MK-U47 - build thread

[opacheco]

One more quick rendering from my drawing, also showing the innards:

Hi ioaudio

do you have an AutoCAD drawing for this mic?

Opacheco.

 

[59flame]

I need the 3 screws for the head basket and the one screw that mounts the body to the bottom bell on the mku47.  Got lost somewhere in the shuffle/  anyone know what type of head and what size these  screws are? Max you out there?

 

[Citrus Hill]

Hey Max,
I make a manual/build book for each project i build, and i was wondering if you could email me a BOM with the manufacturer/part number of the components you sent in your kits.  I purchased two kits from the original batch and i'm just now getting around to building them.  (Long story)  If it's not possible, i completely understand.  I've already pulled the values from the schematic, i'm just looking for the details on the specific components you chose for the build.  If anyone needs to repair the mics in the future, i want them to have the correct info to purchase the right replacement parts.
Thanks again for the nice kit!  I'm really looking forward to finally building these.
Thanks,
Citrus Hill

[email protected]

 

[gbruler]

Hey guys,
Is it normal that the mic's PSU drops in voltage after around half an hour?
Lately we've heard some distortion out of the mic and we've noticed that when we bias the voltage to 105 it drops to 102-103. So now we've biased it to 107, and after 30 minutes it drops down to 105ish.
Thanks

 

[Delta Sigma]

Are you biasing the mic after it's warmed up? Warm it up for an hour or two and set for 105 see if it drifts. 2V isn't much, I doubt it's causing your distortion. Can you describe the distortion? Is it always there or on transients?

Was it you that had trouble with a muffled sounding Beesneez capsule? Did you get that resolved?

 

[ChrioN]

Ioaudio, if you see this, please send a PM or make yourself contactable 

 

[kosi]

I'm selling a complete MKU47, if anyone should have interest !
https://groupdiy.com/index.php?topic=65455.0
already sold

 

[vineyardgray]

I'm on vacation for March Break and thought I'd spend some free time finally getting this MK-U47 up and running.  Of course, now I see all the build pictures are missing! 

I don't suppose anyone made a file with Max's build post?

Regards,

Matt

 

[bancho]

I'm on vacation for March Break and thought I'd spend some free time finally getting this MK-U47 up and running.  Of course, now I see all the build pictures are missing! 

I don't suppose anyone made a file with Max's build post?

Regards,

Matt

On the same boat here... let me know if you have any luck  :-\

 

[Delta Sigma]

Strange, both Dany & Max's publicly shared dropbox files are suddenly dead links. I wonder if Dropbox changed their public link format.

 

[rainton]

Strange, both Dany & Max's publicly shared dropbox files are suddenly dead links. I wonder if Dropbox changed their public link format.

Yes they did.

There's no public folder anymore.

The files are still there but Max and Dany will have to share them manually once more...

 

[vineyardgray]

Some of the images are still interspersed throughout the thread - i will post them here for easy reference - one at a time so they stay on GDIY's servers.

Attached is the MK-U47 schematic.

 

[vineyardgray]

Mk-U47 Wiring Diagram

 

[vineyardgray]

Mk-U47 Tube Wiring Diagram

 

[Voodoobeat]

On the same boat here... let me know if you have any luck  :-\

same here, wanted to start building and all the pictures are gone  :-\
has anybody by chance saved them?

 

[Voodoobeat]

i wrote Max and he kindly sent me the pictures. So here you go

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:

-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------
BUILD:

Schematic:

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

 

[DjaiTeam]

Thanks for your effort putting this up gain Voodoobeat.

 

[Voodoobeat]

i need a replacement for the 10nF Styroflex. i have this Koweg 10nF 160v cap, will it be good?

 

[vineyardgray]

Thanks Voodoobeat for re-posting the pictures!  Much appreciated. 

I'd assume that your capacitor will be fine as they are both 10nf, but I couldn't say for sure about the voltage.

 

[Phrazemaster]

A  lot of the pictures just show up with little question marks - the recent reposted ones.

What happened to the original posts? I thought they would remain here at GDIY?