TYPE AA Crossover Build

[sootshe]

Researching a build of the type AA & from what I can gather, when you use the auto former you should have the resistor attached to it. 

 

Attached is the schematic & I can't see any resistor attached to the auto former.

 

Am I correct in that you can substitute a 3636 for the T2A? & should there be a resistor added to this schematic?

 

Attached are some photos of DeanG builds that I want to replicate & I don't see any resistor there either.

[geoff.]

Some use the resistor to attenuate the level to the driver.

 

Others change the cap and autoformer tap values to achieve “similar” results.

 

There was great thread recently about that.

 

If I can find it...

[sootshe]

29 minutes ago, geoff. said:

Some use the resistor to attenuate the level to the driver.

 

Others change the cap and autoformer tap values to achieve “similar” results.

 

There was great thread recently about that.

 

If I can find it...

Yes.... a bit confusing. If I remember rightly they were saying you need the resistor to enable you to adjust the autoformer to it’s different values. Thanks 

[geoff.]

I found this on another site before I could find it on here, which is probably where it originated, lol

[sootshe]

Thanks for that...but my question relates to the adjustment of the autoformer to reduce the mid level. In the ALK designs there is a resistor across the autoformer that I have read is required to enable you to adjust the auto former levels.

It connects to the taps of the auto former. Is this required for this type AA crossover design?

 

See attached pic of ALK uni.....& there's a resistor across the auto former of the ALK Jnr as well. .

[mboxler]

The stock Type AA crossover needs no resistor, as the load on the 13uf high pass capacitor is twice the impedance of the squawker, which is across taps 0 - 4.

 

If you want to keep the 13uf capacitor and use a different output tap number, then you need a specific resistor value across the squawker.

The 16 ohm resistor placement in the schematic looks weird, but it will work for output taps 0 - 3.  I would use a 14.5 ohm resistor, but that wouldn't change things that much.

 

If you want to choose any output tap number, you need to replace the 13uf capacitor with 48uf (I use two 24uf capacitors in parallel), and put a 10 ohm resistor across taps 0 - 5. You could also add a 35uf capacitor parallel to the 13uf capacitor.  The 10 ohm resistor keeps the load somewhat constant regardless of the output taps used.

 

I hope that helps.

 

Mike

[sootshe]

1 hour ago, mboxler said:

The stock Type AA crossover needs no resistor, as the load on the 13uf high pass capacitor is twice the impedance of the squawker, which is across taps 0 - 4.

 

So the stock crossover has no user adjust for the squawker?

 

If you want to keep the 13uf capacitor and use a different output tap number, then you need a specific resistor value across the squawker.

The 16 ohm resistor placement in the schematic looks weird, but it will work for output taps 0 - 3.  I would use a 14.5 ohm resistor, but that wouldn't change things that much.

 

I'd like to keep the 13uf cap rather than going to a 40uf, cap as it keeps the cost down. So are you saying in this scenario, I can't change the squawker level....that it has to be just one particular setting??

Quote

 

If you want to choose any output tap number, you need to replace the 13uf capacitor with 48uf (I use two 24uf capacitors in parallel), and put a 10 ohm resistor across taps 0 - 5. You could also add a 35uf capacitor parallel to the 13uf capacitor.  The 10 ohm resistor keeps the load somewhat constant regardless of the output taps used.

 

So if I change the cap value to 48uf & put the 10ohm resistor in, I can use any tap I want....like in the ALK design??

 

& in all these scenarios can I use the 3636 auto former??

Quote

 

I hope that helps.

 

Mike

 

[Blvdre]

I think the standard approach is to drop the autoformer tap from 4 to 3, and replace the 13 uF with a 6.8. That will reduce the output of the mid driver by 3dB

[mboxler]

So the stock crossover has no user adjust for the squawker?

 

Well, you can adjust it, but the corner frequency of the stock 13uf capacitor will no longer be around 400 hz.  

 

I'd like to keep the 13uf cap rather than going to a 40uf, cap as it keeps the cost down. So are you saying in this scenario, I can't change the squawker level....that it has to be just one particular setting??

 

Same answer as above, unless you add a resistor across the squawker.  If you want the corner frequency of the stock 13uf capacitor to be around 400 hz, the load across

taps 0 - 5 has to be twice the impedance of the squawker, or 29 ohms.  If you move the output to taps 0 - 3, the impedance in quadrupled (58 ohms).  A 14.5 ohm resistor in parallel with the 14.5 ohm squawker gets you to 7.5 ohms.   7.5 times 4 = 29 ohms across taps 0 - 5.

 

So if I change the cap value to 48uf & put the 10ohm resistor in, I can use any tap I want....like in the ALK design??

 

Yes.  

 

& in all these scenarios can I use the 3636 auto former??

 

Yes. 

 

 

 

 

 

 

 

 

 

[sootshe]

30 minutes ago, mboxler said:

So the stock crossover has no user adjust for the squawker?

 

Well, you can adjust it, but the corner frequency of the stock 13uf capacitor will no longer be around 400 hz.  

 

I'd like to keep the 13uf cap rather than going to a 40uf, cap as it keeps the cost down. So are you saying in this scenario, I can't change the squawker level....that it has to be just one particular setting??

 

Same answer as above, unless you add a resistor across the squawker.  If you want the corner frequency of the stock 13uf capacitor to be around 400 hz, the load across

taps 0 - 5 has to be twice the impedance of the squawker, or 29 ohms.  If you move the output to taps 0 - 3, the impedance in quadrupled (58 ohms).  A 14.5 ohm resistor in parallel with the 14.5 ohm squawker gets you to 7.5 ohms.   7.5 times 4 = 29 ohms across taps 0 - 5.

 

So if I change the cap value to 48uf & put the 10ohm resistor in, I can use any tap I want....like in the ALK design??

 

Yes.  

 

& in all these scenarios can I use the 3636 auto former??

 

Yes. 

 

 

 

 

 

 

 

 

 

 

Thanks so much Mike....sorry I'm a bit lame on the heavy technical stuff, but I do have a reasonable grasp of some of these things.

 

I will go with the 48Uf version & the 3636 as that's what I'm familiar with from building & using ALK uni's & AP12-500's.

 

Thanks so much again for clarifying. 

[mboxler]

22 minutes ago, sootshe said:

 

Thanks so much Mike....sorry I'm a bit lame on the heavy technical stuff, but I do have a reasonable grasp of some of these things.

 

I will go with the 48Uf version & the 3636 as that's what I'm familiar with from building & using ALK uni's & AP12-500's.

 

Thanks so much again for clarifying. 

 

What Klipsch model are you putting it in?  Is 400 hz the desired cross?

[sootshe]

11 minutes ago, mboxler said:

 

What Klipsch model are you putting it in?  Is 400 hz the desired cross?

 

I'm building a set of Belles.

Mid horn & driver will be either the Elliptrac 400 or the Fastrac with the A55G driver, so crossover can be say, 500 or 600Hz. 

 

Something like either of the attached.

[sootshe]

Here's a link to the La Scalas I built....I think the original build thread is a bit too old....I couldn't find it, but this will give you an idea.

 

[mboxler]

Nice!

 

Just to be clear, the 48uf capacitor will get you around 400hz to the squawker. For 500 hz, use around 40uf.  For 600hz,  33uf.

 

Mike

 

 

 

 

[sootshe]

15 minutes ago, mboxler said:

Nice!

 

Just to be clear, the 48uf capacitor will get you around 400hz to the squawker. For 500 hz, use around 40uf.  For 600hz,  33uf.

 

Mike

 

 

 

 

 

Oh, I see. Thanks.

 

The Belle will go nicely up to 5 or 600Hz with the Crites woofers, so will choose one of those crossover points.

 

Does the inductor stay the same at 2.5mH?

[mboxler]

11 minutes ago, sootshe said:

 

Oh, I see. Thanks.

 

The Belle will go nicely up to 5 or 600Hz with the Crites woofers, so will choose one of those crossover points.

 

Does the inductor stay the same at 2.5mH?

I would think 2.5mH would be okay.   This is an electrical low-pass filter.  The natural rolloff of the loaded woofer plays into it as well.  

I have Khorns.  Perhaps someone with Belles could jump in.

[sootshe]

1 hour ago, mboxler said:

I would think 2.5mH would be okay.   This is an electrical low-pass filter.  The natural rolloff of the loaded woofer plays into it as well.  

I have Khorns.  Perhaps someone with Belles could jump in.

 

I see the ALK Jnr uses 2.5mH & the 40uf cap. It adds a .2mH for the squawker to stop it running full range & has different value caps & inductors for the tweeter section. 

[mboxler]

Ahh, the fun with passives.  After all the work building them, you always wonder if a component here or there would have made an improvement.

If you want the tweeter attenuated, you need even more changes.

 

If I were to go to all the effort to build a pair of speakers, I'd go active.  Even bi-amped, with a passive between the squawker and the tweeter, will sound great.

You can easily play with the woofer to squawker crossing points and voltages.

 

Six or seven years ago, I had Al build me a bi-amp, extreme slope version of his ES5800.  He removed the tweeter autoformer and added the squawker autoformer.

The picture of the ES5800T on his website is mine.  It sounded great, but I wanted the flexibility to go fully passive as well.  I built a simple low pass/hi pass filter to

put ahead of it,  using a 2.5 mH inductor and two 24uF capacitors.  Now I have four options...single wire, bi-wire, passive bi-amp, active bi-amp. 

 

Mike

 

[sootshe]

Ahhhhh....too many options! They are a work of art though....very nice.

 

I'm on the last leg of my journey & have been through active systems before & am now simplifying things. I now run an integrated amp & just need some big friendly fellas that can loaf along without any fuss & not have a room full of cables. 

 

It's all fun though. 

[sootshe]

Need help from the experts.

 

I've settled on the attached schematic design & can anyone help me to confirm the layout I have come up with from this schematic?

 

I'm not sure about the connection to the 3636 auto former.