VAMISOUND VM55 Instruction Manual

VM55
BUILDING
INSTRUCTIONS

Dear DIY friend,
first of all thank you for your support and choice of the VAMISOUND product.
We wish you a happy DIY and the joy of a new microphone in your arsenal!!
Jan and Milan
VM55 BUILDING INSTRUCTIONS

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Document info
Document name
VM55 building instructions
Document revision
1.0
PCB revision
1.1
Date
October 2023
Project difficulty
Complexity of soldering
Risk of electrick shock
Changes and notes
Before you start building your new microphone please carefully read this
building instructions.
Attention: VM55 is a medium-heavy project. The circuit is made up of only
a few components. However, it should be borne in mind that certain manual
skills will be required or the successful completion of the mic construction.
Good soldering experience and soldering stations with fine soldering tip are
recommended. If you do not have this, please delegate the construction
to a more experienced technician with proper equipment. We are not
responsible for malfunctioning construction or injuries associated with
improper assembly of our kits.
VM55 BUILDING INSTRUCTIONS

VAMISOUND VM55 full kit includes a microphone body consisting of several parts, printed circuit board,
transformer, capsule, capacitors, resistors and one teflon pin. You also received a paper microphone box with
foam filling. Under the top foam filler you will find the capsule and transformer.

As mentioned the VM-14 transformer and capsule can be found in the second layer under the microphone. Just
remove the top layers of foam.
Now that you know what to find where we can get to building.
Start fitting the pcb with resistors. On the right notice that the R1 resistor is placed in the air and one of its
legs is on the teflon pin.

Continue by fitting the output capacitor (the yellow one), the zener diode (ZD) and capacitor C1 one leg of
which is also on the teflon pin.
In next sequence install electrolytic capacitor C3. Also pair of caps C5 and C6. Place fet transistor Q1 in place
and solder its pin to the teflon pin.
Install output transformer VM14. Attach the transformer using the two cutted legs from the resistors to the
board. Make sure the transformer does not wobble on the board.
The two primary cables on the VM14 transformer are blue. Secondary cables are red. Insert the primary cables
into the pads on the board that are marked P+ and P-. Insert the secondary cables into the S+ and S- pads on
the board.

Notice the two white dots (or black on some pieces) on the transformer near the bottom edge of the circuit
board. They mark the beginning of the transformer windings and will help you solder the wires into the correct
holes.
Solder the blue primary wire, which is marked with a dot, to the pad on the board that is marked as P+. Solder
the red wire of the secondary winding, which is marked with a dot, to the pad that is marked as S-.
Be sure to check the phase against other commercial microphone after finishing the microphone and swap the
wires if necessary. So leave a margin in the cable length in case you need to swap the S+ and S- cable. We're
only human and although we have carefully measured all transformers the human factor can play a role here.
Wire secondary cable marked withs dot to
„S-“ pad on the pcb in same way as you
can see on this photo.
Wire primary cable marked withs dot to
„P+“ pad on the pcb in same way as you
can see on this photo.

Take the microphone body and the small screwdriver included in the kit and unscrew the bottom of the
microphone with the XLR insert.
ATTENTION!!! Screw the three screws in the bottom of the microphone inwards (clockwise - tighten)!!!!! Do not
try to unscrew them outwards through the microphone tube.

Unscrew the XLR insert out of the bottom part of the microphone.
In the next step solder the XLR connector insert to the board. Carefully align the connector to the board so that
the pins are directly on the rectangular soldering pads on the board. Be especially careful not to overheat the
connector pins and melt the plastic part.
Connect the connectors ground lug using the resistor foot to the pad marked number 1 on the board. This is
used to connect the metal chassis of the microphone body to the 0V on the board and PIN 1 of the XLR
connector.

Unscrew the front metal ring of the microphone and remove both grilles and the inner plastic separation ring.

Take the capsule and the insulating tape (strip) that was included in the parts. Carefully peel off the yellow
covering film from the tape and stick it without much pulling around the whole capsule. Trim the overhanging
piece of tape.
Then insert the taped capsule into the microphone head as shown. It's just to test that capsule sitting there.
Don't put it all the way in yet.

Now take the two included teflon insulated wires and solder them carefully to the capsule. The red wire to the
central terminal and the white wire to the side terminal as in the picture. Make sure both wires measure
exactly 60mm including the exposed soldering section. No less.
Take the microphone head and insert the rear grille, then the grey spacer ring with the circular cutout as you
see in the picture. Finally insert the capsule, put the front grille on top of it and then screw everything together.

Now you can clearly see where the front of the microphone is located and where the capsule diaphragm goes.

Now it's time to solder the cables leading from the capsule to the circuit. Before that, however, do not forget to
shorten the Teflon pin so that its metal part is 3mm long.

Solder the red cable directly to the teflon pin from the bottom side of the circuit board. The white one to the
pad marked BCK on the circuit board. Notice that the microphone head is now with the diaphragm facing
downwards.
Carefully clean the capsule connections with isopropyl alcohol.

At this stage you can carefully connect the microphone to the preamp and measure the voltage on the XLR pins
and on the different points of the circuit (on zener diode, on drain and source of FET).
Slide the microphone tube onto the microphone head part. Do not screw anything on. Note that the XLR insert
sticks out because the cables from the capsule have enough slack (hence their min. 60mm length).

Now screw the bottom of the microphone and the XLR insert together.

Carefully unscrew (= counterclockwise) the three hexagonal screws from the bottom out into the microphone
tube. Again, be careful not to unscrew these screws all the way out of the tube. Screw them out only about to
the edge of the microphone tube so that they do not protrude.
Now comes probably the most tricky part of the whole construction. Be patient and do it very carefully and
slowly. You have to fit the circuit board into the two rails in the head section of the microphone and then fit the
whole microphone tube.

Before you close the microphone completely make sure that the circuit board fits snugly into the two cutouts
(rails) in the head section of mic and that the microphone cables are not pinched anywhere.
Now that the microphone is completely closed, you can unscrew (= counterclockwise) the last three hexagonal
screws. Again, make sure they don't come out through the microphone tube.

Congratulations. Your new microphone is now ready for sound tests.