Posted by Wayne Parham [ 70.234.97.75 ] on February 24, 2008 at 19:05:47:
In Reply to: Re: OK, I'll quit re-inventing the wheel posted by Bill Epstein on February 24, 2008 at 18:18:02:
Never quit experimenting! That's at least half the fun!
Here's the chart for 1" compression drivers. It only works for crossovers designed for 8Ω and with (second-order and higher) crossover frequencies around 1.6kHz.
Attenuation ( < 5kHz ) R1 R2 C1
==============================================
6dB 12Ω 30Ω 0.47µF
8dB 12Ω 20Ω 0.47µF
10dB 16Ω 16Ω 0.47µF
12dB 25Ω 16Ω 0.47µF
14dB 30Ω 14Ω 0.33µF
16dB 40Ω 12Ω 0.33µF
18dB 50Ω 12Ω 0.22µF
20dB 75Ω 12Ω 0.22µF
==============================================
R2 is connected across the crossover tweeter output. R1 is connected after that, placed in series with the driver. C1 is connected in parallel across R1.
I've tried these values on 1.2kHz crossovers and they work well, but once you get much below that, the values change. That's because of the reactive values of the crossover. The chart is different for 1kHz and below. I've worked out values for 1kHz, 800Hz and 600Hz, so let me know if you need them and I'll post them. But frankly, I wouldn't use a PSD2002 below 1kHz, not even with flea-power. I don't know about the DE250.
Understand that the selection of these values isn't really so much about crossover frequency as it is about the inductances and capacitances in the tweeter circuit. I'm talking about it in terms of crossover frequency as a sort of shorthand, since the values required to make a 1.6kHz crossover for an 8Ω driver fall into a fairly narrow range of values. But if you were to range too far away from typical crossover values, the chart might have to be altered too.
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