advanatge of 1s order over 2nd or 3rd order?

[Professor smith]

can someone explain the advantages?

[Curmudgeon]

First, I'd refer you to Vance Dickason's most excellent Cookbook.

First order crossovers with almost any driver will require significant care in handling the tradeoffs. If nothing else, it tends to require (expensive) drivers with excellent bandwidth and power handling.

From my own experience, pure first order, that is acoustic first order response in and far out of band really is not feasible. The multi-slope first order, popularized by Thiel uses a first order roll-off at the crossover frequency, followed by another pole about an octave or so out, by which time the driver's rolloffs kick in.

High end breakup on the woofer and mid usually need to be trapped out, as the breakup is likely to be only 15-25 dB down, which, even if not measurable on a composite frequency response curve, will be audible.

If the mid/tweet voice coils are vertically aligned (or more accurately, the sound sources) there will be a -15 degree slope of the smoothest axis. Hence the tilt back of some speaker systems.

Aside from the (frequently disputed) phase linearity issues, I like it because it provides a broad crossover region which can often sound seamless.

I squuz in this reply before leaving for dinner appt., so it's probably even less coherent than usual. Apologies.

[wakibaki]

1st. order WHATs?

They're less difficult to design. They have less pronounced adverse effects. Such as phase shift, or passband ripple.

w

[Professor smith]

I am speaking of 1st order crossover network although I am also interested in the acoustic slope too.

Curmudgdeon you say

I like it because it provides a broad crossover region which can often sound seamless.

But how does this affect the off axis response?

[PeteMcK]

Power

[Curmudgeon]

Originally Posted by Professor smith

I am speaking of 1st order crossover network although I am also interested in the acoustic slope too.

Curmudgdeon you say But how does this affect the off axis response?

The crossover behavior is based on the combined electrical and acoustic responses; so for a true first order, that would be one pole electrical rolloff (-6 dB/octave) and NO acoustic rolloff.

I think you're asking about my use of the word "broad"? I meant broad frequency span; the overlap is roughly an octave.

[pheonix358]

Originally Posted by Curmudgeon

First, I'd refer you to Vance Dickason's most excellent Cookbook.

If the mid/tweet voice coils are vertically aligned (or more accurately, the sound sources) there will be a -15 degree slope of the smoothest axis. Hence the tilt back of some speaker systems. .

That should read "If the mid/tweet voice coils are NOT vertically aligned (or more accurately, the sound sources) there will be a -15 degree slope of the smoothest axis. Hence the tilt back of some speaker systems."

I refer you to Vance Dickason's most excellent Cookbook.

[Curmudgeon]

Loudspeaker Design Cookbook, by Vance Dickason, 7th edn, P. 157. "Because of the 90 degree phase difference, a -15 degree tilt will occur in the vertical polar response with high-pass and low-pass driver separated by a distance of one wavelength at the crossover frequency (+15 degrees for the reversed polarity connection)." Acoustic centers are assumed aligned for obvious reasons.

Figure 7.8 shows the negative max output lobe, the dotty line is the normal polarity, and the heavy line is the reverse polarity. Figure 7.10D shows the tilted cabinet for a horizontal max output lobe.

It's the even order alignments that do not have the tilt.

[pheonix358]

Hi Mate, I have the fifth edition but let us see if we can agree on this. From what you have said the answer in your book may be in 7.10. Compare A,B,C, and D. The only diagram with acoustic centres on the same plane is C. This is why most quality speakers with 1st order slopes use a stepped baffle.

Terry

[head_unit]

In an electrical engineering class, a first order highpass plus first order lowpass sum more perfectly than steeper slopes.

In real life with real drivers, it just doesn't work that way because the drivers have some inherent phase and magnitude changes versus frequency.

If you read Vance's book enough, and read other posts in threads with "crossover" in the title, what you'll find is that you have to really measure the drivers and make a kind of empirical design. All that theoretical stuff is great as a background to understand what is going on, and maybe useful for electronic crossovers, but doesn't apply well with real drivers.