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Author Topic: How cabinets are measured  (Read 3772 times)

lindsay Dean

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Re: How cabinets are measured
« Reply #10 on: January 11, 2019, 02:45:00 pm »

I can always tell when a non-musician/vocalist is running sound when he says "the monitors are not supposed to sound good just be loud"
wait?......😳....what?
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Luke Geis

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Re: How cabinets are measured
« Reply #11 on: January 11, 2019, 09:12:34 pm »

Except I am a musician and singer with 27 years experience playing in bands, et all.

Monitors can be made to sound good subjectively, but I contend that a singer that really wants A LOT will have one that doesn't sound good no matter what you do. The distortion and harmonics alone is one reason. The second is that by the time it's that loud, A LOT of stage wash from the mic will be in the speaker as well. Don't even get me started on intermodulation and its effects.

The number of tricks employed in order to make a stable monitor that gets up to a true 130db SPL is astronomical. Some of the tricks will make your head spin. The truth is, a truly loud monitor mix will not sound very good by most subjective measures. Now that isn't to say that you cannot have a loud and good sounding monitor mix, but when I say it is meant to be loud, not sound good, it is standing on the shoulders of an objective goal, not a subjective measure. A monitor mix that sounds like an angel resting its wings on your shoulders, that doesn't get loud enough, is a worthless monitor mix from an OBJECTIVE standpoint. A monitor that isn't raped to death by corrective and musical EQ, WILL be louder than one that is.

This is why I say monitors are meant to be heard, not sound good. Once you have the needed SPL from the monitor, then you can work on making it sound pretty. My experience anyway, has lead me to that fact. I will say that better monitors tend to sound better and maintain stability too. So it's not so much that no F$%*s are given about the quality of sound, but that if I have to choose between loud or pretty, I am going with loud and then see how pretty it can be made after I have the needed level.
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Mark Wilkinson

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Re: How cabinets are measured
« Reply #12 on: January 25, 2019, 12:29:22 pm »

Saw Meyer's M-Noise in LSI a few days ago.   https://m-noise.org/

In the 'Real World SPL' link found down the page under M-Noise Education,
the speaker on the ground / mic on the ground technique is shown starting at about 1:40. 

I know many folks are aware of this technique....just thought the link might help make it clearer to those that aren't.

This 'lay speaker on side, tilt to perpendicular to mic pointing into hard surface ground',
has been giving me results that match pretty well indoors to outdoors....surprisingly close really.
I'd rather be more than 1m back though, as recommended in the vid...always feel like too much triangulation is going on up close for decent timing adjustments.
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Ivan Beaver

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Re: How cabinets are measured
« Reply #13 on: January 25, 2019, 03:54:46 pm »

Saw Meyer's M-Noise in LSI a few days ago.   https://m-noise.org/

In the 'Real World SPL' link found down the page under M-Noise Education,
the speaker on the ground / mic on the ground technique is shown starting at about 1:40. 

I know many folks are aware of this technique....just thought the link might help make it clearer to those that aren't.

This 'lay speaker on side, tilt to perpendicular to mic pointing into hard surface ground',
has been giving me results that match pretty well indoors to outdoors....surprisingly close really.
I'd rather be more than 1m back though, as recommended in the vid...always feel like too much triangulation is going on up close for decent timing adjustments.
The idea behind M noise is a good one.  A lot of thought was put into the noise.  It makes sense to me, much more than simple pink noise. 

I am glad that Meyer is releasing the wav file and encouraging others to use it.

But putting a full range speaker on the ground is not generally what I consider the best way to measure them, it gives a false sense of the low freq output, vs up in the air where they would normally be located.

I would "argue" that different types of measurements should/could be done different ways, in order to get a real world usable measurement.

Some cabinets should be measured MUCH further away than 1m to get a usable number that will translate to a modeling program.  While other cabinets are fine at 1m.

Some cabinets will give greater than usable numbers at 1m, and other cabinets will give lower than usable numbers.  It depends on a number of different factors involved.

BTW, I did a quick measurement using the M noise and the same NTI XL2 meter on a non Meyer loudspeaker (that is suitable for being measured at 1m).

I got 9.5dB higher peak output than the normal loudspeaker specs, so they are correct, maybe the spec sheet needs to change.

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Mark Wilkinson

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Re: How cabinets are measured
« Reply #14 on: January 25, 2019, 04:23:34 pm »

The idea behind M noise is a good one.  A lot of thought was put into the noise.  It makes sense to me, much more than simple pink noise. 

I am glad that Meyer is releasing the wav file and encouraging others to use it.

But putting a full range speaker on the ground is not generally what I consider the best way to measure them, it gives a false sense of the low freq output, vs up in the air where they would normally be located.

I would "argue" that different types of measurements should/could be done different ways, in order to get a real world usable measurement.

Some cabinets should be measured MUCH further away than 1m to get a usable number that will translate to a modeling program.  While other cabinets are fine at 1m.

Some cabinets will give greater than usable numbers at 1m, and other cabinets will give lower than usable numbers.  It depends on a number of different factors involved.

BTW, I did a quick measurement using the M noise and the same NTI XL2 meter on a non Meyer loudspeaker (that is suitable for being measured at 1m).

I got 9.5dB higher peak output than the normal loudspeaker specs, so they are correct, maybe the spec sheet needs to change.

In complete agreement with different measurement needs....along with exaggerated low end from mains on ground.
I guess I've just found as a simple DIY tuner type, that the both on the ground technique gives the best consistency I can achieve.
And then I can pretty simply adjust low end when on a stand or subs..
Wish I had one of your guys cranes  :)

Yep, I like the idea of M-Noise a lot too.  Makes intuitive sense. 
First thing I did was go bang some spoons taking a Smaart transfer, to see if Smaart is as fast as Meyer's SIM3 (since Meyer said SIM2 wasn't fast enough).

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Steve-White

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Re: How cabinets are measured
« Reply #15 on: March 15, 2020, 05:14:34 pm »

Ok, many manufacturers specs based upon half-space.  My understanding is this is with a non-reflective baffle surrounding unit under test to create the half-space plane.

Do they operate the in true half-space or calculate it?

Can someone enlighten me on this?
« Last Edit: March 15, 2020, 10:48:17 pm by Steve-White »
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Luke Geis

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Re: How cabinets are measured
« Reply #16 on: March 15, 2020, 11:16:55 pm »

I think most compute it. They take a measurement at a distance like 2 meters away and then add +6db for a 1-meter measurement, and then if calculating half-space, add yet another +6db if it isn't already actually half-space loaded. This assumes an anechoic chamber for all the measurements.

Half space calculating is a challenging question. Technically if the speaker is 50' in the sky and you take the measurement from the ground, you are getting a half-space measurement. If the speaker is on the ground and you take the measurement 50' above the speaker, again it is a half-space measurement. The ground plane doubles the energy either way. I think with most subs, a half-space measurement is calculated to better the result?

I don't agree so much with the measure at 2 meters and then scaling it back to 1 meter bit. I think it gives the measurement a +3db boost than is real. Most speakers don't start abiding by the inverse square law until around 10'-12' where they will then actually drop off per the rule. Within that 10'-12' the speaker is only losing -3db per doubling of distance ( line array type crap, yadda yadda ). So if you measure at 2 meters or roughly 6.5' away, and then add +6db, chances are good that you are adding back +3db more than is likely. I think measurements are taken at 2 meters to help acquire a more even response from the speaker measurement. At 1 meter you are pretty close to the speaker and the beaming and coverage of the woofer and horn may not have propagated or evened out much yet but at 2 meters ( a more realistic listening distance ) at least the measurement will be a little more telling of what you would actually hear. The likely +3db boost the stats get is just a plus.
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Steve-White

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Re: How cabinets are measured
« Reply #17 on: March 15, 2020, 11:52:08 pm »

^^^ Thanks Luke, that's helpful.

FWIW:  My employer has a chamber - I figured it was electrically "quiet", isolated and such.  Little did I know, it's all that and is also acoustically "quiet".  Large enough to hang an aircraft on straps to emulate flying and run the avionics for testing.  Real strange experience being inside there - real quiet, finger foam all around.  It was great - wish I had access to it for some testing.

Anyway, I have some testing to do and it will probably be above 250hz on out.

Considering setup.  I'll have to play around - will be outside in backyard.  Considering throwing a moving quilt on the lawn and laying cabinets on their backs, measuring from above.  Should be fun, neighbors outta love it.
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Luis_Marquez

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Re: How cabinets are measured
« Reply #18 on: March 16, 2020, 01:57:47 am »

I think most compute it. They take a measurement at a distance like 2 meters away and then add +6db for a 1-meter measurement, and then if calculating half-space, add yet another +6db if it isn't already actually half-space loaded. This assumes an anechoic chamber for all the measurements.

Half space calculating is a challenging question. Technically if the speaker is 50' in the sky and you take the measurement from the ground, you are getting a half-space measurement. If the speaker is on the ground and you take the measurement 50' above the speaker, again it is a half-space measurement. The ground plane doubles the energy either way. I think with most subs, a half-space measurement is calculated to better the result?

I don't agree so much with the measure at 2 meters and then scaling it back to 1 meter bit. I think it gives the measurement a +3db boost than is real. Most speakers don't start abiding by the inverse square law until around 10'-12' where they will then actually drop off per the rule. Within that 10'-12' the speaker is only losing -3db per doubling of distance ( line array type crap, yadda yadda ). So if you measure at 2 meters or roughly 6.5' away, and then add +6db, chances are good that you are adding back +3db more than is likely. I think measurements are taken at 2 meters to help acquire a more even response from the speaker measurement. At 1 meter you are pretty close to the speaker and the beaming and coverage of the woofer and horn may not have propagated or evened out much yet but at 2 meters ( a more realistic listening distance ) at least the measurement will be a little more telling of what you would actually hear. The likely +3db boost the stats get is just a plus.

Luke. Thanks and to others sharing. I have a spot made out for testing in my dirt back yard. Their is a minimum of 30 ft away from any object. So now gong to try “measurements done in different ways”. Speaker on 4ft scaffold mic on ground @ 2m, speaker on ground sideways mic @2m, speaker on ground cones pointing to sky mic on 50ft Pvc pipes pointing down to speaker. REW software and waiting for a umc202hd interface.
Do I run on default REW settings or can someone share some info? Can m-noise be set for use on REW?

I am very green at this measurement process. So my goal is to get comfortable with the process and understand traces. I have several passive speakers in figuring out some odd beaming or harshness. So far unsuccessful in pinpoint where the problem lies. Smaart is not in my budget and don’t want to burn the free trial with in unpredictable weather and limited free time.
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Chris Grimshaw

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Re: How cabinets are measured
« Reply #19 on: March 16, 2020, 04:50:36 am »

REW is fine. I've been using it to set up my systems for years.

REW uses a swept sine sweep. There are lots of good reasons for that - check out the Help file for a lot of good info.


You'll need drivers for the UMC202HD - download from the Behringer website.
You can see the config page in REW here: https://youtu.be/uD9HBQ6lSEo?t=43

If your speakers are passive and have uneven directivity, you might find you need to alter the crossover. Not too difficult for boxes with active crossovers, but if there are passive crossovers inside the cabinets, it'll be more tricky.

Chris
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Re: How cabinets are measured
« Reply #19 on: March 16, 2020, 04:50:36 am »


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