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AA network question


AudioDon

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I'm confused about what I see in my pair of AA La Scala networks.  One appears to be original with the big cans, the other was changed at some point and the wire routing appears to be a little different but effectively similar. They both have rheostats for the Tweeter and mid drivers. The confusing part to me is that in the CAD schematic I got here dated 82092B, I see that the positive input leg splits before it gets to the 13uF cap, feeding the squawker  with the 13uF cap, and the tweeter with the 2-2uF caps.  In both of the networks, the 2-2uf caps are taken after the 13uF cap.  There are the other components but I'm just trying to separate out how the caps are fed.

 

What am I missing?

 

Thanks, Don

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14 hours ago, AudioDon said:

I'm confused about what I see in my pair of AA La Scala networks.  One appears to be original with the big cans, the other was changed at some point and the wire routing appears to be a little different but effectively similar. They both have rheostats for the Tweeter and mid drivers. The confusing part to me is that in the CAD schematic I got here dated 82092B, I see that the positive input leg splits before it gets to the 13uF cap, feeding the squawker  with the 13uF cap, and the tweeter with the 2-2uF caps.  In both of the networks, the 2-2uf caps are taken after the 13uF cap.  There are the other components but I'm just trying to separate out how the caps are fed.

 

What am I missing?

 

Thanks, Don

Hey Don

 

Can you post the schematic you have (I believe it's 820928, not 82092B???).

 

The latest schematic I have is revision 900102, which appears to be what you have installed?  I'm also assuming the rheostats are variable L-Pads.

 

Mike

 

 

TypeAA.jpg

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Definitely NO rheostats in an original AA.  Two different cap types and wired differently is not optimal, to say the least.  The schematic above hasn't changed in a long time.

 

Certainly recommend the Crites folks for network rebuilds or for parts.  Outstanding customer service for many years.

 

https://critesspeakers.com/

 

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AudioDon, that alone could explain why one of your squakers sounds distorted. The above shown circuit is right and everything else is added by someone later on and it is not original. Normally you do not need to adjust the SPL of any of the drivers if you have the original ones and the genuine AA network.

 

If you still have this zener diodes in just try to listen without them, just unscrew one of them. Be careful not to damage the tweeter by switch on or off noise of your amp, but the gain of sound quality is significant.

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4 hours ago, jimjimbo said:

Definitely NO rheostats in an original AA.  Two different cap types and wired differently is not optimal, to say the least.  The schematic above hasn't changed in a long time.

 

Certainly recommend the Crites folks for network rebuilds or for parts.  Outstanding customer service for many years.

 

https://critesspeakers.com/

 

Thanks,  The La Scals's I've seen like mine, which were sold along with a Rodgers Electronic church organ,  have the variable L-pads which I previously called rheostats. They're 2-wire tapped off the positive leg.  I called Crites a few days ago, and they just got back to me a moment ago.  I guess their answering machine was down for a day or two. Nice folks 

Edited by AudioDon
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4 hours ago, mboxler said:

Hey Don

 

Can you post the schematic you have (I believe it's 820928, not 82092B???).

 

The latest schematic I have is revision 900102, which appears to be what you have installed?  I'm also assuming the rheostats are variable L-Pads.

 

Mike

 

 

TypeAA.jpg

Hi Mike,

It's funny, the copy I downloaded the other day looks identical except for the Zener.  Thanks for providing this.

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3 hours ago, KT88 said:

AudioDon, that alone could explain why one of your squakers sounds distorted. The above shown circuit is right and everything else is added by someone later on and it is not original. Normally you do not need to adjust the SPL of any of the drivers if you have the original ones and the genuine AA network.

 

If you still have this zener diodes in just try to listen without them, just unscrew one of them. Be careful not to damage the tweeter by switch on or off noise of your amp, but the gain of sound quality is significant.

KT88,

Thanks for bringing this up.  I'll check it out.  I think I found the source of the noise. I'll update the other posting.

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10 hours ago, mboxler said:

Hey Don

 

Can you post the schematic you have (I believe it's 820928, not 82092B???).

 

The latest schematic I have is revision 900102, which appears to be what you have installed?  I'm also assuming the rheostats are variable L-Pads.

 

Mike

 

 

TypeAA.jpg

Hi Mike,

Here's the one I downloaded the other day. The last 8 in the date isn't very clear to me and I thought it was 8/20/92B instead of what's written with the year first. Now that I've seen the schematic you posted, I can see where the Zener has been edited out of mine. Don

CCI06102021.thumb.jpg.eb66f9a653a8f89800a2d27d81b3f63f.jpg

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