stereohermit Posted March 23, 2007 Share Posted March 23, 2007 Is the new K-77F tweeter ferrofluid, by chance? Also, what slopes are they running in the AL-4 ... 24 db/octave perhaps? And the mid lo-pass? I see they lowered the freq. to 4500, which should be better for the power response. Quote Link to comment Share on other sites More sharing options...
Daddy Dee Posted March 23, 2007 Share Posted March 23, 2007 I think that the 4500 hz cutoff on the K77 is accomplished with a sixth order crossover. It's just friendlier to the K77, not the result of a beefier K77. Now, I should add the disclaimer that I'm a non tech type. So, what I am relating, might be correct. I'm sure there are others who can say more about the AK4 crossover. It's a pretty impressive rascal. Quote Link to comment Share on other sites More sharing options...
Guest " " Posted March 23, 2007 Share Posted March 23, 2007 stereohermit I have 2 sets of the k-77-f's. None have burned out yet so I have not opened one up yet. This drawing was posted a while back......I don't think it is an exact representation since I drew one and it did not come out quite the same. There are differences in the AL-4 and AK-4, this might actually be an AK-4 conceptually. Quote Link to comment Share on other sites More sharing options...
LarryC Posted March 23, 2007 Share Posted March 23, 2007 I think that the 4500 hz cutoff on the K77 is accomplished with a sixth order crossover. It's just friendlier to the K77, not the result of a beefier K77. Now, I should add the disclaimer that I'm a non tech type. So, what I am relating, might be correct. I'm sure there are others who can say more about the AK4 crossover. It's a pretty impressive rascal.That's my understanding too, Dee -- a 6th order filter for a 36 dB/octave slope below 4500 Hz, plus a "poly switch" that opens at a certain voltage and closes again when the voltage falls back below the threashold. Quote Link to comment Share on other sites More sharing options...
BEC Posted March 23, 2007 Share Posted March 23, 2007 I have rebuilt a few K-77Fs. No ferro fluid in the ones I had apart. They are just a copy of the K-77M made in the Philippines instead of by Electro-Voice. From what I can tell on the K-77F, I would think they are good for about 2 watts, so you would need to cross over to them very steeply to cross as low as 4500 hz. And, I know it is possible to blow one in a LaScala with the AL-4. Bob Crites Quote Link to comment Share on other sites More sharing options...
Triodedick Posted March 25, 2007 Share Posted March 25, 2007 Here is a photo of the cross-over of the new La Scala II. Quote Link to comment Share on other sites More sharing options...
stereohermit Posted March 28, 2007 Author Share Posted March 28, 2007 Ah....VERY interesting. Good to see they finally went to fixed resistors for level attenuation. I found many years ago that good fixed resistors sounded way better than the autoformer. I recommend Caddock or Vishays. What also works well are stacks of parellel, small fine resistors. I'd calculate the value of the mid system to eight ohms to help linearize the impedence envelope.The autoformer would let impedednce climb, with increasing frequency, giving the system upper mid glare when used with amps of highish output impedence.The resistors klipsch is using are a tad high on inductance, unfortunately, since cost is a factor.I'll have to give these new La Scala.'s a listen! Quote Link to comment Share on other sites More sharing options...
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