Hi Y'all,
I'll attach a drawing with additional dimensions, let me know if you need anything else. Two sheets will give you additional wood for braces. The sealing at the removable panels is critical.
By the way, I think the port could also be circular, see attached drawing, but, I'd like to get bjorno to confirm this.
Regards,
I'll attach a drawing with additional dimensions, let me know if you need anything else. Two sheets will give you additional wood for braces. The sealing at the removable panels is critical.
By the way, I think the port could also be circular, see attached drawing, but, I'd like to get bjorno to confirm this.
Regards,
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Thank you both so much!!!! I may go with the circular port and use a router to smooth out the edges.
I am so excited to get a solid 20hz in my home theater room!
I am speechless...I really am.
I have printed out the PDF's for this project and also modeled it in hornresp....it is smaller than I thought and close to flat from 30 to 100 hz. Really nice! Excursion also seems perfectly under control.
I am starting to think more about horn design....it must be an entirely different way of thinking. Whereas vented, ported, bandpass etc..etc...is all about the volume of the enclosure, it appears as if the horns are more concerned with the lengths of the sections....maybe I am finally starting to get it?!
I have a high pass filter at 18hz built into my amp...do you think this is enough to protect my drivers?
I am starting to think more about horn design....it must be an entirely different way of thinking. Whereas vented, ported, bandpass etc..etc...is all about the volume of the enclosure, it appears as if the horns are more concerned with the lengths of the sections....maybe I am finally starting to get it?!
I have a high pass filter at 18hz built into my amp...do you think this is enough to protect my drivers?
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Hi permo,
Post #44: "...high pass filter at 18hz built into my amp...do you think this is enough to protect my drivers?"
Do you have any additional data on your amp, and the filter in question? Take a look at the displacement in Hornresp, as long as you keep the input power low enough that the excursion stays below Xmax at the peak @ 27Hz your low cut should protect you. I'm saying that without knowing the Q and the order of the particular filter, so be careful.
If one sub does not give you enough volume, I'd recommend multiple subs. Parts Express has a very nice sale on this driver right now.
Regards,
Post #44: "...high pass filter at 18hz built into my amp...do you think this is enough to protect my drivers?"
Do you have any additional data on your amp, and the filter in question? Take a look at the displacement in Hornresp, as long as you keep the input power low enough that the excursion stays below Xmax at the peak @ 27Hz your low cut should protect you. I'm saying that without knowing the Q and the order of the particular filter, so be careful.
If one sub does not give you enough volume, I'd recommend multiple subs. Parts Express has a very nice sale on this driver right now.
Regards,
I would sure hope that these two drivers (cone area nearly the same as a standard 15") would be more than enough for me! I did get the great deal on the drivers though..both shipped to me for less then $100. By one sub, you mean two driver in one enclosure correct?
This is all the information on the subsonic filter that I got from a parts express tech
"ALL DAYTON AMPS HAVE SUBSONIC FILTER AT 18 TO 21 HZ BUILT IN"
http://www.daytonaudio.com/media/resources/300-812-dayton-audio-apa150-manual-42740.pdf
Hi permo,
I think you'll be fine with that particular amplifier/filter. I would check some more with the manufacturer, or Parts Express, on the character of the subsonic (low-cut) filter, as it is not listed in the "manual".
Yes, by sub I ment the whole thing (drivers + enclosure).
There is a thread on multiple subs: http://www.diyaudio.com/forums/subwoofers/134568-multiple-small-subs-geddes-approach-138.html
For my own use one of these dual 8x12 subs would be enough, but the approach described in the above thread is intriguing.
Regards,
I think you'll be fine with that particular amplifier/filter. I would check some more with the manufacturer, or Parts Express, on the character of the subsonic (low-cut) filter, as it is not listed in the "manual".
Yes, by sub I ment the whole thing (drivers + enclosure).
There is a thread on multiple subs: http://www.diyaudio.com/forums/subwoofers/134568-multiple-small-subs-geddes-approach-138.html
For my own use one of these dual 8x12 subs would be enough, but the approach described in the above thread is intriguing.
Regards,
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I have an email out to Dayton Audio tech support, I will see what they say.
My current home theater sub is a canned boston acoustics with a 10"driver in about 1.5 cubic feet tuned to around 50hz. Built in 120 watt amp. I bought it a while back. this will be a MASSIVE upgrade.
Here is a simulation showing the impact of a 18 Hz BW2 HPF and a 80 Hz LR4 LPF acting on the excursion of one of the posted simulations:
b
Attachments
Hi permo,
Post #53: "...enclosure is basically a 30hz horn...I am still concerned about the safety of my subs with sub 30hz material...".
When I plug the drawing values into Hornresp I end up with about a 19Hz -3dB point. In bjorno's graphs it looks like -3dB right @ 20Hz even with the 18Hz HP (green curve). Bjorno has the displacement dip right around 20Hz, with the values from the drawing you end up at about 21Hz in Hornresp. If we assume, that your amplifier can put out short time burst of twice its rated power (i.e.: 300W instead of 150W) you are looking at a displacement of 11mm @ 28Hz.
So, if your driver's T/S parameters are anywhere close to the ones bjorno used in his design-and, if the power rating of the driver's is even remotely in the ball park, you should have a 20hz T-TQWT that can safely handle your amplifier's undistorted output, particularly with music and home theater signals (I always advise against high-power sinewave testing, that's for manufacturer's that have a box full of extra drivers laying around).
Regards,
Post #53: "...enclosure is basically a 30hz horn...I am still concerned about the safety of my subs with sub 30hz material...".
When I plug the drawing values into Hornresp I end up with about a 19Hz -3dB point. In bjorno's graphs it looks like -3dB right @ 20Hz even with the 18Hz HP (green curve). Bjorno has the displacement dip right around 20Hz, with the values from the drawing you end up at about 21Hz in Hornresp. If we assume, that your amplifier can put out short time burst of twice its rated power (i.e.: 300W instead of 150W) you are looking at a displacement of 11mm @ 28Hz.
So, if your driver's T/S parameters are anywhere close to the ones bjorno used in his design-and, if the power rating of the driver's is even remotely in the ball park, you should have a 20hz T-TQWT that can safely handle your amplifier's undistorted output, particularly with music and home theater signals (I always advise against high-power sinewave testing, that's for manufacturer's that have a box full of extra drivers laying around).
Regards,
Hi permo,
Post #53: "...enclosure is basically a 30hz horn...I am still concerned about the safety of my subs with sub 30hz material...".
When I plug the drawing values into Hornresp I end up with about a 19Hz -3dB point. In bjorno's graphs it looks like -3dB right @ 20Hz even with the 18Hz HP (green curve). Bjorno has the displacement dip right around 20Hz, with the values from the drawing you end up at about 21Hz in Hornresp. If we assume, that your amplifier can put out short time burst of twice its rated power (i.e.: 300W instead of 150W) you are looking at a displacement of 11mm @ 28Hz.
So, if your driver's T/S parameters are anywhere close to the ones bjorno used in his design-and, if the power rating of the driver's is even remotely in the ball park, you should have a 20hz T-TQWT that can safely handle your amplifier's undistorted output, particularly with music and home theater signals (I always advise against high-power sinewave testing, that's for manufacturer's that have a box full of extra drivers laying around).
Regards,
Wow, it seems to good to be true! All from a 55 liter box. I am so greatfull that you guys helped me. I am heading to the lumber store today to purchase materials. I am going to build an MDF version to start I think.
I am still brainstorming a way to make the panels air tight, rigid, but also removable. I am thinking some sort of weatherstripping or flexible gasket type seal.
Apparently i still have some work to do in hornresponse. I entered the info from the detailed plans in, but my spl response is not the same as what you guys modeled. I like yours better!!!
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Hi permo,
183.6 Liter_external (51.675"H x 10.065"W x 21.539"D). If you post your Hornresp input screen I'll take a look at it.
For removable panels take a look at geitman's thread: http://www.diyaudio.com/forums/subw...ped-horn-th-spud.html?perpage=25&pagenumber=1, he did it for his TH-SPUD, interesting thread. I like two runs of wheather stripping, one to each side of the screws: Speaker Gasketing Tape 1/8" x 1/2" x 50 ft. Roll 260-542.
I'll attach a drawing with thoughts on braces and screws:
Regards,
183.6 Liter_external (51.675"H x 10.065"W x 21.539"D). If you post your Hornresp input screen I'll take a look at it.
For removable panels take a look at geitman's thread: http://www.diyaudio.com/forums/subw...ped-horn-th-spud.html?perpage=25&pagenumber=1, he did it for his TH-SPUD, interesting thread. I like two runs of wheather stripping, one to each side of the screws: Speaker Gasketing Tape 1/8" x 1/2" x 50 ft. Roll 260-542.
I'll attach a drawing with thoughts on braces and screws:
Regards,
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.Are these braces just centered within the duct so that they don't cause a disturbance in airflow? Here is how I get a way small volume...I entered the numbers from the diagram you so awesomely provided.
Here is where I get only 55 liters or so:
Hi permo,
The braces can be centered, or better offset by about the width of the wood from the center line, both left and right.
That is not the input screen, so I cannot tell if you have entered the same T/S parameters. Also, Hornresp volumes are net volumes.
Here is the input screen I come up with for Rev.01 (Post #33):
Regards,
The braces can be centered, or better offset by about the width of the wood from the center line, both left and right.
That is not the input screen, so I cannot tell if you have entered the same T/S parameters. Also, Hornresp volumes are net volumes.
Here is the input screen I come up with for Rev.01 (Post #33):
Regards,
Attachments
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FWIW, a few years ago, I build a T-TQWT with a single Tangband W69 and it worked well down to 30 Hz, as modeled.
Tang Band W69-1042J 6"x9" Subwoofer 264-837
Tang Band W69-1042J 6"x9" Subwoofer 264-837
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