I wanted bandpass / slot loading without the annoying peak my last SLOB with these 12" had. It was OK, but needed too much EQ - so I try not to have such peaks there. The overall size is very close to my other dual opposed 12" sealed sub.
There is no particular reason for the size other than fitting the chipboard panels I have available. The only thing I would actually like to improve is the port area which would need extra wood. I might actually try to fit in a larger port.
@freddi I tried to find this menu but I failed. Can you display the particle velocity using the record I posted? Wanting to see the particle velocity was the motivation to use this different model (which gives se results).
There is no particular reason for the size other than fitting the chipboard panels I have available. The only thing I would actually like to improve is the port area which would need extra wood. I might actually try to fit in a larger port.
@freddi I tried to find this menu but I failed. Can you display the particle velocity using the record I posted? Wanting to see the particle velocity was the motivation to use this different model (which gives se results).
Yes, mouth velocity is OK, but the rear (or front in this case) particle velocity as shown in port output only was as Freddi pointed out.
Double the port area and longer port to match the tuning looks like this (grey port inlet, black port outlet):
This is IMHO acceptable - or definitely an improvement with some rounding of the panel edges.
This is a slightly larger box which still fits the available chipboard. The folded port is not very optimal, but in this case I hope the folding will work for me - better lowpass for the unwanted frequencies and lower Q peak at the low end. I might be wrong of course
So this is now the build candidate.
Double the port area and longer port to match the tuning looks like this (grey port inlet, black port outlet):
This is IMHO acceptable - or definitely an improvement with some rounding of the panel edges.
This is a slightly larger box which still fits the available chipboard. The folded port is not very optimal, but in this case I hope the folding will work for me - better lowpass for the unwanted frequencies and lower Q peak at the low end. I might be wrong of course
So this is now the build candidate.
You know that that's just a bassreflex woofer with some front acoustic mass? It doesn't matter (a lot) how around you mount the chassis.
So this is the same bass reflex chamber without the front resonator (in grey) compared to the box with it. The peaks will not be there since the port is folded.
Not a great difference, but still an advantage in the "trading efficiency for bandwidth" game.
A more fair comparison would be to make a box of the same volume with the same tuning:
That 1 dB advantage and a bit more low end due to the air mass loading on the front is there. Is it worth it? IMHO yes - but more due to the fact that this woofer does not really look good and it is better that it will be hidden inside the box.
The folded port will most probably be less efficient (lower peak on the low end) and also effectively longer due to end corrections and wide rectangular shape, again shifting the low end cut off a bit lower. I am curious how this will turn out in a real box.
Not a great difference, but still an advantage in the "trading efficiency for bandwidth" game.
A more fair comparison would be to make a box of the same volume with the same tuning:
That 1 dB advantage and a bit more low end due to the air mass loading on the front is there. Is it worth it? IMHO yes - but more due to the fact that this woofer does not really look good and it is better that it will be hidden inside the box.
The folded port will most probably be less efficient (lower peak on the low end) and also effectively longer due to end corrections and wide rectangular shape, again shifting the low end cut off a bit lower. I am curious how this will turn out in a real box.
- GRS 12SW4-HE is real close in spec to your 12" driver
https://www.parts-express.com/pedocs/specs/Spec Sheets/292-820--grs-12sw-4he-spec-sheet.pdf
https://www.parts-express.com/pedocs/specs/Spec Sheets/292-820--grs-12sw-4he-spec-sheet.pdf
