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ALK crossover wihout transformer


Stig

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Al Klappenberger,

Howdy Al-I'm building La Scala's from the floor up with new stock parts except the crossover. I've been following the threads on your venture and it sounds like positive results. I was looking at the schematics of your crossover and was wondering if you went without the transformer what it would do to the value of the caps and inductors in your squawker circuit. I realize the entire cicuit was conceived with the idea of presenting a stable 8ohm. load to the amp. I'd like to try resistor attenuation circuit for squawker. Have you already fought this battle and lost? I noticed the 18db highpass on the k-77 is real close to textbook figures. I would like to keep that and also the 12db on the mid bandpass. From your experience with the network is it worth my time to try it without transformer? Would like to know what bandpass parts 6 and 12db to try if it is feasible.

Hope this hasn't been covered already.

Thanks,

Stig

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Stig,

Yes, you can replace the transformer with a resistor pad if you like.

The theory behind the transformer is that it allows closer coupling between

the squawker and the amp giving better damping then a pad. I have been told

that Klipsch is the only speaker maker that uses transformers. Everybody else

uses pads! The engineering details of the pad are that it must be designed to

operate between 8 Ohms and the squawker impedance, which is actually 13 Ohms

(I measured it) while yielding about 6 dB loss. Remember that it will replace

the 10 Ohm swamping resistor also. You will also have to connect the tweeter

inverted. Connect the + (red) wire to common and the - lead to the pad.

I would not advise changing any other values or the number of

elements in the filters. If you reduce the order of the filters you may run

into phasing problems at the crossover.

Al K.

By the way, the values would be ("L" pad") 12.9 Ohms across the 2.2 uF cap (replaceing the 10 Ohm swamping reisitor) and 8.06 Ohms in series with the squawker. This will yield about 6.2 dB loss.

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Al, I have a stupid student-type question...how would you go about designing a x-over that said "what the hell" to impedance and tried to get the k-horns/belles/etc. the flattest possible anechoic response...speaker response versus load for amp...can you fill me on this?

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quote:

Originally posted by Al Klappenberger:

Stig,

Yes, you can replace the transformer with a resistor pad if you like.

The theory behind the transformer is that it allows closer coupling between

the squawker and the amp giving better damping then a pad. I have been told

that Klipsch is the only speaker maker that uses transformers. Everybody else

uses pads! The engineering details of the pad are that it must be designed to

operate between 8 Ohms and the squawker impedance, which is actually 13 Ohms

(I measured it) while yielding about 6 dB loss. Remember that it will replace

the 10 Ohm swamping resistor also. You will also have to connect the tweeter

inverted. Connect the + (red) wire to common and the - lead to the pad.

I would not advise changing any other values or the number of

elements in the filters. If you reduce the order of the filters you may run

into phasing problems at the crossover.

Al K.

By the way, the values would be ("L" pad") 12.9 Ohms across the 2.2 uF cap (replaceing the 10 Ohm swamping reisitor) and 8.06 Ohms in series with the squawker. This will yield about 6.2 dB loss.


Al,

Thanks for your response and thanks for sharing the fruits of your labors with

the BB tweakers.

Stig

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SunnySal,

It is not entirely a stupid student question. And somewhat profound.

In truth, much or all of this is about impedance. We are working with impedance because it is an inherent propery of the systems. Perhaps that should have been the first answer. We're working with systems which are not simple.

Gil

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