New B&C dual 15" design

Caleb Dueck

Junior
Jan 11, 2011
540
19
18
Montana
Why would this type of cab be preferable to using ground stacked sub/s benefiting from ground coupling run to ~100 Hz, and tops taking over from there? Would you not gain about 6 dB (or 3?) of free bass that way effectively needing half the volume of subs for equal output? Ty for any answer on this!
The goal is to have the full frequency range, or nearly so (say, to 40Hz), be phase coherent with the rest of the mids/highs. Flown mains with subs on the ground can't do this. The goal is to have a single acoustic origin, or as close as possible, flat (no haystack) to 40-ish Hz, and then extra subs for the 20+Hz haystack.

It helps to think in terms of 'natural bass' vs 'effect bass'. Rock and roll kick drum and EDM is largely an effect; a natural sounding bass guitar is more natural, along with deep bass singers, detuned guitars, floor toms, etc.
 
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Reactions: Ossian Ott
Jan 19, 2011
999
59
28
41
Oslo, Norway, Norway
drbentsen.no
Why would this type of cab be preferable to using ground stacked sub/s benefiting from ground coupling run to ~100 Hz, and tops taking over from there? Would you not gain about 6 dB (or 3?) of free bass that way effectively needing half the volume of subs for equal output? Ty for any answer on this!
Having full-range mains equals more options in terms of crossover frequency/slopes between mains and subs.
As an example, if I run mains L/R and center clustered subs, I usually prefer full-range mains. But not always.
Or, I can use my mains without subs.
etc....
 
Oct 25, 2018
119
15
18
60
Bideford, Devon. UK
I'm possibly wrong, but that driver collection looks to me to be more expensive, heavier, and more prone to failure/operator error than a pair of 21s - imagine one of the 18s losing drive! I hope someone can explain the thinking and advantages behind driving non-identical drivers into each other, plus its disadvantages other than those I have noted.
 
Jan 19, 2011
999
59
28
41
Oslo, Norway, Norway
drbentsen.no
I'm possibly wrong, but that driver collection looks to me to be more expensive, heavier, and more prone to failure/operator error than a pair of 21s - imagine one of the 18s losing drive! I hope someone can explain the thinking and advantages behind driving non-identical drivers into each other, plus its disadvantages other than those I have noted.
Generally speaking, isobaric boxes gives you high output with extended low end from a smaller box, in this case a equal 2x21" would be bigger than this 21"+2x18" arrangement.
IME I find that they also have less distortion, but this could be more about the designs that I've heard than about the isobaric principle itself.
 
I'm possibly wrong, but that driver collection looks to me to be more expensive, heavier, and more prone to failure/operator error than a pair of 21s - imagine one of the 18s losing drive! I hope someone can explain the thinking and advantages behind driving non-identical drivers into each other, plus its disadvantages other than those I have noted.
Compared to a pair of 21s in an isobaric configuration, the 21+ 2x18 configuration looks like it results in a shallower box with less of a need for internal bracing due to the configuration of the 2x18 baffle and the ports. There's also a possibility that the pair of 18s requires a smaller box than a single 21 would, further reducing the cabinet size (the cabinet volume is calculated only for the rear speaker(s) in an isobaric configuration), but I haven't checked that.