The first box I built I tried to keep group delay to a real minimum, as low as I could. But info I just found on the internet suggests that as long as the delay isn't more than a period or two of the frequency then it shouldn't be a problem. By that definition then:
at 30hz, anything less than 33.33ms is acceptable
40hz - 25ms
50hz - 20ms
60hz - 16.666ms
and so on...
But is it one period? or should it be more around half? I'm really curious to know what rule most of you box builders have as far as minimising group delay.
I'm asking because I'm planning on making a new box for my sub, because it really drops off fairly sharply at 50hz, and I enjoy bass between 30-50hz so it's a problem for me. But a flatter response = bigger box = more group delay. So let me know how you guys go about this.
For the record the design I'm looking at (with a much flatter response) building has the following group delay:
50hz - 7ms
40hz - 12.5ms
35hz - 17ms
30hz - 23.5ms
25hz - 27.5ms (it peaks here)
20hz - 21.3ms
My previous design: (the one currently in my car)
50hz - 7ms
40hz - 9.6ms
35hz - 10.7ms
30hz - 12.5ms
25hz - 17.9ms
20hz - 32ms (it peaks @18.3hz @34.8ms)
I don't notice the delay with my current box so I'd like to know if I would notice it with the new box. This is still very early in the planning stages so I'm open to changes I'm just trying to get a flat response because I really notice the decrease in loudness at lower frequencies with my current box.