Re: MK-U47 - build thread
« Reply #680 on: March 12, 2019, 06:07:32 AM »
I've taken liberty to resurrect the build information.
If this should disrupt anyones copyright please let me know and I will delete this post.

MK-U47 Tube Microphone Kit featuring:

Costum Headbasket made by Flea with Pattern Switch
Brass made body tube and bottom bell, bead-blasted and nickel-plated
Stainless internal structure
Bv.08 Transformer with 8 seperate sections from my own production
6028 single supply circuit with all parts including

including (back left to right):

body tube
bottom bell with power resistor mounted + internal structure
Headbasket pattern switch
Transformer + resistor board
High-Z board with screws, teflon isolators, shims for variable capsule mount height
solder lugs and subminiature reed-contact
Black rubber band for tube shock-mount
Tube deck + tube sockets, screws,

(front left to right):
Wiring, yellow wire sleeve, shrink tube
Binder connector for mic and cable
Bv.08 Transformer
PIO and styroflex capacitors, resistors

to complete the microphone, you'll need:
a capsule + holder
a single supply 105v PSU
a microphone cable (cable connector to mic included)

Completed kit with Flea capsule holder:



Wiring Plan:

we start from the bottom up.

Use small pieces of wire to bridge contacts as shown

wire the connector according to the original schematics
Solder a lug to the end of one black wire
1: White
2: Blue
3+4+6: Black x 2
5: Red

Unscrew this resistor

Solder yellow and red wire

use shrink tube for isolation

mount the resistor back in

unscrew the ring of the connector and place it
in the bottom bell, aligning the keyway/slot

carefully place the ring and tighten

unscrew the nut and place the solder luck and re-tighten

paint the transformer/resistor board (not shown: use a file after breaking)

Solder together the boards as shown, check for right angle

place and solder all resistors as shown

place and solder all wires as shown

Be careful handling the transformer
place and solder the transformer as shown

Before soldering the big capacitors it's time to mount the whole thing into the mic

insert the screws and attach the nuts, do not overtighten!

Place and solder the two green capacitors as shown

The yellow sleeve will be cut like this to fir through the hole

Carefully cut and drill (pierce) the rubber band as according to this measurements

unscrew these parts

mount the tube sockets, check for orientation!

bend and add a solder lug

attach and solder short black wire

Wire up as shown

attach the rubber band

mounting the tube deck

feed through the wire sleeve

attach the yellow, red and blue wire to the corresponding pins

Be careful with overheating when building the highZ portion of the circuit

bend and place the solder lugs as shown

a small wire bridge, do not solder yet

the reed contact must be oriented and placed carefully BE VERY CAREFUL HERE

do not bend the contact after soldering or i will break

you can hold the tiny contact like this for placement

to have free access, slide the middle lug away

the contacts inside the glass envelope must be oriented this way

solder second side only after orientation is correct

more wire bridges and placing parts, place everything before soldering, solder quickly

the teflon feed throughs

push the carefully to place, grabbing them by the top teflon part

solder the two black wires

mount the highZ board + spacer as shown

attach the wires to the teflon feed throughs

attach the rest of the wires

place the tubes

Shown with a Flea capsule holder


Re: MK-U47 - build thread New
« Reply #681 on: July 16, 2019, 09:55:50 AM »
In case anyone is interested, I have a fully assembled iOAudio MK-U47 for sale:
« Last Edit: July 22, 2019, 09:25:34 AM by vinylwall »
Jimi Ray


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