ALK B Crossover Question

[geoff.]

I would like use to the PRV D2200Ph in lieu of the K-55 on this crossover. It has been tested by another forum member to mimic the K-55 but it has a 2” throat so I can use the ZXPC 18 x 10” horn on it.

 

The D2200Ph also runs solidly up to 9000 Hz, so...

 

Can I change the circled inductor value to .30 mH to limit the squawker to 6000 Hz without messing anything else up?

 

 

[mboxler]

Looks to me that the 5.6 ohm resistor across the K55 equates to a 4 ohm load on the .15mh/4.3uh components.  That's already around 6000hz.  Your 8 ohm driver appears to be around 10 ohms at 6000hz.  If you put a 6.7 ohm resistor across the PRV D2200Ph you'll end up with a 4 ohm load, and can keep the other component values as is.

 

The .3mh/2.2uh values on the ALK Universal are used for an 8 ohm load and are placed ahead of the autoformer to get the 6000hz low pass.

 

Depending on your speaker, you may need to tweak the low pass to the woofer and high pass to the D2200Ph.

[JohnA]

That is a question best asked of Al.  Will he respond? 

[geoff.]

Thank you all for the replies.

 

There were already a handful of suggested changes I was going to implement. 

 

I will probably just use an ALK A crossover instead.

 

I liked the idea of the adjustable tweeter attenuation, even though I have not yet found a need to knock the tweeter down in any speaker I have modded.

 

But it was the steeper woofer filter that made me want to try this over the ALK A.

 

It will likely wind up crossing between 400 and 500 Hz anyway with the big ZXPC horn.

 

 

[DeanG Crossovers]

Build it once build it right.

 

 

[geoff.]

Dean, how do you tin the ends of those Litz inductors?

 

 

[DeanG Crossovers]

Like this:

 

 

[geoff.]

Thanks, again, Dean!

[DeanG Crossovers]

Sure. Make sure you wear safety glasses while doing it. 

[mboxler]

2 hours ago, geoff. said:

...how do you tin the ends of those Litz inductors?

 

For me, dipping the end of the litz wire into solder flux before tinning really speeds up the process.

[Curious_George]

On 6/17/2022 at 2:11 PM, geoff. said:

Thank you all for the replies.

 

There were already a handful of suggested changes I was going to implement. 

 

I will probably just use an ALK A crossover instead.

 

I liked the idea of the adjustable tweeter attenuation, even though I have not yet found a need to knock the tweeter down in any speaker I have modded.

 

But it was the steeper woofer filter that made me want to try this over the ALK A.

 

It will likely wind up crossing between 400 and 500 Hz anyway with the big ZXPC horn.

 

 

I’m not too familiar with the ALK B network, but the universal A seems to be the best choice for an economy version of a good crossover. It can be whatever you want it to be with your favorite parts. It will need a separate attenuation network, but that is easy if you need it, which you have said you have not.

 

Also, if you want a steeper woofer slope, don’t be afraid to try a 40uF to 80uF across the woofer and experiment. 

[Curious_George]

13 hours ago, Crankysoldermeister said:

Build it once build it right.

 

 

There are two ways to do things - right and twice.

[Blvdre]

12 hours ago, Crankysoldermeister said:

Sure. Make sure you wear safety glasses while doing it. 

Years ago, when I worked on the bench repairing electronics, I was soldering together two wires that didn't have a good mechanical connection (my fault) and one of the wires popped off and splashed flux in my eye (wasn't wearing my glasses). Luckily, I had contact lenses in. Ruined the lens, but saved my eye. Always wear your safety glasses when soldering.

[consistent]

Hi

I thought Al revised this network for the woofer value of 5 ohm not 4 ohm (mH: 2.4 instead of 1.3 and uF: 30+1 instead of 39+1 with 62 instead of 39) and respective change for the mid was placing a 10 ohm resistor across the autoformer instead of 5.6 ohm and a coil 2.0 mH instead of 1.3mH

[geoff.]

@consistent, yes, and thank you for chiming in.

 

That was the handful of suggested changes I was going to implement.

 

It was likely you that shared them the first time I made a note of them. Did I give you a “heart” on your original post, lol?

 

I take screen shots as things have a tendency of disappearing on the internet, Mandela effect, you know...

 

 

 

[consistent]

oh...it obviously dropped the crossover to around 513hz, both revisions appear to have used a Cheyby 2nd order instead of Butterworth

[DeanG Crossovers]

Burn that schematic. 

[Curious_George]

On 6/20/2022 at 7:44 PM, Crankysoldermeister said:

Burn that schematic. 

No doubt…

[geoff.]

...still, I wonder, lol

 

Ya, ALK A with a cap across the woofer.

[Curious_George]

10 hours ago, geoff. said:

...still, I wonder, lol

 

Ya, ALK A with a cap across the woofer.

Geoff, do you have REW to make measurements?