At what frequency does driver spacing no longer matter?

[Face]

I'm using a LR2ish @ 350hz for my WM crossover. Since the TM and W cabinets are separate, I could flip the W cabinet to either bring the woofer within 16"(center to center) to my mid, or 24"(center to center). I currently have the woofer in the closer arrangement. I have yet to spike the cabinets and am afraid bass may be a little thin after doing so. Plus, I'd like to install them only once.

What it really boils down to, at 350hz, is driver spacing still a concern?

Also, with the woofer within 2" of the floor, will it make testing more difficult?

TIA,
Mike

[Kal Rubinson]

Rule of thumb is that the interaction between the drivers becomes fairly insignificant then the distance is less than 1/2 the wavelength of the common frequencies. At 350Hz, that distance is about 20".

Kal

[krips]

im assuming thats center to center ?

[Kal Rubinson]

By default.

[AJINFLA]

Rule of thumb is that the interaction between the drivers becomes fairly insignificant then the distance is less than 1/2 the wavelength of the common frequencies.

Kal

I would say 1/4 wavelength, based on the rules of physics.
cheers,

AJ

[krips]

could you attempt to explain the reasoning for this ?

[dlr]

I'm using a LR2ish @ 350hz for my WM crossover. Since the TM and W cabinets are separate, I could flip the W cabinet to either bring the woofer within 16"(center to center) to my mid, or 24"(center to center). I currently have the woofer in the closer arrangement. I have yet to spike the cabinets and am afraid bass may be a little thin after doing so. Plus, I'd like to install them only once.

What it really boils down to, at 350hz, is driver spacing still a concern?

Also, with the woofer within 2" of the floor, will it make testing more difficult?

TIA,
Mike

At 350Hz you'll be OK in either position IMO as far as CTC is concerned. I assume that it being a large 3-way you'll be listening at a fair distance.

More important than CTC in your case is the most often neglected floor bounce. My favorite 3-way used a 10" box with a separate MT on top. I could also flip it. Before software such as can be found at the FRD consortium was available, it was not as clear. You've selected a good Fc that helps reduce the impact of floor bounce in both the midrange and the woofer, placing it into the stop-band of each driver.The floor is definitely NOT the best place for your case. That will place it too close to the floor for this Fc and will affect some aspects of imaging.

Back then I built a test box, then experimented with the woofer at different heights. I found that the best sound came with the woofer about midway between floor and midrange. That's what I built and was very satisfied with that arrangement. You can see some of the details at my web site.

In my case the CTC came out to 13" with the woofer 15" up from the bottom of the box. Listening height includes any additional height from spikes.

I would definitely suggest the position with the woofer in the upper position.

Here's a link to the design page.

My 3-way

dlr

[AJINFLA]

could you attempt to explain the reasoning for this ?

Two sources producing the same frequency will be correlated at 1/4 wavelength (of that frequency) apart. Above this spacing, they will begin to decorrelate. With acoustic sources like loudspeakers, in living rooms, this gradual decorrelation may be audibly benign, as Kal points to a rule of 1/2 wavelength in his experience. Keep in mind that unless stopband filters are used, there will be greater decorrelataion above the HP, but again, at LF, this may be audibly benign.

cheers,

AJ

[Face]

Thank you all!