18" DAYTON RSS460HO-4 v2015
Fs Hz, VAS L, Qts, Xmax mm
18.80, 272.00, 0.322, ± 12.8
Ports: 110 mm PVC pipes (internal?)
length + bend = lower freq (?) (how much total length?)
A cylindrical shape that has a diameter of 12 centimeters and a depth of 75 centimeters has a volume of: = 8.5 liters
4x ports = 34L (+/-)
"18" driver occupies 6.5/7 litres" (+/-)
364L - 41L = 323L (net)
Alignment DAYTON RSS460HO-4, VB = 323.0 L, FB = 20.0 Hz
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No, 750 mm includes bends, too. Most likely I need to do some trial and error with port lengths to get the desired Fb.
Today's progress - four sides plus bracing glued and screwed. Building to be continued Monday
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Yes, its big, about the same size as real cinema subwoofers. You have to have a big box for these kind of frequencies if you don't wat to use massive EQ and power amps to get any reasonable SPL. But then, it's only 450 mm deep, so the footprint is about the same as your average large 15"...18" sealed sub. Behind the screen or built into (false) wall is certainly a possibility, or behind the sofa for nearfield back massage
Or look at it this way - it's about the same size as an average bookshelf, so in this new digital age, out goes the bookshelf and in comes the e-reader and a subwoofer.
Well, I simmed bandpass enclosures before deciding on the box type, and they turned out to be bigger...
Anyway, it's almost done, only ports are left to be installed - will do it in the weekend
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Yes, bp4/bp6 will benefict from higher sensitivity, a couple dbs and shorter fr range ~90/100Hz, against larger size generaly speaking. They can be smaller in size but the lower extension will probably sufer the most. Your speaker, in this case, can also/should be calibrated for best stiff response (tight) and faster step response/alignment. Note in my previous post. Best.
Finally got the vents installed A quick test with sine wave generator and good old pair of ears confirms frequency response from 18 Hz up at room-rattling SPL (using one channel of my ~120 W/ch stereo amp). So I'd call the endeavour a success Still haven't got the proper amplifier, though, and last news were it's put on a backorder, so it's taking a while till I can set up the thing properly.
A quick test with sine wave generator and good old pair of ears confirms frequency response from 18 Hz up at room-rattling SPL (using one channel of my ~120 W/ch stereo amp). So I'd call the endeavour a success Still haven't got the proper amplifier, though, and last news were it's put on a backorder, so it's taking a while till I can set up the thing properly.Attachments
I've read somewhere that symmetrical port placement is beneficial at high power levels -- supposedly had to do something about equal pressure around the driver. I don't know how true that is and I'm certainly not going to abuse the driver with double the RMS rating amplifier playing low crest factor program hours on end, but I like symmetry, get a bit of OCD with that, even
Meanwhile, I cobbled together a passive line level crossover and wired my small "lab amp" - a BTL STA540SA ripped out from some cheap PC speakers and fitted with a leftover 18,5 V power supply from my long-dead laptop, yielding around 18 W at 8 ohms - to drive the sub. Sounds good and plenty loud even with that minuscule amp.
Meanwhile, I cobbled together a passive line level crossover and wired my small "lab amp" - a BTL STA540SA ripped out from some cheap PC speakers and fitted with a leftover 18,5 V power supply from my long-dead laptop, yielding around 18 W at 8 ohms - to drive the sub. Sounds good and plenty loud even with that minuscule amp.
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Two placed close together will give the system an extra 6dB of low bass.
I think you get a similar gain if they are separated in a smaller room.
The Tannoy B950 (Celestion drivers) used two 18" drivers in one 300litre vented box
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