Simple bass unit using the Dayton PA310

[Brian Steele]

For this potential build, I'm looking at using the spare PA310 I now have on hand to build a "small" bass unit that can do 42 Hz and can be carried with one hand (with a handle mounted on top). I basically used the same spreadsheet that I used to design the "Boom Unit", modified to include a center brace for the vent. The sims look pretty decent. I'm wondering if I should go with a higher Fb for a little more midband efficiency, but I can see this just being placed in a corner and covering 40 Hz to 120 Hz. The sim suggests that Xmax will be exceeded just above 100W, but my experience with the PA310 suggests that it can take a little more than that and not sound too bad. Particle velocity at the vent seems pretty low at 100W and surprisingly modeling this alignment as a vented box produces very similar results at low frequencies.

Thoughts? I may end up committing this to wood this weekend. Let's see if I can screw up with that build as much as I did building the "Boom Unit"...

[freddi]

that looks really good - can you get any significant punch gain in the same 73 liters (did I get that wrong?) without losing much low end?

here's one with a small straight vent https://i.imgur.com/39zYzwg.jpg

[Brian Steele]

Originally Posted by freddi

that looks really good - can you get any significant punch gain in the same 73 liters (did I get that wrong?) without losing much low end?

here's one with a small straight vent https://i.imgur.com/39zYzwg.jpg

Net box size works out to 75.1 liters. The HornResp sim suggests a slightly smaller volume.

Interestingly enough, the peak linear output, according to the sim, will only be slightly lower than the TH I built for that driver. It will require more power to get there though, and there's no "natural cooling" of the motor as one would get with a TH design where the driver's butt is hanging out in the mouth of the TH. OTOH, it won't have the TH's disgusting response above 120 Hz .

I'm really tempted to build it to see if the response matches the sim. To answer your question, it can be given more "punch" in the same volume, basically by using larger vents, but the low end will suffer, the gain in sensitivity will be about one or two dB, but power-handling will increase, so peak output will also go up a bit. As it is, I'm struggling to convince myself to design a bass unit with an Fb that's above 42 Hz, considering what modern dance music is like .

[Brian Steele]

Originally Posted by Brian Steele

To answer your question, it can be given more "punch" in the same volume, basically by using larger vents, but the low end will suffer, the gain in sensitivity will be about one or two dB, but power-handling will increase, so peak output will also go up a bit.

And here we go - this is a version with larger vents that tunes the enclosure to 47.5 Hz. Passband output has gone up by around 2dB it seems. External box size remains the same. Particle velocity at the vent remains low.

[freddi]

would there be tall versions of these PA310-8 alignments with significant box depth reduction?

[Brian Steele]

Originally Posted by freddi

would there be tall versions of these PA310-8 alignments with significant box depth reduction?

Unlikely. The box's dimensions are a significant part of the alignment. Shallower box = shorter port = higher Fb.

BTW, I was all set to build the ~40 Hz version of this box today (my first build since my minor stroke early this month), and ended up being tied up with other issues. I also have another idea I want to explore about designing a vented system where a "stub" chamber on the vent can help to reduce port resonance effects (all simmed via Hornresp), and I may end up building that first...

[Fidstang]

If it were me, I'd go for extension over a few dB more in the passband. That driver is a good value, but with the limited Xmax, I feel a fuller sound will be more beneficial in a vented alignment.

[Brian Steele]

Originally Posted by Brian Steele

I also have another idea I want to explore about designing a vented system where a "stub" chamber on the vent can help to reduce port resonance effects (all simmed via Hornresp), and I may end up building that first...

Preliminary results look promising - looks like 6-12dB of suppression around 400 Hz by adding a stub to the vent that's a few inches long, and lightly stuffed. Dealing with that 200 Hz peak is proving to be more difficult though.

[Brian Steele]

Originally Posted by Fidstang

If it were me, I'd go for extension over a few dB more in the passband. That driver is a good value, but with the limited Xmax, I feel a fuller sound will be more beneficial in a vented alignment.

Yeah, I find it hard to design a bass box that has an Fb that's higher than 40 Hz. I might compromise with a 42 Hz Fb for this design, and just accept that peak SPL in the passband might be limited by one or two dB. Or just use dynamic EQ/limiting to limit input to the system around the frequency when in-band excursion may become a problem.

[PB2]

I'd go for a mid 30s tuning.
I have to wonder how much you'd save in box size with passive radiator(s) and
if it would be better sounding eliminating the upper band response issues.
I'm thinking a pair of 12" or 15" PRs.