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[Art Welter]

Silas,

In the pictures you posted the cone is clearly visible, why would you need to remove the grille to measure excursion?

According to the specs, the speaker should do 31mm (just under 1.25”) peak to peak, but I measured only 16mm (just over 5/8”) before clacking.

If that is the case with yours, though your rms limiter is probably set too conservatively the peak limiter might be too liberal.

Art Welter

[Silas Pradetto]

Art Welter wrote on Fri, 22 May 2009 17:54

Silas, In the pictures you posted the cone is clearly visible, why would you need to remove the grille to measure excursion? According to the specs, the speaker should do 31mm (just under 1.25”) peak to peak, but I measured only 16mm (just over 5/8”) before clacking. If that is the case with yours, though your rms limiter is probably set too conservatively the peak limiter might be too liberal. Art Welter

I do agree that the RMS limiter was set too low. I left it that way for this show because I was running the entire rig on two circuits so I didn't figure I even had the extra power available (Itechs were reporting 100 volts at their inputs!). With the RMS power rating supposedly capable of 1400 watts per sub, I'm sure I can open it up to 1000 at least without any issue. Right now my peak limiter is barely higher than the RMS rating; I can probably open that up to 3000 watts or more, maybe even turn it off and just leave the clip limiter on. I will see how hard I can beat them and let you know  


And I can't get a ruler or sharpie anywhere near the woofer with the grille there; I can probably guesstimate but I like precision.

[Dave Rickard]

Silas Pradetto wrote on Fri, 22 May 2009 11:53

The ports cannot be modified they are built into the enclosure glued with PL Premium. There is no way to get it apart without destroying it.

Is there a reason you can't remove the drivers and shorten the ports from inside?

[Silas Pradetto]

Dave Rickard wrote on Fri, 22 May 2009 22:15

Silas Pradetto wrote on Fri, 22 May 2009 11:53  The ports cannot be modified they are built into the enclosure glued with PL Premium. There is no way to get it apart without destroying it. Is there a reason you can't remove the drivers and shorten the ports from inside?

Yes, yes there is. The port is literally part of the enclosure. I will see if I have any construction pictures to show you why. The port is held in on FOUR sides with PL Premium--front, top, and sides. Remember it's not tubes, it's a slot in the top and bottom, with a vertical brace from the top/bottom of the enclosure to the middle of the port. So literally, it's not going to happen unless someone wants to use a rasp on it for a couple days. Even then, the inside of the cab is so heavily braced you probably can't get your hand in there at all.

I'll see what I can come up with. I don't think a 4Hz deviation in the tuning frequency is going to make such a major difference in sound? But maybe I'm wrong...

[Ron Kimball]

Silas Pradetto wrote:

I don't think a 4Hz deviation in the tuning frequency is going to make such a major difference in sound? But maybe I'm wrong...

Actually your box is the size of two of my 1x15 minisubs put together so I inputted your speaker specs into BoxPlot and found that the box ends up flatter when tuned to 38hz rather than 42hz. The output at 40hz is the same either way (-6db) and the excursion limit at full power is moved down a few hz. Looks perfect to me! Your drivers look real good in a box that size - mine have a broad 4.5db peak at 80hz whereas yours are much better with only a broad 1.5db peak at 75hz. BTW how many people were you covering outdoors with a pair of these?

[Elliot Thompson]

Silas Pradetto wrote on Sat, 23 May 2009 03:48

Yes, yes there is. The port is literally part of the enclosure. I will see if I have any construction pictures to show you why. The port is held in on FOUR sides with PL Premium--front, top, and sides. Remember it's not tubes, it's a slot in the top and bottom, with a vertical brace from the top/bottom of the enclosure to the middle of the port. So literally, it's not going to happen unless someone wants to use a rasp on it for a couple days. Even then, the inside of the cab is so heavily braced you probably can't get your hand in there at all. I'll see what I can come up with. I don't think a 4Hz deviation in the tuning frequency is going to make such a major difference in sound? But maybe I'm wrong...

Before you start cutting up the box (which I would not recommend) you need know one thing. The box is too small for the speakers, which is why the frequency response chart in SMAART offers a steady decline like walking down a hill.

You can re-tune the box as often as you like however, it will not offer an improvement for the woofers need more space.

Here is a portion of what I wrote in January

Elliot Thompson wrote on Tue, 06 January 2009 03:35

The Qts requires a big box The fs is too high to be classed as a subwoofer 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,

Here is your measured chart

Silas Pradetto wrote on Thu, 14 May 2009 01:21

You seem very happy with the sound of the box. I would not recommend you alter the tuning. As I explained to you in January, those speakers require a big box. That is the only way to achieve a flatter, more extended response when measured in SMAART.  

Enjoy the cabinet gain of the box and, leave the tuning alone.

How was the bass track I sent on your Lab Subs?

Best Regards,

[Dave Rickard]

Silas Pradetto wrote on Fri, 22 May 2009 20:48

Dave Rickard wrote on Fri, 22 May 2009 22:15 Silas Pradetto wrote on Fri, 22 May 2009 11:53  The ports cannot be modified they are built into the enclosure glued with PL Premium. There is no way to get it apart without destroying it. Is there a reason you can't remove the drivers and shorten the ports from inside? Yes, yes there is. The port is literally part of the enclosure. I will see if I have any construction pictures to show you why. The port is held in on FOUR sides with PL Premium--front, top, and sides. Remember it's not tubes, it's a slot in the top and bottom, with a vertical brace from the top/bottom of the enclosure to the middle of the port. So literally, it's not going to happen unless someone wants to use a rasp on it for a couple days. Even then, the inside of the cab is so heavily braced you probably can't get your hand in there at all.

I see.  BTW, Void acoustics has a bass test track on their site.  

http://www.voidaudio.com/support.asp  

Look for "30 Hz Test Track" toward the bottom of the page.  It may be too low for your purposes, but it's interesting nonetheless.  

[Art Welter]

Silas,

A dot of white out helps to see the cone movement, the applicator would fit through the grille, as would a dot of white paint on a toothpick.
The ruler does not have to be next to the speaker, as long as your view point is a good distance out compared to that distance.

Anyway, my 4015LF Xlim measures only 1/2 what it should be, it should be easy for you to tell the difference between 16 mm and 31 mm peak to peak.

Art

[Art Welter]

I just went out to the shop and re-tested my 4015LF, and it tests fine now, in box it hits 30 mm peak to peak with no clacking, and 18 mm P to P before audible distortion, just as it should.

I suspect there may have been a bit of debris, possibly a piece of glue in the gap that was causing the clacking noise and premature distortion before, and it has pulverized in use, the speaker performs fine now.

In fact, I’m still feeling a little funny from the 10-15 HZ testing ...

Art Welter