BSC with opposing woofers?

[stan]

I have been wondering about something lately. If you have a cab with woofers on opposite sides, driven in phase, how does that affect baffle step? This has already been shown to cancel vibration, but I don't recall reading how it would affect baffle step.

What if there were 4 woofers, one on each side of the cab, driven in phase?

Is there an easy way to model this?

Stan

[454Casull]

Re: BSC with opposing woofers?

Off the top of my head I was going to say that opposing woofers would eliminate the need for BSC since the radiation pattern is fully omni before they start beaming.

Then I remembered that for certain frequencies below the baffle step transition you might have comb filtering as output from the rear woofer may not be uniformly in phase with the output from the front woofer. Maybe for most baffles it's not a problem... but I don't care to do the math right now.

[Jeff B.]

Re: BSC with opposing woofers?

Off the top of my head I was going to say that opposing woofers would eliminate the need for BSC since the radiation pattern is fully omni before they start beaming.

Then I remembered that for certain frequencies below the baffle step transition you might have comb filtering as output from the rear woofer may not be uniformly in phase with the output from the front woofer. Maybe for most baffles it's not a problem... but I don't care to do the math right now.

Yes, but how well it works is going to depend on how high (or how low, maybe I should say) you plan to cross those woofers.

[billfitzmaurice]

Re: BSC with opposing woofers?

If you have a cab with woofers on opposite sides, driven in phase, how does that affect baffle step?

Typically it doesn't, as you'd cross over well below the baffle step frequency anyway.

[davepellegrene]

Re: BSC with opposing woofers?

If the woofers are playing in the baffle step region how could you properly cross to the mid on the other side of the cabinet. wouldn't the woofers become directional at that frequency?
Dave

[billfitzmaurice]

Re: BSC with opposing woofers?

If the woofers are playing in the baffle step region how could you properly cross to the mid on the other side of the cabinet. wouldn't the woofers become directional at that frequency?

That depends on their size, but probably, and that would result in a cardioid radiation pattern. But taking opposed woofers high enough to go directional or reach the baffle step would be a very odd configuration. You seldom see them crossed higher than 200Hz.

[fjhuerta]

Re: BSC with opposing woofers?

If I were to do something like that, I'd probably design a monopole speaker with no BSC, add a second one on the rear, and start measuring... I've wanted to build a bipole, and that's the way I'd do it.