MK-U47 - build thread

ioaudio said:

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

Click to expand...

Hi ioaudio

do you have an AutoCAD drawing for this mic?

Opacheco.

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?

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]

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

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?

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

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

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

vineyardgray said:

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

Click to expand...

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

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

Delta Sigma said:

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

Click to expand...

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...

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.

Mk-U47 Wiring Diagram

Mk-U47 Tube Wiring Diagram

bancho said:

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

Click to expand...

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

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

Thanks for your effort putting this up gain Voodoobeat.

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

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.

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?