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ALK xover - DIY for Forte II schematic


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On 24-6-2017 at 1:55 AM, Alexander said:

Had an issue with one of the squawkers not firring but traced it down to a bad tinning of the 30mh coil. Sometimes I have a problem trying to articulate  but here goes. The first overwhelming impression was as if the re caped stock xo  had a restrictive grill on  and we had removed it with the ALK xo.  Not to say the former was bad but rather how much better the upgrade was. After listening for a while the detail and 3D sound became more and more evident . I really like the new sound this xo gives you. I tried to do an AB comparison but the (out of) phasing was unbearable.  Guess it goes to prove that there are/were drivers out of phase and  that was one of the things ALK was fixing.  All in all it was worth the time and effort to build this, it was a rewording experience and looking forward evaluating this and future component upgrades as money allow.

 

They sound bigger and fuller is another....

 

Interesting to hear your first impressions! Is there any change in tonal balance with the ALK crossovers?

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On ‎6‎/‎25‎/‎2017 at 6:46 AM, Lasz said:

 

Interesting to hear your first impressions! Is there any change in tonal balance with the ALK crossovers?

Hmmmm, I would say the mids/highs seem to be a bit more forward but it could be because they seem to be smoother & clearer. Have since put the  stockers  back in and want to re do some of the layout.

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  • 4 years later...
  • 5 months later...

Is there an advantage to the ALK over the stock Forte networks?

 

I found revised networks on the web for JBL L100s, which have very high quality drivers and really basic crossovers.  The revised networks, I think by Jantez, were much more complicated and expensive, and tested flatter, but in listening, the original crossovers were preferred, or at least the aftermarket crossovers didn't sound any better. 

 

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10 hours ago, attanasio666 said:

Hello guys. I decided I'm gonna build this network but there's just one thing I'm not sure I understand. In the Woofer section of the schematics, the "0.66mh" and the "6.8 ohms". Are those the measurements for the woofer coil or are they parts I need to add?

 

I believe that's how Al simulates the K-25-K woofer.   Don't include those components.

 

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  • 1 year later...

Hello, I have some questions. I built this crossover network and did some other mods to the speaker. I kept one speaker stock. The modded one also has a Crites titanium tweeter and a tractrix horn for the tweeter. I measured both of them, outside, with the mic at 2 meters. As you'll see in the REW file I will share, there was some cancelation around the mid/woofer crossover point. I inverted the polarity of the mid driver and it got rid of that. The thing is, there is also some null all along the mid frequencies that weren't there with the stock components. These nulls seem to be pretty high Q so if you smooth the data, the nulls disappears so I don't know if they can really be heard. Still, does anybody have some explanation or can help?

Here's the link to the files: https://drive.google.com/drive/folders/17IMTjnHnIr2-0JBnd034awx8SE9JdlrU?usp=sharing

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1 hour ago, attanasio666 said:

Hello, I have some questions. I built this crossover network and did some other mods to the speaker. I kept one speaker stock. The modded one also has a Crites titanium tweeter and a tractrix horn for the tweeter. I measured both of them, outside, with the mic at 2 meters. As you'll see in the REW file I will share, there was some cancelation around the mid/woofer crossover point. I inverted the polarity of the mid driver and it got rid of that. The thing is, there is also some null all along the mid frequencies that weren't there with the stock components. These nulls seem to be pretty high Q so if you smooth the data, the nulls disappears so I don't know if they can really be heard. Still, does anybody have some explanation or can help?

Here's the link to the files: https://drive.google.com/drive/folders/17IMTjnHnIr2-0JBnd034awx8SE9JdlrU?usp=sharing

 

Edit...when you say "this crossover network" are you talking about the Universal or ???

 

Before we chime in, does the crossover already have the mid polarity reversed at the autoformer so that when you "inverted the polarity of the mid driver" you ended up with no polarity change at all?

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1 hour ago, mboxler said:

 

Edit...when you say "this crossover network" are you talking about the Universal or ???

 

Before we chime in, does the crossover already have the mid polarity reversed at the autoformer so that when you "inverted the polarity of the mid driver" you ended up with no polarity change at all?

I'm talking about the Forté II ALK crossover design. It is different from his universal design. In the stock xover, the mid has inverted polarity but not in ALK's design.

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2 hours ago, attanasio666 said:

I'm talking about the Forté II ALK crossover design. It is different from his universal design. In the stock xover, the mid has inverted polarity but not in ALK's design.

 

I'm assuming you have followed the schematic on the first post.  To make testing easier, I'd first move the tweeter circuit from after the 27uf capacitor to before it.  I don't know why Al does that, but it does complicate things, at least in my simple mind.

 

I'm not sure why, but it appears to me that Al pushed the woofer to mid crossover from around 500hz to around 650hz.  The mid to tweeter crossover was moved to 6500hz.  I'd be curious if the mid can even get to 6000hz.  Not sure if the woofer can get to 650hz either.

 

To be sure,  I'd run plots of the individual drivers to verify my theories.  I know it's a pain, but the good news is you can leave the back off while measuring the mid and tweeter.  If I'm right, I can suggest changes to the schematic.

 

Mike

 

 

 

 

 

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1 hour ago, mboxler said:

 

I'm not sure why, but it appears to me that Al pushed the woofer to mid crossover from around 500hz to around 650hz.  The mid to tweeter crossover was moved to 6500hz.  I'd be curious if the mid can even get to 6000hz.  Not sure if the woofer can get to 650hz either.

 

 

Stock forte II network has the crossovers at 650 and 7,000

 

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14 hours ago, winglet said:

 

Stock forte II network has the crossovers at 650 and 7,000

 

 

Thanks.  I couldn't find those anywhere.  Without the acoustic measurements, I can only comment on the component values.  

 

Al must have followed those points as well, as the first simulation shows.

 

The second plot is the stock crossover.

 

Mike

 

 

Screenshot (235).png

Screenshot (236).png

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34 minutes ago, winglet said:

Does that stock forte ii simulation include the 40ohm resister across the tweeter?  I thought it was supposed to tame that hump.

 

 

Yes it does.  I don't have a K75K so I used an 8 ohm resistor.  That brings the load down to 6.6 ohms in my simulation.  Again, this is a voltage simulation only.  

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