8 Subwoofers on ceiling !!

[elangoas]

Elangoji ,unless adding a minidsp kind of product ,how you are going to match the time and phase alignments for 8 subs...

Did some reading, and setting time-delay for each subs = phase ?..

The other reason i wanted to group two sub-woofers in the same location is to use the same delay for a pair of subs, not separated by more than a ft..

Thought of an other weird workaround / remember reading somewhere on other forum..

What if i can use a 6 (or) 7 channel AVR with multi-channel analogue inputs connected to AVR's sub pre-out, and use the speaker outputs on AVR to drive the subwoofers?.. The AVR has independent delay (distance) & speaker level for all the speaker channels.. Would this negate the need for mini DSP?..

 

[rejin]

Power amplifier - Sonodyne (8 channel amplifier, capable of 90 watts continuous power at 4 ohms)..

Hi @elangoas .

isn't this too much to ask from a normal 8 channel amplifier?
Since you are going to drive all the 8 channels from the same signal, the high power requirement on all the channels are going to be simultaneous. Can the amp deliver that power requirement?

1 more thought. Since you are mouting the sub woofer placement on the ceiling at pre determined locations, what can be done if there is a peak or null at the listening position after installation. Can a DSP help to solve this?

Why didn't you consider bigger driver (2 or 4 nos), since you don't have many seating locations? I hope you are not looking for even bass at every location in room.

(I am a total newbie on these topics, these may be wrong questions ).

 

[elangoas]

isn't this too much to ask from a normal 8 channel amplifier? Since you are going to drive all the 8 channels from the same signal, the high power requirement on all the channels are going to be simultaneous. Can the amp deliver that power requirement?

I don't think so.. More the subwoofers you have, lesser the power needed for each sub..

The power amp is rated at 90watts of continuous power at 4 Ohms when all 8 channels are driven simultaneously, which is like having the ability of 720 watts of continuous power output.. Should be sufficient enough IMO..

1 more thought. Since you are mouting the sub woofer placement on the ceiling at pre determined locations, what can be done if there is a peak or null at the listening position after installation. Can a DSP help to solve this?

The predetermined location of subs is most widely considered a better placement of 4 subs in a symmetrical room to produce smoother freq response.. Am trying to add 2 subs at the same location, but on ceiling which should help in more SPL.. Instead of keeping on floor, i have thought on ceiling so as not to rob the living room space..

Just a rough guess.. With listening position in-between 8 subs, there shouldn't be any huge peaks and nulls.. A small variation should just be fine..

Why didn't you consider bigger driver (2 or 4 nos), since you don't have many seating locations? I hope you are not looking for even bass at every location in room.

The more the subs you have, better (smoother) would be the response, capable of higher SPL, possibility of higher crossover to contain the room resonance upto 100Hz.. I have had the same sealed sub in my room & my brothers room.. When i measured the in-room response of the same subs, it is capable of doing 20Hz and rolling off post that, which i think is more than enough..

If you can & have the possibility of having good, smooth bass, why loose the advantage is my thinking / logic..

I am a total newbie on these topics, these may be wrong questions ).

No probs.. Am not an expert either.. Just have some hands-on experience with dual/multiple subs in my room and some inferences.. Thatz all..

 

[raghupb]

@elangoas
Have you considered external crossover and speaker line level filtering.
It sounds much more complicated than what you have going now.
You can distribute the 8 subs as:
FL (+2 stack)
C (+1 floor)
FR (+2 stack)
SL/SLB (+1 ceiling)
SR/SRB (+1 ceiling)
LFE (1 floor/ceiling)

This assumes you have some floor space at LCR
Cheers,
Raghu

 

[Amarendra]

I don't think so.. More the subwoofers you have, lesser the power needed for each sub..

The power amp is rated at 90watts of continuous power at 4 Ohms when all 8 channels are driven simultaneously, which is like having the ability of 720 watts of continuous power output.. Should be sufficient enough IMO..



The predetermined location of subs is most widely considered a better placement of 4 subs in a symmetrical room to produce smoother freq response.. Am trying to add 2 subs at the same location, but on ceiling which should help in more SPL.. Instead of keeping on floor, i have thought on ceiling so as not to rob the living room space..

Just a rough guess.. With listening position in-between 8 subs, there shouldn't be any huge peaks and nulls.. A small variation should just be fine..



The more the subs you have, better (smoother) would be the response, capable of higher SPL, possibility of higher crossover to contain the room resonance upto 100Hz.. I have had the same sealed sub in my room & my brothers room.. When i measured the in-room response of the same subs, it is capable of doing 20Hz and rolling off post that, which i think is more than enough..

If you can & have the possibility of having good, smooth bass, why loose the advantage is my thinking / logic..



No probs.. Am not an expert either.. Just have some hands-on experience with dual/multiple subs in my room and some inferences.. Thatz all..

When you mount subwoofers in the ceiling are these just passive drivers or are these actual subwoofers as in lets taga harmony/ Wharfedale types and if yes how does the ceiling take its weight ?

 

[RajithKumar]

Im not expert on this ,but IMO ,The AVR stuff which you have mentioned may or may not work .Instead of mounting sub on ceiling ,do some research to do double bass array .This may improve a lot ,but however I will sugest to add a minidsp to do this. Many of people on globaly have done this and its a proven method.

 

[elangoas]

@elangoasHave you considered external crossover and speaker line level filtering.

External crossover wouldn't be required IMO.. The AVR already has it.. The idea is to make use of AVR's crossover and place subs at ideal locations in the room to largely contain the room resonance..

It sounds much more complicated than what you have going now.
You can distribute the 8 subs as:
FL (+2 stack)
C (+1 floor)
FR (+2 stack)
SL/SLB (+1 ceiling)
SR/SRB (+1 ceiling)
LFE (1 floor/ceiling)

This assumes you have some floor space at LCR

This sounds more complex and an installation for sooper skilled.. because subs are at different location in the room and you would need to set time-delay for each independently.. I would be inviting more trouble..

Moreover, i think subs at different locations especially above & below front speakers, would help reduce height resonance in the room, which they are very strong near walls.. My brothers listening position is well away from boundaries.. So i think it wouldn't help him much..

I have used the room mode calculator to identify the resonant frequency in the room for subwoofer crossover of 100Hz.. Attaching an image of the same..

Visualise the length mode on a side view of the room.. The resonant frequncies are 26, 51, 77, 103 Hz..

Same way visualise the width mode from a ceiling pint of view.. The resonant frequencies are 51Hz and 100Hz..

Visualise height mode from side of the room.. The resonant frequencies are 57Hz..

Guessing from the above chart and from what i have done with 2 subs on ceiling in my room, most likely i would be able to contain most of resonance upto 100Hz with multiple sub-woofers and effectively reducing room treatment in that range..

 

[raghupb]

Agreed. It is way more complicated than your approach.
Was tempted to throw it in as I've read about successful bass arrays.
Good luck in your pursuit. Keep updating us so that we can learn.
Cheers,
Raghu

 

[elangoas]

When you mount subwoofers in the ceiling are these just passive drivers or are these actual subwoofers as in lets taga harmony/ Wharfedale types and if yes how does the ceiling take its weight ?

They are passive subwoofers.. Just like connecting speakers from an amplifier..

Below is an image of my room on how i erected support for passive subwoofers on ceiling using shorter walls of the room..

Side view for an understanding..

View from the floor

Would do a similar thing for my brother too..

 

[Amarendra]

They are passive subwoofers.. Just like connecting speakers from an amplifier..

Below is an image of my room on how i erected support for passive subwoofers on ceiling using shorter walls of the room..

Side view for an understanding..


View from the floor


Would do a similar thing for my brother too..

So these are sub woofer drivers enclosed in boxes which are diy right ? Are there any designs for these boxes or any basic designs work ?

 

[elangoas]

Im not expert on this ,but IMO ,The AVR stuff which you have mentioned may or may not work .Instead of mounting sub on ceiling ,do some research to do double bass array .This may improve a lot ,but however I will sugest to add a minidsp to do this. Many of people on globaly have done this and its a proven method.

I thought of a Single Bass Array (SBA) on the front wall, positioned at 1/4th the room width and height.. Easy to do & mount on front wall than on ceiling, but he has a 135inch vinyl screen which is blocking that effort.. If i need to do SBA, then the screen has to be acoustically transparent to position them behind the screen correctly on front wall.. Have been pushing him for AT screen, no luck yet.. There is window there behind the vinyl screen, bit of civil work which is delaying / postponing the SBA effort..

On DBA, from what i have read, is to replicate the SBA on front wall & rear wall.. I would love to do DBA.. Front wall is defnetly possible to position correctly, but wouldn't able to position them at correct location on rear wall as there is a door to the room..No luxury of dedicated room.. So limitations.. Moreover am not skilled enough to attempt DBA..

Agreed. It is way more complicated than your approach. Was tempted to throw it in as I've read about successful bass arrays. Good luck in your pursuit. Keep updating us so that we can learn.

Got it.. Thank you.. Defnetly thought of Single Bass Array (SBA).. As mentioned above, some limitation in the room.. If he gets that, then bass array will be more easier.. Sure, will keep sharing updates once the idea is finalised..

 

[marsilians]

In ceiling subs are not a good idea if one understands how they interact with the speaker generated waves.i would invest first in 2 high quality subs with high level inputs rather than LFE and then decide on additional ones.

The room DSP suggestion earlier is a good start to fine tune the system.

While I am not a bass head but having listened to rather cheap REL subs Q201, it really made me realize on the potential for enhancing the bottom end. Of course there are other subs that can create the same magic, but sharing my experiences

 

[elangoas]

So these are sub woofer drivers enclosed in boxes which are diy right ?

Yes.. Sealed ones..Boxes are made of 18mm plywood..

Are there any designs for these boxes or any basic designs work ?

I collected inputs from one of the FM (@Ravindra Desai ) on the sealed box dimension when i built them as i didnt have much of DIY with subwoofer.. Passive & sealed sub was the easiest to attempt also allowing me to mount.. Hence tried..

From what i understood from him is that, as long as internal volume of the box remains the same, you have some liberty to adjust the L x W x D.. My enclosure dimensions are 15 (L) x 15 (W) x 17(H) inch..

 

[elangoas]

In ceiling subs are not a good idea if one understands how they interact with the speaker generated waves.

These DIY efforts aren't in-ceiling subs, but subs mounted to ceiling at right locations in the room to save living room space.. The subs away from room boundaries sounds good in my limited experience..

I have had dual subs in my room stuck to the front room corners on the floor and also now have dual subs on ceiling at ideal locations, where the room resonance is largely reduced.. Feels nice.. So w.r.t subwoofer it is the location in the room that influences its output..

Given a chance, i would have subs on ceiling in the living room.. For dedicated HT space, yes on floor.. You have much liberty there..

i would invest first in 2 high quality subs with high level inputs rather than LFE and then decide on additional ones.

Am sure you would have a reason when you say this.. Why 2 subs when even 4 can help to a great extent for smoother response?.. Also why high level inputs and not use LFE?.. Wouldn't a sub pre-out be easy to handle with external amplification and that too with multiple subs in consideration..

The room DSP suggestion earlier is a good start to fine tune the system.

Yes DSP would help to tame huge peaks.. Depending on where the peak is in the room, and if it is in the upper limit on the crossover range, would be easy to add chunky trap (absorption) to contain it fairly..

While I am not a bass head but having listened to rather cheap REL subs Q201, it really made me realize on the potential for enhancing the bottom end. Of course there are other subs that can create the same magic, but sharing my experiences

Thanks got it.. The sub drivers that am considering (12 inch IWAI) for the build, i have them with DIY in my room and is capable of reaching 20Hz and slightly lower in a sealed config..

 

[marsilians]

.. Also why high level inputs and not use LFE?.. Wouldn't a sub pre-out be easy to handle with external amplification and that too with multiple subs in consideration..

Thanks for the clarification on the inceiling vs. not situation.

Re high level, I have come to realize the fantastic and seamless integration it offers vs. LFE. The beauty about it is you will only realize the lack of it when you switch off the sub when your speakers feel they lost their bottom end. IOW, high level makes your speakers sound very full including bookshelves or stand mounts.

I have always felt the need for subs in stereo setups as well. So started off with Polk then SVS and HSU. Now I will never go back to them after trying REL Vandersteen and Sonus Faber with High Level integration.

 

[elangoas]

Thought of an other alternative - Layout B.. Thinking, which among of the two would be better A Vs B ?..

 

[sbg]

Thought of an other alternative - Layout B.. Thinking, which among of the two would be better A Vs B ?..

I think, it may not matter. For the kind of efforts and time/resources being put. You can even consider a literal "subwoofer crawl" to get the sweet spot- as the whole of the ceiling is available.

...hmm, can these not be placed in an circular fashion ( subwoofer's Halo )

 

[ONEMANARMY]

I think this is a brilliant idea as far as utilization of space is concerned.
With 8 subs and rockwool treatment you should be able to achieve both high spls and even distribution
More power to you

 

[elangoas]

I think, it may not matter. For the kind of efforts and time/resources being put. You can even consider a literal "subwoofer crawl" to get the sweet spot- as the whole of the ceiling is available.

Great, thanks.. Have the UMIK-1, should be able to validate them.. But hoping it would be good, as it is close to ideal positions..

...hmm, can these not be placed in an circular fashion ( subwoofer's Halo )

My brother too asked if circular would be good.. I wasn't so sure.. I was thinking more on the lines of standing waves between surfaces in a rectangular room is also rectangular..

 

[elangoas]

I think this is a brilliant idea as far as utilization of space is concerned.
With 8 subs and rockwool treatment you should be able to achieve both high spls and even distribution
More power to you

Thanks..Gives a great flexibility of having a HT setup in a living room..