How heavy should the subwoofer cabinets be ?

[noslepums]

I am in the process of designing my sub cabinets.

(Details: 2 cabinets, roughly 1 cu. ft. each, sealed, Peerless 12" XLS,
boosted/eq'd, flat to maybe 25Hz, music only, no HT, not sure about
decibel target but don't want to rattle the walls or break glass items.
Will have active X-overs and dedicated subwoofer amp.)

So........
I am seriously considering adding either lead plate or lead shot
to the design. How heavy should I make each cabinet before getting
to the point of diminishing returns ? For example, it will be very easy
to get each box up to 200 pounds. Is this necessary, or will I not
hear any difference past, say, 100 pounds ?

I should add, the cabinets will just be sitting on the carpet, not on spikes,
not part of any other structure.

 

[maxo]

weight dont matter, as long as you are using a tried a true design or if make your own
you need to know what are you doing as it not matter of just getting any woofer or speaker you can buy
and stick it in a "box" there is math and calculations behind that
there are many types of drivers "speakers" with many flavours of freq response and specifications
that you need to input for example on hornresp software to caluclate and simulate the freq response of the cab per see
so a driver suited for a pa folded horn sub, will not work for example on a bandpass car enlosure


Baltic Birch Plywood 1/2" or 3/4"
depending but for a 12" i suggest 1/2" thick

you dont need to add metal inside as bracing
actually with wood you can do pretty nice

also the glue is the key
you need to use PL glue, is the best for speaker building
also fill all the junctions and gaps with your glue
you dont want any air leaks so the enclosure must be airtight
you will need to use a gasket on you between your woofer and the wood

Happy Building.
Max.

Opps just re read your post
for 1cu feet you 1/2 or even 3/8 will do
maybe 1/4
not sure for that kind of small box
but somebody can chime in and advice

i am not fan of MDF

 

[ßart West-VL.]

Heavy is not always good, when it starts to vibrate, and it will, it doesn't stop easily!
It has to be a very rigid construction.
If it's no problem for you to build heavy, consider using granite plates three inches thick. That'll do the job just fine...
Or, concrete slabs: that is what I fantasize about when thinking 'heavy sub'. Or a masonry sub, nice looking! With a ring poured out of concrete as a baffle.
I'll stop now, fantasy is running wild again...

 

[planet10]

The only reason for mass loading a sub is to keep it from walking (a much more elegant way of preventing that is to use a pair of woofers push-push). As far as the cabinet goes light & stiff is where you want to go.

Without doing a sim, 1 ft^3 seems rather small for a 12" unless you are using a Linkwitz transform. This means high internal pressure differentails and you will need to brace it well to prevent the box from ballooning.

I'd suggest 18mm quality plywood.

dave

 

[freax]

The only reason for mass loading a sub is to keep it from walking (a much more elegant way of preventing that is to use a pair of woofers push-push). As far as the cabinet goes light & stiff is where you want to go.

Without doing a sim, 1 ft^3 seems rather small for a 12" unless you are using a Linkwitz transform. This means high internal pressure differentails and you will need to brace it well to prevent the box from ballooning.

I'd suggest 18mm quality plywood.

dave

Coming from someone who has made the walls shake quite a bit, it not only prevents the sub from going walkies but a heavier subwoofer also makes a better coupling with the floorboards and the resulting connected walls.

If vibrating walls is your thing that might be an advantage, thats what I've found anyway.

 

[ßart West-VL.]

...a heavier subwoofer also makes a better coupling with the floorboards and the resulting connected walls...

How?

 

[Wavebourn]

My floor is attached to subwoofer. It is under the floor, concrete short horn (really waveguide). It works from 40 Hz and down. Woofers are in concrete boxes, work from 40 Hz ro 120 Hz (subject to change), and are in molded concrete boxes. Can't complain. And don't see the need to measure, the mass is the result of the size, if it is more it is fine. But anyway it is more than would be if I made them from some plywood. I don't complain.

 

[Wavebourn]

Coming from someone who has made the walls shake quite a bit, it not only prevents the sub from going walkies but a heavier subwoofer also makes a better coupling with the floorboards and the resulting connected walls.

If vibrating walls is your thing that might be an advantage, thats what I've found anyway.

I am afraid it is disadvantage, especially if your house was not insured against earthquakes (just kidding; I believe insurance company will find the way to refuse the payment). Shaking chairs, yes. It is advantage, when watching movies.

 

[AndrewT]

Too heavy for the wife to lift and throw out with all your other belongings when she's had enough ?

 

[Wavebourn]

Too heavy for the wife to lift and throw out with all your other belongings when she's had enough ?

Right. My woofers are the single item that can be taken and thrown (arrays are in walls, subwoofer is under the floor). It is good. Also, after I made this system, my wife complained that I spoiled her tastes, she can't stand reproduction from systems sold in stores anymore! It is good as well. Do your best, and your wife will (probably) like it. Do it for your wife, for your kids, for your grand-kids. And you will find support in your endeavors.

 

[noslepums]

My understanding on this topic is..........

To avoid mechanical resonance of the box in the range of subwoofer frequencies,
the box must have high enough stiffness and LOW enough mass to put its resultant
resonant frequency high enough to not be met by the driver's operation.

An opposing condition is that the mass of the box must be HIGH enough to fully
oppose the woofer's motion (Newton 3rd Law).

We know that folks have used sand in making their enclosures, and it works well,
possibly for both anti-vibration and dead weight.

What I'm interested in here is how heavy is heavy enough ?

 

[badman]

My understanding on this topic is..........

To avoid mechanical resonance of the box in the range of subwoofer frequencies,
the box must have high enough stiffness and LOW enough mass to put its resultant
resonant frequency high enough to not be met by the driver's operation.

An opposing condition is that the mass of the box must be HIGH enough to fully
oppose the woofer's motion (Newton 3rd Law).

We know that folks have used sand in making their enclosures, and it works well,
possibly for both anti-vibration and dead weight.

What I'm interested in here is how heavy is heavy enough ?

As Planet10 mentioned, opposed woofers helps allow you to keep it nice and light. Extensive bracing does plenty well, with heavy OR light cabs, for subwoofer duty.

 

[noslepums]

One woofer per box.

 

[planet10]

One woofer per box.

Push-push has so many advantages i endeavor to always have 2 drivers per box.

dave

 

[jbell]

I built lightweight sonotube subs wrapped in black grill cloth with 2" thick oak tops and downfiring subs.

I put them in the front of a church as "plant stands" so they would be disguised and no one would know what they were...

One day, a helpful parishioner decided to water the plants before service started.

I think at least the front three rows got baptized when the praise team kicked it up...

Sonotube... not heavy enough....

 

[ßart West-VL.]

haha, where was the camera?!

I built lightweight sonotube subs wrapped in black grill cloth with 2" thick oak tops and downfiring subs.

I put them in the front of a church as "plant stands" so they would be disguised and no one would know what they were...

One day, a helpful parishioner decided to water the plants before service started.

I think at least the front three rows got baptized when the praise team kicked it up...

Sonotube... not heavy enough....