D-87M Build By Andrew Schaapdsa
As
a musician and recording enthusiast, I have sought to achieve better recording
results by using several different microphones.
Until the recent surge of the DIY movement, many of the most highly
sought after microphones were out of reach for a typical consumer. The recent DIY explosion has made owning one
of these incredible microphones a reality.
This is a step-by-step approach to making a clone of a vintage Neumann
u87 microphone. More information on the
microphone can be found here:
http://recordinghacks.com/microphones/Neumann/U-87
Ok,
let’s get started. First, we source our
parts. Keep in mind there are several
different places to get microphone bodies and parts but these are some of the
current favorites. The PCB:
http://www.vintagemicrophonepcbkit.com/DU87.html
The
pcb version I chose is the D-87M. This is the latest version of the PCB at the
time of this writing and fits the SYT5 body.
There is a bill of materials (BOM) listed at the top of this site that
should be current as well. Click on the
“order” menu on the top of the site and make your selections under the “Vintage
Microphone PCB D-U87 Project. Select the
following:
1. D-U87M (Blue) (Switch PCB Not Included)
2.
Switch PCB (Blue) For D-U87M
I
also opted for the StyroFlex Capacitor Kit for U87 Buid (ALL)
The
microphone body:
http://store.studio939.com/product/syt-5-microphone-body-kit
On
the drop down box on the order page for the SYT5, select “body kit – 3
pin”.
This
will include the 3-pin XLR insert for the microphone.
I
used the Cinemag transformer for my build.
http://store.studio939.com/product/ami-microphone-transformers
From the dropdown box select: Cinemag
CM 13113.
When I ordered there was a shockmount
option available from Studio939’s store as well. At the time of this writing, only the U47 mount
was available.
For the capsule I ordered from Eric Heiserman. Eric can be contacted over at
groupdiy.com. His handle is tskguy. Just ask him
for pricing and time table. Capsules are
also readily available from Peluso. P-K87i capsule
The hardest part is waiting for the parts to arrive. Before we begin populating the PCB’s, a few
words of advice. Make sure to use a good
soldering iron. I picked up a temperature-regulated
iron from Radio Shack. It’s not cheap
but it performs a lot better than some of the cheap iron’s I’ve tried in the
past.
Also, invest in a good n0-clean solder. It will make your life a lot better.
Next,
R18 and R19 need to be matched to within 4% of each other. My multimeter
doesn’t have this sensitivity so I followed a method I learned about from Chunger’s build thread called a wheatstone
bridge.
http://www.head-fi.org/t/295983/tutorial-how-to-match-resistors-up-to-0-01-using-a-cheap-dvm
The
black and red leads are extensions from my multimeter
while the yellow goes to the 9v battery negative lead and the green goes to the
positive side. I had to swap about 8-10
resistors out before I found a match which ended up being 2.188k.
Now
I’m ready to start populating the PCB. I
start with the resistors and diodes and work my way up to the capacitors and
larger components.
The
yellow tantalum and blue electrolytic capacitors have polarity so make sure the
“+” and “-“ go in the right holes on the pcb.
The
isolating pin on the main board gets pressed into “GG” on the pcb. Also notice that
the middle leg of the black JFET gets attached to the isolating pin and not the
through hole on the PCB.
The
smaller board gets populated next. Note
that only one leg of R7 gets placed in the through hole of the PCB. The other end gets attached to the isolating
pin that goes in the hole labeled “g”. Also
notice that the cap next to the isolating pin has a leg attached to the
isolating pin as well and not the through hole.
I
wait to place R4 and R5 on the PCB until last.
These are sensitive to fingerprints and getting bodily oils can change
their value. I use gloves from this
point on.
Next
it’s time to connect the two pcb’s
to each other. They are connected with 4
wires. I use 26 gauge silver teflon wire. This wire is readily available in a variety
of colors from eBay. The thin gauge keeps micro-phonics to a minimum.
The
boards are connected as follows:
“a” à “aa”
“b” à “bb”
“c” à “cc”
isolation
pin à isolation pin
I
solder the wires from the back of each pcb to keep things looking clean. Be sure to keep some slack in the wire if you
need to take the boards apart in the future for trouble-shooting.
And
the connected wires to connect the switch pcb. I connected the wire to the isolation pins at
the base and cut off the excess pin length.
Next
I populate the switch pcb with the switches. Two of the switches are two- position while
the third is three-position for the polar patterns. Make sure this goes in the “PAT” slot. I solder the middle pin on each switch first
so I can make any final alignment adjustments to the switches before soldering
the rest of the pins.
Wire
up the switch PCB next. Again, leave a
little extra length in the wires to allow for possible troubleshooting in the
future.
“OMN”
à PAT 1
“CRD” à
PAT 2
“8” à
PAT 3
PAD
à PAD holes 1 & 2
LC
à
LC holes 3 & 2
Next
I wire up the transformer. I have the Cinemag CM 13113:
red
à p+
brown
à p-
yellow
à s+
orange à
s-
I
feed the yellow and orange wires through the opening in the pcb
before working the transformer into place.
It’s a snug fit. The red and
brown wires I feed through the hole next to the solder points for the
transformer so I can solder them all from the back side.
Then
I take zip ties and secure the transformer to the pcb
so it doesn’t fall out when that cheap microphone stand you haven’t bothered to
upgrade collapses and your u87 clone falls to the floor.
Now
it’s time to connect the switch pcb to the frame. Take the washers and spacers and fasten
them.
Next
I wire up the 3-pin xlr insert.
1
à 1
2
à 2
3
à 3
I
use a little heat shrink on the connections as well to tidy things up.
Alright! It’s time to pump a little 48v phantom power
into this baby to see what we have cookin! Connect your mic preamp of choice, preferably
one that works, and turn on the phantom power.
We’re going to calibrate the drain on the microphone to 11.5 volts. Take your multimeter
and put the red probe on r6. This is right next to the FET. Take your black probe and put it on the
ground hole. Take a small flat-head
screw driver and tweak the pot until you measure 11.5 volts.
Now
for the capsule installation. Hang in
there, we’re getting close.
The
spacing isn’t quite right for the capsule on this mount so I also had to drill
some extra holes.
In
my effort to extend one of the holes because it wasn’t quite where it needed to
be, I exerted a little to much power and the drill
slipped out the side.
The
screw still held well so it wasn’t too bad of a mistake.
My
capsule is tskguy’s capsule. The wiring to the capsule is as follows:
“RBK”
à “Rear Backplate”
“RD”
à “Rear Diaphragm”
“FBK”
à “Front Backplate”
“FD”
à “Front Diaphragm”
There
is no front to the capsule as both sides are identical, so just choose the side
that’s the most beautiful. The capsule
comes with (2) wires and screws. Use the
screws to fasten the wires to the backplate.
Next
I’m ready to fasten the PCB’s to the frame of the microphone body. For whatever reason I didn’t have screws that
came with the body. I found these at
Home Depot and they worked well. You’ll
need (8) total screws.
Oh,
did I mention I built two? Gotta have a pair of these babies.
If
I had to do it again I’d probably make the switch wiring a bit shorter. I probably made them a bit longer than
necessary but I doubt if these will effect the sound of the mic. The capsule wires are probably more critical
here and they aren’t too long.
They
both worked from the start so I figure with my level of expertise I may have
gotten lucky. The sound? Well, they sound un-hyped. The are very smooth
on the top end with a nice, well balanced low end. I’m very happy with them. Best microphones I own without a doubt.