Joemeek JM27 User Manual

The Capacitor mic history and principle

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 JM27 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 JM27 contains all the classic design
elements and the sound of the nest microphones in the world.

Origins and Manufacture

The Joemeek JM27 is manufactured under the supervision of
PMI Audio Group. All mics are tested for quality control.
The JM27 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]

JM27

Thank you for purchasing the JOEMEEK JM27.

With proper use and care, your JM27 will give

you years of quality recording. Please read the

following instructions carefully, and enjoy using

your JM27.

Joemeek® is a registered trademark of PMI Audio Group.

©2003 PMI Audio Group. All rights reserved.

Joemeek Users Guide

JM27 Description

Operation

Using the JM27

The JM27 is a microphone in the tradition of classic studio micro­phones. It is a medium sized diaphragm true capacitor microphone
with a Cardioid head. This feeds the FET type pre amplier for low
noise. The output balancing is handled by a quality audio output trans­former.

The capacitor element is manufactured to the classic ‘concentric elec­trode’ design which provides smooth extended frequency response.
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 polarized by phantom power. The microphone body is made of
machined brass; Connection is via screened balanced audio cable
with 3 pin XLR connectors.

Care of Your JM27

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.

1) Keep the microphone dry.

2) Avoid wind or air blasts directly onto the capsule.

NEVER blow at the capsule. This is the most important single rule for
capacitor microphones. Damage caused by blasts of air on the capsule
are often permanent and require the complete replacement of the ca­pacitor element (microphone head).

So, never use the microphone in the open air without substantial wind
protection. Use of a pop shield in windy environments is essential. With
instrument recording in the studio though, unprotected use will give the
best sound.

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 polarizing
voltage, and this will cause crackling noises and low output.

The JM27 is capable of handling very high sound volume levels so it
can be used safely close to musical instrument ampliers. Often the
best sounding instrument are close miced, so it is good to take advan­tage of the JM27’s high dynamic capability in these situations. It is also
a very low noise microphone and suitable for low level or distant miced
instrument recording to the highest quality.

For voice recording, avoid singing directly into the capsule unless an
efcient pop shield is used.

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, or under a 100 watt light bulb for a couple of hours.

The JM27 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. A few seconds is often needed for the
microphone to reach optimal performance, but be sure to have all audio
levels off for the st 30 seconds during power up.

Warranty

The JM27 is warranted from defects for a period of 1 year, parts and
labor. Register for your warranty at www.joemeek.com.

The JM27 gives a very true sound, meaning that the quality of a
recording will depend on microphone placement, and of course, the
performer and the surroundings. The response of the microphone
is CARDIOID; this means that it is much more sensitive to sounds
from the front than from the rear. It is important to remember this
when micing up instruments that project sound from different parts;
i.e. drums, piano, reed instruments etc. The mic placement will affect
the sound quite a bit, so do plenty of experimenting before a take.
Remember that different areas of an instrument often produce very
different sounds, instrument micing is a highly Creative business and
a good technique can make all the difference to the nal mix. Once
again, do plenty of takes, and don’t be afraid to experiment. The
JM27 is an extremely capable recording tool: used properly, profes­sional results will be achieved.

Pre amplication is also important to improve the microphone’s
sounds. Quality systems like the new Joemeek TwinQ can optimize
the JM27’s performance.

Specication

Dimensions 137X22mm

Frequency Response 30Hz-20KHz

Sensitivity 10mV/Pa-40+/-2dB

(0dB= 1 V/Pa 1000Hz)

Polar pattern Cardioid Diversity> 12dB
(300-3000Hz)
b Diversity> 15dB(1000Hz)

Impedance 200 ohms

Equivalent noise level 18dB (A Weighted)

Max SPL for 130dB
O.5% THD@1OOOHz

Weight 135g