[AlliumPorrum]

What would be highest feasible highpass crossover frequency, if 12" GR servos are used on a W- frame? Is it good for ~100hz, or should I- or L- baffle be used in this case?

[Danny Richie]

What would be highest feasible highpass crossover frequency, if 12" GR servos are used on a W- frame? Is it good for ~100hz, or should I- or L- baffle be used in this case?

I have measurements on our W and H frames showing solid output up to a crossover point of 300Hz.

[AlliumPorrum]

But I have often heard that U- or H- frames would be *best* for frequencies below 100hz or such, and higher frequencies should be played on I- shaped open baffle to minimize baffle diffractions etc. Any comments on this..?

[Toaster]

It depends on a number of factors for the GR system, including how steep the low-pass filter is, the usable frequency range of the drivers and of the plate amps used. The main limitation for an H-frame is the quarter-wave resonance of the structure. The frames recommended for the SW12 OB drivers are quite shallow, so the main resonance should be above 400Hz. Also, the recommended construction includes the use of thick foam 'No-rez' damping, which should reduce the amplitude of the 'duct' resonances of the H-frame.

[Danny Richie]

And it depends on the depth of the H frame. The higher you play it the shorter the side panels need to be.

I tend to shoot for 200Hz and down. Any higher and you start getting up into the mid-range. Splitting the mid-range into dissimilar drivers or causing a phase shift in that area is a no, no. And the mid-range really is the 300Hz to 500Hz region.

[bdp24]

Danny---For a W-frame or an H-frame crossing over at 80Hz or below, what is the maximum frame depth you would go (assuming a frame width of 13" or so)?

[Danny Richie]

Danny---For a W-frame or an H-frame crossing over at 80Hz or below, what is the maximum frame depth you would go (assuming a frame width of 13" or so)?

80Hz is a pretty low crossover point if concerning yourself with a cavity resonance. You want the output level of the sub to be down as much as possible before reaching cavity resonance of the enclosure. Let's say you quadrupled that number to 320Hz. By the numbers you could have a H frame three and a half feet deep and still not have enough output at 320Hz to hit the resonance of the cavity.

I think I have been using H frames just under 14" of total depth and getting real solid output that is flat to 20Hz. Anything more is just overkill.

[bdp24]

Yeah, concern over cavity resonance was the reason I asked. Thanks for the info.