DJK
Post #139 are thoes tops similar to these http://www.youtube.com/watch?feature=endscreen&NR=1&v=48qUpmBjQsQ?
Post #139 are thoes tops similar to these http://www.youtube.com/watch?feature=endscreen&NR=1&v=48qUpmBjQsQ?
Not at all.
The tops in the video are a joke, the 'horn' does nothing at higher frequencies.
You must use proper drivers suited for a horn, and build a properly designed horn.
Hornresp (by David McBean) has made it possible for a non-technical person to test a driver and horn design without making any sawdust, wasting any time, or money.
Any cabinet with any driver will make sound (noise), but designing something that sounds good (works properly) takes skill, not luck.
The skill of David McBean makes it so you don't need to be skilled, but to get lucky you still need some basic knowledge.
The tops in the video are a joke, the 'horn' does nothing at higher frequencies.
You must use proper drivers suited for a horn, and build a properly designed horn.
Hornresp (by David McBean) has made it possible for a non-technical person to test a driver and horn design without making any sawdust, wasting any time, or money.
Any cabinet with any driver will make sound (noise), but designing something that sounds good (works properly) takes skill, not luck.
The skill of David McBean makes it so you don't need to be skilled, but to get lucky you still need some basic knowledge.
The captions say it all, scale it up or down as needed.
An impedance variation of 2:1 (fig. 5.10C) will have a ripple of ±3dB.
As the horn mouth and length approach infinity the output becomes smoother, but output at the Fc of the horn drops to zero (you can have too big of a mouth).
Increasing the throat size makes the horn shorter, but also raises the Fc.
Hornresp knows all this, but you knowing this will save you time in using Hornresp.
On selecting drivers, the higher the mass corner, the higher the response will go before needing EQ. For a bass horn pick the lowest efficiency driver that has a mass corner close to where you intend to cross it at.
Mass corner = 2(Fs/Qes).
These are simplifications, but they should help you get started.
(suggested use for old large-throat short horns)
An impedance variation of 2:1 (fig. 5.10C) will have a ripple of ±3dB.
As the horn mouth and length approach infinity the output becomes smoother, but output at the Fc of the horn drops to zero (you can have too big of a mouth).
Increasing the throat size makes the horn shorter, but also raises the Fc.
Hornresp knows all this, but you knowing this will save you time in using Hornresp.
On selecting drivers, the higher the mass corner, the higher the response will go before needing EQ. For a bass horn pick the lowest efficiency driver that has a mass corner close to where you intend to cross it at.
Mass corner = 2(Fs/Qes).
These are simplifications, but they should help you get started.
(suggested use for old large-throat short horns)
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Driver Properties
Name: 12BR70
Type: Standard one-way driver
Company: Beyma
No. of Drivers = 2
Mounting = Standard
Wiring = Parallel
Fs = 35 Hz
Qms = 1.89
Vas = 135 liters
Cms = 0.38 mm/N
Mms = 54.38 g
Rms = 6.328 kg/s
Xmax = 6 mm
Xmech = 9 mm
P-Dia = 252.3 mm
Sd = 500 sq.cm
P-Vd = 0.3 liters
Qes = 0.44
Re = 5.6 ohms
Le = 1 mH
Z = 8 ohms
BL = 12.34 Tm
Pe = 125 watts
Qts = 0.357
no = 1.268 %
1-W SPL = 93.18 dB
2.83-V SPL = 94.73 dB
-----------------------------------------
Box Properties
Name:
Type: Vented Box w/ Active HP Filter
Shape: Prism, square (optimum)
Vb = 4.98 cu.ft
Fb = 29.42 Hz
QL = 6.178
F3 = 31.95 Hz
Fill = minimal
No. of Vents = 1
Vent shape = other
Vent ends = one flush
Av = 31.22 sq.in
Lv = 14 in
-----------------------------------------
Active 12 dB/oct. HP Filter
Fx = 31.48 Hz
Qx = 1.93
Name: 12BR70
Type: Standard one-way driver
Company: Beyma
No. of Drivers = 2
Mounting = Standard
Wiring = Parallel
Fs = 35 Hz
Qms = 1.89
Vas = 135 liters
Cms = 0.38 mm/N
Mms = 54.38 g
Rms = 6.328 kg/s
Xmax = 6 mm
Xmech = 9 mm
P-Dia = 252.3 mm
Sd = 500 sq.cm
P-Vd = 0.3 liters
Qes = 0.44
Re = 5.6 ohms
Le = 1 mH
Z = 8 ohms
BL = 12.34 Tm
Pe = 125 watts
Qts = 0.357
no = 1.268 %
1-W SPL = 93.18 dB
2.83-V SPL = 94.73 dB
-----------------------------------------
Box Properties
Name:
Type: Vented Box w/ Active HP Filter
Shape: Prism, square (optimum)
Vb = 4.98 cu.ft
Fb = 29.42 Hz
QL = 6.178
F3 = 31.95 Hz
Fill = minimal
No. of Vents = 1
Vent shape = other
Vent ends = one flush
Av = 31.22 sq.in
Lv = 14 in
-----------------------------------------
Active 12 dB/oct. HP Filter
Fx = 31.48 Hz
Qx = 1.93
Question regarding the djk PPSL design using the Martin Sound 1844 drivers
Hi djk,
I seriously consider using your PPSL design for the Martin Sound #1844 drivers (please see attached file) for home use (not PA).
1. Is it correctly understood that the total internal volume for each box (Fb = 31Hz) for two drivers is 8 cf? (I just want to make sure about the size before I start drawing)
2. It says "minimal fill" in the simulation. Would 1" of foam/fill on all internal surfaces be ok, or what will you recommend?
3. Are the two drivers in each box wired with the same polarity or one of them reversed?
Thanks a lot!
Best regards
Peter
Hi djk,
I seriously consider using your PPSL design for the Martin Sound #1844 drivers (please see attached file) for home use (not PA).
1. Is it correctly understood that the total internal volume for each box (Fb = 31Hz) for two drivers is 8 cf? (I just want to make sure about the size before I start drawing)
2. It says "minimal fill" in the simulation. Would 1" of foam/fill on all internal surfaces be ok, or what will you recommend?
3. Are the two drivers in each box wired with the same polarity or one of them reversed?
Thanks a lot!
Best regards
Peter
Attachments
1) Yes, the net-net volume is 8 cu ft. The boxes are 36W x 24H x 30D (3/4" ply) and take about 1-1/2 sheets per box (IIRC).
2) I don't actually use any fill for PA, minimal to prevent reflections getting out of the port should be fine. Use your judgment here.
3) The driver you can see the magnet on is wired with reverse polarity.
Depending on your room gain you may be able to lower the Q of the filter. In one home I was able to lower the Q to 1 (no boost) and the response was still flat to 30hz. Use your judgment here too, especially if playing records (you need the filter).
Bigger boxes can go even lower:
Box Properties
Name:
Type: Vented Box w/ Active HP Filter
Shape: Prism, square (optimum)
Vb = 10 cu.ft
Fb = 25 Hz
QL = 5.962
F3 = 24.39 Hz
Fill = minimal
No. of Vents = 2
Vent shape = other
Vent ends = two flush
Av = 23.98 sq.in
Lv = 13.87 in
-----------------------------------------
Active 12 dB/oct. HP Filter
Fx = 25 Hz
Qx = 2
2) I don't actually use any fill for PA, minimal to prevent reflections getting out of the port should be fine. Use your judgment here.
3) The driver you can see the magnet on is wired with reverse polarity.
Depending on your room gain you may be able to lower the Q of the filter. In one home I was able to lower the Q to 1 (no boost) and the response was still flat to 30hz. Use your judgment here too, especially if playing records (you need the filter).
Bigger boxes can go even lower:
Box Properties
Name:
Type: Vented Box w/ Active HP Filter
Shape: Prism, square (optimum)
Vb = 10 cu.ft
Fb = 25 Hz
QL = 5.962
F3 = 24.39 Hz
Fill = minimal
No. of Vents = 2
Vent shape = other
Vent ends = two flush
Av = 23.98 sq.in
Lv = 13.87 in
-----------------------------------------
Active 12 dB/oct. HP Filter
Fx = 25 Hz
Qx = 2
Dispersion horisontal vs vertical
Have any of you measured the dispersion on a PPSL? How does it measure closer to its useful upper frequency range? Horisontal versus vertical dispersion?
As the frequency extension is limited by how well you optimise the design of the plenum, I guess this also limits/controls the dispersion as well.
Regards
Have any of you measured the dispersion on a PPSL? How does it measure closer to its useful upper frequency range? Horisontal versus vertical dispersion?
As the frequency extension is limited by how well you optimise the design of the plenum, I guess this also limits/controls the dispersion as well.
Regards
It would narrow above the slot width, 800hz for 7", but the 1/4W notch from the cavity depth will be lower than this.
http://http://forum.speakerplans.com/cheap-1-bolt-on-horns_topic55178_post550941.html?KW=1000000#550941
http://http://forum.speakerplans.com/cheap-1-bolt-on-horns_topic55178_post550941.html?KW=1000000#550941
reading this topic a few times ,got me intrested.
when truck space is an issue ,and amp power isn't,th are out of the picture.
only way to get more output is higher x-max drivers like the 18nlw 9600.
taking this driver as an example,with an x-max of 14mm,it has enormus vd at full trust.
what wil be the minimum width of the plenum,without getting compression issue's ,using djim config.
they wil be crossed at 80~100 hz max
the driver height is total 24 cm.
edit/ if one would give the plenum also a horizontal v-shape will this undo the "ppsl"effect?
erik
when truck space is an issue ,and amp power isn't,th are out of the picture.
only way to get more output is higher x-max drivers like the 18nlw 9600.
taking this driver as an example,with an x-max of 14mm,it has enormus vd at full trust.
what wil be the minimum width of the plenum,without getting compression issue's ,using djim config.
they wil be crossed at 80~100 hz max
the driver height is total 24 cm.
edit/ if one would give the plenum also a horizontal v-shape will this undo the "ppsl"effect?
erik
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I was considering designing a PPSL with the woofers mounted from the back of the slot manifold instead from the inside of manifold slot. I figured it would be easier to mount them that way if I used passive radiators that were a little larger so I can access the woofers (I had designed a PPSL with access panels and realized the hole is same as would be for PR 
). The PR's would be on the sides of the cabinet which is perfect for cancelling movement. I will post a pic when I do some google sketchup. Worth going PR? I have not seen one yet, and have not designed with PR. My version of WinISD can't do PR's. I have some free 10" sony car subs that model well in BR on WinISD. Many car subs cannot be rear mounted (like my sony's) due to thier stupid need to make the speakers pretty (with crappy plastic surround covers and basket covers). I will most likely build these with on speaker mounted normal, and one from rear, but plan on doing different woofers in future and will build cabinet with both mounted from rear.
I built some speakers years ago that had a PR, and they sounded great. PR will also be good for speakers that need weird port lengths...
). The PR's would be on the sides of the cabinet which is perfect for cancelling movement. I will post a pic when I do some google sketchup. Worth going PR? I have not seen one yet, and have not designed with PR. My version of WinISD can't do PR's. I have some free 10" sony car subs that model well in BR on WinISD. Many car subs cannot be rear mounted (like my sony's) due to thier stupid need to make the speakers pretty (with crappy plastic surround covers and basket covers). I will most likely build these with on speaker mounted normal, and one from rear, but plan on doing different woofers in future and will build cabinet with both mounted from rear.I built some speakers years ago that had a PR, and they sounded great. PR will also be good for speakers that need weird port lengths...
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