Discuss M-21 Giveaway Build Pics in the DIY Subwoofers forum. If going SLLT, you might also consider a deeper tuning. Try the folllowing in WinISD:
1100 Liters, 11.5 Hz tuning ...
If going SLLT, you might also consider a deeper tuning. Try the folllowing in WinISD:
1100 Liters, 11.5 Hz tuning using a 10" port (should be 33.7" long), and a 4th order highpass at 9.6 Hz.
1.1-1.2 kW should be sufficient.
In compound with 1" mdf, I would not see any problems.
But I'm no expert on this, though I think that Rodney Alvarez could tell you more if you ask him kindly.
Since h is the only one I know of having build an SLLT (have a look in the members build database), he should have some experience with that.
To the OP; if you want solid low end extension, go with the 1100 liter box tuned to 11.5hz. 12.50hz would actually be a better tuning though. It would gain you more from 12hz and up.
If you want more above 20hz, I would say build a box 395 liters tuned to 14hz.
It would give you 4dB from 20hz and up as opposed to the lower tuned box. But, with the lower tuning, you would gain 4dB around 12hz or so.
I think you'd be better with a higher tuning. You give up a lot of headroom for that low tuning.
Sealed can be done, but you will need to get a berhinger feedback destroyer to eq the response you want. I'm not sure aesthetic is happening with a ported monster that size.
I do use a behringer right now on my subs. If my room acted like Kevin's simulation in the M-21 application notes, I could probably build a 200L (7cu ft) sealed box and eq it flat out to 15hz. That wouldn't be much bigger than my current PB-13U
You've got me seriously thinking of going sealed now. With the much smaller enclosure I have a lot more ability to play with shapes, finishes, etc and make it a beautiful box. As well, if I sell my existing subs I would have the money to put a lot of power behind the sub.
Oh, I'm sorry, I still had the pre-production parameters of the M21 in WinISD.
The actual parameters changed my opinion to 1100 Liters/12.1 Hz with 10" port 30" long (better 11" port 37" long, but I don't know where to get this measure) and approx. 1.3kW.
Tuning to 14Hz might look better in the 20Hz range, but what about room gain?
My simulations, the difference in maximum spl is less than 2dB >20Hz and less than 1dB >30Hz, would it be noticeable?
If I were to power a big concert hall with this sub, i would agree to sub_junkie and choose the 14Hz tuning or even 15Hz, but the target room does not look that big.
Even sealed might be a good option, as the TO already stated, but I would be curious to see him build an SLLT with the M21.
Greetings
RJdaMoD
I think I'm leaning toward sealed, because it has a much better chance of remaining part of my system then. When you build a sealed sub is it safe to assume you don't have to worry about the exact volume of the enclosure? ie. if my goal is a 7 cu ft box but I build it in an irregular shape so it is somewhere around that volume, does it matter what the exact volume is?
I think I'm leaning toward sealed, because it has a much better chance of remaining part of my system then. When you build a sealed sub is it safe to assume you don't have to worry about the exact volume of the enclosure? ie. if my goal is a 7 cu ft box but I build it in an irregular shape so it is somewhere around that volume, does it matter what the exact volume is?
