Excellent - thank you
So I assume it doesn't affect the sound too much, if at all ?
The front baffle dimensions do affect the sound, but not so much in the frequency range of the subwoofer.
The shape of the edge of the baffle affects the degree of and behavior of diffraction that occurs I think mostly at frequencies related to tweeters, and the proximity of the tweeter to the edges affects the time that happens relative to the initial launch, and how that combines, which is why you see speakers with very large radiused edges, particularly near the tweeters, tapered curves on baffles, and tweeters mounted at different distances to the top edge and the sides, or maybe even different distances to sides, if it's an application where the buyer will be tolerant of asymmetry. Horns that are sufficiently directional and have the taper built into the horn essentially are the baffle, a least in this sense, and so the front baffle size and shape ceases to matter, at least that's my understanding.
The front baffle dimensions also affect at what frequency the 'baffle step', happens. The larger the smallest dimension, the lower the frequency, but so long as you're not building them into a wall, it always happens. At some point, the baffle is narrow or short or whatever enough that it doesn't keep the sound going straight forward. On an infinite baffle, the driver is loading 'half space', (half a sphere output). At a dimension proportional to wavelength (I don't recall), below that the waves stop 'seeing' the baffle, and radiate into full space (omnidirectionally), and load into 'full space', which makes a 6 dB reduction. I believe the transition is a 6 dB/octave slope, and if you wanted to correct it, you could do so by adding a second driver (usually woofer), which gives you back the 6 dB of output down load, and give it a complimentary shelving filter so that it sums flat before applying the same crossover as the woofer. Or, you can just apply a shelving filter to the whole speaker.
Or you can arrange a crossover from a mid-bass to woofer at that range, and build the shelf function into the crossover blending the drivers with two different output levels offset for that step.
Of course, once you put it into a room, there are a whole bunch of boundaries that complicate thing, so you can also do what most people do, just hope the whole jumble works out well. This compensation may be built into some speakers, but cheap speakers, probably not. They don't have enough components to perform the compensation, but that could still be okay depending on room placement and surrounding objects, or at least of relatively minor concern compared to the real world issues likely going on.
But, again, if you're talking subwoofers, not an issue, and not really what you're asking about in any meaningful way, I'd guess. The real issue to keep in mind is to make sure your material and screws or whatever don't have an issue being near the edge. I.e., if the screws get a good fit, they usually are a little tight, and if they're too close, or the material can't take it, (which is the same thing) they can push the material one way or another. If you pre-drill with something on the generous side, enough to grip, but not more friction than necessary, and even possibly pre-screw with a clamp applied on both sides near the edge(cutting the thread grooves with the screw), that could be a decent preventative measure. I don't think it's a likely problem, but it's worth considering and going slow while you do it.
