Sub-woofer on ceiling / In-Ceiling Subwoofer

[elangoas]

Great!
As long as you know what you are doing.

Its not just the HUGE subs that you have got there, but the whole armory that I can see in the background...!!!
Wow and just wow!

Personally I am against electronic tuning of the room.
If I speak loudly (not shout) and hear no echo, even a small one, then I am ok with the room as is.
If there is an echo, then I would treat it lightly for stereo and moderately for surround.

I would straighten out the driver response, if required, from the near field response.
If it has small quirks, I won't even bother to do that.

That's it. That way, I am not fiddling with the work of the music director to iron out flaws in my room acoustics or in my signal chain.
But that's just me.

Thank you for your views..

With subs working below 120Hz, they should dissapear anyway, no?

For now, i have crossed it to 80Hz to mains.. Sounds very nice for stereo and movies are even better.. Honestly, i never had a chance to hear what a good tweaked set-up feels like.. So all i do is compare it with my previous set-up and see if there is an improvement (just learning to measure responses)..

That's a lot of assuming there...with no concrete theory. I suggest you keep it simple. Really very simple.

Sure.. Thanks..

Dunno.
What I do know, for sure, is that with the type of subs that you are dealing, build such an enclosure and keeping it rock steady would be a challenge not worth accepting.

Ok.. The present ones, that i have suspended from ceiling, hardly vibrates when i watch thick action scenes (or) stereo with some deep bass.. So this made me think, what if i mount to false ceiling using that as enclosure itself..

Also, i have seen some images on AVS forums, where some have used the space above the room, besides the listening room as enclosure itself.. So thought, why not do it in a different way where most ceiling are unused at home (india)..

Kindly note that I am sharing my personal opinion and they could be biased towards the KIS (keep it simple, dummy) theory.

Good luck!

Regards,

Ravindra.

Thank you very much again for your detailed inputs.. Am yet undecided, evaluating the challenges in this task..

 

[elangoas]

Tried a crossover of 60Hz of subs to mains.. Feels like the subs are giving up.. So i changed it back to 80Hz..

If i had to minimise the height mode peak of +10dB than the nearest freq, where should i place additional subs in the room?.. But thinking if addition of 1 (or) 2 subs will help minimise the peak at 60Hz and also improve the dips in the response between 20 - 80Hz..

I don't mind procuring an used multi-channel power amp to drive multiple subs..

Here is my room layout..

Was thinking ,if addition of one more sub above my listening position, wall mounted at midway height of the room would help minimise the height mode peak & also improve the dips.. But, where in the room would be a good place to position them?..

If two subs, think 1/4 and 3/4 room height should help, should also benefit of +6dB additionally in SPL, more helpful for movies..

 

[manoj.p]

Having tried the subs suspended from ceiling, and the response it offers if mounted at ideal locations, i would like to try 4 subs (2 drivers in each location & opposing each other) with 18mm plywood as false ceiling + use the false ceiling as a sealed enclosure for subs + to hold height speakers.. I was anyways planning to get false ceiling done..

Would i have a remote chance of improving the dip if i were to use 4 subs (2 drivers in each location & opposing each other)? like below image.. My room also would look tidy with subs hidden inside false ceiling.. Should i (or) shouldn't i do it?..

If you mount all the four subs in the ceiling, you will not be able to get rid of any height mode. Think of this scenario as trying to get rid of width mode by putting all the subs in one corner.

Having said that, it’s hard to get rid of height mode just by sub positioning. Main reason is we do not have much flexibility in mounting subs height wise. Unless you think of mounting on front wall or back wall.

In your current situation - If it were me, i would have tried to see if cross over at 60 and measuring combined front + sub response gives a better output. You should be able to measure it and make an informed decision.

As for mounting subs in false ceiling, it’s my pipe dream if I ever return to india. Having tried infinite baffle sub, I prefer that in comparison to other sub implementation. However, you have two major challenges. Make sure there is no flexing of false ceiling (sturdy enough) and there is no leakage of air. The false ceiling should be braced enough and sealed to give you best output.

As for opposed drivers with out of phase to each other - it’s a very common thing in IB. It helps in cancelling the dual opposed mechanical forces and vibrations. It’s actually preferred to mount subs that way. I have it the same way in my IB arrangement.

 

[manoj.p]

Tried a crossover of 60Hz of subs to mains.. Feels like the subs are giving up.. So i changed it back to 80Hz..

If i had to minimise the height mode peak of +10dB than the nearest freq, where should i place additional subs in the room?.. But thinking if addition of 1 (or) 2 subs will help minimise the peak at 60Hz and also improve the dips in the response between 20 - 80Hz..

I don't mind procuring an used multi-channel power amp to drive multiple subs..

Here is my room layout..

Was thinking ,if addition of one more sub above my listening position, wall mounted at midway height of the room would help minimise the height mode peak & also improve the dips.. But, where in the room would be a good place to position them?..

If two subs, think 1/4 and 3/4 room height should help, should also benefit of +6dB additionally in SPL, more helpful for movies..

Not sure if you measured subs + main after crossing over at 60 hz. If your subs give away after 60 hz, it’s as expected. Your mains should take over from there.

As for that 10 dB peak, you should be able to pull it down using eq in your avr. Either through room correction or manually.

 

[elangoas]

Not sure if you measured subs + main after crossing over at 60 hz. If your subs give away after 60 hz, it’s as expected. Your mains should take over from there.

Nope, didn't take measurement.. But changed the crossover on AVR to 60Hz for L-C-R and played a test clip of Rampage (Atmos file).. I felt the sub was giving up, producing like "darrr" sound.. (volume was -14dB on AVR scale)..So i switched the crossover back to 80hz..

The amplifier driving the subwoofer is not clipping.. So i think the subwoofer driver is reaching excursion limit if crossed at 60Hz..

In your current situation - If it were me, i would have tried to see if cross over at 60 and measuring combined front + sub response gives a better output. You should be able to measure it and make an informed decision.

Sure, will check the measurement with subs, L + R with 60Hz crossover..

As for that 10 dB peak, you should be able to pull it down using eq in your avr. Either through room correction or manually.

Thanks.. got it.. As of now, i run the set-up without Audyssey calibration.. The bass feels good (or) so much better than before without EQ engaged for both movies / music.. Hence, thought if there is any chance of minimising the height peak of 10dB using one more sub at height midpoint of the room (or) two subs wall mounted at 1/4 & 3/4 room height on the left/right side of the screen..

If you mount all the four subs in the ceiling, you will not be able to get rid of any height mode.

understood it now..

Having said that, it’s hard to get rid of height mode just by sub positioning. Main reason is we do not have much flexibility in mounting subs height wise. Unless you think of mounting on front wall or back wall.

True..If it is possible to minimise the height mode with one / two subs, & improve the dips below 80hz, i will try for it.. If it is not possible, i will leave it as it is and use Audyssey as you suggested..

As for mounting subs in false ceiling, it’s my pipe dream if I ever return to india. Having tried infinite baffle sub, I prefer that in comparison to other sub implementation. However, you have two major challenges. Make sure there is no flexing of false ceiling (sturdy enough) and there is no leakage of air. The false ceiling should be braced enough and sealed to give you best output.

As for opposed drivers with out of phase to each other - it’s a very common thing in IB. It helps in cancelling the dual opposed mechanical forces and vibrations. It’s actually preferred to mount subs that way. I have it the same way in my IB arrangement.

Vow.. Thank you very much for the detailed input.. Kind of clears lot of my doubts.. Please share a pic of your subs..

 

[manoj.p]

Its bizarre that your sub makes that sound for 60 hz crossover but happy at 80hz.

Be careful. It may have become self aware and unhappy if you take away its workload...

 

[elangoas]

Its bizarre that your sub makes that sound for 60 hz crossover but happy at 80hz.

Be careful. It may have become self aware and unhappy if you take away its workload...

I will recheck with some more movies if that happens again and do a measurement with 60Hz crossover to mains and update here..

 

[elangoas]

Not sure if you measured subs + main after crossing over at 60 hz.

I tried measuring the response with a 10Hz - 20Khz full range signal for L + R, with a crossover at 60Hz in AVR,stereo mode (Audyssey disengaged).. I wasn't sure of which smoothing to apply.. So did both 1/48 smoothing and 1/6 smoothing for the same response..

Looks like the height mode peak stays even after using crossover of 60Hz..

 

[elangoas]

Made some progress with wooden structure on ceiling as planned earlier.. Had to chase the carpenter to get this done..

Located a scrap wood dealer near home..

The scrap wood is sold Rs 38/Kg.. So for my entire ceiling of 14ft x 11ft area and planned partitions, had to pick approx 120Kgs of wood to build the frame..

Approx cost of raw material - Rs 4,500 + Rs 300 to ship it to my location.. Totally Rs 4,800/-..

Explained the carpenter with details on spacing from ceiling and two columns of wooden structure to hold 6 sealed speakers.. (Dual passive sub-woofers and 4 height speakers for Atmos)..

Labour cost for two carpenter - Rs 1,500 and hardware (L-brackets, screws) Rs 1,000.. Totally Rs 2,500/-.

Total money spent on raw material, hardware & labour to erect the wooden structure on ceiling Rs 7,300/-..

Have planned for broadband absorption on ceiling inside the wooden frame and covering it with black spandex to absorb scattered projector screen light on to the ceiling..

Am hoping this would make the room tidy and improve picture quality..

 

[Naveenbnc]

Wow...so much is happening in this thread lately !!!! I didn't check in a while....
Great going elango !!!

 

[elangoas]

Wow...so much is happening in this thread lately !!!! I didn't check in a while....
Great going elango !!!

Thank you.. Pending carpentry work.. Will share pics when they are fixed to ceiling..

 

[elangoas]

The earlier two DIY sealed subwoofers which i had in my room + the Sonodyne SPA 202, 2 channel power amp which was used to power the subs, i moved them to my brother, which he is also using it on ceiling..

This time ordered 4 pieces of 12 inch IWAI subwoofer drivers..

Two sealed boxes of the dimension 15 x 15 x 17 (H) were made like before using 18mm Plywood..

The above two subs are mounted to ceiling firmly at 1/4th and 3/4th room width & mid of room length to reduce the width & length room modes..

Two more sealed boxes of the dimension 8 x 18 x 30 (H) were made using 18mm Plywood..

The shallow boxes were made to place it near window and behind the Acoustic Transperant screen, also at mid height of the room to reduce the height room mode..

Was able to hide it behind the screen and placed them inbetween L-C-R, slightly above ear level..

The subwoofers were not finished aesthetically as they are anyways hidden behind screen and to the wooden fixture on ceiling.. So the enclosure will not be visible to the eye..

Also picked up an used, faulty Parasound 5 channel power amplifier (HCA 2205 A), of which only 4 channels work, which would be used to power the Quad DIY sealed subs..

An other reason, i picked up the used 5 channel amplifier, was one power source for all 4 subwoofers, also the freq resp of the amplifier was rated from 5Hz.. So i thought it should have some control below 20Hz, incase the sub is able to dig below these levels..

Cost of the build

Sub drivers - 4 pieces of IWAI 12 inch subwoofer shipped to my location, approx Rs 21,000
Enclosure - Enclosure material & Labour to build, approx Rs 7,000
Amplifier - Parasound HCA 2205A - Rs 20,000
Cables & speaker connector - Rs 2,000

Totally spent Rs 50,000 for 4 subwoofer driver + enclosure + used amplifier..

After hooking up everything, i noticed that one of the subs on the front wall (inbetween L-C-R) wasn't working.. Must be my error in internal cabling, so couldn't do the Audyssey calibration.. Will try to fix this weekend and measure the response ( Below 90Hz) at my listening position..

For now two subs on ceiling & one sub inbetween the L-C-R work and fairly adjusted the levels.. The single sub in between the L-C-R feels fantastic.. if am able to fix the other one on the front wall, should be even better..

 

[elangoas]

A clear picture of the subs and heights firmly fixed to wooden structure on ceiling..

Speakers with white grille - Present height speakers (A pair)..
Black drivers - Subwoofers
Box with no drivers - To accomodate 2nd pair of heights in future..