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Discussion Starter · #1 · (Edited)
Yes, I would like to build a 12ft3 @ 16.5Hz variation of a Full Marty for (2) B&C 21DS115-4 woofers. In fact, I would also like to incorporate a SpeakerPower SP1-4000 plate amp in the enclosure.

First a little background.

I completed a buildout of our basement in 2015 featuring a 2,700ft3 area to be used as a family room/home theater. The space features carpet over concrete slab and stud wall/drywall construction over poured concrete walls. My first sub was a little SVS PB-1000 that I parlayed into a Rythmik FV18-PC.


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Post Audyssey and some REW filters loaded in my miniDSP, the Rythmik actually fills the space quite well and will give me about 110db at 20hz and up to 114dB above that before running out of headroom. Because my room EQ's very well across the seats in the location I'm using and I can run pretty flat from 12Hz-100Hz, I'm not interested in adding a second. I just want the most bass in that location in a reasonably sized package that can score some WAF points.


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Recently, I've latched onto the idea of building a Full Marty subwoofer with
a 21" Pro driver but started wondering what would happen if I built the cabinet a wee bit larger and threw another 21" driver in the same enclosure. Leaving the port alone.

From what I gather from using the Marty Variation Excel sheet available on these forums, the enclosure would like so;

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Though the enclosure is much smaller than ideal, here's how it looks with WinISD modeled with a 16hz BW2 HP filter and a simulated 3,200W;

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So, as the title states, I'm looking for a sanity check to make sure I'm not missing anything obvious and hopefully get a second set of eyes to help guide me through this process.
 

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Take a look at PSA's TV42 IPAL, dual 21" B&C IPALs and a Speakerpower 6000w amp. Might give you a good idea on size.
 

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Discussion Starter · #3 ·
The overall size of what I posted is similar to a TV42 and only a bit larger than a regular Full Marty. It’s just hard to tell how the internal volumes compare because the TV is tuned around 12Hz.
 

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Discussion Starter · #5 ·
I think it would be fun for sure!

I really want to start but would like help with a double/triple check of my dimensions, port configuration and tuning. It would be my first DIY subwoofer for a HT application.

By the way, below is a screen grab of what the single FV18 will do at the MLP in the 16Hz tuning mode, in High Damping before compression starts;

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Even though the box I have calculated is much smaller than optimal for (2) B&C 21's, I think it would work pretty good in my space.
 

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