Microphone repairs and capsule
We are an official service/repair point for
are specialized in (studio) condenser microphone
Also we can modify and improve the electronics in
We have extensive experience with the following
- Neumann U47
- Neumann U67
- Neumann U87
- Neumann U89
- Neumann M49/M50/M147/149
- MCA SP-1
- Devine BM-600 / ISK BM-600
(N.B: We DON'T service dynamic-
and ribbon microphones!)
As modifications you can think of:
the reduction of self noise, raising the maximum output
(maximum SPL), increasing the frequency response
(better LF response), better symmetry of output,
replacing the FET and changing the capsule.
Modifications can make a relatively inexpensive
microphone sound noticeably better. Many
Chinese-made microphones can be significantly
Do you have a Devine BM-600 microphone
bought from that nice offer and it appears to be a bit
noisy and sounds a bit 'thin'?
In that case it is good to know that we can upgrade
your microphone with better components.
Less noise and a significant better frequency response.
By default, a frequency of 20 Hz. is already 5 dB
attenuated with respect to the higher frequencies.
After modification, the microphone is flat to 20 Hz.
and the output is only 1 dB attenuated at 10 Hz! The
Price for this modification is 25 Euro.
We also modify the phase of the microphone so that it
is in accordance with the European
time the capsules in a condenser microphone will
Problems that then arise include reduced treble and a
stronger noise or 'bubbling sound' of the microphone,
especially if one closely speaks or sings into the
The cause of this is surface conduction on the
membrane, so that leak currents occur.
Incidental 'ticks' (so called 'popcorn noise') can also
be caused by a polluted capsule. In these cases a
capsule cleaning should be considered.
The capsule itself is very fragile, the membrane has a
thickness of 3-6 microns, while the vapor-deposited
gold layer is hardly more than one molecule thick!
Cleaning of the membrane with a cotton swab is almost a
guarantee for the destruction of the capsule.
In addition, there is a risk that the gold layer by
such an operation will be sanded away.
Here is an example of a
microphone capsule which is 'cleaned' by an unexperienced person.
Most of the gold on the membrane has disappeared. It is clear to see
that the vapor-deposited gold has flaked off and is then literally
'wiped' of the membrane. The only remedy to get the microphone in
good shape again was to replace the microphone capsule.
An expensive repair, which could have been avoided. This is the
reason why we advise not to clean the membranes in a microphone
yourself without proper knowledge, equipment and experience.
This is an example of a very dirty capsule from a
Neumann U87 microphone
Needless to say, that no quality can be
Typically, the contamination will be less. It is not
recommended to wait too long before cleaning the
capsule. Except that the quality will gradually
decline, it will also be difficult to clean the capsule
so that it will be in ‘new’ condition.
This is the difference between a 'normal' polluted
capsule before and after
the capsule is like new
After cleaning the microphone will be tested
and the screws in the headbasket will be secured. Now
the microphone can be sent back to the owner.
The price for cleaning a capsule of studio microphone
is 45 Euro (Ex. BTW/VAT and the costs for shipping).
Prices for microphone modifications upon request.
Click HERE to contact
Many 'historical' tube microphones (Telefunken
ELA M251, Neumann M49 etc.) use an AC701 tube. These tubes have not
been produced for many years and are therefore becoming very scarce.
If they are already available, the quality is often questionable
(often coming from rejected batches) or even sometimes 'counterfeit'
copies are found that do not meet the original specifications.
When the microphone starts to make a soft 'rustling' sound, it is
often a sign that the tube in the microphone is approaching the end
of its life.
The solution can be very expensive, because the original AC701 tubes
sometimes are sold for prices around $1495!
Fortunately, we can offer an affordable solution in such cases.
After a long search we found a replacement tube for the AC701, which
can revive the microphone in its former glory. Often even the
microphone's self noise is lower than with the original AC701.
However, a small modification of the microphone and the power supply
is required. You will of course receive your original AC701 back, if
you want to be able to restore the microphone in its original state
when you sell it. For more information about replacing the AC701,
Here is an example of a solid-state microphone modification.
We took a cheap MXL 440 microphone. (July 2015 Price:
59, - Euro)
microphone, advertised as a ‘large diaphragm
microphone' actually contains a small capsule
(effective diameter 17 mm.) Surrounded by a brass ring,
to make it appear a larger capsule when looking through
The microphone has a moderate front/rear ratio, while
the electronics are constructed with simple SMD
components. No attention seems to be paid to the
matching of components, while the self noise is rather
high and there is a DC offset between the audio signal
begin with, the capsule was replaced by a large
membrane SK-12 capsule.
The original printed circuit board was removed and is
replaced by a new circuit, built up of selected
The result is an extremely low-noise microphone with
excellent quality, higher signal output, and a very low
distortion (about 0.02% at high signal levels), which
can measure up with much more expensive microphones!
Such modifications can be carried out at various
is another example of a microphone modification:
this case it is a JoeMeek JM27 pencil microphone.
microphone design is very simple (upper microphone); a
single FET with a small 2: 1 transformer. The problem that
manifested itself with this microphone was that it could only handle
low sound pressure without distortion, while the self noise was
polarization voltage on the microphone capsule was low, just over 30
this microphone the original circuit board was replaced by a
self-designed circuit. Although the space in a pencil microphone is
very limited, a DC / DC converter could still be implemented, which
ensures a higher polarization voltage.
microphone now has a higher output than in its original state, while
much higher sound pressures can be handled without distortion. Also
the self-noise is now minimal. (Lower microphone)
maximum output voltage at less than 0.1% distortion is 800 mV!
If you want to send in a microphone for repair:
- Ensure good packaging, you do
not want any new damage during transport!
- Add a description of the problem, there are so many
microphones coming in on a regular basis, that it is impossible to
search all previous email correspondence to trace the description of
the problem of the microphone in question. Also mention the
- Do not add any accessories such as shock mounts,
pop screens, etc.
Send the microphone with as little accessories as possible (but well
- If the microphone has its own power supply (ie no standard phantom
power), we also need the corresponding power supply and cable,
because there is a lot of diversity in microphone cables and power
information about microphone repairs, please use the
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