many years ago i replaced 2 18" bass reflex subs (JBL B460 based on their 2245) with 2 smaller sealed boxes. The smaller boxes are 30"x24"x18" (internal volume about 5.4 cu. ft).
my hope is to squeeze the existing 4 12" (Audio Concpets DV12) woofers into a smaller boxes and yet retain the quality and quantity of bass.
From what I know TLs would be too large, and dipoles (boxless) would require extensive EQ. One choice is Aperiodic (Fs is 19Hz, Qts is 0.44 and Vas is 380 liters).
Any other ideas?
my hope is to squeeze the existing 4 12" (Audio Concpets DV12) woofers into a smaller boxes and yet retain the quality and quantity of bass.
From what I know TLs would be too large, and dipoles (boxless) would require extensive EQ. One choice is Aperiodic (Fs is 19Hz, Qts is 0.44 and Vas is 380 liters).
Any other ideas?
How about the Elliot Sound Products EAS project? He offers circuit boards to build the EQ circuit, which is designed to operate similarly to the Bag End ELF/INFRA processor.
Big sub small box? That's a bit of an oxymoron isn't it?
... LT if you have the excursion. Probably better than aperiodic.
... LT if you have the excursion. Probably better than aperiodic.
paulspencer said:
nah.
Tumult in 90L sealed is considered big sub small box. But then, fancy that - it has the excursion. EQ and LT will be used, should be flat in-room below 15hz. You also need POWER for LT. In my case, 1200W will be available. Should hit 120dB before it runs out of excursion.
C
cjd said:
Depends on your idea of big 😀
Yes 90L is small for a driver like the Tumult ... but still big in a small or medium room that isn't a dedicated room.
I find when you use eq, the extra power is not as much as you would expect. I have found that you can often more easily over drive the amp trying to get more output in the midbass. The excursion isn't very much and you might feel the urge to crank ... but then you get clipping. On the other hand, start using eq to get a sealed sub flat down low and, subjectively you expect to have power issues with the amp. But now the driver starts moving vigorously but the amp isn't having any problems at all.
I knew this from simulations, but after playing around with some PA amps recently with clipping indicators, it became more apparent subjectively. As a general rule with high excursion drivers, you will be amplifier power limited in the midbass, and driver excursion limited in LFE use.
If you use eq with a LT, the boost is for only a portion of the bandwidth, hence 3db of boost does not require twice the amplifier power.
What amp are you using for your Tumult and how much power?
I have heard the Tumult in a 200L vented box tuned low and it was very impressive, both clean and deep.
paulspencer said:
yes 90L is a bit big. I am looking at boxes that would be small ehough to hide under or behind a sofa.
Navin, I have two subs with a 12" driver each (Stryke AV12). I have them in 70L test boxes but plan to put them in smaller sealed boxes ~28L with a LT. I have one each side of the couch, coffee table style. They are quite useful as a table right now in fact. There is also the added benefit of direct field acoustics - the response is not dominated by room modes, although they still do have some effect. I find this to be the best way to deal with pragmatic and acoustic issues at the same time. While you give up some of the gains from corner loading, the sub is much closer and thus has less drop in output due to distance. They operate almost as subwoofer headphones. The only downside is that you need to cross lower.
right now my subs use 2.7 cu. ft (about 75 liters) each. I was hoping to halve this but 28 liters is even better. I would very interested to look at this smaller sub's design.
If you want to halve the volume, think Isobarik. The extra cost of drivers puts people off but you've already got those so it's not an issue.
isobarik did cross my mind and so did a lot of designs incl. push push TL.
a simple way to think of isobarik is toassume that one has only half the number of woofers as the other half are not radiating into the room.
looks like there are 3 small box options
1. Use EQ to damp the peak and extend F3
2. Use aperidoic port to damp the peak
3. Isobarik.
the amp i intend using to drive these woofers is an old carver M1.0t. I alos intend to try a 100W rms amp that a friend of mine has built. In fact he told me he could build me 4 channels. if i need them. I like the carver as it is very compact and runs cool enough to be hidden.
ofcourse i could look at driving 2 woofers with the carver and 2 others using the home made 100W amps described above and use different alignments for each pair of woofers (one isobarik box using 2 woofers, and 2 single woofer boxes using EQ or an aperiodic vent).
a simple way to think of isobarik is toassume that one has only half the number of woofers as the other half are not radiating into the room.
looks like there are 3 small box options
1. Use EQ to damp the peak and extend F3
2. Use aperidoic port to damp the peak
3. Isobarik.
the amp i intend using to drive these woofers is an old carver M1.0t. I alos intend to try a 100W rms amp that a friend of mine has built. In fact he told me he could build me 4 channels. if i need them. I like the carver as it is very compact and runs cool enough to be hidden.
ofcourse i could look at driving 2 woofers with the carver and 2 others using the home made 100W amps described above and use different alignments for each pair of woofers (one isobarik box using 2 woofers, and 2 single woofer boxes using EQ or an aperiodic vent).
I'm using 170L or 6cubic feet on my tumult tuned to 10hz. It is indeed impressive when the entire house rattles and not a sound is heard(except the rattles of course) And In the audible region it is very clean and tight. Exceptionally low group delay of <8ms above 25hz.
- Status
- Not open for further replies.