In Reply to: 4Pi Pro questions for Wayne, et al posted by Till E. on January 07, 2003 at 18:25:48:
TillE and Wayne,
Since the Altec drivers are 16 ohm, then the 1.6 khz hi-pass crossover from Parts Express will actually be 800 hz, that is due to the difference in the driver impeadance. When TillE came to my house, I had the Altecs running off of my 1.6khz hi pass with 14 ohm for R2 and 30 ohm for R1 with .47 ufd for compensation, for the bottom (using JBL 2226J also 16 ohm) I had 2 mh air-core coil. I had been breadboarding that crossover to put in my Altec A-8's. but have not had time to do so yet.
Now Wayne, I have a question for you, What I did using the 16 ohm Altec driver did not make much of a difference to the crossover since using a 8 ohm driver it is still seeing the parallel 14 ohm resistor in parallel with the 30 ohm resistor and 8 ohm driver which bottom line crossover would see minimum of 5 ohms and max of 10.2 ohms depending on frequency because of the compensation cap. If you substitute the 16 ohm driver, the min and max values only change to 7.46 ohms and 10.7 ohms, I see very little change here due to the attenuation ciruit. the only difference I noted was taking the 2418 JBL driver (8 ohm) out and wired the Altec (16 ohm) in, was a tad more efficient, plus the better top octave of the Altec aluminum diaphram versus the JBL titanium. So my question to you is, since a 8 ohm 1.6khz crossover should equal a 800 hz crossover for 16 ohms (and it should), what would the R1 and R2 values be, I already have experimented and found the .47 ufd good for me. Give me your opinions here. The way I described above, I liked with tubed amps, with solid state, I put a 30 ohm resistor across the 16 ohm Altec compression driver, (15 ohm across it took too much off top, 30 ohms seems okay for solid state, the tubed amp liked it wide open)
Allright, I am ready for the onslaught of attackers now.
thanks for listening to my $0.02 worth gang, Ron
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