nextamp

FYI left clicking on the pic also expands it to the full schema ....

the schema shows a 5 ohm resistor in the HF circuit. this (apparently) pads back the sensivity of the tweeter to match that of the woofer. this will work to my advantage in a bi-amp config since I may use a flea power amp for the tweeter. the 5 ohm resistor will be eliminated & I won't be throwing away the watts that were consumed in the 5 ohm resistor.

the schema shows a 3rd order HF xover w/ a notch filter at the output. the notch filter flattens the tweeter's impedance. the schema also shows a 1st order LF xover w/ a Zobel network at the output. the Zobel flattens the woofer's impedance.

copy the image to your PC & then open it to see the full schema.

I want to Bi-amp a pair of RB-75's This will be a true bi-amp setup so the RB-75 crossovers will be removed from the circuit. Amplifiers will connect directly to the drivers. I plan to use line-level passive crossover between the pre-amplifier and the power amplifiers. Q1) What is the crossover order inside the RB-75 (i.e. 1st order, 2nd order, 4th order, etc.). Q2) Is there any impedance compensation network included in the RB-75 crossover. Q2b) Will I need to keep an impedance compensation network between the woofer amp and the woofer. Q3) Is the tweeter sensitivity padded back (e.g. -3dB) from the woofer in the RB-75 crossover. I've read that 1st order crossovers are great for audiophile quality, and I would like to go that route. However I've also read that 1st order crossovers tend to work better with low power systems instead of high power systems. Where more power tends to make the over-extended driver breakup modes more audible. From other research, I've selected a 1 to 4 ratio of power split betwen the tweeter / woofer. Using available amps, I''ll use something like 15 watts tweeter & 60 watts woofer or 30 watts tweeter & 120 watts woofer. I know the latter will be over-powering the RB-75, but I'll be careful. The tweeter watts will probably be tube & the woofer watts will probalby be solid state. Q4) I use 1st order crossover, what should the power amp sizing be to play well with that choice (e.g. 5 watts tweeter / 20 watts woofer). I have another system that is Bi-Amped with 900 Watts total. It uses a Marchand 4th order Linkwitz-Riley electronic crossover. That system sounds great LOUD; but this Klipsch system will be a different animal (I want detail, detail, detail). Also I've read some bad things about high order crossovers (e.g. 4th order) that they destroy group delay (hence transient response). Another guy in some review bi-amped RF-7's w/ a Marchand crossover & said it didn't sound good (could have been setup error). These are arguments against 4th order.