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Old 5th February 2011, 12:58 AM   #351
tb46 is offline tb46  United States
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Hi jbell,

It's probably of little use to continue this discussion until you or somebody else can take direct comparative measurements, that would also include actual observation of Xmax @ high power to see what is really happening inside a tapped horn, and then there is still the difference in the way these boxes would actually sound. If I were you I'd stay out of the cold.

I just put a "box of similar size" into Hornresp as a BR, and compared it to the tapped horn, a more appropriately sized box would be around 100 L_net (2nd SPL graph).

For what it's worth:

Regards,
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Old 5th February 2011, 01:12 AM   #352
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Jbell, a measurement with phase, spl and coherence, would be awesome, and just the way Tom Danley has published charts.


and of course the fact that we yet have impedance charts seems very strange considering the effects of bracing, leaks etc are much easier to evaluate with such a chart.
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Old 5th February 2011, 04:19 AM   #353
soho54 is offline soho54  United States
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The new subwoofer testing site I have been hinting around about in now live, and I can be shared!

Data-Bass

You will find some good stuff here from the first round of testing, and as soon as it stops snowing there will be a new round of testing with new horns, and even more measurements.
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Old 5th February 2011, 11:42 AM   #354
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Quote:
Originally Posted by soho54 View Post
The new subwoofer testing site I have been hinting around about in now live, and I can be shared!

Data-Bass

You will find some good stuff here from the first round of testing, and as soon as it stops snowing there will be a new round of testing with new horns, and even more measurements.
Nice site! However, I think that, for the driver tests, you should include published specs as well as measured specs. Let's see whose marketing department got a hand on the parameters .
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Old 5th February 2011, 12:53 PM   #355
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Quote:
Originally Posted by tb46 View Post
Hi jbell,

It's probably of little use to continue this discussion until you or somebody else can take direct comparative measurements, that would also include actual observation of Xmax @ high power to see what is really happening inside a tapped horn, and then there is still the difference in the way these boxes would actually sound. If I were you I'd stay out of the cold.

I just put a "box of similar size" into Hornresp as a BR, and compared it to the tapped horn, a more appropriately sized box would be around 100 L_net (2nd SPL graph).

For what it's worth:

Regards,
Trade-offs seem to be similar to those of bandpass alignments - you get get greater extension, or high efficiency. With my POC#2, sims suggest a few dB of higher sensitivity compared to a vented alignment, but of course the box is bigger too. Then of course there's the difference at high SPLs to be considered as well.
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Old 5th February 2011, 04:05 PM   #356
tb46 is offline tb46  United States
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Hi soho54,

Great site, very well done and informative. I'm missing the 1m/2.83V small signal measurement though. It's still a good comparative curve. Also, it would be nice to have the full T/S data set (found it, it's on the driver page :-)).

Good luck with this endeavour, Regards,
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Last edited by tb46; 5th February 2011 at 04:17 PM.
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Old 5th February 2011, 06:06 PM   #357
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Quote:
Originally Posted by jbell View Post
you show me the horn resp of your ported cab vs the ss15....
I donít have Hornresponse, but I already posted the Kappalite 3015LF Med Vented PA Subwoofer Cabinet by Jerry McNutt, Eminence speaker LLC in post #343.

Jerry has published plans for most of the Eminence speakers, I have found them to work fine, and agree well to real world results.

His 4.091 Vb 44Hz Fb box has 125 dB + output, as does the second Hornresponse ported box Tb46 posted in #351, which also includes a sim of your SS15.

On paper, the ported boxes and the SS15 are within 3 dB in the sub range.

By interpolating your test results and possible 2 dB spl difference that your test of the Behringer 89 dB spl cabinet you read as 91 dB, looks like the actual SS15 build may be almost exactly the same in the 45-120 Hz range as a front loaded box.

I agree with Tb46 that we wonít know how the real box performs in terms of actual SPL until someone takes direct comparative measurements.
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Old 5th February 2011, 08:31 PM   #358
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Default 2nd round of tests.

Ok, so the cab is now sealed up and braced as per Jbell's design. After this test I don't think anymore bracing is necessary. I neglected to mention the speaker was in fact a Kappa3015lf.
Test done just like the last one, 2.89 volts. (I coulndn't get the volume slider adjusted right on the money like last time). distance of 1 meter, ratshack digital meter. Meter pointed at center off horn mouth. Test was oudoors on asphalt. I exptended the freq. range this time to see where it would drop off.

the results:

40hz 101db
45hz 104
50hz 107
55hz 110
60hz 111
65hz 111
70hz 112
75hz 112
80hz 111
85hz 109
90hz 111
95hz 111
100hz 111
105hz 111
110hz 112
115hz 113
120hz 114
125hz 114
130hz 114
135hz 114
140hz 114
145hz 113.
150hz 111
155hz 109
160hz 108
165hz 105

Monday the neighbors will be at work and i'll do a 28volt test.

If someone will explain to me how it's done, I will do a test to find out the drop off at various distances from the box. i'm interested to see if the box follows the inverse law from the speaker, or from the mouth of the cab.

regard,

jeff
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Old 5th February 2011, 08:55 PM   #359
Xoc1 is offline Xoc1  United Kingdom
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Quote:
On paper, the ported boxes and the SS15 are within 3 dB in the sub range
Real speakers don't exist on paper and they certainly don't reside inside a computer.
Real speakers get hot and compress. Real ports run out of velocity and compress.
The computer sims that we love so much are only a guide.
What J Bell shares with us is practical real world experience, and this is confirmed by the experience of others who are confident enough to try his designs.
As for only 3dB, well I would love to be able to add 3dB to my reflex cabinets. The only way I know how to do this is add another speaker.
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Old 5th February 2011, 09:05 PM   #360
jbell is offline jbell  United States
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Originally Posted by weltersys View Post
I donít have Hornresponse, but
looks like oliver was right, we don't have much to talk about.

and btw... the b2013p that I measured is 2 years old and WELL broken in... (lots of rockband...) I didn't happen to have a brand new one available, but I've measured them before and been within a half db of the measured chart that comes with them.


Quote:
Originally Posted by Xoc1 View Post
Real speakers don't exist on paper and they certainly don't reside inside a computer.
Real speakers get hot and compress. Real ports run out of velocity and compress.
The computer sims that we love so much are only a guide.
What J Bell shares with us is practical real world experience, and this is confirmed by the experience of others who are confident enough to try his designs.
As for only 3dB, well I would love to be able to add 3dB to my reflex cabinets. The only way I know how to do this is add another speaker.
AND.... the real game changer here.... TH's are directional.... I've measured up to 12db front to back. Which explains why I LOVE the 28v10m test.....

Makes a BR vs TH comparison, like bringing a knife to a gun fight.
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