nextamp Posted February 15, 2011 Share Posted February 15, 2011 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. Quote Link to comment Share on other sites More sharing options...
djk Posted February 16, 2011 Share Posted February 16, 2011 The stock crossover will be a very difficult transfer function to duplicate, I wouldn't bi-amp. Just replace your caps in the passive network with better, and bi-amp to a subwoofer. Quote Link to comment Share on other sites More sharing options...
nextamp Posted April 30, 2011 Author Share Posted April 30, 2011 Quote Link to comment Share on other sites More sharing options...
nextamp Posted April 30, 2011 Author Share Posted April 30, 2011 copy the image to your PC & then open it to see the full schema. Quote Link to comment Share on other sites More sharing options...
nextamp Posted April 30, 2011 Author Share Posted April 30, 2011 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. Quote Link to comment Share on other sites More sharing options...
nextamp Posted April 30, 2011 Author Share Posted April 30, 2011 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. Quote Link to comment Share on other sites More sharing options...
nextamp Posted April 30, 2011 Author Share Posted April 30, 2011 FYI left clicking on the pic also expands it to the full schema .... Quote Link to comment Share on other sites More sharing options...
nextamp Posted May 2, 2011 Author Share Posted May 2, 2011 Quote Link to comment Share on other sites More sharing options...
nextamp Posted May 2, 2011 Author Share Posted May 2, 2011 Quote Link to comment Share on other sites More sharing options...
Klipsch Employees Trey Cannon Posted May 4, 2011 Klipsch Employees Share Posted May 4, 2011 OK, First let me say that when you remove the network you loose the voicing Klipsch engineers chose for the speaker. Your choice, but not suggested. Xover point is 2k HF is 2nd order LF is 4th order There were 3 revisions of the network schematic. RB-75.pdf 1 Quote Link to comment Share on other sites More sharing options...
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