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Old 5th February 2013, 08:56 PM   #21
tb46 is offline tb46  United States
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Hi Lee in Montreal,

Here is a rough stab at your horn (using your numbers). V_net is 813.6 Litres, that's one big box. One of bjorno's TQWPs would be 309.1 L, and a TH 569.8 L. All of those 2pi/2.83V.

Regards,
Attached Images
File Type: jpg Levan_Horn_JBL_2442H_Input.jpg (35.9 KB, 141 views)
File Type: jpg Levan_Horn_JBL_2442H_Schematic.jpg (20.5 KB, 134 views)
File Type: jpg Levan_Horn_JBL_2442H_SPL.jpg (27.3 KB, 135 views)
File Type: jpg TH_T-TQWPJBL_2442H_SPL.jpg (37.1 KB, 132 views)
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Old 6th February 2013, 02:48 AM   #22
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Quote:
Originally Posted by tb46 View Post
Here is a rough stab at your horn (using your numbers). V_net is 813.6 Litres, that's one big box. One of bjorno's TQWPs would be 309.1 L, and a TH 569.8 L. All of those 2pi/2.83V.
Oliver,
Big box is great at 60 -300 Hz ;^).
Are all three using the same driver?
What do they look like at Xmax?
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Old 6th February 2013, 04:01 PM   #23
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Quote:
Originally Posted by tb46 View Post
Hi Lee in Montreal,

Here is a rough stab at your horn (using your numbers). V_net is 813.6 Litres, that's one big box. One of bjorno's TQWPs would be 309.1 L, and a TH 569.8 L. All of those 2pi/2.83V.

Regards,
Well, this certainly gives insight as to why these are regarded as legendary subs for club use in a solidly built rooms, think of the box at MoS. Looks like when used in groups they should have pretty flat in-room response with tons of sensitivity.
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Old 6th February 2013, 04:56 PM   #24
tb46 is offline tb46  United States
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Default Post #22

Hi Art,

All with the JBL 2242H, and close to factory T/S (recalculated somewhat using Hornresp).

I'll attach the Hornresp Export files (for what it's worth), that way you can do some fine tuning, and get the low cutoffs similar, etc. None of this is optimized.

Regards,
Attached Images
File Type: jpg Levan_Horn_v_TH_JBL_2442H_SPL.jpg (30.1 KB, 103 views)
File Type: jpg TH_v_TQWP_JBL_2442H_SPL.jpg (32.5 KB, 32 views)
Attached Files
File Type: txt 2242H_Levan_Xmax.txt (486 Bytes, 11 views)
File Type: txt 2242H_TH_Xmax.txt (450 Bytes, 8 views)
File Type: txt 2242H_TQWP_Xmax.txt (446 Bytes, 9 views)
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Old 6th February 2013, 06:18 PM   #25
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Originally Posted by tb46 View Post
Hi Art,

All with the JBL 2242H, and close to factory T/S (recalculated somewhat using Hornresp).

I'll attach the Hornresp Export files (for what it's worth), that way you can do some fine tuning, and get the low cutoffs similar, etc. None of this is optimized.
Thanks, Oliver.
Box is too big for my taste, and the low Xmax driver limits output by about 6 dB.
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Old 6th February 2013, 06:25 PM   #26
tb46 is offline tb46  United States
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Default Post #23

Hi turbodawg,

4ea. in series/parallel @ Xmax:

Regards,
Attached Images
File Type: jpg 4ea_Levan_Horn_JBL_2442H_SPL_Xmax.jpg (28.6 KB, 36 views)
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Old 6th February 2013, 06:31 PM   #27
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Originally Posted by weltersys View Post
Thanks, Oliver.
Box is too big for my taste, and the low Xmax driver limits output by about 6 dB.
First, I wish to thank everyone who added their grain of salt and contributed with technical specs and infos.

Second, I also apologize for not having been too present in my own thread for the past 48 hours. I build racecars and design parts and this is entering full season, so I have a lot of work on my plate.

As was stated in my first post, this is NOT a sub for everyone's home theater or man cave. It is strictly clubbing material and for a permanent instal. Also, all the data I supplied is for half a Bertha (otherwise known as an Emerald, and both being legends among the club scene). The original Bertha uses TWO 18" woofers and measures 60" wide x 48" tall x 36" deep. The original Emerald is half as tall. My version is deeper and allows 3 extra feet of path.

To get full low end punch, it should be used with the Levan extension, and/or two up. The advantage of building half Berthas is that at 24" tall, they are easier to move around and they go thru any door. Not so at 48" tall ;-) Huge clubs usually will need only three full Berthas with Levan extensions to shake your guts. we're talking clubs with the capacity of 1000 dancers on the floor, with warehouse tall ceilings.

A front loaded horn such as this one as an advantage over a TH when size doesn't matter. Wider frequency range, and more articulate bass. Not just 2 octaves or single note bass bins. Also, while I am set on this driver, I am more than willing to explore what can improve the response and excursion (the 2242 has 18mm total excursion). Bigger/smaller back chamber. Bigger/smaller throat. The overall length with the Levan horns when used as single 18" woofer is 162" / 4.1m, and that extension can eve be a full 48" deep if wanted, bringing the total length to 174" / 4.41m. Which shows how that design can be modulated. The mouth dimensions with the Levan extension is 96" x 24". If the cabinet is stacked two up, the mouth then gets to 96" x 48".

Last edited by Lee in Montreal; 6th February 2013 at 06:47 PM.
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Old 6th February 2013, 07:07 PM   #28
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Originally Posted by Lee in Montreal View Post
Also, while I am set on this driver, I am more than willing to explore what can improve the response and excursion (the 2242 has 18mm total excursion). Bigger/smaller back chamber. Bigger/smaller throat.
Lee,

Having designed and built many BR, TH, & FLH over the years, and having used Hornresp recently (by comparison to the first 30+years) to evaluate designs, I have found the measured response to deviate +/- 3 dB or more from predictions.
Changing throat and chamber size won't have that much of a deviation.
Sure, a higher compression ratio will increase sensitivity, but that is of little advantage when the cone buckles and tears- Hornresp won't tell you at what point that will happen.
Experience shows your throat dimensions are about right for a light cone like the 2242.

As a race car builder, you must know that the only replacement for displacement is an increase in RPM, not possible in subwoofers.

Using a driver with double the displacement (and a much heavier, stiffer cone) properly powered will guarantee a 6 dB increase in output.
With that capability available for less money, I just don't understand not using it, especially with the big investment in plywood and time you are planning.

Have fun, good luck with your build!

Art

Last edited by weltersys; 6th February 2013 at 07:10 PM.
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Old 6th February 2013, 07:25 PM   #29
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Hi Art. Thanks for the constructive comments. Heavier cone may be stronger, but also usually also means reduced frequency range. Being able to play 30Hz to 200Hz can be very practical when getting the 2242. In term of driver price, I have acces to close to a hundred 2242, with moderate use at under $400 each. Buying a JBL woofer also means that in 10 years, I will be able to source original replacement cones. The higher efficiency of the 2242 over the BC (3+db) means I need half as much amp power. Everything is a compromise obviously. I did hear good thing about BC products and i am not being snobby... ;-) In regard of the BC18's specs,a hight Qts of 0.39 doesn't look too good to me in a horn. Looks better suited for bass reflex.
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Old 6th February 2013, 08:06 PM   #30
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Quote:
Originally Posted by Lee in Montreal View Post
Hi Art. Thanks for the constructive comments. Heavier cone may be stronger, but also usually also means reduced frequency range. Being able to play 30Hz to 200Hz can be very practical when getting the 2242. In term of driver price, I have acces to close to a hundred 2242, with moderate use at under $400 each. Buying a JBL woofer also means that in 10 years, I will be able to source original replacement cones. The higher efficiency of the 2242 over the BC (3+db) means I need half as much amp power. Everything is a compromise obviously. I did hear good thing about BC products and i am not being snobby... ;-) In regard of the BC18's specs,a hight Qts of 0.39 doesn't look too good to me in a horn. Looks better suited for bass reflex.
I find the sound of vocals coming through a ground located speaker to be odd, so don't ever cross subs much higher than 100 Hz.
The B&C drivers work great in BR, TH or FLH, 30-300 Hz would be achievable in a FLH. The cone strength is almost overkill for BR.
As far as efficiency, they have less power compression due to better cooling, which will easily offset the difference.
It really comes down to displacement, you will need almost two of the 2242 to match a B&CTBW100.
For that cost, you could almost afford to get a B&C21SW152, which would be in another class entirely.

Below you can see the response of a BC18SW115-4 in BR and the Keystone TH, which sims (and measures ) around 131 dB at 40 Hz within it's rated power and excursion. The Keystone is way less than half the size of your design, yet has similar output to 35 Hz of four of the Berthoids..

For a fixed installation with the potential to build huge cabinets, I'd be torn between TH and FLH. Without a lot of experimentation, I'd probably opt for Josh Ricci's Othorn, which in actual measurements blows away the big Bertha or the JBL cabinets mentioned earlier in the thread.

Art
Attached Images
File Type: png TH, BR.png (125.5 KB, 42 views)

Last edited by weltersys; 6th February 2013 at 08:09 PM.
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