can PA subwoofers be used for HT

[sekhar]

hey hi everybody ,
i am very new to the field of speaker design , i have recently made a 500W rms amp for my frnd but due to financial problems he is nt able to take it . So i thought why nt add this amp for my ht system.
As in my country good subwoofer r nt available or r very expensive I was thinking that could PA subwoofers be used at my home for watching movies or listening to songs . I have a room with following dimentations 13 X 15 Fts.
I am including details of two 18inch drivers . plz help in choosing the right driver and designing a enclosure with lowest frequency response.




regards
sekhar

[richie00boy]

Generally PA drivers are not suitable as they are aimed more at high sound pressure levels with big boxes, than going deep in small boxes. You may have more luck with car sub-woofers.

[Racket Scientist]

PA woofers can be used, but depending on the setup are probably not optimal, as already stated. I use two sealed 18 PA cabs in my basement setup, but its a big room, and I'm not trying to go real deep. They're supplying bass from about 40 to 150 Hz. I also use them for PA duties, so it makes sense for me. If I were picking something specifically for a HT sub, I'd probably be looking at some of the LABsub designs (but only if I needed pretty loud, deep bass). For most people, its probably best to stick with subs designed for HT. The car subs can be tricky because the car environment is different, so more boundary loading is assumed.

[18Hurts]

I would not buy PA speakers for a HT sub

I did build one though, had a pair of Cerwin Vega W15P 15" woofers laying around and the PA boxes. Calculated that the 3/4" plywood PA boxes had an internal air volume of 3.8 cu. ft. (107.5 liters) The Vas of my woofers was 7.3 cubic feet with an Fs of 35. I loaded them isobarik (face to face/push pull) so the woofers "see" 7.3 cubic feet and threw an 18" passive radiator on the back. Noted my actual Fs was around 32Hz (20 years old) so tuned the passive to 21.4 Hz with weights.

In short, it works and it goes below 20Hz flat frequency response and handles all the power the Carver M1.5t amp supplies (over 500 watts)

I was lucky since the Fs dropped low enough for the passive to extend the response down to HT territory. The Isobarik setup allows twice the power input in half the required space which worked well for my project. I can live with the sensitivity dropping from 95dB 1w/1m to 92dB since I had enough to work with.

If you want loud and low and don't mind a very tall cabinet, maybe one of those 12" Peerless subs tuned in a very tall folded horn? It will go down to 18 Hz and hit around 130dB in your room at 400 watts. You better have a tall ceiling or lay it down since it is around 8 to 10 feet (2.5 meters to 3 meters)

At least with the PA idea, we know you don't have an issue with BIG!

[sekhar]

thank u guys for the valued suggestion , So as richeeboy said car subwoofer may be a choice for HT , here are two car subs avaiable at my place , tell me which is suitable with wat kind of encloser .


regards
sekhar

[MaVo]

Contrary to common belief, pro audio subs work well in HT, if you use the correct enclosure. Horns love woofers with a relatively high resonance frequency. Look out for tapped horns or (if you dare to put a >300Liter monster in your home) a front loaded horn design. Both will be big, but also deliver high SPL for the big fun with the movies.

Check danleysoundlabs.com for some impressions on tapped horns.

[AndrewT]

the data included in post5 tells us virtually nothing.
You would be buying blind.

But they are over a killowatt each so they must be good!

[18Hurts]

I looked up the Peavey 18" and it is interesting,

In a folded horn subwoofer, it puts out 108dB 1w/1m down to 30 Hz. Although not the 20Hz and under HT sub response, can the horn be made larger so it goes below 20Hz without Xmax exceeding 9mm at 500 watts? My next build is a horn so I'm trying to wrap my cranium around how it all goes together--with my weak knowledge on infrasonic horns, would the Peavey make the most sense if size is not a consideration? How would a horn respond in that size of room?

I'll leave it up to the folded/tapped horn experts on this forum, is a horn loaded sub in the cards, sekhar?

[AndrewT]

Originally Posted by 18Hurts

it puts out 108dB 1w/1m down to 30 Hz.

could you post Hornresp input parameters and output chart?

[18Hurts]

Andrew,

The specs are for a Peavey SPFH folded horn PA subwoofer already built. I wonder if it will go down to 20Hz or lower with a larger horn? I'm just starting out with horns so am not to the point of plugging in the Low Rider Black Widow 18" driver to see how low it can go. If it can go to 18Hz F3 at 100dB sensitivity--I'm pulling out the table saw and a stack of wood!

I'll leave that idea to those that are more familiar with the program, I'm still learning.

Peavey SPFH Folded Horn Sub with FREE Mic

Frequency response:
30 Hz to 300 Hz
Usable low frequency limit (-10 dB):25 Hz
Recommended crossover: 150 Hz or lower
Power handling:
1600 W program
3200 W maximum output
800 W continuous (70.4 V RMS)
Sound pressure level, 1 watt, 1 meter:
108 dB SPL (2.83V input)
Maximum Sound pressure level, 1 meter:
137 dB SPL continuous
143 dB SPL maximum output
Transducer complement:
One 1808-8 Low Rider® Black Widow® woofer
Impedance (Z): 8 ohms Nominal 6.21 ohms Minimum
Input connections:
Two 1/4" phone jacks
One 4-pin Neutrik® Speakon® jack
Enclosure materials and finish:
Baltic birch plywood and MDF with durable carpet covering
Transport provisions:
Grab bar handle along top rear edge, and built-in casters.
Dimensions (H x W x D): 36" x 24" x 34"
Net weight: 150 lbs. (68.2 kg)