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[Art Welter]

Steve,

I think Silas is tuning the cabinet a little too high, not too low.

The low B is around 32 HZ,  I like to hear the fundamental. With a 38 HZ tuning, in a 3.4 cubic foot box, the 4015 F3 is about 35 HZ, measured outdoors at 10 meters.

But considering the intended use is for drummers and DJs....

[Silas Pradetto]

Fs on the Definimax 4015LF is 42Hz, as far as I know it will be fine in a cab tuned at 42Hz. Eminence Designer puts the F3 at 34Hz, which I think is plenty low. A 35Hz Butterworth high pass filter will be 3dB down at the knee of 35Hz, so I think I'll be good for excursion, the low B, and everything else.

I mean come on, my LABs are high passed at 35Hz too...

Link to definimax specs: http://eminence.com/proaudio_speaker_detail.asp?web_detail_l ink=DEFINIMAX4015LF&speaker_size=15&SUB_CAT_ID=1

[Elliot Thompson]

Silas Pradetto wrote on Tue, 06 January 2009 01:51

Fs on the Definimax 4015LF is 42Hz, as far as I know it will be fine in a cab tuned at 42Hz. Eminence Designer puts the F3 at 34Hz, which I think is plenty low. A 35Hz Butterworth high pass filter will be 3dB down at the knee of 35Hz, so I think I'll be good for excursion, the low B, and everything else. I mean come on, my LABs are high passed at 35Hz too... Link to definimax specs:  http://eminence.com/proaudio_speaker_detail.asp?web_detail_l ink=DEFINIMAX4015LF&speaker_size=15&SUB_CAT_ID=1

If you feel it is best by all means.  

Looking at the TS Parameters it is a terrible driver for high output bass applications.

The Qts requires a big box
The fs is too high to be classed as a subwoofer
The no.% is too low (94 dB for a 15 is Home Hi Fi)
The xmech is 15.5 mm one-way or 31 mm peak to peak. I actually let Eminence calculate the xmax/xmech and it gave me an xmax of 8.859 and, a xmech of 13.29 mm one way.

Don't expect more than 700 watts from each driver under long-term conditions. Power compression comes into play above 700 watts at frequencies ranging from 66 - 51.7 Hertz.

Best Regards,

[Art Welter]

Elliot,

You said:

“You also may want to check a thread where I mentioned how rolling off lower frequencies can cause more harm than good.”

I checked, but could not find that thread.

Care to explain your theory?

[Elliot Thompson]

Art Welter wrote on Tue, 06 January 2009 03:45

Elliot, You said: “You also may want to check a thread where I mentioned how rolling off lower frequencies can cause more harm than good.” I checked, but could not find that thread. Care to explain your theory?

Many tend to roll off essential frequencies then, increase the volume to make up the loss in SPL of the missing frequencies to make it sound more balanced. By doing so the xmax is used up even more at the higher frequencies, and the user ends up exceeding the driver's mechanical limits.

I'll see if I can find that thread.

Best Regards,

[Eric Wong!]

Art Welter wrote on Mon, 05 January 2009 22:45

Elliot, You said: “You also may want to check a thread where I mentioned how rolling off lower frequencies can cause more harm than good.” I checked, but could not find that thread. Care to explain your theory?

Correct me if I'm wrong- is it this thread:

http://srforums.prosoundweb.com/index.php/m/388333/1479/

[Elliot Thompson]

Eric Wong! wrote on Tue, 06 January 2009 03:57

Art Welter wrote on Mon, 05 January 2009 22:45 Elliot, You said: “You also may want to check a thread where I mentioned how rolling off lower frequencies can cause more harm than good.” I checked, but could not find that thread. Care to explain your theory? Correct me if I'm wrong- is it this thread: http://srforums.prosoundweb.com/index.php/m/388333/1479/

Thank you Eric. That is the post I was refering to.

Best Regards,

[Silas Pradetto]

Elliot Thompson wrote on Mon, 05 January 2009 22:52

Art Welter wrote on Tue, 06 January 2009 03:45 Elliot, You said: “You also may want to check a thread where I mentioned how rolling off lower frequencies can cause more harm than good.” I checked, but could not find that thread. Care to explain your theory? Many tend to roll off essential frequencies then, increase the volume to make up the loss in SPL of the missing frequencies to make it sound more balanced. By doing so the xmax is used up even more at the higher frequencies, and the user ends up exceeding the driver's mechanical limits. I'll see if I can find that thread. Best Regards,

Well this isn't going to happen with these subs. First, I actually know what my subs are supposed to sound like, and I don't boost entire passbands when I know one frequency is lacking. I also employ RMS and peak power limiting with my amps. Second, I own 8 LAB subs, and if I need more bass, I have the weaponry.

I simply need a compact, lightweight, decent sounding drum sub/DJ monitor sub, and I HOPE these will fit the bill. The primary goal is to have plenty of bass within the first 10 feet or so of the subs to keep the drummers and DJs happy. I'll see on Thursday when the woofers arrive how the subs are going to work. Measured data will follow then.

Elliot, do you think you could explain some more about T/S parameters and what to look for in a sub driver? Or should I just search?

[Art Welter]

Elliot,

The scenario you just described:

“Many tend to roll off essential frequencies then, increase the volume to make up the loss in SPL of the missing frequencies to make it sound more balanced. By doing so the xmax is used up even more at the higher frequencies, and the user ends up exceeding the driver's mechanical limits.”

is far more likely to result in thermal rather than mechanical failure.

In over thirty years of looking at failures,(and making a few) I have not seen a mechanical failure that could be attributed to setting a hi pass too high.

Give me one real world example (of the “many”) of a sub high passed too high, where the cone, spider, or surround ripped or the voice coil was flattened rather than burnt.

[Elliot Thompson]

Art Welter wrote on Tue, 06 January 2009 04:12

Elliot, The scenario you just described: “Many tend to roll off essential frequencies then, increase the volume to make up the loss in SPL of the missing frequencies to make it sound more balanced. By doing so the xmax is used up even more at the higher frequencies, and the user ends up exceeding the driver's mechanical limits.” is far more likely to result in thermal rather than mechanical failure. In over thirty years of looking at failures,(and making a few) I have not seen a mechanical failure that could be attributed to setting a hi pass too high. Give me one real world example (of the “many”) of a sub high passed too high, where the cone, spider, or surround ripped or the voice coil was flattened rather than burnt.

Art,

The examples I’ve seen or should I say heard are:

The voice coil bouncing up and down with the cone while the spider is unattached. It sounds like chains banging against a metal shutter.

The voice coil jumps out of its magnetic gap and dislodged itself. Which in turn, prevents coil from re-entering the magnetic gap.

The cone tears in an angular fashion, which started from the voice coil and, proceeds to rip all the way up to the surround.

Please bear in mind that driver failures vary based on music material involved during such accidents. When a driver doesn't have enough xmax, you have enough power to exceed the mechanical limits while having the subs high-passed @ 50 Hertz. This is due to having 60, 70, and, 80 Hertz offering a strong enough signal to move the cone. So the only thing needed is a strong dynamic signal with a powerful amplifier to reinforce the material and you can exceed the driver’s limit. I’ve witnessed woofers “popping” away and the user has no idea why the drivers are making that sound. It’s an unfamiliar sound, which many never heard before.


Since we are talking pre-recorded material where 40 – 30 Hertz is common, when a track has all it’s information lying within 40 – 30 Hz region, that DJ is going to raise the fader until he/she gets the sound they are accustomed to hearing.

If we were discussing live music, it would be different story for it’s rare to have 98% of your bass residing from 50 Hertz – down.

Driver failure always boils down to not having enough speakers for the job. Some resort to feeding their speakers more power and rolling off the lower notes as a means of protection, which solves the problem. However there are some that find such methods useless. It did not work and, the only alternative is to buy more speakers. Those who fall into that category tend to be DJs playing tracks that offer all its energy below 50 Hertz. So as far as they are concern, you turned down their bass and, they will raise the fader to get it back.

Best Regards,