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scanspeak 10" [message #33131] Mon, 02 April 2001 00:08 Go to next message
dtkky is currently offline  dtkky
Messages: 3
Registered: May 2009
Esquire
Hello Wayne,
I have been surfing your website and would really like to try building a pair of corner horns for some scanspeak 10" that I have. The T/S parameters are as follows:
Sd 298cm2
Vas 270 litres
Fs 20 Hz
Qts 0.22
Xmax 5.5mm
Re 5.5 ohms
Pmax 130W
Le 0.12mH
Sns 91 dB
Do you think it's feasible to cover 30Hz to 500 Hz?
Your Pi-align software suggested a 2.1 cu.ft. box tuned to 34.5 Hz. (correct me if I'm wrong). This is smaller than what Boxplot suggests as optimal. Is this always so?
Also, can I stack 2 corner horns one on top of the other with a midrange horn in between? (D'appolito style)
I would really appreciate your words of wisdom before I start cutting up my wood.
David Tan
Re: scanspeak 10" [message #33132 is a reply to message #33131] Mon, 02 April 2001 08:51 Go to previous messageGo to next message
Wayne_Parham is currently offline  Wayne_Parham
Messages: 123
Registered: May 2009
Master
PiAlign will often pick a smaller box than BoxPlot's "align" function does. Seems like for motors having very large Q, it recommends larger boxes than BoxPlot's align function and with those having smaller Q's, it recommends smaller boxes. It's a different alignment.
Your system's response curve [message #33138 is a reply to message #33131] Tue, 03 April 2001 10:37 Go to previous messageGo to next message
Wayne_Parham is currently offline  Wayne_Parham
Messages: 123
Registered: May 2009
Master
I took a moment to enter your specifications into PiAlign, and then the resulting cabinet into BoxPlot. The response curve is nice and smooth.

Specifications:

PiAlign

[entered values]
Vad = 9.5 cu. feet
Frd = 20 Hz
Qd = 4.5
[calculated values]
Ideal Ve = 2.1 cu. feet Actual Ve = 2.1 cu. feet
Ideal Fre = 33.75 Hz Actual Fre = 33.4 Hz
Ideal Qe = 1.22 Actual Qe = 1.25

This is obtained by having enclosure volume of 2.1 cubic feet and a port of 2.2" long. If it's cylindrical, it should be 2.3" diameter and if it's rectangular then it should be 2.72" x 1.53".

I would consider the cylindrical port to be in tolerance if a 2.25" diameter port were used that was 2.25" long. Likewise, I would also consider a rectangular port of 2.75" x 1.5" and 2.25" long was also within tolerance. But don't forget to calculate the volume displaced by the woofer, tweeter, port and anything else internal. This should be added to the enclosure volume when determining actual box dimensions. And don't forget wood stock size - whether you use a cylindrical or rectangular port - its dimensions are inside dimensions.

BoxPlot

[entered values]
Fs = 20 Hz
Vas= 9.53 cu. feet
Qms = 2.2
Qes = 0.25
Qts = 0.22448 Note: You didn't specify Qms and Qes; These
Re = 5.5 ohms values were chosen because they derive
Le = 0.12 mH Qts to be 0.22, as you specified.
Pd = 130 watts
Sensitivity = 91dB@1W/1M
Box Volume = 2.1 cu. feet
Box resonant frequency = 33.4 Hz

From the specifications you've given, this will make an excellent bass reflex or cornerhorn speaker. While its sensitivity is a bit low, I think you can expect good performance. I would assume maximum output to be about 110dB at full power. All in all - 40Hz and 110dB - that's pretty good for a 100 watt ten inch woofer.

Let us know how it turns out!

Re: Your system's response curve [message #33140 is a reply to message #33138] Tue, 03 April 2001 14:47 Go to previous messageGo to next message
dtkky is currently offline  dtkky
Messages: 3
Registered: May 2009
Esquire
Hi Wayne,
Thanks for taking the time to confirm my findings. In view of the lowish sensitivity, I would like to use 2 speakers per side.
Now, would it be better if I use 2 drivers in one enclosure that is double the volume or can I stack one corner horn on top of another and get away with a smaller footprint?
Re: Your system's response curve [message #33141 is a reply to message #33140] Tue, 03 April 2001 16:30 Go to previous message
Wayne_Parham is currently offline  Wayne_Parham
Messages: 123
Registered: May 2009
Master
You can put two drivers in one cabinet if you like, or you can separate them and tune them individually. There is very little difference either way if the the two separate cabinets are tuned the same as one larger cabinet housing both drivers.
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