Anyone know what these are

I picked these up at an estate sale recently, and am wondering if anyone can explain their purpose. They weren’t hooked up when I bought them, but the estate included a high-end Linn / Legacy / Conrad Johnson system, so I thought they might be interesting.

Circuit looks like a capacitor, a few resistors, and a wound spool of wire, all on a basic switch. There are two of them. Guessing maybe some sort of filter that goes between an amp and speakers? Thanks.
 Yes there are electrolytic caps. Low pass passive crossover in my estimation.
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Thanks @grannyring I see it now.

Ok, with more coffee and less fuzzy vision than I had yesterday (comes and goes) I can see most of the circuit.

It seems that all parts are in parallel. However, 2 of the resistors are switching in or out, changing the parallel resistance from 5 Ohms (10 Ohms / 2) to 2.5 Ohms (10 Ohms / 4). Lowering the parallel resistance reduces the effectiveness (depth) of the notch filter.

This makes it most likely a shunt-type notch filter. Impossible to tell what exactly it’s doing without full analysis of the driver as well as knowing the coil and cap values.

It could have been an experiment to remove ringing in a driver, with the switch allowing for different levels of suppression.

In any event, this is clearly a DIY hobbyist’s experiment which would only be useful for his particular speaker/experiment. No use at all for anyone else. If I purchased this (I wouldn’t) it would be for experimental parts only.

This could all be confirmed with an Ohm meter. If you want to understand more about this type of circuit (or whatever it ends up being) come over to the DIYAudio / multi-way forum where we can post pictures and discuss with a number of speaker builders. :)


Thanks for all the responses.  I really just bought these on a whim.  They were only $5, so I figured worst case, I could keep them around for parts.

I'll try to dig up more details on the exact parts used in these.
Not exactly sure, but they look a lot like the low pass filters from Legacy Audio used for some of their late 80s early 90s loudspeakers. Classic, Focus......etc. Bill from Legacy would just give them to you if you asked, if you had a problem with too much bass in your room caused by standing waves. This is a few years before they came out with the Steradian.