https://www.eminence.com/pdf/Delta_Pro_18A_cab.pdf
Delta Pro-18A Two By 18 Subwoofer
F3 : 48.75 Hertz
Cabinet Recommendations | Eminence Speaker
" For your knowledge, Fb represents the box tuning frequency. F3 is the –3dB frequency the cabinet can produce. This is considered the lowest audible frequency. It is a point 3dB down from the mid-band piston response. "
Delta Pro-18A Two By 18 Subwoofer
F3 : 48.75 Hertz
Cabinet Recommendations | Eminence Speaker
" For your knowledge, Fb represents the box tuning frequency. F3 is the –3dB frequency the cabinet can produce. This is considered the lowest audible frequency. It is a point 3dB down from the mid-band piston response. "
The only way to get a relatively small box with two huge Vas spec drivers, especially if tuning near/at/below Fs, is to go [clamshell] isobaric loading if vented or sealed with a Linkwitz-Riley Transform filter [LRT].
Since you want vented [isobaric], then HR predicts Xmax limited to >120 dB/m/24 Hz/250 W/1pi:
Vb = 125 L net, 164.6 L net w/vent duct
vent = 396 cm^2 x 100 cm long
With a vent this large, maybe better overall to combine the cab, vent volumes to create a TQWT variant.
GM
Since you want vented [isobaric], then HR predicts Xmax limited to >120 dB/m/24 Hz/250 W/1pi:
Vb = 125 L net, 164.6 L net w/vent duct
vent = 396 cm^2 x 100 cm long
With a vent this large, maybe better overall to combine the cab, vent volumes to create a TQWT variant.
GM
First steps with WIN ISD ....
300 liters
FS 25 Hz
This is very interesting .....
Now should you simulate the ports to achieve this response ?
Attachments
GM, I do not want "a relatively small box". I want the 300 liter box and 2 speakers designed by Eminence from the attached PDF ( again !)
But get to 25/30 hertz with the lowest SPL drop I can achieve. It does not matter to me if this will be sacrificing the overall performance of the design, - which does not interest me too much, or almost nothing - above 40/50 Hertz. (This is what Eminence designed for PA use.)I know my English is very poor, but ... so much
?https://www.eminence.com/pdf/Delta_Pro_18A_cab.pdf
Delta Pro-18A Two By 18 Subwoofer
Hummmmm ....... everyone look at this ....:
Maximum Acoustic Power (dB-SPL/Hz at 1 m)
https://www.eminence.com/pdf/Delta_Pro_18A_cab.pdf
20 hertz: 91 DB
30 hertz: 109 DB
40 hertz: 124 db
I think I will copy exactly the design of Jerry McNutt, and I will be happy, I will even be able to sell the cabinet as "an exact copy of the original Eminence design", if WAF were to become too complicated / nervous in the future .....
And I will not bother Tony, - from Eminence, technical assistance - because I think he would give me the same advice I am giving myself ....:
"Leave it like this! For your requirements at home, you will travel in first class"
( A greeting to him, he has been very kind in another opportunity that I needed his advice, great person )
....:Maximum Acoustic Power (dB-SPL/Hz at 1 m)
https://www.eminence.com/pdf/Delta_Pro_18A_cab.pdf
20 hertz: 91 DB
30 hertz: 109 DB
40 hertz: 124 db
I think I will copy exactly the design of Jerry McNutt, and I will be happy, I will even be able to sell the cabinet as "an exact copy of the original Eminence design", if WAF were to become too complicated / nervous in the future .....
And I will not bother Tony, - from Eminence, technical assistance - because I think he would give me the same advice I am giving myself ....:
"Leave it like this! For your requirements at home, you will travel in first class"
( A greeting to him, he has been very kind in another opportunity that I needed his advice, great person )
News to me, all previous comments along with mine, Brian's, Freddy's posts strongly indicated size was a major issue, so when I went to finish/post I stuck with what I started to post several days ago, but had to deal with some storm damage first.
Re 300 L, I see nowhere before today where you have stated that you want a 300 liter box for dual drivers, only that you posted simming a 300 L box several hours AFTER I posted.
Re driver output below box tuning, this is just the driver 'flapping in the breeze' [uncontrolled], distorting its [HF] response above Fb and eating up amp power maybe required higher up to keep it from clipping as this series of animations very graphically shows: Welcome Secrets of Home Theater and High Fidelity
In short, a vented speaker should always be tuned to handle the lowest frequency desired to be reproduced; if not, then some type of high pass filter should be used to protect/limit the driver's output below Fb.
GM
Re 300 L, I see nowhere before today where you have stated that you want a 300 liter box for dual drivers, only that you posted simming a 300 L box several hours AFTER I posted.
Re driver output below box tuning, this is just the driver 'flapping in the breeze' [uncontrolled], distorting its [HF] response above Fb and eating up amp power maybe required higher up to keep it from clipping as this series of animations very graphically shows: Welcome Secrets of Home Theater and High Fidelity
In short, a vented speaker should always be tuned to handle the lowest frequency desired to be reproduced; if not, then some type of high pass filter should be used to protect/limit the driver's output below Fb.
GM
" Another trade-off for this augmentation is that, at frequencies below 'tuning', the port unloads the cone and allows it to move much as if the speaker were not in an enclosure at all. This means the speaker can be driven past safe mechanical limits at frequencies below the tuning frequency with much less power than in an equivalently sized sealed enclosure. For this reason, high-powered systems using a bass reflex design are often protected by a filter that removes signals below a certain frequency."
Bass reflex - Wikipedia
Hi GM
For this same reason, my simulation looks good but it's very bad !
The controller to use has a Fs of 28 hertz and I am simulating at 25 Hz ..... But it seems that this error went unnoticed, I take for granted that my thread should not arouse much interest in most of the readers ... .and less with that statement: "vintage speaker JBL for subwofer" ....
Yes, you're right, I did not say anywhere that I wanted a big box. Maybe I took it for granted when I uploaded the photos indicating the place where I will put the cursed artifact. (see the red cross) Waf has no problems, and in that corner a large box enters without problems, - in a vertical sense even more - although it did not resolve yet whether it will be in the form of a prism or rectangular.
I will continue then with my construction, according to the original design of Eminence with two speakers and in 300 liters. ( 10.7 ft)
The experience of simulation has helped me to corroborate something that I believe had already raised here.
Two speakers in a box of the same liters can not be tuned as low as one !
(See the first and last example of PDF boxes of Eminence)
One speaker 36.01 hertz F3 / 36.01 Hz /10.45 Ft
Two speakers 48.75 hertz F3 /48.75 Hz / 10.7 Ft
I hope that the storm has not produced any severe material or physical damage to any person, which is the most important thing....
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I was thinking that a single box of 300 liters will be very heavy and voluminous .....
Maniobrar the same during the construction process and then descend it to the ground floor of the house will be very difficult for a single person .....
That changes all the previous study of the box to be built ....
I'll see that I lose or win if I go for two smaller boxes ....
Does anyone know any really serious study about the importance of bass in stereo ?
What I read in the post number 70 of this link does not satisfy me much .....
https://kenrockwell.com/audio/stereo-subwoofers.htm
Can you really perceive differences between a bass mono or bass stereo? (in 20 to 40 hertz, sub frecuency's)
I see a contradiction here ...:
" While low frequencies are less directional, and the direction of a low-frequency sine-wave point-source may be less perceptible, critical to fine music reproduction are low-frequency interchannel phase differences present in true stereo recordings. When reproduced properly with stereo subwoofers (or two full-range speakers), these phase differences are critical to reproducing the sound space of the original concert hall."
" Not being able to locate the subwoofer is good, but the sum of low bass in mono is always bad for true stereo recordings.
All this applies to true stereo recordings, which means most of the classic recordings. With popular music, there is rarely a concert hall involved, and having low stereo is primarily a matter of where the bass effects are filtered."
What instruments of a symphony orchestra would be perceived with better sound stage having stereo subwofers?
The group of contrabasses is usually on the right, (we agree that this situation is not a near-field recording as in a jazz trio, although these contrabasses are close, almost on the proscenium, not the same with the location of the timbal's ( drum's)
These are at the back and in the center of the stage ....
Wow, the more I find out, the more doubts I have ...!
Maniobrar the same during the construction process and then descend it to the ground floor of the house will be very difficult for a single person .....
That changes all the previous study of the box to be built ....
I'll see that I lose or win if I go for two smaller boxes ....
Does anyone know any really serious study about the importance of bass in stereo ?
What I read in the post number 70 of this link does not satisfy me much .....
https://kenrockwell.com/audio/stereo-subwoofers.htm
Can you really perceive differences between a bass mono or bass stereo? (in 20 to 40 hertz, sub frecuency's)
I see a contradiction here ...:
" While low frequencies are less directional, and the direction of a low-frequency sine-wave point-source may be less perceptible, critical to fine music reproduction are low-frequency interchannel phase differences present in true stereo recordings. When reproduced properly with stereo subwoofers (or two full-range speakers), these phase differences are critical to reproducing the sound space of the original concert hall."
" Not being able to locate the subwoofer is good, but the sum of low bass in mono is always bad for true stereo recordings.
All this applies to true stereo recordings, which means most of the classic recordings. With popular music, there is rarely a concert hall involved, and having low stereo is primarily a matter of where the bass effects are filtered."
What instruments of a symphony orchestra would be perceived with better sound stage having stereo subwofers?
The group of contrabasses is usually on the right, (we agree that this situation is not a near-field recording as in a jazz trio, although these contrabasses are close, almost on the proscenium, not the same with the location of the timbal's ( drum's)
These are at the back and in the center of the stage ....
Wow, the more I find out, the more doubts I have ...!
lets say your Delta performs more like it would if lossy Le is not applied - to keep the graph pretty (dunno how it would behave as not had one)
you could apply 6dB boost centered at 30Hz and if done like EV and CV did by using an underdamped 2nd order electrical highpass filter, get flatter response and kick out the useless cone pumping stuff below tuning. Old EV Interface EQ boxes can be sometimes found cheap at Ebay and think in EV's literature there's a schematic plus capacitor sizes for various tuning they used.
maybe GM can figure out how to set hornresp for that filter - i could only get a lumpy fudge - also ask for a good vent
you could apply 6dB boost centered at 30Hz and if done like EV and CV did by using an underdamped 2nd order electrical highpass filter, get flatter response and kick out the useless cone pumping stuff below tuning. Old EV Interface EQ boxes can be sometimes found cheap at Ebay and think in EV's literature there's a schematic plus capacitor sizes for various tuning they used.
maybe GM can figure out how to set hornresp for that filter - i could only get a lumpy fudge - also ask for a good vent
according to hornresp, Delta Pro18a's 28Hz free air resonance would go up an octave to 56Hz in a 150 liter sealed box. James Novak's method in the little red book raised the resonance before venting by 1.56 IIRC (?) that would take 300 liter Vb going by hornresp.
I think 150 liters tuned to ~30Hz with a 6dB boost at 30 would be "ok" What size and aspect vent would you recommend for his 150 liter bass reflex box?
here's a non lossy Le sim of 150l vs 300l - an EV Interface box set for 30Hz peaking would be nice to make the little box perform well. The smaller box might have more "punch"
I think 150 liters tuned to ~30Hz with a 6dB boost at 30 would be "ok" What size and aspect vent would you recommend for his 150 liter bass reflex box?
here's a non lossy Le sim of 150l vs 300l - an EV Interface box set for 30Hz peaking would be nice to make the little box perform well. The smaller box might have more "punch"
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its got a "500 watt" rating - but a 2.5" diameter multi-layer coil to extract whatever from a 67 ounce magnet slug. The OP hasn't specified an amp yet. Maybe a vent that handles 300 watts ??? With 6dB peaking @30Hz hornresp says 75 watts midband will be ~440 watts input at 30Hz.
did Novak publish anything regarding porting a horn at its throat? - seemed like there was something in the little red SAMS book (?)
did Novak publish anything regarding porting a horn at its throat? - seemed like there was something in the little red SAMS book (?)
Boys, I follow you ...
I see that there is a lot to learn and I would not reach the rest of my life to measure up to your knowledge, so I thank you very much but I will continue with WINISD, Hornresp is too complicated for me, I tried but my vehicle got stuck in the mud very soon.
But I imagine that you can arrive at similar results, is not it?
I'm correcting the driver database in WinISD, the version I used did not have the Delta Pro 18 A, and a locker alerted me about badly loaded data. Now everything is in order, although I do not see big differences in the results.
It's early morning here, I promise to upload my graphics soon.
Thanks again for taking the trouble to model my project, which will be very useful for other owners of this driver or with the intention of buying it.
This driver looks very robust and imposing, I think it will be a glory to hear those basses once finished !
PS: I can not guarantee eternity, it was just a witty phrase, but I really thank you sincerely
I see that there is a lot to learn and I would not reach the rest of my life to measure up to your knowledge, so I thank you very much but I will continue with WINISD, Hornresp is too complicated for me, I tried but my vehicle got stuck in the mud very soon.
But I imagine that you can arrive at similar results, is not it?
I'm correcting the driver database in WinISD, the version I used did not have the Delta Pro 18 A, and a locker alerted me about badly loaded data. Now everything is in order, although I do not see big differences in the results.
It's early morning here, I promise to upload my graphics soon.
Thanks again for taking the trouble to model my project, which will be very useful for other owners of this driver or with the intention of buying it.
This driver looks very robust and imposing, I think it will be a glory to hear those basses once finished !
PS: I can not guarantee eternity, it was just a witty phrase, but I really thank you sincerely
FWIW, HR 'says' Eminence's 500 W continuous/1 kW 'fast' transients at tuning seems the practical max in 150 L....... A 7" dia. vent needs damping before any boost, so not a practical alignment unless done as a TQWT.
No throat 'tapping' and not aware Novak contributed any horn design details in the ' little red SAMS book' assuming you mean this one: How to Build Speaker Enclosures: Alexis Badmaieff, Don Davis: 9780572004163: Amazon.com: Books
GM
Yeah, HR specs a little higher Vas apparently, so calcs ~209.45 L, which either power limits the 7" dia. [damped] vent to 250 W/500 W or huge vent = TQWT for 500 W/ 1 kW 6th order alignment, so all things considered, the 150 L alignment is a better choice overall as it's only a couple of dB louder down near/at tuning, which probably will get damped out to lower its stronger pipe horn harmonics.
GM
Yes, the same.
It seems much simpler than previous versions or have many hidden functions that I have not yet found. .
The online help is an interface of the previous versions ..
The Delta Pro 18 T / S of the database were not, if Delta Pro 15.
But they are already loaded correctly, the software says that, when there is bad data, it warns with a box in red, when they are OK, in green ....
I think it's based on the international convention of the operation of traffic lights ...
I sorry .....,I can not with my genius....Let me tell you that I am simulating 208 liters (36x60x96 cm) or 216 liters (48x60x75 cm) to maintain the golden proportions, although I think WINIsd also has this function when calculating the dimensions of the box.
But that is not important for now, that step will come later.
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