Take for example a 15" speaker with 90x90 1" waveguide and a 5" speaker with dome. Do you need to sit further away from the 15" speaker, and why?

Cheers,
Mattias

That being said, most crossovers aren't brick-wall filters, and most large-diameter cones have serious on-axis peaks between 1 and 2 kHz. Crossover type can make a difference too, from what I recall.

So, at the risk of over-generalizing:

1. The lower the crossover, the closer you can sit.

2. The closer the vertical distance between the drivers, the closer you can sit.

3. The steeper the crossover slope, the closer you can sit.

4. The smoother the out-of-passband response from the woofer, the closer you can sit.

5. Even-order crossovers integrate a bit better at close range than do odd-order crossovers.

I'm sure this is incomplete, but it's a start.

Regarding the example you give, in most cases I'd expect the 5" plus dome to work better up close simply because the angular separation between the drivers is so much less. However, with a suitable crossover the 15" plus waveguide just might work better up close.

Perhaps the ideal for ultraclose range is a coaxial driver.

Duke

Duke

HI Duke,

Intuitively, I would have thought the less the lsope the closer you can sit, since the sound will be more "blended between the 2 drivers, whereas, if the slope is steeper, the sound is "more obviosuly split" between the 2 drivers. So, given constant spacing in both cases, if case 1 has a woofer & mid crossed at 500 Hz (say) with a 12 db slope, the sound may blend in better than case 2, where the slope may be 24 db. I say thin in the context of eh Altec VOTT setup...do you think making the slope steeper between the dome & the horn makes the sound more coherent or less, at smaller listening distances?
BTW, I use a 24 db slope in my system, and cross it at 1500hz, but I kow the traditional passive Altec Xover uses 12 db & crossed at 800 Hz.
-akhilesh

As an example from another frequency realm, subwoofers with a steep-slope upper cut-off do a better job of "disappearing" than subwoofers with a gentle-slope upper cut-off, again because if we can hear the upper frequencies (even at reduced volume) we can better locate the sound source. I recently had the chance to compare plate amps with 12 dB/octave and 24 dB/octave high pass filters, and the latter enabled me to cross over almost an octave higher before the subwoofer's location could be detected.

Duke

As for crossover slopes between a midwoofer (or midrange) and tweeter, in my experience, it's a balance. I think first and foremost, summing should be good. Directionality should be matched. Both of these are somewhat dependent on crossover frequency and slope.

If the loudspeaker is physically large, then each subsystem is probably further apart than a smaller speaker. For example, the midrange driver of a midhorn is probably further from the tweeter in a large horn speaker than the midwoofer is from the tweeter in a small mini-monitor with a 6.5" woofer and a 1" dome tweeter. To me, it stands to reason that localization of sounds from the mini-monitor would be difficult even just a few inches away. The horn might need a few feet to integrate properly. Then again, the horn probably sounds just fine 30 feet away, whereas the mini-monitor might be straining.

Some would offer the coaxial arrangement as a solution that allows large horn sound with the close-up integration of the mini-monitor. It definitely removes the problem of having a vertical stack, but I've never found one that I could live with the compromises it brings. Not to say there aren't some good coax and multi-driver horn/manifold setups out there. There are some really nice ones. They just aren't my cup of tea.

Duke