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AL crossovers


CECAA850

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11 minutes ago, wdecho said:

My understanding is that the AL crossover was designed to be used with the K55M driver which is more efficient than the K55V driver used with the AA crossover hench the difference between the attenuation of the two autotransformers.  

But it turned out not to be more efficient than the K-55V. 

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The story I heard was that the prototypes of the K-55Ms had higher output, so the crossover was made compensate for that.  Then the actual production models showed up and did not have the higher output.  But anyway, I did my own testing and pronounced all to be essentially equal.

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I did not listen to them.  I can say with certainty that I would not like the midrange recessed that far back behind the bass and treble.  I like hearing the midrange at the same level as the other two drivers.

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1 hour ago, wdecho said:

But after some thought if one has to buy autotransformers one could just build the AA's. Or just buy a pair from you.

 

I personally like the idea of the 4500hz crossovers for the money and changing the tweeters. 

I don't have your experience swapping components and XO's but instead of updating my stock AA's I ended up with an A/4500 XO and different tweeters and I am thrilled with the sound.  It's very dynamic especially at mid SPL and above, and it has lots of energy in the midrange for trumpet, baritone and percussion.

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I thought I would go ahead and post the test results after changing out the autotransformer.  So you can compare them next to each other, I will post one of the crossover with the T3A and one of the crossover after just changing the autotransformer.

 

AL mod 1.JPG

AL mod 1-1.JPG

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14 hours ago, wdecho said:

The question still remains if it is worth it for someone short on funds to replace just the caps in the AL and remove the notch filters being that the transformer is the biggest expense. I personally think removing the notch filters in an AL crossover and replacing the caps will sound better than the stock AL.

I'm thinking that all the AL T3A transformers are screwed up.

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  • 2 months later...
2 hours ago, John Albright said:

 The low spike in the squawker in Bob's graphs may show what I was hearing in my Type ALs.

Bob and I were talking about it and he commented that a spike like that should be audible.  I don't trust the T3A's any more.  From now on I'll just toss them.

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  • 2 weeks later...
31 minutes ago, mboxler said:

Would it not be more flexible to place a 26uf cap after the autoformer?  Seems that you could change the output taps to whatever value you want without the need to change the cap. 

 

Mike

I hope you're not asking me.  I have no idea.  I can build and listen but not design or explain what's going on.

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1 hour ago, mboxler said:

Would it not be more flexible to place a 26uf cap after the autoformer?  Seems that you could change the output taps to whatever value you want without the need to change the cap. 

 

Mike

 

The Squawker high pass cap would have to be larger, about 30 uF but it could be placed after the Autoformer and the taps could be changed more readily.  However, its inductance would affect the woofer, it would begin to look more and more like a dead short as frequency dropped and it would be exposed to all frequencies resulting in its saturation at lower system power levels (due to the power in bass frequencies).  Saturation would change its inductance and the response curve of the frequencies it passed to the squawker.  All bad.  It's best to protect the autoformer from frequencies it doesn't need to pass. 

 

Al K's swamping resistor does that with less "cost" to sound quality and also stabilizes the impedance across the squawker's range.  With his design, you can change the taps as desired without changing the high pass cap. 

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