I've got some speaker plans that call for a simple crossover on the tweeter, comprising only a capacitor in series with the tweeter and a resister in parallel. The midbass drivers have no crossover. (It's the simple crossover for the Ariel speakers, http://www.aloha-audio.com/Arieltxt2.html#top.) I can't get over the suspicion that there's a typo or something. The tweeter is rated at 6 ohms. The plans call for a 2uF capacitor and 16ohm resistor. I've tried calculating what the crossover frequency would be, and I keep getting very high numbers at or above the limit of the audible range.

So, the questions are,

1) How do you calculate the crossover frequency for that simple crossover (cap inline, resistor in parallel).

2) Could 2uF be correct?

BTW, the designer, Lynn Olson, said he was not pleased with the results, and he designed a fancy, high order crossover for the system.

Best regards,
Jive

"Jive Dadson" wrote in message .. .
I've got some speaker plans that call for a simple crossover on the
tweeter, comprising only a capacitor in series with the tweeter and a
resister in parallel. The midbass drivers have no crossover. (It's
the simple crossover for the Ariel speakers,
http://www.aloha-audio.com/Arieltxt2.html#top.) I can't get over the
suspicion that there's a typo or something. The tweeter is rated at 6
ohms. The plans call for a 2uF capacitor and 16ohm resistor. I've
tried calculating what the crossover frequency would be, and I keep
getting very high numbers at or above the limit of the audible range.

So, the questions are,

1) How do you calculate the crossover frequency for that simple crossover (cap inline, resistor in parallel).

2) Could 2uF be correct?

BTW, the designer, Lynn Olson, said he was not pleased with the results, and he designed a fancy, high order crossover for the system.

Best regards,
Jive

Jive,

The simple crossover with that cap (disregarding the resistor for the
moment) would give a frequency of 9937.5Hz which does seem a bit high
(I calculated for the tweeter having 8 ohms impedance - at 6 ohms it's
over 13kHz). The formula is: 0.159/((cap value in FARADS)*impedance of
driver). In this example 2uF = 0.000002.

The resistor may be used as attenuation, or to modify the effect of
the cap - unfortunately I couldn't find a formula for working out how
the two components react together.

I think the best answer to your question is: suck it & see.
Personally, I've never used a simple crossover on a tweeter - I
normally use second order Linkwitz-Riley or Butterworth, both give
good results. If you haven't got the formulas, send me an e-mail and
I'll pass them on.

One last thing, if you haven't already, grab a copy of "The
Loudspeaker Design Cookbook" by Vance Dickason, it has entire chapter
on crossovers - well worth the investment.

PT

P.S. Good luck with the project.