Basically I've been out of the game for a few years and want some help getting back into the swing of it (well, making some noise).

I'm crap at using the sims software so been using various AI to help.

Basically it's recommended a cabinet of 180 litres before driver and port subtracting off that. Does this look about right for this driver?

 Optimized Design

Cabinet dimensions: 60 cm (W) x 80 cm (H) x 65 cm (D)

Internal volume: approximately 180 liters (before subtracting port and driver displacement)

Port dimensions: 60 cm (W) x 12 cm (H) x 18 cm (L)

Simulation Results

Frequency response: flat between 35-80 Hz, with a -3 dB point around 33-34 Hz

SPL: approximately 118-120 dB at 40 Hz, 600 watts RMS

I stipulated 600 watt power handling as they'll be run off a Berry amp 550 w @8r

Any help would mean the world to a struggling old gaffer. Thanks

I'm always happy to have a play around in WinISD, so here's a few thoughts.

1: P.Audio have previous for changing the spec of their drivers, without necessarily changing the model number. I say that because the TSP's you quoted don't match those on the PDF http://p-audio.co.uk/pdf/E_18ELF.pdf" rel="nofollow - Here , or anywhere else I can find them. So, first, it might be worth checking them.

2: If the TSP's are right for the particular version of the driver you have, the general box guidelines your AI has given you aren't a million miles off, though there's a couple of things I'm not sure about.

2A: If the 60*80*65 dimensions are external, you certainly have enough space inside the box for about 180l net even after accounting for port, driver, bracing etc. (assuming it'd be built with 18mm timber), which is great. However, if that is the case, the port would be a max of 56.4cm wide, not the full 60cm of the box width. If the stated box dimensions are internal (to match the width of the port), then you've a lot more than 180l available, so it doesn't make sense for the AI to be suggesting those dimensions. Little inconsistencies like this are why a lot of people still don't trust AI generated results.

2B: If we stick with 180l net and a 56.4cm wide vent with everything else the same, the box tuning should come out just around 37Hz. That gets a reasonable looking frequency response prediction from WinISD, though only reaching ~38Hz. The red line in the background is the same box size etc for the TSP's that I linked to earlier - not terrible but I'm reluctant to recommend a tuning that results in much of a hump in the response - some people find that gives a more exaggerated boominess or muddiness to the sound.

Note that even allowing the 12.5l for the vent, 7l for the driver, 4l for some handles and 8l for bracing, the box would still only need to be 69cm tall to fit everything in, not the 80 from your AI results.

HTH,

David.

Yes it looks like your T/S specs are correct, I just copied mine off an old ad for the drivers.

Material will by 18mm and the vent will span the width of the bottom, so yes 564mm would be the correct width. 

So off your recommendations I will reduce the box plan to 69cm high x 60cm wide x 65cm deep.

38 hz would be fine as I'll be setting a 40hz hpf filter anyway. I wonder if I should just use the B&C Sub 18 plan for this driver or would that be a bad move?

Thanks again for your help. It's exactly that sort of kindness that made me join the forums all those years ago. 

The B&C design is actually slightly smaller (after allowing for similar deductions for the driver, handles, bracing etc) and should end up tuned a little lower - that flattens the hump around 60Hz a bit but slightly increases the risk of pushing the driver beyond it's maximum linear excursion, so would not be my first choice.

Cheers,

D.