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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => LAB Subwoofer Forum => Topic started by: Mark Wilkinson on October 05, 2016, 01:09:00 PM
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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
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Methodology seems good. Interesting results! Thanks.
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Thanks for the feedback, Don.
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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.
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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 ;D
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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?
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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.....
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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.
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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 !
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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".
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The problem is that there is no "sharp point" of the signal-so exactly where is the "arrival".
Yes, that lack of a "sharp point " has driven me crazy at times...
I'm thinking maybe a relatively steep 48dB low pass, and the use of linear phase x-overs, makes for a better grab handle for the delay finder....or perhaps better said, a 'grab plateau'.
I'm mean, if electrical x-over group delay variations have been nearly eliminated, shouldn't any freq the delay finder hooks onto within the passband read close to the same delay ?
I realize group delay variation's from the raw sub itself have to be taken into account too, and those variations if signifigant will screw the plateau idea up....
....but fortunately in the case of the labhorns and OS's, the raw sub phase looks nicely flat, so group delay variations are minimal here too.....
..... maybe all this together accounts for the delay finders' tight spread of measurements? ? And in this case maybe it doesn't matter too much, what freq it hooks on to ? ?
Just thinking out loud...make any sense?
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Yes, that lack of a "sharp point " has driven me crazy at times...
I'm thinking maybe a relatively steep 48dB low pass, and the use of linear phase x-overs, makes for a better grab handle for the delay finder....or perhaps better said, a 'grab plateau'.
I'm mean, if electrical x-over group delay variations have been nearly eliminated, shouldn't any freq the delay finder hooks onto within the passband read close to the same delay ?
I realize group delay variation's from the raw sub itself have to be taken into account too, and those variations if signifigant will screw the plateau idea up....
....but fortunately in the case of the labhorns and OS's, the raw sub phase looks nicely flat, so group delay variations are minimal here too.....
..... maybe all this together accounts for the delay finders' tight spread of measurements? ? And in this case maybe it doesn't matter too much, what freq it hooks on to ? ?
Just thinking out loud...make any sense?
Think of it like this.
Let's draw a line on the road. And the "simple question" is "When does X cross the line".
A motorcycle is pretty easy to tell when it crosses.
But what about a tractor trailer? Is "crossing" the front? the rear? the middle? Exactly where is the "middle". The whole vehicle? or just the trailer?
So with a low freq wave-what is the "arrival? When it starts to get to the mic? Or the largest point?
Does the delay finder lock onto the harmonic distortion? because it has a "sharper" impulse, or the larger "round" mound of the lower freq?
One easy way to get really confused-do this test.
Use a sub-cross it over in a "normal" freq (let's say 100hz or lower).
Now use the delay finder in whatever program you are using.
Does the number it gives make any sense? If you were to measure the physical distance from the mic to the cabinet-add the physical delay inside the cabinet and add any digital delay.
In most cases you will find that the presented time/distance is much longer than the actual distance.
The reason is that the program has a specific "point" that it is looking for. Where that "point" is, varies.
As usual-there is not a "simple" answer.
And with many other things-the deeper you dig- the more you realize how far there is yet to dig.
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One easy way to get really confused-do this test.
Use a sub-cross it over in a "normal" freq (let's say 100hz or lower).
Now use the delay finder in whatever program you are using.
Does the number it gives make any sense? If you were to measure the physical distance from the mic to the cabinet-add the physical delay inside the cabinet and add any digital delay.
In most cases you will find that the presented time/distance is much longer than the actual distance.
The reason is that the program has a specific "point" that it is looking for. Where that "point" is, varies.
AFAICT, that is the exact test I did....maybe I'm missing something.....pls check out the testing methodology in orig post..thx.
If I'm not missing anything, here's what's so cool....the delay finder readings tie exactly! with expectations...
.....expectations being processor/ amp delay, plus physical mic distance, plus physical horn length.
And better yet, delay finder numbers repeat tightly .... none of the usual bouncing around.
Like I was saying in the last post, I'm really thinking the use of linear phase x-overs for sub testing (along with the inherent flat-ish phase of the horn subs) let's this be so.
I like your train analogy, but it doesn't seem like it's so much of a matter of when each the train cars cross the line in serial order. Aren't the cars (frequencies) all on parallel tracks heading toward the line? It seems like it's a matter of when a reference point on each of the cars' crosses the line, the reference point being phase angle. What I'm thinking is due to all the flat phase, all the cars' reference points are crossing the line at about the same time....choose almost any car I think, results won't vary much !!
Wish I could force smaart's delay finder to lock onto selected freqs....would be great to thoroughlycheck this out.
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Wish I could force smaart's delay finder to lock onto selected freqs....would be great to thoroughlycheck this out.
What's so hard? Use a tone instead of pink noise. Smaart doesn't care what it's listening to when it is finding the delay, you only need full bandwidth for full bandwidth measurements. If you don't get repeatable results with the tone add some pink noise or music under it.
Mac
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What's so hard? Use a tone instead of pink noise. Smaart doesn't care what it's listening to when it is finding the delay, you only need full bandwidth for full bandwidth measurements. If you don't get repeatable results with the tone add some pink noise or music under it.
Mac
Why are we still talking about the delay finder not working at sub freqs. Everyone has watched this video right?
https://www.merlijnvanveen.nl/en/study-hall/120-why-the-impulse-response-won-t-work-for-subwoofers
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@ Mac, great, thx.....I've tried that before with just sine and couldn't get a lock....didn't think of adding some pink...
@ David, Yes, excellent helpful video.
But I'm not talking about how the delay finder doesn't work for sub frequencies......
I'm reporting an experience/methodology where it does work, and apparently very accurately.
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But I'm not talking about how the delay finder doesn't work for sub frequencies......
I'm reporting an experience/methodology where it does work, and apparently very accurately.
Yes the times may be very close-that is just an indicator that the path lengths are close.
But does the numbers the delay finder gave you make sense in relation to the actual distance from the sub?
THAT-is the whole point of my post.
As with any measurement system, just because you get a number-DOES NOT always mean that it is "correct".
As with many things audio, the question may have several "correct" answers.
It depends on SPECIFICALLY what "question" was asked of the measurement system.
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But does the numbers the delay finder gave you make sense in relation to the actual distance from the sub?
THAT-is the whole point of my post.
Hi Ivan,
YES, like I said, the numbers in the delay finder accurately reflect the actual distance from the sub...
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Hi Ivan,
YES, like I said, the numbers in the delay finder accurately reflect the actual distance from the sub...
I guess I sound like a "doubting thomas", but the delay distance "should" be greater than the actual distance, in order to account for the physical path length of the horn.
In every case that I can remember, the delay time was much, much longer than the actual distance between the mic and the cabinet.
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I guess I sound like a "doubting thomas", but the delay distance "should" be greater than the actual distance, in order to account for the physical path length of the horn.
In every case that I can remember, the delay time was much, much longer than the actual distance between the mic and the cabinet.
The delay time will also include the delay present from a HP filter if it is engaged, though that is dependent on the crossover/DSP topology integration, some platforms don't change with the HP filter in or out, Bennett Prescott's reporting of the "Digital Tower of Babel" has still not been addressed by the various DSP makers.
If hurricane Matthew had not occupied about three (24 hour) days time, I'd already have measured the delay of a "new" pair of subs (using 20 year old Hartke woofers) that were half way finished before it appeared on the weather report's local radar.
Cheers,
Art (survivor of two hurricanes, multiple car, and four airplane crashes) Welter
My last name seems to define my life, according to Webster's dictionary...
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I guess I sound like a "doubting thomas", but the delay distance "should" be greater than the actual distance, in order to account for the physical path length of the horn.
In every case that I can remember, the delay time was much, much longer than the actual distance between the mic and the cabinet.
Can't blame you for doubting....I'm surprised too.
The delay distance was greater than the actual distance, like it should be.
If I may re-quote what I wrote in reply #12 ..."the delay finder readings tie exactly! with expectations...
.....expectations being processor/ amp delay, plus physical mic distance, plus physical horn length"
When you asked earlier if I had reset the delay finder for each test, it prompted me to look at the stored traces' 'info' boxes to see what the delays were.
When i saw how tightly they were grouped, I said damn...never seen that before measuring subs.
So I'm like, how close are they to what I think they should be?
I measured the delay of signal processing alone, then added in the delay for distance from mic to subs, and finally added in delay for the horn length.
Bingo...the same.
If I get a chance today, I've got a set of experiments in mind to see if the above is repeatable, and dissect a little further...will report..
Art, glad to hear you are surviving being a "welter".....funny, thx !
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Art, glad to hear you are surviving being a "welter".....funny, thx !
Mark,
It all seems funny afterwords :^)...
I'm trying to learn more from the mistakes of others than my own, but it seldom seems to work that way ;^).
Back to the question you raised in the first post:
"I'd be interested if people think this testing methodology holds water...."
It seems OK, but the Lab Sub minimum impedance is almost the the same as it's DCR, a pair with parallel drivers is only 2.145 ohms, which is almost a 6 dB sensitivity gain at 2.7 volt compared to a "one watt" voltage.
When that is taken into account the sensitivity no longer looks freakishly high.
"Freakishly High", sounds like a good band name..
Art
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If I may re-quote what I wrote in reply #12 ..."the delay finder readings tie exactly! with expectations...
But having the same arrival time is RELATIVE, not absolute.
The actual arrival time is absolute, the difference in arrival times is relative.
They each have their own merit and place. But ARE NOT the same and should not be confused with each other.
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But having the same arrival time is RELATIVE, not absolute.
Hi Ivan, the second part of that quote in reply #12 that was chopped off addressed the absolute....the absolute was correct too.
Speaking of absolute timing...that's where i started out this fine morning.
Measured the electrical processing delay for 2 filters: one IIR, the other FIR. Both being the same 24BW@27hz HPF and 48LR@100 LPF.
(Needed this first timing component for figuring absolute timing expectations out on the driveway...)
Also took about 10 delay finder 'pings' for both the FIR and IIR filters ....to see the spread of results.
The spread was about the same, 0.42ms vs 0.46ms.....so already I knew my idea about linear phase filters making it easier for delay finder was baloney.
Back to Merlijn's video !
But I went ahead and hauled out on the driveway, and marked off the usual 8m testing distance (2nd component of absolute timing.)
Then I got transfers with FIR x-over, and IIR x-over.
The delay finder ping spread for both FIR and IIR tightened up a little, maybe some form of averaging going on combining electrical and acoustical?? No clue...
Timing measurements for FIR and IIR were the same, after their processing delay difference found earlier was accounted for.
The only good news in alot of useless testing, is that using either IIR or FIR bandpassed signal to sub, I got believable distances.
Both gave about a 10.5ms horn length, when mic distances and signal processor delay were removed.
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Back to the question you raised in the first post:
"I'd be interested if people think this testing methodology holds water...."
It seems OK, but the Lab Sub minimum impedance is almost the the same as it's DCR, a pair with parallel drivers is only 2.145 ohms, which is almost a 6 dB sensitivity gain at 2.7 volt compared to a "one watt" voltage.
When that is taken into account the sensitivity no longer looks freakishly high.
"Freakishly High", sounds like a good band name..
Hi Art, afterwards and I also are all too well acquainted ; )
You know, I was a bit surprised at the sensitivity the labs measured.... but I dunno if anything's wrong...
And it get's more puzzling when thinking about impedance. I've measured the labs impedance very carefully, 1,2,3, and 4 at a time.
Even measured a bank of 4 two different ways, as a box individually and as all 4 in series/parallel to equal one box.....to see if there was any diff.
In a 4 bank, I'd call a single lab with drivers in parallel a 5.5 ohm nominal...not dipping below 3 ohms. I feel pretty solid here..
So I know this makes the numbers I posted look even more freakish ....
Here's more puzzle, I've been doing boatloads of testing a DIY on top of my two orbit shifters all summer long. Know the balance between the DIY and OS (4 ohm) very well.
I put the DIY on 2 labs after testing the other day, using settings for the OS subs, and the 2 labs were clearly stronger.
So I dunno...
I'm going off into hypothesis world like I always do, and am left wondering if a 2.83v bandpassed rms measured pink signal that I use has more energy than whatever "2.83v signal" is normally used???
(But one weakness in that theory is the OS sensitivity I measured tied right to published spec.)
?? :)
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I'm going off into hypothesis world like I always do, and am left wondering if a 2.83v bandpassed rms measured pink signal that I use has more energy than whatever "2.83v signal" is normally used???
Here is an interesting experiment.
Use pink noise and band limit it pretty tight and measure the voltage.
Now don't touch any gains, and widen the freq bandwidth (higher and/or lower).
Notice how the voltage rises-even though the drive level does not.
So a wider bandwidth signal has more overall energy than a narrow bandwidth signal.
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1)In a 4 bank, I'd call a single lab with drivers in parallel a 5.5 ohm nominal...not dipping below 3 ohms. I feel pretty solid here..
So I know this makes the numbers I posted look even more freakish ....
2)I'm going off into hypothesis world like I always do, and am left wondering if a 2.83v bandpassed rms measured pink signal that I use has more energy than whatever "2.83v signal" is normally used???
(But one weakness in that theory is the OS sensitivity I measured tied right to published spec.)
Mark,
1) Silas Pradetto did impedance testing with his Labs, the impedance minima is near the DCR. Unfortunately, his reports were lost in the transition from the old "LAB" to "Pro Sound Web".
A "nominal" impedance is just that, something of an average, but for sensitivity tests the impedance minima should be used. Wayne Parnham's PI subs, basically a larger Lab, also read near the Lab 12 DCR, and Hornresp simulations on nearly every FLH and TH I have designed all have impedance minima near the DCR of whatever driver used.
2)Unless things have changed since I last looked, Jeff does not publish a measured response for the Orbit Shifter, making the sensitivity a bit questionable, though it does appear to be an average of the pass band he references.
I have never been able to get what I consider a reliable "RMS" voltage using pink noise (probably due to cheap meters..), so have always used sine waves at various frequencies, setting the voltage ( 1.41V for 2 ohm, 2V for 4 ohm, 2.83 for 8 ohm etc.), at 60 Hz, where the meter should be most accurate. I do my testing at 2 meters, and subtract 6 dB for the inverse distance rule.
I also like to test at the excursion minima, which usually happens to be the impedance minima, the speaker draws the most power at the frequency where forced air cooling is the least. After the sine wave tests (which also can be used to measure distortion) I then match them to the pink noise tests, so an accurate reference 1W/1M SPL is known.
Art
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Here is an interesting experiment.
Yes, it is interesting.
I've tried it before and found it shows that each octave, or any equal slice of an octave (ie 1/3) or octaves (ie 3) , gives the same voltage.
I guess it's part of the pink noise definition...
the devil of the details is in these definitions huh?
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Mark,
1) Silas Pradetto did impedance testing with his Labs, the impedance minima is near the DCR. Unfortunately, his reports were lost in the transition from the old "LAB" to "Pro Sound Web".
A "nominal" impedance is just that, something of an average, but for sensitivity tests the impedance minima should be used. Wayne Parnham's PI subs, basically a larger Lab, also read near the Lab 12 DCR, and Hornresp simulations on nearly every FLH and TH I have designed all have impedance minima near the DCR of whatever driver used.
2)Unless things have changed since I last looked, Jeff does not publish a measured response for the Orbit Shifter, making the sensitivity a bit questionable, though it does appear to be an average of the pass band he references.
I have never been able to get what I consider a reliable "RMS" voltage using pink noise (probably due to cheap meters..), so have always used sine waves at various frequencies, setting the voltage ( 1.41V for 2 ohm, 2V for 4 ohm, 2.83 for 8 ohm etc.), at 60 Hz, where the meter should be most accurate. I do my testing at 2 meters, and subtract 6 dB for the inverse distance rule.
I also like to test at the excursion minima, which usually happens to be the impedance minima, the speaker draws the most power at the frequency where forced air cooling is the least. After the sine wave tests (which also can be used to measure distortion) I then match them to the pink noise tests, so an accurate reference 1W/1M SPL is known.
Art
Art, I can't try to address the info you offer re Silas, Wayne, and Hornresp. I can only say I've measured the Lab's impedance with DATS, Terrasonde's ATB, and old school rms voltage and current, sine by sine. Measurements always tie closely, and I have to believe they reflect reality.... a 4 bank minima is right around 3 ohms, nominal something above 5 ohms. (If I have time, I'll try to send my sub passband-noise and measure rms current and voltage to come up with a "measured nominal" next time I have em all out. I'd really like to see this kind of meas as a manufacturer spec (along with full imp curve of course) , where they specify the passband, and use measured voltage and current instead of 'pick a number').
I took a quick 1 Lab dats below just now, because all my old data is on a retired PC. You'll see the minima isn't that far from DCR.
It's really cool how the minima's raise and maxima's lower as you add boxes...shows the great design work by mr. Danley imo.... I don't have the right cabling make an easy to show 4 box test right now...
Also took a dats of an OS. I figure you know this site, but in case not, data-bass makes the best sub measurements I've found http://www.data-bass.com/data?page=system&id=119&mset=131
And yeah, that damn pink voltage can sure bounce around, can't it? Even when I use a minute or so averaging, still end up with average to average variations up to 0.20 v.
For sensitivity, I just normalize whatever average shows up to 2.83v, and also normalize whatever SPL LEQ that was measured over the same period..
Oh, a bit of a swerve if I may...how do you measure distortion? I've been trying with REW. Results seem reasonable, but I'd like a way to find some confirmation...thx.
1 Lab then 1 OS
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1)I took a quick 1 Lab dats below just now, because all my old data is on a retired PC. You'll see the minima isn't that far from DCR.
2)Also took a dats of an OS. I figure you know this site, but in case not, data-bass makes the best sub measurements I've found http://www.data-bass.com/data?page=system&id=119&mset=131
3)And yeah, that damn pink voltage can sure bounce around, can't it? Even when I use a minute or so averaging, still end up with average to average variations up to 0.20 v.
For sensitivity, I just normalize whatever average shows up to 2.83v, and also normalize whatever SPL LEQ that was measured over the same period..
4)Oh, a bit of a swerve if I may...how do you measure distortion? I've been trying with REW. Results seem reasonable, but I'd like a way to find some confirmation...thx.
Mark,
1) Yes, that's why it is easiest to just assume the impedance minima will be the same as the DCR.
2) Josh does great work, Jeff should just use his measurements on his site, but he gets all huffy when distortion is brought up ;^).
3) With only a VOM to measure voltage, I have no way to average the huge peaks and troughs.
4) I downloaded REW about a half year ago, but have hardly used it. Still going with the "old school" method, run a sine wave, look at the difference between it and the harmonics using an RTA, look up the difference on my handy-dandy nomograph, and after repeating the process every 5 Hz or so, hours later it's done :'(
The example below has a 124.7 dB fundamental, the second harmonic is 99.9 dB a 24.8 dB difference, I'd round down to the whole number, so distortion is around 6%.
Art
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Thanks Art,
You know, I bet every speaker manufacturer wants to hide when it comes to talking about distortion at anywhere near quoted output ;D
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Thanks Art,
You know, I bet every speaker manufacturer wants to hide when it comes to talking about distortion at anywhere near quoted output ;D
Other than Welter Systems, that does seem to be the case ;^).
I have shared distortion specs along with frequency response whether they look pretty or not.
It is funny (ha,ha..) to see specifications extrapolated from AES power ratings (an open air speaker with impedance much higher than it's nominal value would suggest) with no accommodation for in cabinet thermal compression, or the fact that a fraction of the rated power may result in exceeding Xmax by such a margin that harmonic distortion components are much higher than the fundamental level.
That said, distortion is so much a part of most pop music it seems most folks simply don't notice it, especially when it's generated from subs.
Art
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Thanks Art,
You know, I bet every speaker manufacturer wants to hide when it comes to talking about distortion at anywhere near quoted output ;D
We've been having Data-Bass independently test our subwoofers. The CEA-2010 burst testing not just measures output but the output within specified distortion limits. Here is some info on their testing:
http://www.data-bass.com/know-how
One confusing things is the Data-Bass does a 2 meter, RMS test vs the 1 meter, peak CEA-2010 spec so you have to add 9db to their numbers for 1m, peak. The Growler and Orbit Shifter both surpassed their rated specs. The Growler was able to average 140db, 1m, peak, 50hz and above while still producing 128.7db at 40hz, 1m, peak, within CEA-2010 distortion limits. The Orbit Shifter was able to average nearly 150db, 1m, peak, 50hz and above while still producing 142db at 40hz, 1m, peak, within CEA-2010 distortion limits.
Growler:
http://www.data-bass.com/data?page=system&id=118&mset=130
Orbit Shifter:
http://www.data-bass.com/data?page=system&id=119&mset=131
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Hi Jeff,
I think it's quite admirable that your subs are tested by data-bass. IMO, the distortion and compression tests amount to a refreshing full disclosure...
How I wish other manufacturers provided such info, either directly or preferably through independent 3rd party testing such as data-bass.
BTW, it's amazing to me how well the Orbit Shifters and Labhorns sing together.
A little bit of level and timing matching and off they go...
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IMO, the distortion and compression tests amount to a refreshing full disclosure...
How I wish other manufacturers provided such info, either directly or preferably through independent 3rd party testing such as data-bass.
I've reached out a few times through email to a few companies about perhaps sending a loaner sub to test but so far no takers. Most of the time I don't get a reply back. Could be the emails hitting the junk bin. Granted I could probably put more effort into it. Perhaps I will give it an effort next year.