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Universal Schematic.


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I want to build a Alk Universal network for my Lascala speakers. Al said that there was a universal schematic floating around on here that I can use. I wanted to see if this is the one that I should follow. I went through a ton of threads looking for it. What I have attached is what I believe is the first rendition of the network. 

 

I have all of the parts in the cart and wanted to check with you guys before I pull the trigger and purchase all of the parts. 

 

I may try the AA and A down the road but am intrigued by the universal. 

good_AA.jpg

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Yes, that is the same as the kit I built many years ago.

 

I have, in the mean time, made a couple changes...

 

Replaced the 1.3mH inductor with a 2.5mH for the woofer.

Replaced the .2mH inductor with a .15mH for the tweeter.

 

The 2.5mH inductor seemed to tighten the bass.  The tweeter inductor swap seemed to smooth out the the top end a little.

 

Mike 

 

 

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Hey Mike,

 

Thanks! I may just grab both values of inductors and see how they sound. I vaguely remember reading that the 1.3 included counting the inductance of the woofer and the 2.5 does not. 

 

I am excited to build these. What did you do for the 7.5mH cap? I am currently going to use Solen for that Clarity Cap CSA for the rest of the caps. Solen is the only one I can find in the 7.5mH value. 

 

Thanks,

Mike

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7 minutes ago, Mikerodrig27 said:

Hey Mike,

 

Thanks! I may just grab both values of inductors and see how they sound. I vaguely remember reading that the 1.3 included counting the inductance of the woofer and the 2.5 does not. 

 

I am excited to build these. What did you do for the 7.5mH cap? I am currently going to use Solen for that Clarity Cap CSA for the rest of the caps. Solen is the only one I can find in the 7.5mH value. 

 

Thanks,

Mike

 

Actually the Clarity Cap CSA 6.8uf will be a better choice..  I got the Solen 7.5uf now.

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8 hours ago, Mikerodrig27 said:

Okay cool. I actually have two of the Clarity cap PX 6.8uf in my parts box that I can use. Why is the 6.8uf a better choice just out of curiosity? Trying to learn some things. 

 

Better may have been a poor choice of word.  In a true 3rd order Butterworth high pass filter, the second capacitor is 3 times larger than the first.   6.8uf is close enough.

The 7.5uf would have been fine also, but I assumed you wanted to stay with CSA's.

 

Looking on Al's website, in the Super AA-X section, you'll see how he converts AA to something close to the Universal.  Can't make out the second cap value, but I believe

it's 6.8uf.  Notice also that he doesn't replace the 2.5mH woofer inductor as a part of the conversion.  

 

Also, schematic doesn't show the 1.5 amp fast blow fuse.  I had it in initially but removed it when I swapped out the woofer inductor. 

 

Have fun with your project!  What squawker/tweeter are you using?  I also made a couple of other tweaks that you may want to try later, but they can

be added to the finished crossover easily.  

 

Mike

 

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Perfect. I will switch to the 6.8uF caps. 

 

I am going to use the stock tweeter and squawker for now. I may change them out down the road. I just need to get away from the original AL network for now. 

 

The speakers have some pretty significant veneer damage. They are the industrials with the plywood construction which I like the look of but I won't be able restore them to original. I was thinking of veneering them with mahogany or walnut. I was also thinking of adding 1/4" or 1/2" plywood to the sides to make them thicker. I don't like the look of the little braces that people put into the horn even though I understand that they are effective. 

 

What is your take on adding bracing to the sides? I also noticed the top pane of wood where the mid and tweeter are could use some sort of bracing as well. 

 

I also saw something about someone adding polyfill to the sealed doghouse where the woofer is. Does this seem like a good idea?

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Yes, I went back and forth with that for a while. I may build the AA down the road just to experiment as the parts cost on it isn't too high. Once I have the Model 3636 autotransformer, I should be able to swap it to different boards. 

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This should be everything you will need. 

 

My Uni's have Jantzen Alumen Z Caps & Superior Z's (all have Dueland ByPass caps) with Mundorf VL236 Coils/Solen Litz.

 

You won't go wrong with the Uni....with the right components it's great for smooth, easy listening. Very clear, open sound. 

LAYOUT.GIF

SCHEMBW.GIF

BELLE CROSSOVER 10.jpeg

3636 ATTENUATION LIST.pdf

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Here are two more threads about ALK Universal crossovers, this one which includes changes to crossover at 4500Hz if you are using an upgraded tweeter .

 

and this one shows how to utilise an AK3 woofer section with the Universal

 

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Awesome! Thanks! There is a ton of great info on this forum.

 

Okay, so what I am gathering is that the version that I posted sends ~1000hz and below to the woofer and roughly 410hz and up to the mid/tweet. The other version that I see posted puts everything ~500hz and below to the woofer ~500hz and up to the mid/tweet. Let me know if this sounds right. 

 

In other words, there should be less mingling between the woofer and the squawker with the 2005 version that I see posted. 

sootshegood job on your build! Looks like a lot of nice boutique parts. Is the point of the bypass cap to save a little money by not having to purchase a 40uf expensive cap vs a 39uf less expensive cap?

 

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