Goodmans Magnum K (and K2) crossover diagram needed

Here they are, both K and K2 diagrams, may the interwebs never be void of them again!


Goodmans Magnum K Crossover.png Goodmans Magnum K2 Crossover.png

For those who want to remove the Lpads on the Ks, here is an altered diagram:


IMG_0850.png

Thanks to all who have contributed to this thread and a special thanks to @chrisng for his tracing and diagram skills! :)


--------- Original Post Below ----------

Hi,

I am after the crossover diagram for the Goodmans Magnum Ks.

In this post here: https://www.diyaudio.com/community/...sovers-and-potentiometers.112926/post-1971834 user alspe had previously uploaded the crossover diagram to google drive. It was some time ago though and the link is now dead. It’s not listed in the way back machine either.

I was hoping to contact alspe, but it looks like they are no longer a member here and I can’t tag them.

I have attempted to trace it, but these old xovers are a mess and I’m finding it difficult.

I thought it would be similar to the K2 but it’s not. Not only because of the Lpads, but the filters are different too.

Anyone got it or able to help?
 

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Welcome to the forum!

If your intention is to renovate this crossover, you don't really need a crossover diagram.

Remove the metal clamp, read the values of the capacitors and replace them with modern bipolar electrolytic equivalents.

There is no need to replace the two inductors (coils) or that single resistor I can see.

Are the level controls functioning properly?

Don't hesitate to ask if you require further assistance.
 
Hi :) my intention is to rebuild the crossover on a prototype board - exactly the same as it was but replacing all wiring too. I understand the inductors are fine, although I may swap out that smaller one with a thicker gauge. This is for a comparison experiment as I have 2 pairs of these. The Lpads are shot so I will remove. I have the values for the caps, they 10uF and 4uF. The resistor you can see is part of the replacement Lpad on the left.

It was really just for ease and tidiness.
 
I see! :cool:

It looks to be a simple crossover arrangement as shown in the first two attachments.

The 10 uF capacitor and larger coil will low pass filter the woofer and the 4uF capacitor and smaller coil will high pass filter the tweeter.

I believe the nominal impedance of the Magnum K2 is 5 ohm (according to Radio Museum) so I would ditch those 30 ohm level controls and, if required, incorporate 8 ohm L pads as shown in the third attachment. You can buy these from Willys Hifi: https://willys-hifi.com/collections/l-pad-attenuators
 

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Hi Galu, thanks for all your effort. I’m of Scottish decent so also have vampiric tendencies ;-) this heat is killer. Anything over 20c and I’m toast. Sensor in my living room this morning said 27c. >_<

Here is a link to a lot of photos of the crossover. I have labelled each wire: https://ibb.co/album/rKBFgz

In your pics:

1. bottom right: low
2. Left Lpad: high
3. Right Lpad: mid
 
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Thanks, that's a comprehensive suite of photographs.

It's a tangle I should be able to unravel. However, juggling with crossover images at my ripe old age can make my head spin! :spin:

There's folks on this forum who can make light work of this and have the software to draw up schematics. Where are they when you need them? :wave2:
 
If you find yourself able to untangle it, I would thoroughly appreciate it. It might sound daft, but the thing that’s frying my brain is the way they’ve tacked certain wires to the legs of the Lpads and caps. I tried tracing it and produced something I thought looked reasonable, then looked again and realised I was wrong. This lead me to just search the interwebs for it but was really surprised that it’s not on all the usual audio sites. It will be after this.. I’ll post it everywhere :p
 
I started to untie the knot before going to bed, but quickly realised that success would necessitate referring to more than one photograph at the same time.

I'd really need to have the physical object in my hands!

Surely there must be a knowledgeable Magnum K owner out there!
 
No problem, thanks for trying. I have 3 pairs of K2s and I could trace the K2 crossover no problem. Idk what’s wrong with me this time! I’ll have another go and report back.

In the meantime, if there are any sympathetic K owners who would like to pop the back off and help me that’d be grand! :cool:
 
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I have 3 pairs of K2s and I could trace the K2 crossover no problem.

The K2 board has three inductors whereas the K only appears to have 2.

1687033456593.png


I think tracing the K2 crossover would be helpful, as the only difference might be the addition of a third inductor.

The K2 crossover may be structured as shown in the attachment and, possibly, the K simply lacks the tweeter inductor - let's see!

3 way 2nd order XO.png
 
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@Galu from memory, I think what you’ve attached is correct. I am out with the family at the moment so can’t check.

@chrisng you sir are a diamond (y):cheers:

If I were to attach a pic of the K2 crossover which I happen to have on my phone, could I persuade you to run your eye over that too?

Also, made a note of the inductors for this one: bottom inductor was 1.47mH, top right was 0.32mH, hadn’t got round to disconnecting and measuring top left. Cap values are 5uF and 10uF.
 

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