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Help With Crossover Design Identification

engstrom

engstrom

New Member
I'm a complete novice to the audio world and I'm hoping someone more experienced can help me understand the design of this crossover. It's from an Allen Organ HC-15 3-way speaker (15" woofer, 4" mid-range, & 1" tweeter).

I looked up a few 3-way crossover designs and the closest matches were 2nd order 3-way crossovers with reverse polarity mid-range. And as far as the tweeter and mid-range go, the diagrams I found online seem to line up perfectly with the crossover I have.

However, the low end of things has a few more components than the diagrams I found online. The designs I found all just have a single capacitor and inductor on the low end woofer but the crossover I have also has a couple more capacitors, a second inductor, and a 12-ohm power resistor.

I took a stab at drawing a diagram of my crossover. Again, I have no idea what I'm doing so apologies for the mistakes I'm sure it contains. If you can help me understand the purpose of these additional components and what that means in terms of the type of crossover design this is, I would greatly appreciate it. Thanks!

IMG_E7341.JPG IMG_E7342.JPG IMG_E7343.JPG
 
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Research Zobel network as it appears a Zobel has also been employed in the low pass filter.

Additionally, the pair of large value(680uf) caps are likely there as a high pass filter to protect the woofer from over excursion when playing the lowest pedal registers on the organ.
 
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the low pass one is quite strange, C4/C5 and C7 would form a high pass filter, L4 and C6 form a low pass, and the R just drops the signal down some.
 
gadget73 said:
the low pass one is quite strange, C4/C5 and C7 would form a high pass filter, L4 and C6 form a low pass, and the R just drops the signal down some.
Click to expand...

me thinks it's drawn wrong. look at the back side. +in goes straight to an inductor. that would be the lowpass.
 
might be right on that, I have a hard time tracing things from pictures. Usually need to hold it in my hands so I can flip it over 58 times to follow stuff.
 
bowtie427ss said:
Research Zobel network as it appears a Zobel has also been employed in the low pass filter.

Additionally, the pair of large value(680uf) caps are likely there as a high pass filter to protect the woofer from over excursion when playing the lowest pedal registers on the organ.
Click to expand...

That is very helpful. Thank you very much!

I'm a little confused by the high pass filter on the low end though. Would the idea be to block very low frequencies (maybe below 20hz or something)?
 
Infinity, and probably others, have used large series caps in a woofer circuit to extend the low end by causing a resonant circuit with the woofer. If C7 is a very large value, and I notice a couple of 680uF and appear to be in parallel, then this may be a low end extension circuit which would make sense in and organ system. The Infinity RS III has a 600uF in series with the woofer for this reason.

http://www.infinity-classics.de/technik/manuals/RS_III_technical_sheet.pdf
 
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