Theorized and tested: "Overdrive 10"...

[Wolf]

The 10" is a LOT more robust.
Wolf

[Ironman129]

Definitely a tight fit! With the BASH300, I bet there is only 3/8" in between. I think next one I might just recess the woofer cutout 1/2" to put a little more space back there.

[BennyD]

Definitely a tight fit! With the BASH300, I bet there is only 3/8" in between. I think next one I might just recess the woofer cutout 1/2" to put a little more space back there.

You could always cut out a rectangular ring out of ½" MDF to space the amp out a little if you are uncomfortable. The amp may stick out a little in the rear, but it's some insurance or piece of mind. Sent from my SM-G920V using Tapatalk

[Wolf]

The space between the PR and UM10 is more critical as that is the tuning of the LP response, and keeps them from contacting each other in operation. The sealed box is of less consequence if off by a 1/4". I'm with Benny in that using 1-1.25" thick rear panel will fix your problem better if it bothers you. I would be fine with what you have there.

Remember to test the tuning of the PR chamber. Just remove the amp and hook up the driver to a T/S generator and run a sweep. The dip between Z peaks is your tuning freq. Or, just use the mass as I described in the layout.

Later,
Wolf

[scottq]

Hey Ben,

is that a special version of Unibox? I don't see this bandpass option (using a PR, rather than port). Would you mind sending? This has given me a few ideas, and wanted to play with modeling a few different things.

Just curious - I see you crossed off the port harmonic jaggedy stuff at the end in your modeled response pic - why not just turn off the checkbox to remove this in the response?

[Wolf]

No- Unibox will not do PR-bandpasses. You model the BPST as it has, then model the PR box with the desired volume and PR and find your tuning mass. (I'm pretty sure it says on the graphic I posted that Unibox won't do it without doing 3 separate models. I put that at the bottom of the graphic) Then you make sure the PR will be fine at level for Xmax in its response.

Later,
Wolf

[JRT]

Interesting design. Have you done any post-build design qualification testing? Maybe measure response outdoors nearfield to see how closely the actual response correlates to the design model response.

[Wolf]

I suppose I could, but I haven't yet. I could likely take an indoor nearfield facing up as well in the middle of my living room. I have 10' ceilings.

I don't have a reason to doubt Unibox though...

Later,
Wolf

[bullittstang]

Great project Wolf! I am huge fan of the small but very capable subwoofer design and this has nailed that for sure.

[xmax]

Sorry if you mentioned it somewhere and I missed it, but how much loss did you
get with sensitivity? Obviously not enough to outweigh the benefits but I'm
still curious.

[Wolf]

In the graphic it says gain +0.1dB, so no loss in output.
Wolf

[xmax]

The +.1 is from the larger surface area of the PR? Although it seems (the design) would provide some useful "compression"
in a very literal way.

[Wolf]

I don't think you understand how the bandpass works. It isn't due to using the PR at all, but to just using a bandpass. A bandpass acoustically filters both ends of the bandwidth the woofer in the design plays. As such, you can have a wider bandwidth and lose sensitivity, or you can have narrower bandwidth and focus on one-note output potential. The points of rolloff affect output and bandwidth. In my alignment, I only gained 0.1dB over the use of the driver normally. This means I got the maximum bandwidth with no loss of sensitivity- in terms of acoustic response. The boost adds the low-end extension where it was needed.

Later,
Wolf

[wogg]

I love this build... small sub with low 20's extension and decent max SPL. Only trade off is crossing to mains at 60Hz or so, which isn't really a trade off if you have decent mains to pair.

I need to play with band passes more, my prior attempts at modeling were in BB6, which ended up trying my patience with trial and error. Difficult when you don't quite understand what you're doing.

[Wolf]

Thanks, Wogg!
Wolf