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Old 6th April 2006, 10:08 PM   #1
morfeas is offline morfeas  Greece
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Default HornResp results: please advice

Attached are the input parameters to hornresp and the result for a BLH using an Altec 604-8G.

The SPL responce is combined direct radiator + horn mouth. Does this look ok? Do I miss something?

Thanks,
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Old 6th April 2006, 10:10 PM   #2
morfeas is offline morfeas  Greece
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Old 8th April 2006, 02:41 AM   #3
GM is offline GM  United States
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Greets!

Not to me, but then it depends on what level of performance/SQ you want, room conditions, etc.. FWIW here's my calc'd compact BLH (big vent BR) with linear expansion:

Vb = 3.55621 ft^3 (100.7 L)
L = 43.46" (110.4 cm)
St = 91.45"^2 (590 cm^2)
Sm = 1016"^2 (6555 cm^2)

This assumes the cab will be at least 28" wide, not in a corner, the measured specs I used may be different, and of course if you use a high output impedance amp, it can change the Vb considerably, but at least it gives you a starting point for a relatively smooth response. At least it should sim good, I don't use Hornresp.

If you're wanting a high SQ (as BLH go) wide BW horn to better match to the HF horn's efficiency, it will need to be huge.

GM
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Old 8th April 2006, 10:27 AM   #4
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FWIW, that SPL graph is horn output only. I think the huge Vas on that driver may be what's killing you. Try doubling up on that CC size as GM suggested, which will increase the bottom end extension. I'd also go to a horn length around 2m and a upper horn cutoff in the 100hz range to get the phase relationship right where the horn output drops off and the front radiation takes over, but then you end up with a Jensen Imperial type design.
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Old 8th April 2006, 11:32 AM   #5
AndrewT is online now AndrewT  Scotland
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Hi Johncr,
how do you know that VAS is big, where does it tell you?

What is CC?
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Old 8th April 2006, 03:21 PM   #6
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Quote:
Originally posted by AndrewT
Hi Johncr,
how do you know that VAS is big, where does it tell you?

What is CC?
I saw the high CMS number and thought maybe he input too high a Vas. So I looked the driver up here: http://www.thielesmall.com/database.asp
and Vas is 625L.

CC is "Compression Chamber". In the HornResp inputs, since this is a rear horn, it is VTC and which is in cc's, 50000 cc's is 50L.
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Old 8th April 2006, 04:16 PM   #7
GM is offline GM  United States
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Greets!

Yeah, the Jensen Imperial is the 'one stop shop' BLH for any of the low Fs, Qts/high Vas drivers, and for semi-compact BLHs, I much prefer a Voigt concept tapered ML-TL over the popular big vent BRs:

L = 48.5"
eta = 0.5
SO = 4"^2 (effective for simming)
SL = 1016"^2

linear taper:

Lhorn = 0.75"
St = 128"^2
Sm = 128"^2

BTW, I just downloaded Hornresp 8.40 and according to the Help Menu it allegedly has a BLH Wizard that sums/plots the driver's and horn's response, though for whatever reason I couldn't get what I consider remotely accurate results.

GM
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Old 9th April 2006, 09:20 PM   #8
morfeas is offline morfeas  Greece
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Thanks for the replies.

I also think hornresp results in the back horn calculation seem not accurate.

The listening room is quiet small and one of the speakers can be placed in a corner.

Have tried also ML-Util calculations and the results are as the attached images
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Old 9th April 2006, 09:25 PM   #9
morfeas is offline morfeas  Greece
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Old 9th April 2006, 09:39 PM   #10
morfeas is offline morfeas  Greece
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Input the ML-Util's output to hornresp... assuming a corner placement
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