MK-U47 - build thread

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ioaudio said:
One more quick rendering from my drawing, also showing the innards:
Render3.jpg

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?
 
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!  :eek:

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!  :eek:

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 said:
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...
 
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.
 
bancho said:
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?

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

MK-U47.jpg

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

MK-U47-Kit.jpg


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:
PICT0125.JPG



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

Schematic:

MK-U47_Schematic.GIF


Wiring Plan:
Mk-U47%20Wiring.jpg


we start from the bottom up.

20140619_174523.jpg


Use small pieces of wire to bridge contacts as shown

20140619_200816.jpg


20140619_200853.jpg


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

20140619_204403.jpg


Unscrew this resistor

20140619_201707.jpg


Solder yellow and red wire

20140619_201935.jpg


use shrink tube for isolation

20140619_202039.jpg

20140619_202120.jpg


mount the resistor back in

20140619_202253.jpg


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

20140619_205327.jpg


carefully place the ring and tighten

20140619_205618.jpg


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

20140619_205701.jpg

20140619_205747.jpg

20140619_205852.jpg


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

20140619_210029.jpg

20140619_210450.jpg


Solder together the boards as shown, check for right angle

20140619_210601.jpg

20140619_210645.jpg

20140619_211701.jpg


place and solder all resistors as shown

20140619_211810.jpg

20140619_213220.jpg


place and solder all wires as shown

20140619_214842.jpg

20140619_215555.jpg

20140619_215607.jpg

20140619_215727.jpg

20140619_225335.jpg

20140619_230005.jpg


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

20140619_230135.jpg

20140619_230235.jpg



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

20140619_230758.jpg

20140619_230922.jpg

20140619_231252.jpg

20140619_231353.jpg



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

20140619_231526.jpg

20140619_231638.jpg

20140619_231942.jpg


Place and solder the two green capacitors as shown

20140619_232206.jpg

20140619_232328.jpg

20140619_232409.jpg

20140619_232504.jpg

20140619_232901.jpg

20140619_233231.jpg


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

20140619_234456.jpg

20140619_234535.jpg

20140619_234601.jpg


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

Rubber_Band.jpg

20140620_004633.jpg


unscrew these parts

20140620_004758.jpg


mount the tube sockets, check for orientation!

20140620_004911.jpg

20140620_012445.jpg

20140620_012525.jpg


bend and add a solder lug

20140620_014549.jpg

20140620_014645.jpg

20140620_014724.jpg


attach and solder short black wire

20140620_021444.jpg


Wire up as shown

Tube_wiring.jpg


20140620_022338.jpg

20140620_022358.jpg

20140620_022603.jpg

20140620_023256.jpg

20140620_024343.jpg

20140620_024458.jpg

20140620_024520.jpg




attach the rubber band

20140620_024752.jpg

20140620_025257.jpg


mounting the tube deck

20140620_025410.jpg

20140620_025459.jpg


feed through the wire sleeve

20140620_030422.jpg


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

20140620_031232.jpg

20140620_031514.jpg


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

20140620_031928.jpg


bend and place the solder lugs as shown

20140620_234527.jpg

PICT0072.JPG

PICT0073.JPG

PICT0074.JPG



a small wire bridge, do not solder yet

PICT0076.JPG


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

PICT0077.JPG

PICT0078.JPG

PICT0079.JPG


do not bend the contact after soldering or i will break



you can hold the tiny contact like this for placement

PICT0080.JPG


to have free access, slide the middle lug away

PICT0081.JPG

PICT0082.JPG


the contacts inside the glass envelope must be oriented this way

PICT0083.JPG

PICT0084.JPG

PICT0085.JPG


solder second side only after orientation is correct

PICT0086.JPG


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

PICT0087.JPG

PICT0088.JPG

PICT0089.JPG

PICT0090.JPG

PICT0092.JPG

PICT0093.JPG

PICT0094.JPG


the teflon feed throughs

PICT0095.JPG


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

PICT0096.JPG

PICT0097.JPG

PICT0098.JPG

PICT0099.JPG

PICT0100.JPG


solder the two black wires

PICT0101.JPG


mount the highZ board + spacer as shown

PICT0103.JPG

PICT0104.JPG

PICT0105.JPG

PICT0106.JPG

PICT0107.JPG

PICT0108.JPG


attach the wires to the teflon feed throughs

PICT0111.JPG


attach the rest of the wires

hiZ-wiring.jpg


PICT0113.JPG


place the tubes

PICT0117.JPG


Shown with a Flea capsule holder

PICT0125.JPG

 
:D

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?
 
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