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Thinking of building a couple of subs


Mar 11, 2023
Derry, NH
I already have a Crown xli2500 to power them.
They will replace my 2 pb1000s.
Use is mainly for music and they will compliment my Forte 2 wich are also powered by a Crown xli2500.
Restricted to something 21" wide and 21" deep. Ide rather not go much taller.
I'm looking at the Martysub cube 15 and Daytona 18" flatpack.
Will start with one sub.
Room is 23'x13' with a 16' hallway in the middle.
My main concern is chest thumping kick drums for music.
I'm thinking the 18" sealedwpuld be better but have also read ported subs can do well for music also.
I listen at and above reference levels sometimes.
The Crown has transformed my Forte into beasts with decent thump now.
Ide like to build something that can keep upwith the Crown/Forte and be very clear and precise.
Subs will be placed where the pb1000s are now
I listen to hard rock and metal mostly.
Any advise would be greatly appreciated.
Thanks in advance.


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Major Contributor
May 27, 2021
Get some speaker design software and you can plug-in the Thiele/Small parameters for the drivers you're considering and you can model performance and optimize the volume and port dimensions or compare to a sealed design, etc. I've used WinISD (FREE).

A smaller woofer will usually "tune" deeper in a small/restricted size box. But with an 18-inch woofer and a smallish sealed box you can probably overcome the tuning and low-frequency drop-off with EQ and amplifier power, especially in a home environment. And you should get more total bass output before distortion compared to a smaller driver.


Major Contributor
Dec 12, 2021
Wodecq, Hainaut, Belgium
The Dayton flatpack with the UM18-22 is a subbas monster altough. It has a response in the mid 20's in that cabinet, even without eq or other dsp. It needs a lot of power, but that crown could be enough for one when bridged in mono. In stereo you will lack power for it. It needs about 1 to 2kW in 8R. I installed 4 of them in a big living room (15x8x5m) of a rich guy and there they are powered with powersoft X4 amps (1600w at 8R per channel). Tops are Harbeth M40.3 and crossover is set at 90Hz LR4 (more or less) with dsp and that can make the whole room shake.
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