Small 30Hz Sub

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This is all interesting and I'm not yet decided. Thanks for all of your contributions and explorations. My time to do reading and research on all these options has been a bit limited but I'm doing my best to keep up.

I agree with the emerging consensus that while it may technically be possible to meet my spec with a sealed enclosure design, the price tag for monstrous drivers is too high for me.

With respect to Circlomanen's tapped pipe design: at first glance it looks good for size and weight, and the recommended driver (B&C 12TBX100) is relatively affordable, but when I looked more closely at the driver specs it seems to have a Fs of 47Hz, and I am not sure that it will actually work well for the lower frequencies? Or can the tapped pipe enclosure work some magic? Is this where I would use the piston excursion calculator?

I'm not sure I have the knowledge to determine whether Lab 12s, for example (which have much lower Fs but also much lower RMS Wattage rating) would make a suitable replacement. I have just downloaded hornresp and am just starting to poke around in it.

My next favoured choice might be the BMS 18N862 (BG-181) Compact Vented design, but I still have to see if I can source BMS drivers around here.

A few people have alluded to the idea of making 4 or more 15" vented boxes, but no specific designs have surfaced yet unless I overlooked something.

A further constraint is that I took advantage of a good deal and bought an amplifier - a Crown CS2000 - so whatever I build will ideally operate happily within its 1000W per channel at 8 ohm (assuming two cabinets).
 
My suggestion would be basically this, assuming 15mm timber.
If you wanted to use 18mm, keep the internal volume, cross section of port and length of port the same. That would add nearly 5.5kg to the total weight.
If you wanted a different bracing layout, the key things to make sure of are that every panel is tied to its opposing panel and that each panel is broken up into smaller sections. Try and keep the volume of any alternative bracing to the same, lest it throw off the box tuning (granted, a litre or so difference wouldn't throw it off by much to be fair).
HTH,
David.
 

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Mark (or anyone), how many of your BMS 18n862 - 30 Hz boxes would you say is suitable per each of your 100 Hz Synergy or PM tops to get balanced output capability?

Thanks

Ditto to the comments that say your goals are realistic and fairly easily attainable...

I built a pair of simple 18" vented using bms 18n862, based on Ricci's DIY..dB v2

Mine are slighty larger boxes than his, tuned f3 at 30Hz....and weigh about 41kg.
Couldn't be happier with them..

Don't know if sourcing might be problem though, given your comments about Beyma and Faital. Have you checked out Lean in the UK or THLP in France?
 
Mark (or anyone), how many of your BMS 18n862 - 30 Hz boxes would you say is suitable per each of your 100 Hz Synergy or PM tops to get balanced output capability?

Thanks


I'd say 4 per top, for normal music outdoors.
6 if dub-step, EDM, or really pushing the tops.

2 indoors normal music, if the room isn't huge.
4 if dub etc and cranking.

So 4 per top really.
Here's a thread i put up elsewhere that has some numbers that might help..
diy single 18"s and OS
 
After wising up, I only started using bassreflex to just "creep in a little", to decrease cone excursion and increase loading, so no insane amps are vital. Slapped my 21DS115 into 23"*23*29.5" boxes including grille, legs and wheels, and boy I'm happy. Definitely looking forward for next step with not yet existing high excursion ligjt 2*12"s, to make the box even smaller, still capable of going down to 30Hz.
 
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