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Multi-Way Conventional loudspeakers with crossovers

Suitable midrange cone, for bandpass mid in Unity horn.
Suitable midrange cone, for bandpass mid in Unity horn.
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Old 25th June 2019, 06:14 PM   #2361
Patrick Bateman is offline Patrick Bateman  United States
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Location: San Diego
Xsim has been an unbelievable time saver for me. I really love how intuitive it is, I can generally do the following in under one hour:

1) measure my speaker's frequency response

2) measure my speaker's impedance

3) save the files, copy them over to my laptop

4) create a crossover simulation in xsim

5) tweak the design
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Old 25th June 2019, 09:59 PM   #2362
charlie2 is offline charlie2  England
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Quote:
Originally Posted by bwaslo View Post
Charlie, it's not just Danley and it's not just horn designs who don't use 'named' crossover types much anymore. Pretty much anyone beyond beginner does that these days. Back in olden times when driver anechoic response measuring gear was out of almost anyone's reach, and before computers were commonly available, and massive math simulations were too long and difficult to be used for an 'iterative design' technique, designers had to rely on broad and unjustified assumptions (that drivers had flat response and flat impedance, that delays from drivers where the same or just some guessed value, etc.)

But now people can measure drivers' impedance, and response curves at a bunch of angles, and true relative delays; and with free simulators get essentially an exact prediction of what will happen with arbitrary crossover circuit topologies and values, and use educated trial and error to optimize results. Design is done for overall result not a mathematical rough assumption. We might sometimes start with component values similar to what an Butterworth (or whatever) filter of the desired order would be to get a general starting point, but by the time in the simulated iteration that component values are tweaked, extra components are injected to flatten or extend response, the curves and circuits are just what gives the wanted overall result. In a good simulator, it takes probably less time to twist the knobs (the mouse wheel in my simlator can be used as a component value 'knob') or stick in other components than it would take to calculate the WhateverWorth filter values.

Keele and Olsen, by the way, aren't crossover or filter shapes, they are researchers who figured out how baffless or horns work. Simulation and iterative design of those aren't as straightforward or quick as crossover filters, so Keele and Olsen's results are still good guides about what directions might be best pursued.
Thanks for the reply input..Bwaslo but as an observation even the guys you mention and the merits they gave in recent years are way behind what was known a long time ago

Must get round to building one been studying and following designs for several years but lack time and commitment......

Last edited by charlie2; 25th June 2019 at 10:04 PM.
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Old 28th June 2019, 12:46 PM   #2363
Dave Zan is offline Dave Zan  Australia
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Quote:
Originally Posted by nc535 View Post
You can use the formulas in that paper if you like but you will do better...still with ABEC
Of course, that's why I have already mentioned, twice, that I plan to use ABEC.
But ABEC or Hornresp don't provide with me with formula that tell me what to look for, they only tell me what the results will be.
I can try lots of simulations with different parameters and try to see how they affect the results but I prefer to analyse it so I have explicit expressions.
That's a personal style preference, other people like to dive in and "try it and see"

Quote:
Keele apparently intended his analysis to be used on an exponential horn immediately above cut off
Keele's analysis is actually not restricted only to exponential horns, he explicitly mentions at the start that the throat impedance can vary with frequency.
Then later he adds some assumptions to simplify the formula.

Quote:
...This is a fairly different situation than Keele analyzed, given the bandpass chamber...
He does include a bandpass(-ish, see #2356) chamber, in fact, but yes, different situation.
However, as I commented, I don't want predictions (yet), I want formulae that show how the factors interact.
The difference between analysis and synthesis equations.

Quote:
Originally Posted by nc535 View Post
Here are the acoustical impedances...
The mids driven from an offset position see a vastly different picture. The impedance in their case is modulated by the very large reflection...
In no way can it be said that the acoustic impedance has reached its asymptote by the mid XO.
Thank you, that actually confirms my expectation.
The impedance is normalised and has indeed risen to the asymptote value of 1, just at 1 kHz, by the time the 1/4 wave notch starts.
Then once the reflection comb filter kicks in it's all over the place from there on up.

Best wishes
David

Last edited by Dave Zan; 28th June 2019 at 12:49 PM.
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