New u87 Body

[joulupukki]

I received mine last week too. The black sticker stripes are bound to fall off and the cardioid sticker is crooked just like what you're showing here. If anyone ever designs a PCB for some actual switches that'd work in this body, I'd be interested. I built the Fuchs U87A circuit in this mic and it's sounding great, but it'd be nice to have the switches accessible instead of needing to open it up and use jumpers.

Actually, the measurements on Dany’s SW67 PCB look like they may fit.



What kind of switches would one use? Just standard mini toggle switches?

 

[AndyM]

What kind of switches would one use? Just standard mini toggle switches?

I will try slide switches, maybe capped with actuators or simply hidden behind the faux switches.
(Still waiting for Dany's PCBs)

 

[thomasdf]

Hi all

So I started with schematics down here, to kicad, to this gerber
Untested yet but the boards turned out great from JLCPCB
Only mistake is the mounting holes are approx 1mm too close to each other, so I have to very lightly bend the mounting rails for the holes to line up. The body can still be assembled without problem.

I offer no guarantee, no help with the build etc. It is pretty much 1:1 the orig schematic and there are plenty of info around.

In case you don't want to use them L1 and L2 must be replaced by a straight wire, and C21 and C22 omitted.

Rename the TXT to ZIP to get the gerber

High Z teflon pins are meant to be Mouser no 534-11218
There are different options for C7, orig is tant but some like to mount bigger caps.

I am slowly starting to build a cardiod only pair of these, I'll report back... If someone else goes first, let me/us know I'll use a pair of UTM transformers and I'd like to use a pair of Arienne's cardiod K87 capsules when available

Cheers

Just wanted to let yall know that I've tested the PCB today and while a sine wave generator feeding the input of the circuit give a sine on the output, and I can set the bias and etc ... hooking a capsule gives a loud (mains?) hum, and no sound so until further investigation, the PCB is still not validated
In touch

 

[jp8]

Just wanted to let yall know that I've tested the PCB today and while a sine wave generator feeding the input of the circuit give a sine on the output, and I can set the bias and etc ... hooking a capsule gives a loud (mains?) hum, and no sound so until further investigation, the PCB is still not validated
In touch

You'll need a Faraday cage to prevent the hum. High impedance input picks up mains hum. E.g. make a cage from chicken wire if it has to be transparant for audio. Or a cookie jar with XLR feedthroughs if it can be a closed cage. Connect the Faraday cage to the PCBA ground or mic body.

Jan

 

[thomasdf]

Thanks, I know about faraday cages and the role of the headbasket grounding in a mic design. The thing is I get only hum, no sound whatsoever behind it .. so I am suspecting a hookup problem somewhere, I'll do some further investigation and report back !