Joemeek JM47 User Manual

What is a JM47?

Just before World War 2, a small company in Germany de­veloped a technology for the manufacture of very high qual­ity microphones using the principle that a charged capacitor
changes the voltage across its plates when one of the plates
is moved with respect to the other. The German company
developed a shape of capacitor and the gold membrane that
forms the ‘moving’ plate.

This development reached a high level of sophistication. So
much so, that to this day the nest studio microphones follow
the design of the original Neumann Company. Fortunately
for some other manufacturers in the world, the technology of
the original company in East Germany became a part of the
technology sharing policy of the Communist world, and it was
taken up by some specialist manufacturers in the Far East.

Today, ne microphones are still manufactured by the original
company, and by the sharing of technology, we now have a
number of products from China that are actually legitimate
high quality microphones in their own right. For many years,
Joemeek has been making occasional “one off”’ capacitor mi­crophones with varying degrees of success.

Attempts to manufacture the microphone economically while
retaining the superior performance were not completely suc­cessful until Joemeek investigated some of the Far East prod­ucts. The JM47 is the result of co-operation with a Far East
manufacturer and a sustained program of testing in the new
Joemeek studio, comparing the production microphone with
the best hand built originals, and with some competing prod­ucts. The JM47 contains all the classic design elements and
the sound of the nest microphones in the world.

Origins and Manufacture

The Joemeek JM47 is manufactured under the supervision of
PMI Audio Group. All mics are tested for quality control.
The JM47 meets all requirements for electronic equipment in
all countries of export.

PMI Audio Group

USA: 23775 Madison Street

Torrance, California 90505

toll free: 877-563-6335 fax: [phone]

email: [e-mail]

UK: P.O. Box 358

Torquay, Devon TQ2 5XS

tel: [phone]

email: [e-mail]

Joemeek® is a registered trademark of PMI Audio Group.

©2003 PMI Audio Group. All rights reserved.

JM47

Ultimate professional quality

Large diameter true

capacitor gold capsule

Ultra low-noise FET Preamplier

Transformer output

48 volt phantom powered

Elastic shock mount

(sold separately)

Joemeek Users Guide

JM47 Description

Operation

Using the JM47

The JM47 is a very high quality true capacitor microphone with
FET impedance converter and transformer output. (NOTE, this
is NOT an electret microphone).
The capacitor element is manufactured to the classic ‘centre
electrode’ design which provides smooth extended frequency
response without low frequency boominess. Quality is further
enhanced by using dynamic feedback actually at the capacitor
element. This original technique eliminates distortions which
can occur when using this type of microphone for high volume
levels.
The capacitor membrane is microne ‘mylar’ with gold sputter­ing, voltage polarised by phantom power.
The microphone body is made of brass with double screening
of the transformer. Connection is via screened balanced audio
cable with 3 pin XLR connectors.

Care of Your JM47

Although the ‘mylar’ membrane on the capacitor is more robust
than the gold foil used by the German originals of the 1930s, it
is still extremely ne and liable to damage if mishandled. There
are two safety factors that MUST be remembered when han­dling these microphones:

1) Keep the microphone dry.

2) Avoid wind or air blasts directly onto the capsule.
All electronic equipment should be kept dry, but it is even more
important to avoid any damp conditions when using high quality
capacitor microphones.
Damp can cause partial short circuits in the polarising voltage,
this will cause crackling noises and low output.
The most important instruction for capacitor microphones is
NEVER blow at the capsule. Damage caused by blast of air
on the capsule are often permanent and require the complete
replacement of the capacitor element (capsule).
Never use the microphone in the open air without substantial
wind protection.

Warranty

The JM47 is warranted from defects for a period of 1 year, parts
and labor. Register for your warranty at www.joemeek.com.

The JM47 is capable of handling very high sound volume levels
so it can be used safely close to musical instrument ampliers.
If the amplier sound is very loud, this may overload the micro­phone amplier. A 10dB pad switch on the microphone elimi­nates this problem. It is also a very low noise microphone and
suitable for voice recording to the highest quality.
For voice recording, avoid singing directly into the capsule un­less an efcient pop shield is used. Occasionally when close
microphone techniques are used in the studio, an excess of low
frequencies occur. The microphone is tted with a high pass
lter to minimise this effect.

Problems

Should the microphone accidentally become damp and fail to
operate properly (start crackling, or go very quiet) then place
it in a warm and very dry environment for 24 hours. The ideal
environment is an airing cupboard.
The JM47 is extremely resistant to physical damage, but if the
microphone fails to work after being dropped, it should be re­turned in adequate packing to the supplier. A double test and
inspection system means that manufacturing faults are almost
unknown but should any fault occur, it will be repaired (or re­placed) free of charge excepting where the fault has been
caused by physical damage.

Connecting Up

Using a high quality balanced and screened audio cable, con­nect the microphone head to the microphone amplier input and
switch on the 48V phantom power. NOTE, the microphone will
not operate unless 48V phantom power is provided.
The microphone should be powered up for at least one minute
before it will operate correctly as the polarising voltage on the
capsule needs to stabilise.
Some background noise is possible during the rst few seconds
after switch on.
Keep the gain controls on the microphone amplier or mixer
well down as the output from the microphone is high (as most
capacitor microphones).

Warranty

The JM47 is supplied with an elastic shock mount system.
Although the microphone is not particularly susceptible to
sounds transmitted through the case, it is advisable to use
this shock mount wherever possible.
To further improve the performance of the mount, it is possible
(but certainly not essential) to remove the wire clips (normally
used to open the microphone holder), this allows the micro­phone more movement in the elastic mount.
The response of the microphone is CARDIOID, this means
that it is very much more sensitive to sounds from the front
than from the rear. The front of the microphone is indicated by
the JM47 logo. To get the best quality, be sure that the sound
source is in line with the front of the microphone.
To get the classic early capacitor microphone voice sound,
the singer should sing very slightly across the front of the
microphone at a distance of 150 to 200mm from the micro­phone. The microphone amplier should be of the highest
quality such as a Joemeek microphone amplier.

Specication

Cardioid only capacitor microphone with FET impedance con­verter and transformer output. Power required, 48V phantom
approx. 1mA.

Frequency response substantially at 20Hz to 20KHz.

Sensitivity approx. -36dBV
Output impedance 200 ohms transformer balanced.

Recommended load impedance 2Kohm.

Signal to noise ratio 74dB.

Dynamic range 126dB