Max SPL testing

[Guiria]

I've run several graphs using REW on my sub and I am pleased with what I see when I'm setting everything up at 75 db pink noise to begin with.

I am curious to see how the sub performs under tougher conditions and thus the question is born:

Is there a proper method to do max spl testing on a subwoofer or do I just turn it up a notch, run frequency sweeps in REW, take note, then turn it up some more until I can't take it? How do you know when to stop before you break something?**

** I am not interested in breaking anything at the moment, this is not a plot to convince my wife that we need a new sub

Your opinions, methodologies, and experiences will all influence how I end up testing my sub.

Thanks in advance.

 

[highfigh]

I've run several graphs using REW on my sub and I am pleased with what I see when I'm setting everything up at 75 db pink noise to begin with.

I am curious to see how the sub performs under tougher conditions and thus the question is born:

Is there a proper method to do max spl testing on a subwoofer or do I just turn it up a notch, run frequency sweeps in REW, take note, then turn it up some more until I can't take it? How do you know when to stop before you break something?**

** I am not interested in breaking anything at the moment, this is not a plot to convince my wife that we need a new sub

Your opinions, methodologies, and experiences will all influence how I end up testing my sub.

Thanks in advance.

Don't do SPL testing without ear plugs or other hearing protection.

 

[mtrycrafts]

I've run several graphs using REW on my sub and I am pleased with what I see when I'm setting everything up at 75 db pink noise to begin with.

I am curious to see how the sub performs under tougher conditions and thus the question is born:

Is there a proper method to do max spl testing on a subwoofer or do I just turn it up a notch, run frequency sweeps in REW, take note, then turn it up some more until I can't take it? How do you know when to stop before you break something?**

** I am not interested in breaking anything at the moment, this is not a plot to convince my wife that we need a new sub

Your opinions, methodologies, and experiences will all influence how I end up testing my sub.

Thanks in advance.

Look through Tom's web site for it. If it is not in there, send him an email and ask
http://www.nousaine.com/

 

[GregBe]

Here is what you do. First calibrate your system, which it sounds like you did. Next find a couple of really bass heavy scenes. Put your spl meter on C weighting and fast and place it at your listening position. Start off at a pretty normal volume, say -20dB below reference and note the peak level. Turn up the master volume by 3 dB. Re-run the scene, and the meter should equally jump by 3 dB. If it does, continue to raise the volume by 3 dBs until the meter doesn't also jump the additional 3 dBs. When that happens, you have reached the limits of the sub. 1-2dBs lower than that master volume is the subs limits in your room, which is all that really matters.

 

[fredk]

** I am not interested in breaking anything at the moment, this is not a plot to convince my wife that we need a new sub

But if you were, that would be a good way now wouldn't it?

 

[croseiv]

I've run several graphs using REW on my sub and I am pleased with what I see when I'm setting everything up at 75 db pink noise to begin with.

I am curious to see how the sub performs under tougher conditions and thus the question is born:

Is there a proper method to do max spl testing on a subwoofer or do I just turn it up a notch, run frequency sweeps in REW, take note, then turn it up some more until I can't take it? How do you know when to stop before you break something?**

** I am not interested in breaking anything at the moment, this is not a plot to convince my wife that we need a new sub

Your opinions, methodologies, and experiences will all influence how I end up testing my sub.

Thanks in advance.

Basically, the best way to do this is out doors, away from any reflective surfaces. Many of the third party measurements of subs that I have seen, do the measurement by placing the microphone on the ground (ground plane) at a specified distance (usually 1 or two meters from the front of the sub). What I've seen measures maximum clean output before compression. You'll know when you start getting compression, because you will increase the amp's volume, but the sub's volume will no longer go up accordingly.


Illka's method seem to be a very good one and I recommend you have a look at what he did:

http://www.hometheatershack.com/forums/subwoofer-tests/971-subwoofer-tests-explained.html

I recommend trying to do it this way (at least conceptually), because then your data can potentially be compared to other subs. Measuring in your room will not allow you to make any meaningful comparison to other sub measurements. I know it may be impossible to do exactly his way, but this gives an idea of good methodology.

Although, it appears you want to know you maximum indoor SPL, but his approach may still help.

 

[highfigh]

Basically, the best way to do this is out doors, away from any reflective surfaces. Many of the third party measurements of subs that I have seen, do the measurement by placing the microphone on the ground (ground plane) at a specified distance (usually 1 or two meters from the front of the sub). What I've seen measures maximum clean output before compression. You'll know when you start getting compression, because you will increase the amp's volume, but the sub's volume will no longer go up accordingly.


Illka's method seem to be a very good one and I recommend you have a look at what he did:

http://www.hometheatershack.com/forums/subwoofer-tests/971-subwoofer-tests-explained.html

I recommend trying to do it this way (at least conceptually), because then your data can potentially be compared to other subs. Measuring in your room will not allow you to make any meaningful comparison to other sub measurements. I know it may be impossible to do exactly his way, but this gives an idea of good methodology.

Although, it appears you want to know you maximum indoor SPL, but his approach may still help.

If it's going to be done outdoors, the mic shouldn't be on the ground because that's a boundary, which is a Maximum Energy/Minimum Velocity location. If you're familiar with Crown PZM or other mics like them, the plane the mic element is mounted to acts as an artificial boundary, which increases the mic's sensitivity. The logic is that, if the boundary is part of the mic, its characteristics won't change, like when a mic is placed nest to walls with different materials on their surfaces.

If this setup was trying to mimic an anechoic chamber, there are other ways to do that, especially if this way is near buildings. Unfortunately, true anechoic chambers are awfully expensive whey they're good to the lowest frequencies.

 

[Guiria]

So it seems one common thing to pay attention to, whether indoors or out, is the SPL of the sub relative to the volume of the source. Once you start to see a diminishing increase in SPL when you increase the source volume that is when you need to call it good.

I would like to try an outdoor test of my sub someday as demonstrated by Illka over at hometheatershack but that'll have to wait.

I am more interested in in-room performance.

I will try GregBe's method but I might try it using REW and frequency sweeps instead of a bass heavy DVD.

I will also take Highfigh's suggestion and use earplugs.

Now the biggest question is, how do I get my wife and kids out of the house for a while...

 

[mtrycrafts]

....
Now the biggest question is, how do I get my wife and kids out of the house for a while...

Yes, that is a a must. Tell her that you want to do some audio testing and when would be the best time for them all to be out of the house. Also, make sure there are nothing of value that might fall and break from the test, especially her things