newb with an idea (probably bad).. point me in the right direction?

marticus

Member
2019-12-10 12:15 pm
Hi guys,

My first post here, and i'm just looking for some top level advise.

RIght now I have a pretty straight forward 5 channel system in my living room, useage is 80% TV / Moveies and 20% music.

right now my sofa is against the back wall with rear surrounds wall mounted to the left and right, and for quite a while i've had the idea of building some kind of storage unit / spacer behind the sofa to create some space between the listener and surrounds.

such as:
01-DIY-skinny-console-behind-couch(pp_w768_h548).jpg



now the question is, does it sound feesable to build a couple of subwoofers into something like that (deeper that the pictured one)?

is there any precident for this? i've seen in wall subs, but i have a feeling this may be a different animal?

Is the fact that the sub will be sitting between the wall and sofa make this a pointless excersise?

would downward firing work? maybe a couple of 10" drivers?

how would you approach something like this?
 

marticus

Member
2019-12-10 12:15 pm
Is there some space beneath the sofa to place the drivers and ports?

Hi,

yeah i guess there's about 15cm in height under the sofa.

i was thinking if the woofers are downfiring and i made some open space at the bottom of the unit behind the sofa it might work? i would be better than pointing them into the back of the sofa i assume?

I don't know much about room accustics but i understand that having them here wouldn't be ideal right? but could having two subs help with that maybe?
 

marticus

Member
2019-12-10 12:15 pm
You can also take a bunch of these: Tang Band W3-1876S - 3" Subwoofer
For example: put 4 of them in a vented box of 8L, tuned to 45 Hz. Maybe 2 or more vents to make it fit.
Result: F3=40 Hz, 100 dB at 60 Watt (4*15 W RMS).
Just add more to of you need more SPL.

OK this is interesting. But I have to admit my knowledge is failing me here.

How deep would these go? Even if I used say 6 of them would it get Down to a usable 30hz for example.

I admit I'm not even certain what 30hz would men in a real world instance. But my main fronts are jamo 606 and they have a 6.5" woofer that will reach down to 50hz iirc.. So I was hoping to get further down to make a difference. If that makes sense.

But maybe I can split the difference and use something a bit bigger but multiply them?
 
A 3" subwoofer is IMO not big enough to produce low bass at HT levels.

You'll have better luck with one or more of the low profile drivers and mount the box below the couch if you can.

Of course the flat 10" would go deeper, BUT:
- Draw us a 272mm diameter, 84mm deep driver in a 15cm enclosure, not be blocked by the sofa or the floor.
- There was no question about how deep the sub needed to go.
 
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OK this is interesting. But I have to admit my knowledge is failing me here.

How deep would these go? Even if I used say 6 of them would it get Down to a usable 30hz for example.

I admit I'm not even certain what 30hz would men in a real world instance. But my main fronts are jamo 606 and they have a 6.5" woofer that will reach down to 50hz iirc.. So I was hoping to get further down to make a difference. If that makes sense.

But maybe I can split the difference and use something a bit bigger but multiply them?

Adding more drivers will only raise SPL. It won't let you deeper. The 6th order bandpass I showed reaches just below 40Hz.
You can tune them a little lower, but they will lose SPL dramatically due to limited xmax.
 
With four SB15NAC30-4 in a 8th order bandpass you will get force cancellation due to opposed drivers and distortion cancellation due to drivers working push pull.
The 8th order bandpass alignment will very effectively low pass filter out a lot of driver noise and distortion for a very clean bass reproduction. The large exit mouth will keep the air velocity down to very reasonable levels and the midbass peak will add a much needed "punch" to the bandpass alignment.

1200 x 1136 x 196 mm if build of 18 mm plywood.

Great efficiency for a very flat "behind the sofa" subwoofer with 30 Hz response.
 

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Of course the flat 10" would go deeper, BUT:
- Draw us a 272mm diameter, 84mm deep driver in a 15cm enclosure, not be blocked by the sofa or the floor.
- There was no question about how deep the sub needed to go.

84mm = 8.4cm

15cm-8.4cm = 6.6 cm

6.6cm - (2*1.7cm) = 3.2 cm leftover for clearance between the subwoofer and the floor/bottom of couch.

Yes, that would be difficult to do.

... unless you raise the couch :)
 

marticus

Member
2019-12-10 12:15 pm
Thanks guys for all the suggestions.

It sounds like this might be a plausible idea in the end.. But it's also clear I have a lot to learn and will need to balance my dreams with realistic achievable goals.

But I can at least start doing some research and learning what can.
 
Thanks guys for all the suggestions.

It sounds like this might be a plausible idea in the end.. But it's also clear I have a lot to learn and will need to balance my dreams with realistic achievable goals.

But I can at least start doing some research and learning what can.

Before you scrap your plan. Tang Band has a 4" beast too:
Tang Band W4-2089 - 4" Woofer
fs = 35 Hz easy to tune lower; like f3 = 23 Hz. :D
And a 8 mm xmax for more power.
They are 13cm wide, so if you fit them tightly between walls, the enclosure will be 17cm deep :rolleyes:
Make them fire to the front at the bottom, beneath the sofa.
 

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