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Playing around, the cheap way. (pics) (Read 17471 times)
Bart_West-VL.
Ex Member



Re: Playing around, the cheap way. (pics)
Reply #15 - 12/09/07 at 17:11:56
 
Finally Finished the DB10, with a clamshell setup.
I was able to lower the resonance to 38Hz! Didn't expect this, but I'm very pleased of course.
Drivers are Monacor SP-250P.
This means 4 Ohm and 200Wrms at the terminal of the box.
The gap is now exactly 1".
I don't think there will be a lot of turbulence because of the relatively low power.
The braces don't take up too much space, because this box is built too long, so I had spare room for this.
They take about 3.1l of space. (about 13/16 gallon)
I was considering building a WO with these drivers, but then I realized I had to finished something once in a while. Roll Eyes



Bart.
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60_and_up
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kids should live.

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Re: Playing around, the cheap way. (pics)
Reply #16 - 12/09/07 at 17:17:12
 
looks good, should get way lower than 38?
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Peace hath higher tests of manhood than battle ever knew. ...
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Bart_West-VL.
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Re: Playing around, the cheap way. (pics)
Reply #17 - 12/09/07 at 18:22:53
 
Thanks 60,

I can't measure frequencies at the moment, no equipment.  :-[
The resonance is at 38Hz, so I guess it would go a little lower, but, correct me if I'm wrong, a 4th order bandpass rolls off quickly, once it's under the resonance?  :-/

Bart

PS. any advice on how to determine the -f3 point?
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Adrian
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Re: Playing around, the cheap way. (pics)
Reply #18 - 12/09/07 at 21:20:13
 
Nice work man Smiley
i think you can determine the f3 point either by ear (not accurate) or by expensive measuring equipment.
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Too much bass never hurts, or does it ?
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60_and_up
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kids should live.

Posts: 933
Re: Playing around, the cheap way. (pics)
Reply #19 - 12/09/07 at 21:41:20
 
Bart_West-VL. wrote on 12/09/07 at 18:22:53:
I can't measure frequencies at the moment,


sure you can, play some of these and if you cant hear it its not there.

top of page look for 'downloads'


http://www.realmofexcursion.com/
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Peace hath higher tests of manhood than battle ever knew. ...
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Bart_West-VL.
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Re: Playing around, the cheap way. (pics)
Reply #20 - 12/09/07 at 22:09:09
 
Thanks Adrian. Smiley

60, nice page, I'll have some tunes going tomorrow, if I find some time. Smiley

B.
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Bart_West-VL.
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Re: Playing around, the cheap way. (pics)
Reply #21 - 12/14/07 at 16:59:51
 
Got a nice multi-meter today, only 50€.
Did some dB testing:
The highest peak was at 42Hz.
At resonance (38Hz) there was an average pressure.
Going down from there, it bumped up again at 23Hz Shocked
At 51Hz the pressure dipped, higher up it got louder again.

I thought you might be interested in these numbers.

Bart.
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PC
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Re: Playing around, the cheap way. (pics)
Reply #22 - 12/17/07 at 03:13:52
 
here is a link I found tone generator software Bart : http://www.nch.com.au/tonegen/index.html
allows sweeps, volume levels, waveforms and single tones all at the touch of buttons.

I found your measurement levels from your db interesting - similar to mine in fact.
using the software mentioned above, I listened and determined

below 12Hz nothing

12 - 23 Hz very low volume but solid waveform (cant hear the low stuff - but can feel the air pressure and hear the house shake and rattle)

23 - 26 Hz -  significant not large peak (coincides with Fs of Driver?)

27 - 35 Hz Consistent volume throughout

35 - 70 Hz tuned peak of 4th Order Bandpass (highest volume)

70 - 110 Hz consistent flat solid lower volume than tuned

110 - 140 (depending on tuning of throat) resonance - nasty box ringing cutout by crossocer at 60 - 80 Hz


Thanks for all your help with achieving my end result - I love it...
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Bart_West-VL.
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Re: Playing around, the cheap way. (pics)
Reply #23 - 12/28/07 at 11:06:05
 
Oops, sorry I didn't respond yet. Embarrassed Thanks for sharing that!

In the mean while I was lucky enough to use a Wicked One for a few days and I was having trouble disconnecting it to go back to the Death Box 10" again, he he!
It bothered me that the DB10" sounded a bit boomy¿ or one-note-like¿ and I was disappointed because I read all those good things that can be with this design.

Till now I had the box standing upright with the opening near the floor.
I thought about 'sag' and maybe that this could have something to do with it, after all, even a isobaric configuration also has sag, no matter how stiff the drivers are.

Now its laying on its side so that the drivers are vertical, with the opening pointing sideways.
It made a big difference being a bit drier and better SQ, a lot less boom boom.

Now I'm considering to make the rear chamber even smaller again, I think it's still a bit large for these drivers, because it has to be half the size when clam shelling drivers.
For now it will have to wait, but when I changed this, I'll let you know about the results.

Thought you might find this useful,
Bart
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Bart_West-VL.
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Re: Playing around, the cheap way. (pics)
Reply #24 - 02/20/08 at 08:00:47
 
My ears where not lying ♪♫
I just discovered this web page and maybe this will let you think twice before using a woofer horizontally.
http://www.subwoofertools.com/forum/sag.htm

I didn't shorten the rear chamber yet, so nothing new at the moment.
(It calculates in WinISD as needing 15.6l or 952inch³ or 0.551feet³
for the rear chamber in a 4th order bandpass box)

To be continued...
B.
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Bart_West-VL.
Ex Member



Re: Playing around, the cheap way. (pics)
Reply #25 - 03/11/08 at 15:13:14
 
Freeware
SineGen description
Precise software sine signal generator/source. Exhaustive parameter control: unlimited editing, accurate sliders, frequency and phase tweaking, double/half frequency. Real-time. Musical notes. Parameter presets. Timer. Well-done UI. Open source code.
http://e-cat.nm.ru/sinegen/

GET IIIIIT‼ Smiley Smiley


Bart Smiley
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Bart_West-VL.
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Formerly know as:
Bart_West-VL.

Posts: 22
Re: Playing around, the cheap way. (pics)
Reply #26 - 12/22/10 at 14:26:06
 
Hello! Cheesy

I've been gone too long and I registered with the same name as a few years back.

So here is an update about the DB10.
I left the DB 6½" longer then what the plans said. So now, finally, I have cut it off!
I get the impression that the sound is the same, maybe a little tighter but I'm not sure.
A nice DVD will reveal that. (suggestions?)

Pics of the cutoff will follow soon.

Bart
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Bart_West-VL.
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Bart_West-VL.

Posts: 22
Re: Playing around, the cheap way. (pics)
Reply #27 - 12/22/10 at 14:51:39
 








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