Guide to WinISD Pro and Hornresp |
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nomis
Registered User Joined: 07 January 2008 Location: France Status: Offline Points: 538 |
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sorry,double post
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wash with gasoline
Registered User Joined: 23 June 2009 Location: california Status: Offline Points: 51 |
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thank you Johan, this is how i am understanding what you have said. assuming that s2 is at the narrowest point at 105.5mm and that i have a 18mm material baffle board with a 100mm by 450mm cut out. and that i just used the curved measurements that i posted for length. does this look rite? ...im not going to build this, im just trying to figure out the way this works. i would think that if i was going to use a throat like this i would want to make the s1,s2 con path longer punnisher style? ...think i might be starting to understand this a little, spending way to much time reading threw your guys posts thank you
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dry with match
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mobiele eenheid
Old Croc Joined: 15 August 2004 Location: Netherlands Status: Offline Points: 1568 |
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Assuming the internal width is 60 cm (external 63,6 cm) the horn seems overall pretty good.
However if the outside measurements are 120 x 90 x 63,6 cm (~687 liters), the total nett simulated volume is too large. The corner deflectors take ~30 liter into account, the outside (5) panels take ~70 liters into account. That's already 687-100 = 587 liters. Minus the volume occupied by the internal panels, bracing, the driver itself (~7 liters), leaves less then the 580 liters you simulated.
Meaning that either the horn path length should be smaller or the Vrc should be smaller. As a rule of thumb; Simulating the nett volume a factor 1.3 times smaller as the total volume is a good starting point.
The Vtc consist of the volume inside the driver cone (say 4500 cm^3 )plus the volume inside the baffle cut-out (1,8 x 42^2 x 0,7854 = 2500 cm^3) 2500 cm^3 + 4500 cm^3 = 7000 cm^3. That's not all that interesting for bass horns but it's a 55% difference
Best regards Johan
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wash with gasoline
Registered User Joined: 23 June 2009 Location: california Status: Offline Points: 51 |
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thank you for helping me figure this out. i was just trying to figure out the way to come to the input data from a drawing, i was not taking into account panel widths on the quick sketch on the last page. as far as punisher style i meant how the driver fires into a kind of triangle shaped area that blends the width of the driver into the full width of the box. im still trying to wrap my head around different throat styles i will post a pic of that sketch with 18mm panels in a min ...i have to reboot my macbook into vista where i have all that stuff saved
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dry with match
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wash with gasoline
Registered User Joined: 23 June 2009 Location: california Status: Offline Points: 51 |
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...ok, here goes a long post. hope i make sense. I am not going to build this box, it is just the first thing i drew up trying to understand this process. It seems to me it is way to big for what it does. Im modeling in .5 x pi knowing that i am going to be useing a group of 4 boxes outside and as i understand it, it should be a simmilar plot as 1 box in .5pi. I did not put a slot throat on this one. Im getting s1 by measureing the shortest length in the center of the driver between the baffle board and the top of the box, 72.4mm converting to cm 7.24 and x by the internal depth converted to cm 56.4 = s1 of 408.336 which hr rounds to 408.34 im getting s2 from the width of the first bend measured between the corner and the center of my angled corner piece 16.46 x 56.4= 928.344 rounded to s2 of 928.34 by hr. what i am doing to place my angled corner piece is measureing between the inner corner straight up and straight to the back and adverageing the 2, then putting a mark at that measurement in a straight line between the inner corner and the corner of the box, then putting a line at a 90deg angle to make my angled corner. to me it seems this would make it so there is no negative expansion? for the con measurements i put a mark halfway on the s measurements, for the first one that would be 378.5mm converted to 37.85 for hr. and the same for s3 and s4 and there cons. for vrc i let sketchup tell me the flat area 173706.5mm then x by the depth 564mm to get 97970466 square mm convert to 97.970466 L minus the 8.6L the driver pdf said it takes, to get a vrc of 89.370466 which i rounded to 89.4 to put in hr. for lrc i measured down from the baffle board at 90 deg. on both sides and adveradged the measurements to 27.93 for vtc i didnt find any info on my driver so i just used te average of 4.5L. for atc i used the area of the speaker because it is just mounted to the baffle board. did you make it this far is there anything im leaving out or got wrong? thanks again for helping me get a handle on this ...tryed to break it up some, dont know if that helps or not. writing is my weakest point. i communicate much better in person
Edited by wash with gasoline - 07 July 2009 at 2:37am |
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subbass
Old Croc Joined: 30 March 2009 Location: bristol Status: Offline Points: 1683 |
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wash with gasoline - you may want to break up that paragraph a little .. gonna make it easier for people to help you
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mobiele eenheid
Old Croc Joined: 15 August 2004 Location: Netherlands Status: Offline Points: 1568 |
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You seem to be doing very well. Definately less choatic then my way of designing.
As there are multiple way's of simulating this, the way you're simulating you should take the part that expands from 0,01 cm^2 towards 408 cm^2 as part of the Vtc (4500 + 5500 as a guess).
An other way is to simulate this as an offset horn. In this case S1 is 0,01 cm^2, S2 = 408 cm^2 and so on.
Best regards Johan
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hanzs23
New Member Joined: 25 July 2009 Location: Czech rep. (EU) Status: Offline Points: 2 |
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Hi, I have 4 pcs of very similiar horn boxes, that wash with gasoline presented above. My boxes are for 15 inch speakers, now with RCF L15P200AK. Schematic picture here: http://merkur_sound.sweb.cz//sub.jpeg (inside width = 40cm) And I did the simulation like wash with gasoline. I only changed a little parameters S1-S4 and T-S parameters of speaker. http://merkur_sound.sweb.cz//hornresp_param.jpg Simulated impedance plot: http://merkur_sound.sweb.cz//hornresp_imp.jpg And I also measured the impedance on real boxes: http://merkur_sound.sweb.cz//imp_horn.jpg You can see the difference between simulation and real measurement. Can somebody help me and tell me what should I change in parameters to receive better simulation?
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mobiele eenheid
Old Croc Joined: 15 August 2004 Location: Netherlands Status: Offline Points: 1568 |
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Hi,
You sim'ed in quarter space, is this also the measurement from a stack of 4 boxes in half space? Simulating a single cabinet gives more of a spiky impedance sim. The more cabinets you stack the flatter the impedance response becomes. A single cabinet outside would be 2,0 Pi.
Also I think the VRC is more like 70 liters.
Best regards Johan
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hanzs23
New Member Joined: 25 July 2009 Location: Czech rep. (EU) Status: Offline Points: 2 |
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Thank you Johan for advice! The measurement was taken on single box lying on the ground. When I changed to 2PI the impedance plot is much better! Vrc parameter I have 120 litres. |
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dj-panoramix
Registered User Joined: 28 September 2005 Location: France Status: Offline Points: 462 |
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in hornresp, for the spl max, do you use the xmax (peak to peak) or the xmax(linear) ? |
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mobiele eenheid
Old Croc Joined: 15 August 2004 Location: Netherlands Status: Offline Points: 1568 |
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The latter (0 - peak)
Best regards Johan
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