Trying to figure out switches


New member
Hi guys,
Trying to wrap my brain around switches. I struggle with being able to conceptualise how they work.
I have a vintage mic called Realistic high ball from the 70s...its a dual impedance mic. Not 100% sure what the intent of the dual impedance, my only geuss is that was common practice for vocal mics to be used in guitar amps back in the day for bands, as well as PAs...might have something to do with it. I believe these can be great as harmonica mics that typically are played through small amps.? Anyway it has its cable built into the mic...can’t be removed. It also appears as if its never been soldered with a TS phono jack. These might have been radio shack back in the 70s, and meant to be modified by the customers. Whats weird on the original box it came in, it shows a pic of a TS phono jack...but the actual cable attached to the mic is 2 core and the copper braided shielding exactly what you see in mic cable....all nice and neatly prepped like it was done in a factory. At first i was thinking thats pretty weird, but again from reading online, the idea was, you select one of the wires ( either black plastic coat or white) as signal, they each have a different impedance...not sure which is which...although just realised i should be able to read on my dmm. All that info may have been included in a manual/ pamphlet in the box, but long gone.

What i want to do is install a switch somehow, thinking a small altoids box, strain relief and add a phone jack so i can plug in a lead to the other side of the box. Then can change impedances. Be some kind fun crazy mic to mess around with in my studio. I got another similar brand different model, when i won the ebay suction...its sounds pretty good, got some character.
I’m struggling to figure out what sort of switch i need. Initially i was thinking a spdt switch, but now my geuss is I need a dpdt switch...would that be correct?...i just no idea with switches. Theres 2 poles, centre pin is ground...flip the swutch one way your connected to the black wire, flip the other way..the white wire...that makes sense. What about the line out that just goes to a interface/preamp and ground i.e tip sleeve? Where would they get soldered on a dpdt switch?..i’m fundamentally confused about what connects to what on switches...any info appreciated, or a good source of info online..i just keep reading stuff by manufacturers..doesn’t help.
Excuse the awful drawing - but take the two conductors from the mic and a spdt switch lets the centre pin connect to one or the other pins - so wire the high and low conductors to the outer two, and then the audio output comes from the centre pin. If you wire it to an XLR, then this connection goes to the XLR pin 2. The cable screen goes to XLR pin 1 and 3. Probably easiest to just put a 3 circuit TRS plug on the mic cable and use a TRS socket and the XLR male chassis connector and switch on a little box. Flipping the switch changes the impedance.


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Much appreciated Rob..that makes sense. Going through my parts bin i have a SPDT switch all wired up from some previous breadboarding thing...i'll breadboard up and have a play around. I have 2 of these mics one is an early version 33-985(earlier) and 33-985A ...the A version sounds like a different much better. now I'm thinking thats because the other one has the higher impedance wire soldered...could be..hoping so. I tested it pretty rough but it worked well enough. i just plugged in a trs and ts cable and held the wires from the mic on the plug,,,,the white wire gives the clearest and loudest signal...really nice sound. i see another on ebay right now...same deal ..list as parts or broken...whats happening is these may have been sold without the phono jack soldered. in the box on ebay right now i can see the phone jack ina compartment in its original box .Sellers are thinking these are broken haha. Making me realise that the early 70s was a much different era...lots more electonics hobbiest than today. gear was designed to be repaired and modded, it was relatively expensive so people did not throw stuff out when they became faulty..they fixed it. These mics were for musicians or audio guys who knew how to solder. You can get them for $25 well worth grabbing one...called radio shack or realistic highball 2 dual impedance mic model 33985 and 33 985A . the earlier 33985 has a decorative screw dead centre of the grill, the newer one does not. i will try swapping wires on my earlier one and report back with my findings...we'll see if it improves...currently it has some bass frequencies missing...built in high pass filter.