In-wall subwoofer?

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I ordered a Behringer feedback destroyer a week ago. BFD enables me to adjust my subwoofer frequency response quite freely.
http://www.snapbug.ws/bfd.htm

I have an Audio Pro B1.35 subwoofer at the moment and I feel I deserve something better 😉

I intend to use the subwoofer only with movies. I don't need high SPL but I wan't clean low frequency (<20 Hz).

I have two possibilities in mind
1. I don't have much room for a subwoofer but I could live with max 30 litre/1 cubic foot box. Peerless XLS-10+passive radiator would be a good choise

2. Second, more interesting possibility would be an in-wall subwoofer. I could fit a 150 litre/~6 cubic foot enclosure behind the wall (and smaller if needed of course). This way I wouldn't lose any floor space but I would have to place the subwoofer in unoptimal place and I would have to use a lot of equalization.
http://www.dvdplaza.fi/forums/attachment.php?attachmentid=5246

My budget for the driver/drivers is 100-400 euros. If I need to order outside EU I have to pay for the taxes and for shipping (26 % toll and taxes and probably 100 euros for shipping) and these extra costs should be included in the budget.

I will use AV-amplifier as a preamp and low pass filter. I've decided to build Hypex UCD400 (good availability) for the subwoofer. Any better ideas?

Questions: What issues should I concider when placing a subwoofer inside a wall?
Which driver would be the best for this application. I can get Peerless very easily but other good drivers would have to be ordered abroad (which is ok if the arguments are good enough).
What kind of enclosure would be the best choise for the suggested driver.

Thanks! 😀
 
I have a nasty 30 Hz room mode since my room is more or less perfect square :cannotbe:

But how did you come up with that SLS ?!? Looks way too good to be true !!! It costs only 70 euros and compares very nicely even with adire audio brahma 😎

I haven't any experience with subwoofer designing so I've probably misunderstood the simulation results...
 

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Audience 50 indeed 🙂

For music I have Jordan JX92S in MLTL enclosure. They are great for my music but A52 kicks butt in HT 😀
I have 42C and pair of 42W in the back.

I've allready given up with SLS since it seems to be quite lousy driver. I've been playing with XXLS drivers for this evening. They seem to work well both vented and closed box. XXLS 830845 costs 199 euros and seems to be rather nice driver.
 

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My view of vented vs closed box.

Vented is fine as long as you do not apply signal below the tuning frequency. Far below that the acoustic output will drop by 24db/oct,
and excursion is rapidly increasing without making sound but damaging the driver. So even with EQ you cannot go below 15-20Hz in most designs, without endangering the driver. Your programm looks like Win ISD Pro, you could have look to the cone excursion vs. frequency, before you decide about the design.

Closed box typically needs EQ already starting from higher frequencies.
Below their resonance frequency they end up at -12db/oct and luckily the cone excursion always shows a reasonable match to the acoustic output. With EQ (or better a proper Linkwitz Transform) you can go for any frequency, even in small designs.
But size is not your concern, as I understood.
 
Sound effects if you go to a good movie theater are around 105 dB at listening position.

Aim for 105 dB at 20 Hz on WinISD, it's a one meter measure but room gain will boost that so it stays at least at 105 dB at listening position.

That's a rough estimation, you may need less or more, I don't know!
 
simon5 said:
Sound effects if you go to a good movie theater are around 105 dB at listening position.

Aim for 105 dB at 20 Hz on WinISD, it's a one meter measure but room gain will boost that so it stays at least at 105 dB at listening position.

That's a rough estimation, you may need less or more, I don't know!

While your theoretical peak output at reference level is 105dB from the main channels, the LFE channel is good for 115dB.

In practice Dolby Reference Level actually means that the dialog plays back at 74dB SPL. If the full dynamic range was used you'd get 105dB main channel peaks although most sound tracks are encoded with the dialog at -27dBFS. When I've checked I've never seen anything with more dynamic range so the loudest possible sound main channel sound is usually 101dB SPL. If you want to play with this you can look at dialnorm values and knock them off 105dB SPL. The LFE channel gets a 10dB boost so the theoretical and typical limits are 115/111 dB SPL.

Home DTS often has lower peaks when you normalize playback for average SPL - I've seen DTS tracks put the average level over 10dB closer to 0dBFS.

You may also playback at less than reference levels - I find reference -5dB to be a nice number. Combine that with the typically unused 4dB and you're at least -9dB from the theoretical values.
 
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