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Modular vented subwoofer
Modular vented subwoofer
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Old 18th October 2019, 12:38 AM   #1
Droco is offline Droco
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Default Modular vented subwoofer

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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File Type: jpeg isolation strip.jpeg (5.7 KB, 180 views)
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Old 18th October 2019, 12:51 AM   #2
Galu is online now Galu  Scotland
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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.
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Old 18th October 2019, 01:05 AM   #3
hollowboy is offline hollowboy  Australia
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Some existing builds are similar, you could mine them for ideas.

La Scala Mod Project Completed - Technical/Modifications - The Klipsch Audio Community

This one tacks an extansion onto a La Scala.
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Old 18th October 2019, 07:52 AM   #4
chris661 is offline chris661  United Kingdom
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I'd go back a step. What's the application where you need such a large subwoofer to be portable?

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
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Old 18th October 2019, 02:23 PM   #5
Droco is offline Droco
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Quote:
Originally Posted by chris661 View Post
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).
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Old 18th October 2019, 02:49 PM   #6
kipman725 is online now kipman725  United Kingdom
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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.
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Old 18th October 2019, 06:42 PM   #7
Droco is offline Droco
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Quote:
Originally Posted by kipman725 View Post
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.
Attached Images
File Type: png 18SW115 606060cm v1.PNG (26.8 KB, 138 views)
File Type: png 21DS115 176L.PNG (25.2 KB, 138 views)
File Type: png B&C 18PZB100 606060cm.PNG (24.1 KB, 136 views)
File Type: png B&C 18Sw115 vented v2.PNG (23.9 KB, 134 views)

Last edited by Droco; 18th October 2019 at 06:45 PM.
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Old 20th October 2019, 02:28 PM   #8
kipman725 is online now kipman725  United Kingdom
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Yes so your approach looks good, more output, less cost.
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Old 21st October 2019, 11:40 AM   #9
kipman725 is online now kipman725  United Kingdom
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I found this thread which is a similar idea and seems to have worked well:
Rock Block - a space saving sub
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