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Something has seemed screwy about this whole question....

Posted by corerosin (A) on May 31, 2007 at 07:13:00

In Reply to: Crossover resistor value to make tweeter less dark posted by avhed on May 29, 2007 at 23:18:54:

...to me. The numbers aren't working out. The Sound Dynamics speakers are a two way with a 6 1/2" woofer and a 1"dome, horn loaded tweeter rated at 8 ohms, right? One would expect the crossover to be in the 2-3Khz range. 15uF is way too large a capacitor for a crossover in that range for an impedance of 8 ohms or even 12.7ohms. Running just the bare bones formula for 8 ohms gives a value of 1,326hz. For the 12.7 ohm load, I get a value of 835hz. The problem is that when you extend the butterworth number for a single element high pass filter, you can cut those crossover numbers in half. So, for 8 ohms the crossover frequency is 663hz. For 12.7 ohms, the crossover frequency is 417.5hz. Neither one of those seem correct.

I am wondering if the 4.7 ohm resistor is in parallel with the tweeter. If it is in parallel with an 8 ohm tweeter, then the 'load' is going to be around 2.96 ohms. Using that load in the formula gives a value at 3,585 hz. And with the butterworth value attached, a crossover at 1,792.5hz. That's closer to what I would have expected for this speaker.

Anyway, I'm wondering whether the 4.7 ohm is connected in series with the tweeter or in parallel. And if it is connected in series, what is the impedance or even just the DC resistance of the tweeter. Knowing these two things would stop my head from scratching.

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