Moved from the thread of hornresp.
This is an idea of "slot loaded bandpass reflex box with push pull drivers", named by xrk971 😀
X, thanks a lot for your time & effort on Beyma G550.
Here is what I have, modified Eminence SigmaPro18:
Fs = 22.88
Qes = 0.268
Qms = 8.643
Qts = 0.26
Mms = 0.13
Re (Ω) = 6.99
BL (TM) = 22.1
Xmax (mm) = 6
Sd (m2) = 0.114
Vas (liter) = 686
Pmax = 400 W
Preliminary target would be: 20-80 Hz in overall 500L Vb.
Thanks a lot 😀
This is an idea of "slot loaded bandpass reflex box with push pull drivers", named by xrk971 😀
X, thanks a lot for your time & effort on Beyma G550.
Here is what I have, modified Eminence SigmaPro18:
Fs = 22.88
Qes = 0.268
Qms = 8.643
Qts = 0.26
Mms = 0.13
Re (Ω) = 6.99
BL (TM) = 22.1
Xmax (mm) = 6
Sd (m2) = 0.114
Vas (liter) = 686
Pmax = 400 W
Preliminary target would be: 20-80 Hz in overall 500L Vb.
Thanks a lot 😀
CLS,
What is your max SPL target? In order to reach 20 Hz, the volume on each chamber has to be close to 225 liters, and that provides no resistance for the powerful motor. So I am running into xmax issues at only 18 volts drive and getting maybe 112 dB.
What is your max SPL target? In order to reach 20 Hz, the volume on each chamber has to be close to 225 liters, and that provides no resistance for the powerful motor. So I am running into xmax issues at only 18 volts drive and getting maybe 112 dB.
Last edited:
No specific target actually. 😱
So, it seems not loading both side of driver(s) as well as I hoped. And it's obvious not as good as a tapped horn.
Or this woofer is not a good choice for such a load. Sigh~
I've been trying on hornresp and no luck either. It's probably not modeled as a tapped horn in hornresp.
So, it seems not loading both side of driver(s) as well as I hoped. And it's obvious not as good as a tapped horn.
Or this woofer is not a good choice for such a load. Sigh~
I've been trying on hornresp and no luck either. It's probably not modeled as a tapped horn in hornresp.
I think you may want a driver with a less powerful motor (lower Bl, higher Qts) and more xmax. This driver you have is ideal for a tapped horn. If I make the chamber smaller it loads better and you can get more power but the the tuning freq rises and you have a nice pro audio style roll off from about 50 Hz. I think a tapped horn is the way to go with this driver. The Beyma's I used worked ok at least it got into mid 120's dB. There are some models from Dayton that get 12 mm xmax for a very reasonable price.
SLBP Sub with Eminence Sigma Pro 18
CLS,
Here are the details of the simulation: 225 liter chambers behind each driver, 1.75 in x 21 in high x 14 in long vents connecting each chamber to central slot with dimensions of 6.0 in wide x 18 in long x 21 in tall, slot leading to front horn with mouth of 18 in wide x 21 in tall x 8 in long. Have not calculated overall box dimensions but it appears to be under 500 liters per your request at 21 in tall.
Sensitivity response with 2.83 volt driver:
Cone displacement at 17 volts at xmax:
SPL vs Freq response at xmax:
Port velocities:
Impedance:
For home hifi use, it should be loud enough and quite sensitive at 96 dB at 2.83V for 25 Hz and 93 dB at 20 Hz. It peaks out at 112 dB near 20 Hz and this is something that you definitely feel and probably all that is needed on transient peaks for normal listening at circa 80 to 85 dB program.
CLS,
Here are the details of the simulation: 225 liter chambers behind each driver, 1.75 in x 21 in high x 14 in long vents connecting each chamber to central slot with dimensions of 6.0 in wide x 18 in long x 21 in tall, slot leading to front horn with mouth of 18 in wide x 21 in tall x 8 in long. Have not calculated overall box dimensions but it appears to be under 500 liters per your request at 21 in tall.
Sensitivity response with 2.83 volt driver:
Cone displacement at 17 volts at xmax:
SPL vs Freq response at xmax:
Port velocities:
Impedance:
For home hifi use, it should be loud enough and quite sensitive at 96 dB at 2.83V for 25 Hz and 93 dB at 20 Hz. It peaks out at 112 dB near 20 Hz and this is something that you definitely feel and probably all that is needed on transient peaks for normal listening at circa 80 to 85 dB program.
Attachments
Last edited:
The current product of Eminence is Sigma Pro 18A-2. Mine is the old version without "A-2".
The differences -as I can see on the datasheet- are only the magnet size (90 vs 120 oz) and power rating (400 vs 650 W), all other parameters are identical. How interesting.
And I've done the following modifications on it:
De-cap, adding phase plug, PVA coating on the cone (both sides), softening the spider by silicon oil and some minor cut (or scratch?).
So, compare to the published numbers, the measured t/s of my own woofer are somewhat different. You may see the dropped fs & Q. (Before the mods, I remember the measured numbers were pretty close to the publish.)
I've been using 4 of them on OB for years. Alas, for OB, this is probably the last choice. This size of driver is hard to sell here, I just have to find ways to use it.
The differences -as I can see on the datasheet- are only the magnet size (90 vs 120 oz) and power rating (400 vs 650 W), all other parameters are identical. How interesting.
And I've done the following modifications on it:
De-cap, adding phase plug, PVA coating on the cone (both sides), softening the spider by silicon oil and some minor cut (or scratch?).
So, compare to the published numbers, the measured t/s of my own woofer are somewhat different. You may see the dropped fs & Q. (Before the mods, I remember the measured numbers were pretty close to the publish.)
I've been using 4 of them on OB for years. Alas, for OB, this is probably the last choice. This size of driver is hard to sell here, I just have to find ways to use it.
CLS,
Do you have photos of your hot-rodded Sigma Pro's? Four of them in an OB would sound indeed very good and I think if you wanted, use two of them in a slot loaded OB like this would be very nice too: http://www.diyaudio.com/forums/full-range/249984-cheap-fast-ob-literally.html
Do you have photos of your hot-rodded Sigma Pro's? Four of them in an OB would sound indeed very good and I think if you wanted, use two of them in a slot loaded OB like this would be very nice too: http://www.diyaudio.com/forums/full-range/249984-cheap-fast-ob-literally.html
Yeah, I like slot loaded, too. And, actually they already are ! 😀
About the modded woofer:
I won't call it a hot-rod, patched rather.
Looked nicer in a distance (on an old V-shape baffle, now history):
🙂
About the modded woofer:
I won't call it a hot-rod, patched rather.
Looked nicer in a distance (on an old V-shape baffle, now history):
🙂
Oh, you were the one with those beautiful SL subs - I have seen that before. Nice setup. Why do you want to change it? I guess the bug to build/improve happens to even the best system owners?
Thanks for the kind words. 🙂 (the system now is slightly different from the pic above, but similar, and no change to the bass section)
I haven't built anything new for more than a year. And yes I've been enjoying the system. My major complain in audio is not enough time, and living in a noisy urban enviornment. But I can't do anything to those factors now.
Funny I've been always attracted by those 'unconventional' things. Karlson is odd enough, maybe that's why I'm interested. LOL ! I've read a lot about it these days and the itch gets stronger, thus the idea of this slot loaded band pass thing.
It's quite a while I haven't built speakers, and it's much much longer I haven't built any boxed speaker. If I do again, it must be and has to be an oddball ! 😀
I haven't built anything new for more than a year. And yes I've been enjoying the system. My major complain in audio is not enough time, and living in a noisy urban enviornment. But I can't do anything to those factors now.
Funny I've been always attracted by those 'unconventional' things. Karlson is odd enough, maybe that's why I'm interested. LOL ! I've read a lot about it these days and the itch gets stronger, thus the idea of this slot loaded band pass thing.
It's quite a while I haven't built speakers, and it's much much longer I haven't built any boxed speaker. If I do again, it must be and has to be an oddball ! 😀
Maybe you want to try the MOAK with your dual 18 inch woofers?
http://www.diyaudio.com/forums/subwoofers/254948-moak-mother-all-karlsonators-aka-magnificent-monster.html
http://www.diyaudio.com/forums/subwoofers/254948-moak-mother-all-karlsonators-aka-magnificent-monster.html
Hi X,
With the woofer specs in post #1, I made a rough drawing of a tapped horn and associated sim on hornresp:
Numbers in green are path lengths in cm, red are cross section areas in cm^2. (The internal width of the box is set to 50cm.)
The sketch is not to scale and I know there'd be quite a lot of problems in the details, but this is more of a concept than a blue print.
Sim:
Helped by the tapering path, it gets pretty low with a short length. 120dB max SPL can be as low as 26Hz or so, not bad for a 202.87 liter box.
Now, here is what I need for your help -- would you please modify the last section and make it a Karlsonator?
Thanks in advance 😀
With the woofer specs in post #1, I made a rough drawing of a tapped horn and associated sim on hornresp:
Numbers in green are path lengths in cm, red are cross section areas in cm^2. (The internal width of the box is set to 50cm.)
The sketch is not to scale and I know there'd be quite a lot of problems in the details, but this is more of a concept than a blue print.
Sim:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Helped by the tapering path, it gets pretty low with a short length. 120dB max SPL can be as low as 26Hz or so, not bad for a 202.87 liter box.
Now, here is what I need for your help -- would you please modify the last section and make it a Karlsonator?
Thanks in advance 😀
This may take a bit longer to model as I have to change the geometry almost from scratch compared to a Karlsonator. Note that when you add the K-aperture it will reduce the effective path length of the system and the tuning will go higher. You can compensate by designing for a deeper extension first before the K-aperture.
I see.
As always, trade-off everywhere. When I was fiddling with hornresp, it's all too often to see a big hole in the 50-60 Hz range in the max. SPL plot. It seems a fixed price to pay for the extended response.
Low tuning moves the optimal load point to the lower frequency, thus a worse load to the driver in a larger area in the higher range. Looking at the excursion plot, the reduction happens in a very narrow range. If I try to enlarge it, I got a strange (and unacceptable) response.
Maybe it's OK to accept a not perfect loading (and a not healthy max. SPL curve) for domestic use. 116-118dB in the 50Hz range (and more at 30Hz) is far more than enough in my apartment anyway.
Or, another design concept could be an optimised loading --excursion reduction in a wider range-- and then EQ the response to the target curve. Hmmm, maybe I should consider more at this.
As always, trade-off everywhere. When I was fiddling with hornresp, it's all too often to see a big hole in the 50-60 Hz range in the max. SPL plot. It seems a fixed price to pay for the extended response.
Low tuning moves the optimal load point to the lower frequency, thus a worse load to the driver in a larger area in the higher range. Looking at the excursion plot, the reduction happens in a very narrow range. If I try to enlarge it, I got a strange (and unacceptable) response.
Maybe it's OK to accept a not perfect loading (and a not healthy max. SPL curve) for domestic use. 116-118dB in the 50Hz range (and more at 30Hz) is far more than enough in my apartment anyway.
Or, another design concept could be an optimised loading --excursion reduction in a wider range-- and then EQ the response to the target curve. Hmmm, maybe I should consider more at this.
- Status
- Not open for further replies.