It's more about PA vs car audio. The Eighteen Sound woofer is a PA woofer suitable for horn loading, which increases the SPL for a given amount of air displacement. The JBL is a typical car audio subwoofer, with a low fs and mediocre efficiency. You cannot drive it near Xmax at frequencies above 50 Hz as it is limited by thermal power handling. It could however be a good choice if you want deep (30 Hz) bass, at the cost of SPL.
Last edited:
Ahhhhhh.........There be a caveat with those 21"s. To get them moving, you need power and lots of it at tall impedance. Just did a 21" tapped horn prototype with a 8 ohm 21"(most are 8 ohm). SMALLEST amp to drive the box I could find (that worked) was a QSC PL380. 1500 w/p/ch at 8 ohms. That is a fairly high budget way to get lows.
AND, the box has to be built very well to deal with those pressures so 13 ply is a must.
There is no substitute for cone area (no replacement for displacement) and amp power.
The question is how much distortion are you willing to accommodate. $1,000 is not much of a budget, but there are deals to be found on Parts Express in the clearance bin.
I used to own 16 LAB subs, THAT was some low end but they were ridiculous to move around and were 260# each. AND they had a power compression problem.
Subs that array well with each other (B-4 designs) are the way to go, especially if time-to-build is a consideration.
Make sawdust!
AND, the box has to be built very well to deal with those pressures so 13 ply is a must.
There is no substitute for cone area (no replacement for displacement) and amp power.
The question is how much distortion are you willing to accommodate. $1,000 is not much of a budget, but there are deals to be found on Parts Express in the clearance bin.
I used to own 16 LAB subs, THAT was some low end but they were ridiculous to move around and were 260# each. AND they had a power compression problem.
Subs that array well with each other (B-4 designs) are the way to go, especially if time-to-build is a consideration.
Make sawdust!
"with a low fs and mediocre efficiency."
You mean like the MTX car stereo woofers like Danley uses?
Here is another dual 15 horn design, one box in excess of 145dB.
Of course it is also a 'car stereo' type woofer, less than 90dB as a direct radiator. Let's see, 1800W is +32.55dB, so 146.22dB minus 32.55 is 113.66dB for 1W.
I guess that is 'mediocre efficiency'.
You mean like the MTX car stereo woofers like Danley uses?
Here is another dual 15 horn design, one box in excess of 145dB.
Of course it is also a 'car stereo' type woofer, less than 90dB as a direct radiator. Let's see, 1800W is +32.55dB, so 146.22dB minus 32.55 is 113.66dB for 1W.
I guess that is 'mediocre efficiency'.
two 15" have the same Sd as one 21".
I would expect a two 15" box to be cheaper to buy/build than a one 21" box.
Stack 4 of these boxes for your 8 15" speakers.
Or even use them as a line array along the ground to get a bit of "projection" towards the audience.
If on test at 100yds ~90m you find that your target has not been reached just add on a couple of extra boxes to the line array.
Use a separate amplifier for each box. One failure keeps the audience satisfied.
You could probably hire a 2x15" box + amplifier from a local company. They would love to rent out four to ten of these packages.
I would expect a two 15" box to be cheaper to buy/build than a one 21" box.
Stack 4 of these boxes for your 8 15" speakers.
Or even use them as a line array along the ground to get a bit of "projection" towards the audience.
If on test at 100yds ~90m you find that your target has not been reached just add on a couple of extra boxes to the line array.
Use a separate amplifier for each box. One failure keeps the audience satisfied.
You could probably hire a 2x15" box + amplifier from a local company. They would love to rent out four to ten of these packages.
"with a low fs and mediocre efficiency."
You mean like the MTX car stereo woofers like Danley uses?
Here is another dual 15 horn design, one box in excess of 145dB.
Of course it is also a 'car stereo' type woofer, less than 90dB as a direct radiator. Let's see, 1800W is +32.55dB, so 146.22dB minus 32.55 is 113.66dB for 1W.
I guess that is 'mediocre efficiency'.
that seems to be I damm good horn design! what is the driver used in this simulation? 113dB@1W with a car woofer, nice job
That's typical for a "four on the floor" sim for that size cab. The size of the box determines the sensitivity, not the driver itself.
It's not necessirliy the best match for the horn. A better impedance match would have less ripple and more efficiency (fairly flat around 40-50%, instead of bouncing between 10 and 60). But it would still be about 113dB/2.83V, down to the high 30's. That's all a function of the horn.
It's not necessirliy the best match for the horn. A better impedance match would have less ripple and more efficiency (fairly flat around 40-50%, instead of bouncing between 10 and 60). But it would still be about 113dB/2.83V, down to the high 30's. That's all a function of the horn.
I did a comparison of the suggestion I made using the clearance eliminator drivers and djk's horn with the jbl driver. I ran the sim in 2pi and at the voltage for rated rms power into nominal impedance.
Looks like if you have the power available, using an assload of cheap drivers will get you more spl from similar volume and driver cost.
Looks like if you have the power available, using an assload of cheap drivers will get you more spl from similar volume and driver cost.
Attachments
"that seems to be I damm good horn design!"
Corner horn with a very small mouth.
" what is the driver used in this simulation? "
SDX15 from CSS (Canada), at the time they were about $265 or so each.
"113dB@1W with a car woofer, nice job "
Corner horn with a very small mouth.
" what is the driver used in this simulation? "
SDX15 from CSS (Canada), at the time they were about $265 or so each.
"113dB@1W with a car woofer, nice job "
An externally hosted image should be here but it was not working when we last tested it.
http://www.creativesound.ca/pdf/CSS-SDX15-data-121107.pdf
87.3dB, 30mm x-maz (one way), underhung coil!
The 12" version may be had on eBay for $500 a pair (free shipping).
http://creativesound.ca/pdf/SDX12.pdf
http://www.ebay.com/itm/Sub-Woofer-Pair-12-Model-SDX12-by-CREATIVE-SOUND-/331125738207?pt=LH_DefaultDomain_0&hash=item4d18a1cadf#ht_1070wt_670
87.3dB, 30mm x-maz (one way), underhung coil!
The 12" version may be had on eBay for $500 a pair (free shipping).
http://creativesound.ca/pdf/SDX12.pdf
http://www.ebay.com/itm/Sub-Woofer-Pair-12-Model-SDX12-by-CREATIVE-SOUND-/331125738207?pt=LH_DefaultDomain_0&hash=item4d18a1cadf#ht_1070wt_670
Last edited:
"It's not necessirliy the best match for the horn. A better impedance match would have less ripple and more efficiency (fairly flat around 40-50%, instead of bouncing between 10 and 60). But it would still be about 113dB/2.83V, down to the high 30's. That's all a function of the horn. "
In general, I like to design bass horns such that a stacked pair look like 5.10C, and a quad stack 5.10D.
5.10C is ±3dB of ripple, most commercial horns are closer to 5.10B for their smaller size. Note how 5.10D has less ripple, but it also has about 3dB less output in the bottom octave.
It's all about the trade-offs you are willing to make.
In general, I like to design bass horns such that a stacked pair look like 5.10C, and a quad stack 5.10D.
5.10C is ±3dB of ripple, most commercial horns are closer to 5.10B for their smaller size. Note how 5.10D has less ripple, but it also has about 3dB less output in the bottom octave.
It's all about the trade-offs you are willing to make.
Last edited:
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.