Speaker Box Design for TV

[aleomans]

Hi All

This is my first post here so, hello, be kind...

I am pulling together a speaker box to house 2 X 6X9 speakers and class D amp for my TV/media pc and am looking for some advice.

The plan is to somewhat hide this speaker box behind the TV in a vertical orientation. See attachment. My wife does not want to see the speakers so I need to make the most of what I can.

So questions:
1. Is it best for an open/port design like some posts I've read or sealed?
2. With the spec below I am having trouble using online calculators to calculate the volume of a speaker box - is Fo the free air resonance?
3. I will also need to try to deaden the sound behind the speaker box as this is a common wall in a block of flats - is this done inside or outside of the box?

Speaker spec:
6x9 Kevlar Coaxial Speaker with Silk Dome Tweeter
Power handling 75WRMS
Nominal impedance 4 ohms
Frequency response 40Hz-20kHz
Sensitivity 90dB SPL @ 1W, 1m
Re 3.4 ohms
Qms 6.34
Qes 0.77
Qts 0.687
Vas 42.82 litres
Fo 44Hz

I also have an 8inch woofer on back order which I'll use in the mix once I've sorted the 6X9's requirements.

Cheers
Al

 

[OffGridKindaGuy]

Put each of those 6x9's in a sealed enclosure of around .2-.3 ft. stuffed full of fiberglass. I get good results with that..

 

[chrisb]

OTOH, if the 6x9 are car audio drivers, most of those are designed to work in at least somewhat "leaky" if not actually aperiodic enclosures - i.e. the old trunk decks, doors - including rear doors of vans, etc.. Some type of vented might give better low end extension, provided not tuned high enough that drivers are unloaded below their resonance if not high pass filtered before the hand-off to the 8". The natural acoustic roll-off in smallish sealed box could certainly protect the drivers from over-excursion, but might be high enough that bass image locations could wander if the woofer is more than a couple of feet away.

 

[aleomans]

Thank you for the replies guys.
I'll go for the filled sealed enclosure of 0.2 to 0.3 cubic ft. As this will have the 8" woofer I am less worried about missing out on the lower frequencies from the 6X9's. The woofer speakers range is 38Hz-4.5kHz but the amp has some low pass filtering which can be tweaked to help the system response.
Al

 

[SS4927]

I once had high end kicker 6 9's with the outboard anodized coils encased in solid acrylic cylinders that had to be stuffed into the boxes so those ate up some more of what little cubes were there to start out with. But I was relly fond of that systems sound with high end alpine clean 35x2 on those and a zapco mono block to go on a pair of 6" subs. The kickers were snappy accurate and loud! they put out enough bass to get the message across with some authrity partly because they were also stupid loud and clear. just dont expect them to rattle any windows out. but nice sounding clear accuracy counts too so I would try them out inside your place with some kind of a sub (sealed too)/.

 

[Ron E]

3. I will also need to try to deaden the sound behind the speaker box as this is a common wall in a block of flats - is this done inside or outside of the box?

There is essentially nothing effective you can do for the common wall short of building another wall between you and the neighbor. You could mount z-channel to the wall and mount 2 thick layers of drywall to that with "green glue" between them, or you could add a whole separate wall cavity spaced away from the wall, stuffed with fiberglass and multiple layers of drywall on each side. If your flat is not on a poured slab, you might reduce transmission via the floor by mounting on some sort of spring or rubber vibration isolators.

 

[aleomans]

Thanks guys and appreciate the replies. For a number of years I have been using some 2.1 Altec Lansing 2.1 speakers I purchased for an old PC now they are humming at the top end of their volume where they have to sit to fill the room - they have done really well for 15 years!

I the expectation that these new speakers will exceed the previous speakers within the limitation of the $20 amp. However as my wife and 3 year old often complain that volume is too high I cannot see this system being pushed to shake any windows!

Luckily the common wall is not against the neighbor (but facing out of the building) but being an identical flat of the one below is likely to resonate on the bass - fortunately the old couple below cannot hear to much or dont complaint when I can crank it up a bit when every one is out.

I am at the stage of speaker box construction as I now have all the speakers including the back ordered 8inch woofer. I cannot wait to built and test. Next stop hardware shop for some MDF and then onto the saw bench.