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I’d still use one amp per woofer. Amp is rated [email protected], [email protected]

So if you run one per amp, each driver gets 1050w
If you run two per amp, each driver gets 775w.

Chris

Only ~ 2 dB difference, hardly worth using a second amplifier, unless driving the cabinets for all they are worth. While the higher voltage swing potential into 8 ohms is typically beneficial, the impedance maxima in a sealed 4 cu ft box is only 45 ohms.



Comparing 18TBW100-4 @ 1050watts and 21SW152-8 @ 775 watts both in 4 cubic foot boxes, the 21 is more sensitive below 55 hz, and has a 3 dB advantage on the 18TBW100-4 at 30 hz, with less power.



The impedance peak is higher in the 21SW152-8, the coil diameter is larger, so the 21 will have lower power compression than the 18TBW100-4. I'd expect the real world results to favor the 21 in both short term and long term power compression.
 

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Only ~ 2 dB difference, hardly worth using a second amplifier, unless driving the cabinets for all they are worth. While the higher voltage swing potential into 8 ohms is typically beneficial, the impedance maxima in a sealed 4 cu ft box is only 45 ohms.



Comparing 18TBW100-4 @ 1050watts and 21SW152-8 @ 775 watts both in 4 cubic foot boxes, the 21 is more sensitive below 55 hz, and has a 3 dB advantage on the 18TBW100-4 at 30 hz, with less power.



The impedance peak is higher in the 21SW152-8, the coil diameter is larger, so the 21 will have lower power compression than the 18TBW100-4. I'd expect the real world results to favor the 21 in both short term and long term power compression.


Sounds like the OP already has 4 of the amps, so why not use em?

Really not sure how you’re figuring 1050w into a TBW. Thats a 4ohm driver, so 1550w bridged to one, or 575w each for two.

Agreed the 21 is a better woofer. Considering it costs twice as much, it better be, lol.

Chris
 

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Sounds like the OP already has 4 of the amps, so why not use em?

Really not sure how you’re figuring 1050w into a TBW. Thats a 4ohm driver, so 1550w bridged to one, or 575w each for two.


Chris

Ah, my reading comprehension fail, I used 1050W in the model when I was comparing them.
 

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Disregard my earlier post, ran a new set of models. The 18 on 1550W on paper shows a 1.5 dB advantage over the 21 on 1050 W, when both are compared in the same 4 cu ft sealed box size.
 

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Disregard my earlier post, ran a new set of models. The 18 on 1550W on paper shows a 1.5 dB advantage over the 21 on 1050 W, when both are compared in the same 4 cu ft sealed box size.


I’m assuming the sealed box discussion is off with the 21 anyway, since it won’t physically fit in the diysg box.

If the OP is still wanting to run the tbw in the 4cf flatpack, a 6cf sealed box could be built for the 21.

I would recommend going ported or Devastator with both drivers to maximize output though.

Chris
 

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I haven't checked the dimensions of the box he has, though he did mention it would be temporary, with larger enclosures to be built later on.
 

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This is a great opportunity to use as an excuse to build those enclosures now.


Sent from my iPhone using Tapatalk
 

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Discussion Starter #31 (Edited)
I’m assuming the sealed box discussion is off with the 21 anyway, since it won’t physically fit in the diysg box.

If the OP is still wanting to run the tbw in the 4cf flatpack, a 6cf sealed box could be built for the 21.

I would recommend going ported or Devastator with both drivers to maximize output though.


Chris
The DIYSG 4Ft^3 box is finished, i will be puting the driver and testing this weekend, just temporarily. I want to see the woofer working :D

I haven't checked the dimensions of the box he has, though he did mention it would be temporary, with larger enclosures to be built later on.
I will be going ported.

This is a great opportunity to use as an excuse to build those enclosures now.


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Yes sir, i have to choose what enclosures to use.

4 Marty cube with the 18TBW100-4 in the back using the XLS1502 and 2 21Cubes with new amps in the front, all tuned to 19HZ, i have to buy another 21SW152-8 and 2 new amps, what amp do you recommend to run the 21's?, and what do you think of this combo?

Thanks again
Luis
 

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Since you already have the 1502's I'd try that first and then see if you need more power to your subs. The cubes are fine but the 21SW can use more, I'd look into a mini-marty or full marty box if you could.
 

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Discussion Starter #33
Since you already have the 1502's I'd try that first and then see if you need more power to your subs. The cubes are fine but the 21SW can use more, I'd look into a mini-marty or full marty box if you could.
Thank you @Trimlock, Yes, i better cool off, just have so many ideas right now.
 

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Discussion Starter #35
I agree on running the 1502’s since you have them.

Its hard to gain much above that, even the 2502 is only another 500w.

Chris
Thank you Chris, i will try them with the 1502's, since i'm going to need 4 new boxes i will ask GSG audio if they can sell me 2 Marty for the 18's and 2 Marty for the 21's, probably full Marty's since there is no mini Marty in 21".

Luis
 

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Thank you Chris, i will try them with the 1502's, since i'm going to need 4 new boxes i will ask GSG audio if they can sell me 2 Marty for the 18's and 2 Marty for the 21's, probably full Marty's since there is no mini Marty in 21".



Luis

GSG will definitely do that. They can give you great recommendations on which boxes to go with too.

Chris
 

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Discussion Starter #37
Hi, i will be assembling the 4FT^3 sealed box with the 18TBW100 tomorrow, according to winisd the Qtc is 0.544, how much polyfill should i add?, something in the ballpark?

Thank you.
Luis
 

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I would add a couple pounds regardless. You'll kill a touch of the upper bass efficiency, and gain a fraction of a dB down low. You don't need a ton, and I would NOT overstuff the box. In my experience Fs does tend to drop a touch, never a bad thing in a sealed box. Easy to try.
 
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