keeping XO out of critical hearing range - myth?

[dvdwmth]

I've heard several people suggesting this as a quideline, and some seem to very insistant about it.

It just occured to me though that the Thor, Pheonix, Mbow, and a few other very highly regarded designs place the XO in this range.

Its hard to take a rule seriously when some of the best designers out there dont seem to follow it.

So does this idea belong in the trash or does it have its place?

[Grahamt]

It is hard to do in a 2 way if you want to keep the center to center distances smaller than the wavelengths at the crossover frequency. A good designer can still make a smooth transition in the critical range.

The rule is probably for people like me who dont know what they are doing.

[dvdwmth]

Originally posted by Grahamt
It is hard to do in a 2 way if you want to keep the center to center distances smaller than the wavelengths at the crossover frequency. A good designer can still make a smooth transition in the critical range.

The rule is probably for people like me who dont know what they are doing.

Heh Heh,

i think thats why it appealed to me too.

[Hornlover]

I live by that rule. If you are going to do a 2 way, then you almost have to put the crossover point there. I only make 3 ways, to avoid just that. I like keeping the 500-5k range unbroken, and covered by one driver. 300-5k would be even better, but finding compression drivers/horns to go that low is difficult.

[Swedish Chef]

Although there is some merit to it I would largely say yes!

If you use active filters with steep slopes (4th order and steeper) and match the directivity of the drivers you can make the crossover point virtually transparent.

The very best systems on the planet are often 4-5 way systems and thus keeping the XO point out of the "vocal range" (which is huge although the fundamentals are in a narrower range) is impossible.

Make sure to keep fq response smooth on and off axis, stick to low distortion drivers and operate them in their best range. Then use digital eq and delay to compensate for room response and driver spacing. Then you can worry about whether the XO point is in the vocal range, IMO!

But remember that if you use passive crossovers their actual response is far from the text book curves. Use a spectrum analyzer to verify.

Cheers
/Magnus

[Pan]

I´d say that this talk about where to cross or not is mostly myths.

Some suggest not to cross in the 2-5k area becasue we have best sensitivity there...... sensitivity to what? Aha, amplitude, but that does not mean that we are most sensitive to phase distortion in the same range just becasue of that.

On a theoretical level the problem is due to phase distortion introduced by the crossing (unless TP) and due to the change in dispersion when transition to another driver.

Some say we should not cross in the 100/200Hz - 1.5/2k range, because in that range we are most sensitive to phase variations between the ears.... but of course that does not mean that we are most sensitive to absolute phase distortion in the same range.

Using a wide range driver for most of the human fundamental range (which more or less coincide with many acoustical instruments) makes sense to me. 150Hz-2.5k or so and a woofer plus tweeter below and above that. The woofer may be crossed to a monster sub at 40 or so for a high output four way system.

Magnus, was it you who send me a email?

/Peter

[Swedish Chef]

Peter,

no it wasn't me. Agree with the rest of your post.

/M