Hi Brian,
Good to hear from you .....
You are correct in presuming that the shape of the baffle makes very little difference for the bass drivers. I have found that rounding the edges (and the overall shape) of the baffle for the full range drivers does have an effect on the sound, but at the lower frequencies it doesn't seem to make much of a difference.
While we're on the subject of open baffle bass, there are a few things I would like to mention .....
1 - In the past, I have strongly recommended the Hawthorne Audio Augie drivers to supplement the lower frequencies of the Betsy baffles.
Since Hawthorne Audio has ceased operation (at least for now), I have been offering the Eminence Alpha drivers in my bass baffles as a replacement. It's a slightly different sound than the Augie, but still very good and very cost effective. A plate amplifier or Crown pro amp drives them very well and by using a pair of them and two plate amps, stereo bass can be added to the system to good effect.
2 - The Alpha bass baffles are available in either a 15" or 12" model.
Both sound good ..... the 15" goes deeper and the 12" is tighter and faster. It's a matter of preference and in my home system I prefer the 12" drivers. The pricing is the same for both bass baffles.
3 - At the 2016 Decware Zen Fest, Steve introduced the attendees to something that I consider a flash of brilliance. He ran his pair of SO Imperial bass speakers in parallel with the ZOB open baffle speakers using a low pass filter on the Imperials ..... everything being driven by the Decware SE84UFO3 mono blocks.
The effect was nothing short of incredible and it blew a few minds hearing how much deep and tuneful bass could be produced by 3 watts per channel.
Of course, not everyone has a pair of SO Imperials in their listening room .....
When I returned home, I tried the same thing with a pair of the Alpha open baffle drivers. Obviously, the sound is not the same as with the SO Imperials, but is still very good and cost effective.
The low pass filters used at the Zen Fest were 80 HZ units and the ones I think work best for the Alpha baffles are 100 HZ units.
There is not as much flexibility with this setup as there is with a plate or Crown amp, since there are no variable crossover and volume controls ..... but the bass integrates very well with the main speakers and the effect is that "everything sounds like it is cut from the same cloth".
My Decware SE84UFO has no problem driving this setup and the sound is pretty amazing and very natural sounding.
The Alpha baffles and plate amps are available on my website and I will be adding the "passive" option with the low pass filters in the near future.
As always, for anyone interested in purchasing any of these items, please mention that you saw them on the Decware website or forum when emailing me.
Best wishes,
Randy