Modular vented subwoofer

Droco

Member
2017-10-12 4:15 pm
How reliable would it be to make a vented subwoofer consisting out of 2 parts. The firs part would be a 60 x 60 x70cm cube with the driver and slotport, but with limited leftover internal volume. The second part would be a 60 x 60 x 50cm cube to add 147 liters of internal volume.

I would only allow a 1320cm² (30 x 44cm) connection between the 2 modules.
I would use a shock absorbing material between the 2 modules to make it airtight, and use "butterfly locks" (see pic) to attach them firmly together.
vlinderslot.jpeg

Reason for this approach is being able to build the sub I want, but making it way easier to transport (in smaller cars, up and down stairs etc).
 

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Galu

Member
2018-04-17 6:50 pm
Having run a mobile disco in the dim and distant past, this strikes me as a jolly good way to provide ease of transportation.

As long as the vent is tuned to match the total enclosure volume and the connecting opening is as large as is viable, I can't see a problem with the idea.
 

Droco

Member
2017-10-12 4:15 pm
I'd go back a step. What's the application where you need such a large subwoofer to be portable?60 x 60 x 120 is smaller than 90 x 80 x 60, which is the size of the Ricci designed Skram, which is what I'm gonna modify to fit my size requirements. A lot of space is taken up by the horn and the large ports to allow high output.

Do you already have the drivers or something?

It looks to me like it'll be a lot of work and hardware, for something where using a better driver might bypass the whole thing.

Chris
'better driver' is nearly impossible. I'm gonna be using the Lavoce San 214.50, which is arguably the best sub at that price. I might upgrade to an IPAL21, but those have specific amp requirements which I can't meet at the moment.

With this design I can have 130db down to 30hz (in half space!) , for around 1000 euro for a pair (including amplifier).
 

kipman725

Member
Paid Member
2007-06-10 12:41 pm
Warrington
I don't see any reason why it won't work if the seal is good, you will probably need 2 latches per box face minimum. The normal approach is just to use a greater number of smaller drivers which will also give better placement flexibility. However as you point out the performance of these 21" drivers is such that they have more output than a pair of 15" drivers at lower cost. 4*RCF LF15X401 should also be able to exceed 130dB/1m/2pi if you wanted something more conventional.
 

Droco

Member
2017-10-12 4:15 pm
I don't see any reason why it won't work if the seal is good, you will probably need 2 latches per box face minimum.
You mean 8 in total? Because that was the plan :) Only wayto ensure the boxes are clamped together at all corners.
The normal approach is just to use a greater number of smaller drivers which will also give better placement flexibility.
Do agree with placement flexibility.
However as you point out the performance of these 21" drivers is such that they have more output than a pair of 15" drivers at lower cost. 4*RCF LF15X401 should also be able to exceed 130dB/1m/2pi if you wanted something more conventional.

I actually want something more complex. Just for the sake of it. Using this Skram-like design also has it own advantages. Also, I modelled those RCF drivers, and youre right thy perform very well.

The RCF 15" in a 30hz tuned box (exactly half the size of my design) can only match my design when 2 are coupled together (so 6dB boost) when using a small port (which doesnt take in to much space) which results in an incredibly high port velocity (over 80m/sec).
RCF LF15X401 vented v1.PNG
When designing the cabin to reach the same velocities as my design the output decreases by a lot, as seen here:
RCF LF15X401 vented v2.PNG
Other disadvantages are an increased price over my design (depending on the store around 20% more for 2 instead of my x1 21" driver) and more amp requirements (3000W vs 1700W for mine)

In all, if I'm trying to reach as much SPL as I can at 30hz, than my design is gonna be hard to top. Using x2 18" drivers in the same 60x60x60cm cabin as the RCF model, then the results only get slightly better, and still very away from mine. With x2 18" the price also skyrockets, as well as amp requirements.
 

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