Large sub wirh multiple passive membrane

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   Hi,
I tought I should build a sub.

21 or 24 inch high quality PA sub driver on the front… and add every side 2 x 12 inch passive membrane (8 in total, so the back could use the amp and handles and wheels)

So it could be around 24 x 24 x 12 inches, and if I can source some light but good passive rad’s… it could be relatively light, very deep tuned and powerful.

I would like to get a BassBoss Makara specs with much lover weight and power, same or better results.

I’ts just an idea… Would make also a “little brother” of it with 15/18 inch and small rad’s but it should be able to go to the same low 20’s as the “big brother” just with reduced levels….

Any recommendations for drivers and rads would be highly welcome.

(I would like to get as light and as small subs as possible, but with high levels…. Like the K-Array or so… some ‘shallow’ units)

Is this a “right way” to do this, or this won’t work for some obvious  reasons…. And that’s why I never saw any subwoofer like this?

Thx in advance.

Edited by madam - 31 January 2025 at 8:20pm

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madam Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 14 June 2020 Status: Offline Points: 23	Post Options Post Reply Quote madam Report Post Thanks(0) Quote Reply Topic: Large sub wirh multiple passive membrane Posted: 31 January 2025 at 8:16pm
	Hi, I tought I should build a sub. 21 or 24 inch high quality PA sub driver on the front… and add every side 2 x 12 inch passive membrane (8 in total, so the back could use the amp and handles and wheels) So it could be around 24 x 24 x 12 inches, and if I can source some light but good passive rad’s… it could be relatively light, very deep tuned and powerful. I would like to get a BassBoss Makara specs with much lover weight and power, same or better results. I’ts just an idea… Would make also a “little brother” of it with 15/18 inch and small rad’s but it should be able to go to the same low 20’s as the “big brother” just with reduced levels…. Any recommendations for drivers and rads would be highly welcome. (I would like to get as light and as small subs as possible, but with high levels…. Like the K-Array or so… some ‘shallow’ units) Is this a “right way” to do this, or this won’t work for some obvious reasons…. And that’s why I never saw any subwoofer like this? Thx in advance. Edited by madam - 31 January 2025 at 8:20pm

godathunder Members Profile Send Private Message Find Members Posts Add to Buddy List Old Croc Joined: 19 July 2004 Location: wicklow Status: Offline Points: 1888	Post Options Post Reply Quote godathunder Report Post Thanks(0) Quote Reply Posted: 01 February 2025 at 10:14am
	without wishing to discourage you, that sounds heavy, fragile, wasteful, inefficient and, ultimately, fairly pointless very little music has any worthwhile content in the low 20hz area, its mainly the preserve of cinema fx. Each of those passive radiators will add to the weight of the box (not to mention the cost of the project) and they will be easily damaged unless you make some sort of protective cover which will then add even more to the weight of the box. passive radiators are used to extract a lower frequency response from a smaller than optimal enclosure size but at the cost of efficiency, meaning youll end up with a smaller but inefficient heavy box, tuned to a pointlessy low frequency with limited use. perhaps you have a purpose in mind that Im not seeing but it doesnt sound like a worthwhile project to me
	LOUDER THAN LOUD

madam Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 14 June 2020 Status: Offline Points: 23	Post Options Post Reply Quote madam Report Post Thanks(0) Quote Reply Posted: 01 February 2025 at 1:46pm
	If I look around 18-21-24 inch PA speakers used to be 160-230 liters ported box… around 80-130 kg… Mostly because of the heavily braced large 18mm plywood cabinet. So I thought if I make is much-much smaller, it could be made easily… nor require the extra bracing, and the only way one can make it that much smaller is using passive radiators… And I geass one needs a lot of them to go low.. and to tune it to the low 20’s… it’s my personal desire… after I had a Nort Chreek Thunder sub that is a 12 inch Peerless xls with PR, capable of 105dB @20Hz with 300Watts… I liked it much… and it makes even pop music much more tempting with a proper low end! Besides if Meyer Sound goes down to 27Hz, Bassboss goes to 23Hz (at -3dB) and I could use a 24 or 48dB/oct high-pass filter under the 20Hz region… I do not wish to use it to special FX… Question is: what B&C, 18 sound or whatever high end PA stuff should be used as main speaker? And what size and version of PR be used (steel, pressed basket… to save on the weight) and how many to go low. I eould make the cabinet as 5 side protective grille if necessary. Thx