Hi Oliver,
In your example you only generate acoustic coupling outside the TH’s. In that case I think you are better off with two single cabs. The use of dual drivers that have a mutual S4-S5 section (preferably a little earlier than S4) gives the advantage of full horn coupling from the point where both channels meet. In other words, the lowest resonance does lower. The second advantage of such construction where the magnets face each other is that you will see a bump in response at the quarter wavelength between the two drivers. Usually I try to designing the last section (S4-S5) as a waveguide rather than a accurate expanding horn. This way you can compensate the driver volume but I also use it to create a small lift in the lowest bandpass of the horn (for TH’s that is between the 1/4WL of the horn and the first system resonance and for traditional horns it is at the first system resonance). The response-bumb at the higher part of the bandpass needs to be EQ-ed down. This can help to prevent the bass-horn from running into compression above its full wavelength at max levels. Oh, and no guesses needed ;
In your example you only generate acoustic coupling outside the TH’s. In that case I think you are better off with two single cabs. The use of dual drivers that have a mutual S4-S5 section (preferably a little earlier than S4) gives the advantage of full horn coupling from the point where both channels meet. In other words, the lowest resonance does lower. The second advantage of such construction where the magnets face each other is that you will see a bump in response at the quarter wavelength between the two drivers. Usually I try to designing the last section (S4-S5) as a waveguide rather than a accurate expanding horn. This way you can compensate the driver volume but I also use it to create a small lift in the lowest bandpass of the horn (for TH’s that is between the 1/4WL of the horn and the first system resonance and for traditional horns it is at the first system resonance). The response-bumb at the higher part of the bandpass needs to be EQ-ed down. This can help to prevent the bass-horn from running into compression above its full wavelength at max levels. Oh, and no guesses needed ;
The TH Spud driver arrangement looks quite promising.
The TH 812 is also similar, as is the DTS 10, and the TH 212.
"when playing back a 35 Hz sine wave at very moderate levels, the d&B Q-Subs have very noticeable harmonics that are completely gone when switching to the TH212."
The TH 812 is also similar, as is the DTS 10, and the TH 212.
"when playing back a 35 Hz sine wave at very moderate levels, the d&B Q-Subs have very noticeable harmonics that are completely gone when switching to the TH212."
An externally hosted image should be here but it was not working when we last tested it.
Hi Oliver,
Not really, our first plan was to design the dual tham for 18Sound 15W1500 but that was not the ideal partner. It did work well with some old 1400 and 1401 series. In other words, high BL with a serious power handling if high output levels are important.
About your drawing, maybe you can switch the drivers for a more optimised high pressure zone (preferably between the drivers).
Not really, our first plan was to design the dual tham for 18Sound 15W1500 but that was not the ideal partner. It did work well with some old 1400 and 1401 series. In other words, high BL with a serious power handling if high output levels are important.
About your drawing, maybe you can switch the drivers for a more optimised high pressure zone (preferably between the drivers).
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Hi Djim,
Would be interesting to so how something like a true PPSL-TH w/ 15" drivers compares to e.g.: the Xoc1 TH18. But, that sounds like a lot of work, and a different thread. I'll see if I can find the time to doodle, and simulate around a little but these next weeks I have a full schedule.
Regards,
Would be interesting to so how something like a true PPSL-TH w/ 15" drivers compares to e.g.: the Xoc1 TH18. But, that sounds like a lot of work, and a different thread. I'll see if I can find the time to doodle, and simulate around a little but these next weeks I have a full schedule.
Regards,
Hi Oliver,
It took a while before we got both paths equalised (that's what lead us to the cone correction). After everything was fixed, the opinions were different. Some just missed something. In my view, every improvement in THD is an optimisation. The only argument for me not to use it is the gain factor of the other arrangement. When subs are only used below full wavelength, I would go for PP arrangements and that counts for other design types as well, as long size and weight is not a problem. Like I said before it beats every single 18" within the range of dual 15's, but that's my opinion of course... ;
It took a while before we got both paths equalised (that's what lead us to the cone correction). After everything was fixed, the opinions were different. Some just missed something. In my view, every improvement in THD is an optimisation. The only argument for me not to use it is the gain factor of the other arrangement. When subs are only used below full wavelength, I would go for PP arrangements and that counts for other design types as well, as long size and weight is not a problem. Like I said before it beats every single 18" within the range of dual 15's, but that's my opinion of course... ;
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"Ever worked with the Q-subs? "
No, I haven't. The above quote, however, was from someone that used them and the Danley too.
http://www.dbaudio.com/en/systems/black-range/q-series/q-sub/
The Q-SUB is an actively driven low compression bass-reflex loudspeaker fitted with a high excursion 18" driver.
"Here is a sketch of a dual B&C 12PS100"
Your driver positions are reversed fro the ones used by Danley, and that gives rise to a bigger cavity effect limiting bandwidth.
I too am looking at a dual 12PS100 design.
This is the basic idea. I was thinking of making the lower front of the cabinet removable to experiment with a Karlson and Keystone opening (after Weltersys).
http://i56.photobucket.com/albums/g196/dkleitsch/12PS100x2.gif
The black line is 2V, I forget what the gray line was. 60V hits x-max on a sine-wave, it should be able to handle more on real program material (the biggest Crest I have is only 1.4KW anyway).
No, I haven't. The above quote, however, was from someone that used them and the Danley too.
http://www.dbaudio.com/en/systems/black-range/q-series/q-sub/
The Q-SUB is an actively driven low compression bass-reflex loudspeaker fitted with a high excursion 18" driver.
"Here is a sketch of a dual B&C 12PS100"
Your driver positions are reversed fro the ones used by Danley, and that gives rise to a bigger cavity effect limiting bandwidth.
I too am looking at a dual 12PS100 design.
This is the basic idea. I was thinking of making the lower front of the cabinet removable to experiment with a Karlson and Keystone opening (after Weltersys).
http://i56.photobucket.com/albums/g196/dkleitsch/12PS100x2.gif
The black line is 2V, I forget what the gray line was. 60V hits x-max on a sine-wave, it should be able to handle more on real program material (the biggest Crest I have is only 1.4KW anyway).
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Hi djk,
I like the bifurcation in your layout in Post #871, it looks simple and efficient, and, on the mouth side, the keystone exit should fit it well.
As to the driver position being "reversed from the ones used by Danley" in my sketch in Post #865, that is intentional. I was thinking about having more control over the throat (S1/S2) area, trying to find external room for wheels, and thinking about the cooling of the driver which has his magnet structure hidden in the throat area of the horn (e.g.: air flow, and cooling backplate/access plate located closely to the driver magnet structure). This was basically a quick study, and maybe somebody can get some value out of it. A dual B&C 12PS100 TH should make one nice loudspeaker.
Regards,
I like the bifurcation in your layout in Post #871, it looks simple and efficient, and, on the mouth side, the keystone exit should fit it well.
As to the driver position being "reversed from the ones used by Danley" in my sketch in Post #865, that is intentional. I was thinking about having more control over the throat (S1/S2) area, trying to find external room for wheels, and thinking about the cooling of the driver which has his magnet structure hidden in the throat area of the horn (e.g.: air flow, and cooling backplate/access plate located closely to the driver magnet structure). This was basically a quick study, and maybe somebody can get some value out of it. A dual B&C 12PS100 TH should make one nice loudspeaker.
Regards,
Using existing material that is a little small
The original design in post 6 is approximately 22.48” wide, making all the reflectors, baffle, base and top 535 mm wide (21.06”).
I have a fairly large amount of 20” X 30” Baltic Birch.
I was wondering how much reducing the width of the cabinet by 27 mm (1.06”), while maintaining all the angles and other dimensions would effect the speakers performance?
.
Do I need to start over and simulate it in HRSP.?
.
I wouldn't be opposed to going with a 15" driver if that would help.
.
It looks to me that this would reduce the volume by about 19 liters, or almost 5%.
.
Am I barking up the wrong tree, or is this possibly do-able?
Thank you for you opinions,
Dave
The original design in post 6 is approximately 22.48” wide, making all the reflectors, baffle, base and top 535 mm wide (21.06”).
I have a fairly large amount of 20” X 30” Baltic Birch.
I was wondering how much reducing the width of the cabinet by 27 mm (1.06”), while maintaining all the angles and other dimensions would effect the speakers performance?
.
Do I need to start over and simulate it in HRSP.?
.
I wouldn't be opposed to going with a 15" driver if that would help.
.
It looks to me that this would reduce the volume by about 19 liters, or almost 5%.
.
Am I barking up the wrong tree, or is this possibly do-able?
Thank you for you opinions,
Dave
Hi Dave, this is definitely doable. The frequency response will be almost exactly identical, output will be slightly reduced, but by less than 1dB by my estimate. Feel free to compare the differences yourself in hornresp - just take the existing hornresp inputs and reduce all the S1-S5 areas by 5% and do "compare previous". You will see that the two traces are very close.
Hi all,
What's the better way to mount these 18" in the wood,I was wondering if they come loose ,your stuck,so I got these at the depo,suggestion are welcomed,Thought about the cleat from the inside and some loctite on the bolt from the speaker side.
A build pic or 2!
What's the better way to mount these 18" in the wood,I was wondering if they come loose ,your stuck,so I got these at the depo,suggestion are welcomed,Thought about the cleat from the inside and some loctite on the bolt from the speaker side.
A build pic or 2!
Attachments
That's a great build NS. Nice work, nice straight cuts, etc. LOVE that woofer and box design. If you build a second, hunt down BB plywood, gesh - that stuff is bullet proof [was cutting some 3/4" BB yesterday]
It certainly deserves a new thread; please remember some day someone will goggle the model number and all the work you put into this will not be found.
Onward!!!....whats with the blue paint?
It certainly deserves a new thread; please remember some day someone will goggle the model number and all the work you put into this will not be found.
Onward!!!....whats with the blue paint?
