moefasta

I think that maybe the offender is not the tweeter, but instead the squaker. Al uses a low pass filter on the squaker in his ALK's. If you roll off the squaker around 6000hz, you might eliminate that bump from 6000-9000hz. Just a thought

Al, thanks again for your reply. Please don't mistake me as being argumentative, I really want to learn. If it is better to use a "swamping" resistor in parallel(short) with the squaker, why should we look to match the impedence as originally designed, other than to restore the function of the 13uF cap? We could use different cap values and bring the impedence down even more with a swamping resistor having even less resistance. I believe this is what you have done(among other things) in your design. I believe that impedence presented by the driver is different than resistance across the poles. The driver is converting electrical energy into sound(which we want), and a resistor is converting electrical energy into heat(only necessary if it is cold). We only have a finite amount of amplifier power available, and the swamping resistor WILL draw current(which could have been used to produce sound). Maybe I am not understanding the concept of presenting a more linear load to the amplifier(be it produced by impedence,resistance, or reactance). It seems to me that if you want the amplifier to send less power to a circuit, you must increase resistance, thus lowering the load. By not wasting current through a resistor, I reason that there is more power available to other drivers(mainly the woofer). I could be making way too much of this issue, and may be over estimating the power loss caused by the swamping resistor. I am assuming an amplifier that can produce 20 volts into an 8 ohm load would flow about .6 amp through a 33 ohm swamping resistor(about 12 watts), and flow about 2 amps through a 10 ohm (ABOUT 40 WATTS!). I understand these are peak levels(not constant power) with no additional headroom, but they are VERY signifigant losses. If my calculations are incorrect PLEASE correct me. Thanks in advance.

Al, thank you for your input. You recommend shorting a resistor across the + and - of the autoformer. Is this preferable to changing the value of the cap. I think it may be in order to maintain a flatter impedence curve seen by the amplifier. On the other hand, in the interest of efficiency, I have a hard time using a heater(resistor) to lower the output of a particular driver(isn't this the reason for the autoformer vs. L-pad in the first place?). I think the question is, is it better to have a flatter impedence curve and waste a little power as heat, or have no power wasted with a high impedence presented to the amplifier at the frequencies filtered to the squaker?

I have a pair of 1974 klipschorns with aa crossover networks. I felt that the squaker horns were much too hot(loud) so I moved the wires on the autoformer from the #5 and #4 taps to the #5 and #2 taps. I felt they sounded much better so I left the taps as such. My problem is that I now have both squaker drivers blown. I suspect that by moving the taps on the autoformer, the increase in impedence has lowered the crossover point too much allowing frequencies too low for the squaker to pass. My question is (after replacing the drivers) in order to cut output from the squaker should I: A)put the taps back where they were and use an L-pad?, B)Leave the taps where I like them and short a resistor across the taps to lower impedence seen by the crossover?, or C)change the value of the caps to to compensate for the increase in impedence? Any advice or comments will be greatly appreciated