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[Mark Wilkinson]

Not sure if this belongs in Subs or Tests, but I dragged my subs out in to the driveway yesterday to make some basic tests. 2 OS's (4 ohm) and 4 labs.
Wanted to measure un-equalized mag and phase, and get a numerical feel for sensitivity.

Fairly reflection free, yea! Measured at 8 meters, calibrated mic on large board on ground.
 
Methodology was to put pink through speaker processing just like music goes through it.
IOW, bandpassed pink using a 24BW HPF@ 27hz , and a 48LR LPF@ 100hz .
The filters were linear phase, so the phase traces are the subs alone. Remarkably flat without usual x-over filters IMO....

Used as close to 2.83v  as possible.  The numbers and traces reflect a rms voltage average and SPL LEQ taken simultaneously over about a minute.  I made minor math adjustments to reported SPL's for not ever being able to hit a 2.83 v average exactly. No doubt there's still some slippage and slop though....

I'd be interested if people think this testing methodology holds water....

Anyway 1 OS, 103.3 dB LEQ,  green trace
            2 OS,  109.5, red
            2 Lab,  112.6, blue
            4 Lab,  118.4, purple

 1/6 smoothing, mag and phase









 

[Don T. Williams]

Methodology seems good.  Interesting results!  Thanks.

[Mark Wilkinson]

Thanks for the feedback, Don.

[David Allred]

Interesting that the OS response when going from 1 to 2 boxes had a comparative loss of output in the 80-100hz region which yielded a smoother response there.  The OS also had a output gain around 40hz, but lost smoothness there.

The Labs, from 2 to 4, comparatively gained output in the 35-45hz region and improved smoothness.

It would be interesting to see what another doubling would do.

[Mark Wilkinson]

It would be interesting to see what another doubling would do.

I so agree.   

It's pretty well known labhorns were designed for use in a bank of 8, maybe dipping down to 6....  I'm short with 4.

I'm wondering if Orbit Shifters smooth out too, as more boxes are added. 
I kinda think not so much because when I measure the impedance of 1 lab alone vs 2 side by side, there is a noticeable single box change.  Not so with 1 vs 2 OS's.

I'm left wondering what it is that makes some folded horns combine for magnitude smoothing, and others not so much?

But this is speculation...need more boxes 

[drew gandy]

It's pretty well known labhorns were designed for use in a bank of 8, maybe dipping down to 6....  I'm short with 4.

What's it been? 15 years?  But as I recall, the labhorn was a "full horn" with 12 boxes in free space or with 6 boxes on the ground.  So, 4 boxes is a little short but the models showed only slight depreciation in response flatness compared to 6 boxes.  The other thing that comes into play, imo, is the non-linear nature of human hearing.  The 6 db difference in level between 2 boxes and 4 boxes at close to full tilt at 50 feet, I think, marks a magical change in the overall experience.   

I'm curious about your subjective opinions of your 2 different sub models.  I assume they get used for different types of gigs so comparison it's always easy?

[Mark Wilkinson]

What's it been? 15 years?  But as I recall, the labhorn was a "full horn" with 12 boxes in free space or with 6 boxes on the ground.  So, 4 boxes is a little short but the models showed only slight depreciation in response flatness compared to 6 boxes.  The other thing that comes into play, imo, is the non-linear nature of human hearing.  The 6 db difference in level between 2 boxes and 4 boxes at close to full tilt at 50 feet, I think, marks a magical change in the overall experience.   

I'm curious about your subjective opinions of your 2 different sub models.  I assume they get used for different types of gigs so comparison it's always easy?

Yes, 15 all too long, all too short, years since building the labs !

As you pictured, the labs and OS's get used differently....and really, just coming down to do two boxes work or are more needed.
Subjective comparison, I dunno...love em both....guess it would take 4 OS's to make any kind of fair comparison

I so agree with the magical change you describe ....sure would like to hear at least 4 OS's ......and  4 TH-118's too....

I'm on the edge of teaming with a local guy who is trying to step up, and has a gig on the calendar that could probably use more than the 4 labs. 
That's the biggest reason for hauling the subs into the driveway and measuring them ........to see how well the labs and OS's might work together.
   
I'm thinking they will work damn well together, looking at their natural phase traces.....

[Ivan Beaver]

That's the biggest reason for hauling the subs into the driveway and measuring them ........to see how well the labs and OS's might work together.
   
I'm thinking they will work damn well together, looking at their natural phase traces.....

Did you change the delay time on Smaart when measuring the different subs?

In my opinion, the best way to see how well they "play together" is to measure one (doesn't matter which one).

Put them next to each other with a mic in the center-at least 15' away.

Don't change the delay or have it on automatic follow, turn the first one off, (after you save a trace) then turn the other one on, adjust the level (up or down it doesn't matter) until it basically has the same SPL over most of the response.

Save that trace.

Now turn them both on.  If you get around 6dB increase in level, you know they will play well together.

[Mark Wilkinson]

Did you change the delay time on Smaart when measuring the different subs?

In my opinion, the best way to see how well they "play together" is to measure one (doesn't matter which one).

Put them next to each other with a mic in the center-at least 15' away.

Don't change the delay or have it on automatic follow, turn the first one off, (after you save a trace) then turn the other one on, adjust the level (up or down it doesn't matter) until it basically has the same SPL over most of the response.

Save that trace.

Now turn them both on.  If you get around 6dB increase in level, you know they will play well together.

Yes, I did use delay finder on each test.  I was thinking I could use the times to tell me if any delay would be needed to be put in between the two.
But all 4 of the delay times fell within 0.25ms...which surprised me given how much trouble we know the delay finder can have at low freq...

I like your method...... less work, less room to screw up, and verification all in one..
Thanks !

[Ivan Beaver]

But all 4 of the delay times fell within 0.25ms...which surprised me given how much trouble we know the delay finder can have at low freq...

The problem is that there is no "sharp point" of the signal-so exactly where is the "arrival".

Granted-at lower freq you have more "freedom" in terms of where the arrival is.

The "automatic" finder can be fooled.

So using the same thing for all the cabinets makes it easier to see how well they "play together".

[ProSoundWeb Community]