New to hornresponse help w/ 50/60-400hz J-horn - diyAudio
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Old 1st April 2015, 11:36 PM   #1
hum4god is offline hum4god  United States
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Default New to hornresponse help w/ 50/60-400hz J-horn

hi

I just got a grasp on how HR works and am very excited and discover something new every day.

I want to build a 50 or 60hz to 300 or 400 hz rectangular j horn.
I started out with using calc from inlows 60hz crescent horn with 10dm26 , then discovered I can let hr calc. a horn for me which got me started w/ 12pe32 down to 60hz.
My space is limited therefore I wanted a simple fold j horn not to restrict high freq. too much.
Max depth is 110cm / 43 dimensions for the mouth would ideally be approx 6000 sqcm 70cm/27 high , 85cm /33 wide .


1. What other drivers would work in this application ? Ev15l, gpa515, any 12 drivers ?

2. How much compression is reasonable to use ? It seems that in theory I could make the throat very small in relation to driver sd but was wondering what general guidelines are ? Does the shape of the throat matter or should I just leave it square ?

3. Is it reasonable to aim for 50hz with my limitation for mouth size ? I have seen truncated mouth mid bass horns claiming to work when put directly on the floor but would like to hear opinions from people who have actually tried this .

4. I have seen bass horns extending below driver Fs , is that recommendable or should I always try to find a driver with Fs matching lowest horn extension?

5. Does it make a difference to have the width expansion of the horn conical or exp or uni
and only height exp. Or should I aim at doing both exp. Or uni ?? what would be the benefit of either ?

6. I am still struggling with VTC and ATC and am not sure what the proper amount for my example with 12pe32 would be ? could someone explain what influence atc and vtc have and how to calc for 12pe32 when driver is mounted directly to the board with no chamber ?


I attached some sims for what I think might work best with my restrictions . I wanted to ask if they make sense or if I missed something or if there might be a better way ?

thanks
malcolm
Attached Images
File Type: png 12pe32 hornresp.PNG (54.5 KB, 159 views)
File Type: png power graph.PNG (47.6 KB, 160 views)
File Type: png impulse.PNG (26.8 KB, 158 views)
File Type: jpg j horn 001.jpg (163.2 KB, 161 views)
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Old 2nd April 2015, 12:54 AM   #2
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1. Sure, but you'd need to tweak the horn parameters to them to get the best performance. Your current driver is very good.

2. This will affect the distortion. At 'home' levels you could go up to 3 (in general) ... at the limits how strong the driver cone is will be an issue. What you have at the moment looks about right. Tightening up the throat will extend the bandwidth of the horn.... but you already have the expected bandwidth (you would expect the driver to play up to 500hz)

3. Yes... you could aim a little lower, which would require a longer horn. If the horn is against a wall/floor... or in a corner, then the mouth size is fine. In free space you might end up with more ripples than you'll like.

4. If you want to be really by the book. No, yes.

5. Less than you might expect, at these frequencies. It starts to matter more at the top of your passband. If you were going to run the horn without a LPF, then I'd say pay attention. OTOH if you're going to tailor it's response so it's 48dB / octave with the -6dB point at 250hz.... then it almost doesn't matter.

6. Set them to zero if you like ..... although as you've probably seen then numbers you have there now are not having any effect either. The would roughly add up to a front chamber with an opening the size of your driver, with about 1 board thickness (say 3/4").



It looks good. Have a play with reducing your back chamber volume if it doesn't harm the output too much. This will control cone movement and flatten the drivers electrical impedance..
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Old 2nd April 2015, 07:44 AM   #3
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Quote:
Originally Posted by hum4god View Post
I am still struggling with VTC and ATC and am not sure what the proper amount for my example with 12pe32 would be ? could someone explain what influence atc and vtc have and how to calc for 12pe32 when driver is mounted directly to the board with no chamber?
Hi Malcolm,

The throat chamber acts as a low pass filter. If you add a very short cylindrical second segment to your design, with S2 = 6000, S3 = 6000 and L23 (Exp) = 0.01, you will then be able to use the Loudspeaker Wizard tool to adjust the value of Vtc to see the effect on the power response in real time.

When the driver is mounted directly to the board, use the Driver Front Volume tool to calculate the volume to use for Vtc (assuming that you have a driver to measure). Set Atc = Sd.

Kind regards,

David
Attached Images
File Type: png Attach_1.png (52.8 KB, 137 views)
File Type: png Attach_2.png (55.6 KB, 40 views)
File Type: png Attach_3.png (42.4 KB, 47 views)
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Old 3rd April 2015, 12:28 AM   #4
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Default Alternative

You may want to look at the work of PWK and use corner horn(s) for the bottom end of an all-horn system. For the design of such systems, it is the mid range performance were the design challenges are to be found. For the bottom end, the following article [1] may be used in conjunction with David's program to simulate the performance of an alternative corner bass horn.

Regards,

WHG


[1] Harris Article
Attached Files
File Type: pdf KH-RMH1.pdf (855.7 KB, 30 views)
File Type: pdf KH-RMH2.pdf (807.5 KB, 22 views)
File Type: pdf KH-RMH3.pdf (407.1 KB, 20 views)
File Type: pdf KH-RMH4.pdf (480.8 KB, 19 views)
File Type: pdf KH-RMH5.pdf (520.2 KB, 18 views)
File Type: pdf KH-RMH6.pdf (392.6 KB, 21 views)
File Type: pdf KH-RMH7.pdf (525.6 KB, 19 views)
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Old 4th April 2015, 03:04 AM   #5
hum4god is offline hum4god  United States
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Quote:
Originally Posted by David McBean View Post
Hi Malcolm,

The throat chamber acts as a low pass filter. If you add a very short cylindrical second segment to your design, with S2 = 6000, S3 = 6000 and L23 (Exp) = 0.01, you will then be able to use the Loudspeaker Wizard tool to adjust the value of Vtc to see the effect on the power response in real time.

When the driver is mounted directly to the board, use the Driver Front Volume tool to calculate the volume to use for Vtc (assuming that you have a driver to measure). Set Atc = Sd.

Kind regards,

David
thanks a lot David for explaining that , and again your program is truly amazing .
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Old 6th April 2015, 09:26 PM   #6
hum4god is offline hum4god  United States
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Quote:
Originally Posted by whgeiger View Post
You may want to look at the work of PWK and use corner horn(s) for the bottom end of an all-horn system. For the design of such systems, it is the mid range performance were the design challenges are to be found. For the bottom end, the following article [1] may be used in conjunction with David's program to simulate the performance of an alternative corner bass horn.

Regards,

WHG


[1] Harris Article
unfortunately , i do not have my corners available to put speakers there .
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