added the delay to the mains the full range system was in phase i believe.

I am fairly new with using smart for anything other than a fancy RTA.

The delay measurement should pass your bullshit detector.  Measured as Art suggests, I'd give multiple looks to any time over 20ms.

Delay finder at sub frequencies is iffy under the best condition.  You may need to look at the impulse response to find the right delay time and enter it manually.

[Scott Carneval]

Where would i set the settings for this? I noticed the delay times seemed weird, but they were weird for the mains as well. When I calculated the diffrence between the subs and the mains, and added the delay to the mains the full range system was in phase i believe.

I am fairly new with using smart for anything other than a fancy RTA.

Not the delay between the subs/tops. The delay setting in SMAART to account for the time (delay) it takes for the sound to travel through your system, out the speaker, and into the measurement mic.


Sent from my iPhone using Tapatalk

[Kyle Gerhart]

Not the delay between the subs/tops. The delay setting in SMAART to account for the time (delay) it takes for the sound to travel through your system, out the speaker, and into the measurement mic.


Sent from my iPhone using Tapatalk

If my settings are wrong for the delay, where do I change them? Again I am a fairly new and novice user of smaart.

[Art Welter]

If my settings are wrong for the delay, where do I change them? Again I am a fairly new and novice user of smaart.

It may be the number in the "console vs. mic" box, but you have a different version than I use, so read the manual for it and find out.

Version 6 has an "auto sm" (small) or "auto lg" (large) that determines the time (distance) difference between the test signal and  mic and automatically. For subs, you may have to raise the HP filter up to 1-2K for the auto function to work properly, then put it back to normal for testing.

[Douglas R. Allen]

Here is a couple of photo's taken of a setup I did. Just as a reference as to what you may see when your getting closer to a good measurement.

The first is just a sub with a low cut and high cut filter on it. You can see the phase on top. It wraps on the low and high side of the subs range. I believe it was 40hz low cut , 100hz high cut.

The second is of the Mid High speaker and sub. 100hz low cut on the tops. No delay added to the mid high. You can see the phase trace of the 2 don't match or lay on top of each other so there is some time difference between the 2 arriving at the microphone.

The third is of the sub and the mid high with NO delay added to the tops. You can see the cancellation going on around the crossover point. 100hz.

You can see the big cut at 100hz. The delay problem causes a loss in output at the crossover point.

I'm sad to say the final picture of them in alignment didn't make it through the years but I hope this might give you an idea as to what you may be trying to look for.

Douglas R. Allen

 

[ProSoundWeb Community]