after seeing the DIY monitorthread develop like this...

I wonder if any of our bros (or sistas) here have built a subwoofer to support nearfields? Had one to tryout in my studio and this became my next got-to-have-thing now... unfortunately, recent (spare-)budget is spend travelling tru Europe with wife and kids, so diy seems the only option left... I have pretty good carpenterskills btw... and even better woodworkerfriends

the one on test (quested) had a processor attached to it, with the possibility to change 45°-90° etc for alignment. As I have serious "playroom" to put the sub, I don't think it's necessary to have this option available?

I always liked these projects:

http://www.customanalogue.com/sub_index.htm#What! No Servo

http://www.linkwitzlab.com/thor-intro.htm

Sealed is the way to go. :thumb:

EDIT: Umm, links no worky? :?

the linkwitzlab stuff looks very well detailed and easy to build.
Any guys around here who had any luck with this?

Sorry Kubi, I find that PSW project too much to read... looks so overinfo'd it scares me to lose the rest of my day searching and reading :shock:

http://www.diysubwoofers.org/

any good?

this all looks very good and inspiring... but I also would like some feedback from any DIY'er/producer/studio/engineer/... around here, who's working with some of these?

My aim is to use it for mix and mastering. Commercial available units seem so freakin expensive, when all they have to do is just making some rumble :?

[quote author="tony dB"] when all they have to do is just making some rumble :?[/quote]

If this is true, I will not bother and just build one. :wink:

I believe that transmission line subwoofer wins both sealed and ported designs:

http://www.hogheaven.com/diyaudio/subwoofers/PATL/patl.html
http://www-personal.engin.umich.edu/~jglettle/section/rapture/bassdesign.html


Sealed ("infinite baffle") is ok if you don't need high SPL output, problem is that you have to boost low freq a lot which overloads the driver (distortion will increase due to limited throw and heat). Ported design is fine if you tune the box rather low (about 20 Hz) so that the group delay will not increase at higher frequencies. You will still need some electrical boost in crossover. The transmission line subwoofer is difficult to build but it gives best performance, tight, deep bass with good efficiency (though not as good transients as sealed). The bandpass design though is more efficient but not the tightest (actually very bad, though Genelec used to make bandpass sw's earlier, not they have the spiral ported design).

[quote author="mhelin"]Sealed ("infinite baffle") is ok if you don't need high SPL output, problem is that you have to boost low freq a lot which overloads the driver (distortion will increase due to limited throw and heat). [/quote]

a driver designed and optimised for this alignment will be fine
the cone excusion for sub woofers is always going to be a problem
... the nature of low and sub is to use the driver at and below the resonace
... for the other drivers you would crossover above the resonance
just the nature of the beast

FOR DIY
and for those with out test gear and modelling software the sealed with a Active EQ curve is an easy project
BUT
it requires the original designer to have done all the correct work

any ported enclosure could have some unexpected outcomes and transmission line ... I think ... is one of the hardest to get right

SO
for small spaces and lower max SPL the sealed and an active EQ is a good compromise

ps
if you have double 15 and 2 inch East or WEST LAKE monitors ... Klipsch ... Bum-Flare JBL ... OLD school Tannoy
forget it
you are gonna need some acoustic efficiency just to begin to catch up

yo tony, i've build loads of speakers, including subs

there are many ways to skin that cat, and NO perfect 'only' way. there are also a lot of wrong ways :green: i do believe that psw sub is for pa use and thus no good to you

what are the main speakers? how big is the room, what dimensions? what amps? what's for dinner?

tls can be nice, but are very difficult beasts. i think they sound slow and sluggsih and are way too big

if size is important, i'd put a (or two) long throw 10"-12" in a small sealed box and use a cheap powerfull 1KW pa amp and eq my way out

but it's possible to get a very nice linear output from 30-80Hz (it's all up to your room actually) with a 12" in a 120L closed box. peerless makes a nice, cheap driver for that purpose, around 150euros, i think

i don't like any kind of open / vented box. they all suck. all of them

Yep, I have Peerless SLS woofers in my mind for my upcoming speaker project.

http://tymphany.com/datasheet/printview.php?id=37

SLS-10 has an f3 below 50Hz in a sealed box, though the box tends to get a little big. It has shorting rings for lower distortion and has been described to sound really tight and good for music. I have seen some distortion measurements and these babies seem to behave very well up to ~500Hz with no significant ups/downs in 2nd or 3rd order distortion and low higher order distortion in general.

They're also cheap.

I'm probably going to use two per side and possibly have some low end equalization, not sure.

Folks on Finnish DVDPlaza forum tested some 22 subwoofers recently:
http://www.dvdplaza.fi/forums/forumdisplay.php?f=157

Most of subwoofers seems to have huge THD. Genelec 7073B which uses 4 12" drivers in ported enclosure(s) has "only" 5% THD < 105 dB level. With other subs like Rel Storm 5 the THD goes above 40% at the same level below 40 Hz frequecies.

7073B: http://www.dvdplaza.fi/forums/showthread.php?t=50470
Rel: http://www.dvdplaza.fi/forums/showthread.php?t=50477

7073B actually has better (shorter) group delay for above 30 Hz frequencies even though Rel is a sealed sub (acoustic suspension type I think).

Clearly these tests show that you need multiple large (12" or above) drivers (and plenty of power) if you want a good subwoofer.

This subwoofer looks *VERY* promising though:

http://www.dvdplaza.fi/forums/showthread.php?t=50462
(http://www.bkelec.com/HiFi/Sub_Woofers/monolith-df.htm)

Low THD, low group delay, excellent transient response (see the impulse response graph) even though the system is a 95 Litre reflex tuned to 20Hz. That's the sub to get if you'll not DIY a one.

Anyway, there's also a DIY Peerless XLS design which uses passive radiator. It's fine at max 100 dB levels, so if it's enough it would be nice DIY project:
http://www.dvdplaza.fi/forums/showthread.php?t=50487
(you can buy the kit from here: http://www.hifitalo.fi/shop/sivut/aw-xp3-400w.htm )

With four of them you could have SPL of 109 dB.