Adding a Pad to a DIY 251

[BrickByBrick]

Hey y’all. Just finished up a 251 build. Capsule is a Beesneez CK12, circuit is a micparts V251 and transformer is an AMI T14.

I bought the body from Studio939 and there’s no cutout on the body for a pad, neither is there a pcb for it.

From my basic electronics knowledge is looks like the pad is a capacitor that is tied to ground right after the capsule. I’m curious if it would be possible to add the pad switch on the power supply and use one of the unused pins on the 7 pin xlr cable. Will this work? Is there a better idea?

 

[kingkorg]

Hey y’all. Just finished up a 251 build. Capsule is a Beesneez CK12, circuit is a micparts V251 and transformer is an AMI T14.

I bought the body from Studio939 and there’s no cutout on the body for a pad, neither is there a pcb for it.

From my basic electronics knowledge is looks like the pad is a capacitor that is tied to ground right after the capsule. I’m curious if it would be possible to add the pad switch on the power supply and use one of the unused pins on the 7 pin xlr cable. Will this work? Is there a better idea?

Maybe use heater voltage via switch from psu to activate a relay using that extra wire. - More complicated

Use a small switch within a body to engage that parallel cap, how often do you need a pad? You won't be opening the body all the time. - Simple

The cap in parallel with capsule although traditional solution for many mics causes some negative effects, possibly even higher distortion. Ideally i would add extra resistor in capsule polarization voltage divider to drop the voltage supplied to the capsule and create pad.

By doing this you also avoid tinkering with the most sensitive Hi Z area of the mic.

 

[Delta Sigma]

If I remember right, Digi-key has a good selection of reed relays which are preferable when switching hi-z components. If you order a few, you're ready for future projects where you want a cardioid only switch.

kingkorg's voltage divider solution sounds much better though.

 

[Gus]

look for the VM1 schematic