Rens Heijnis                                      custom-built audio equipment

B&K  DPANeumannSchoeps  AKGSennheiser



Microphone amplifier CMA-16 for the Schoeps MK series capsules

Universal microphone amplifier. Suitable for al the Schoeps MK capsules. Also the old series.
The microphone body is made of high-grade stainless steel, which provides high mass.
Available with the active powered 4 and 6 pin XLR connector.


Improve the sound of your Schoeps microphone by retrofitting and separated power supply.

When you are not satisfied with the sound of your Schoeps microphone such as the CMC 5 or 6: too muddy,
lacking vibrancy and detail.or anything else, it is possible to retrofit your microphone with optimized electronics
to improve the sound.
After retrofitting your microphone has a tighter low, more vibrancy detail and high frequency.
At the former
microphones page you can read the theory about retrofitting:

A retrofitted microphone has a new printed circuit board with trough-hole components.
All the components are selected for there proven sound quality.


Power Supply for active powered Schoeps microphones

Technical Specifications PS-402
Number of channels: 2
Input: 4-pin XLR female connector
Output: 3-pin XLR male connector
Power requirements: 105-120V and 210-240V, 50 to 60 Hz
Power consumption max: 3W
Weight: 1 kg
Dimensions: 108mm × 165mm × 52mm (4.3” x 6.5” x 2.1”)


Microphone Cable for active powered microphones

A special microphone cable is necessary between the microphone and power supply.
The standard microphone cable is a Mogami starquad cable:
Mogami 2534
For the +60V norm it is supplied with 4 pin XLR connectors.
Every cable length is available.
The output of the power supply is a normal 3 pin XLR.

For microphone cables with an other sound than the Mogami see: Microphone Cables


Retrofitted CMC-6 with active power


This modern Schoeps CMC6 version also has a poor sounding SMD printed circuit board.
After retrofitting the Schoeps microphone, the complete PCB will be replaced for a
PCB with components proven for the sound quality and a through hole setup.


Retrofitted CMTS501 with active power

Schoeps CMTS501 or Studer SKS501 stereo microphone retrofitted to active power.
2 channel power supply with 60V.

The original design had only 1 Fet as amplifier so it's worth to retrofit.


Battery powered pre-amplifier for active powered Schoeps microphones

4 channel pre-amplifier with Lithium ion batteries and the latest developments in improved sound quality.
Light weight: 3,3kg. Dimensions: 28cm × 25cm × 10cm
Input: 6 pin XLR for active powered microphones.
Recording time 30 hours including microphones power.


Sonodore MPB-502


Pre-amplifier for standard B&K /DPA Microdot and active powered Schoeps microphones

Special light weight (2,9kg) 3 channel pre-amplifier with Lithium ion batteries and the latest developments in improved
sound quality.
With DPA MircoDot (4060serie) and active (6pin) microphone input. With battery power for the microphones.
Recording time 34 hours with active microphones, 43 hours with only DPA MicroDot.
Back view

Audio samples

Mendelssohn, Seikilos String Quartet.
Recorded by Gonzalo Noqué with Retrofitted Schoeps (60V) with MK21
Horus preamp and converter
24bits 44KHz Audio sample

Beethoven’s Für Elise played by Dr. Charles Metz on his fortepiano.
Recorded by Barry Hufker with Retrofitted Schoeps (60V) with MK2S
24bits 96KHz Audio sample

ST. Charles Singers: "The Blue Bird"
Recorded by Hudson Fair with Retrofitted Schoeps cardioid and Sonodore MPB-502
24bits 96KHz Audio sample

Direct comparison standard and retrofitted Schoeps, 7 different audio samples. 
Retrofitted 24bits 96KHz zip  Audio sample A

Standard 24bits 96KHz zip   
Audio sample B
Equipment: Schoeps CMC6, Preamp Forssell SMP-2, AD Forssell MADA-2.
ade by Ivo Sedlacek

Interesting comparison between retrofitted Schoeps and normal DPA4006
Retrofitted Schoeps CMC6, 4 channel version MPB-502, van den Hul integration hybrid cable, sounddevices 788t
88,2 kHz  Audio sample 24bits     Audio sample 16bits  
Standard DPA4006 48V,Vovox sonorus direct cable, sounddevices 788t
88,2 kHz  Audio sample 24bits      Audio sample 16bits  


Reference on the retrofitted Schoeps CMTS501 microphone withan active 60V PCB. 

Barry Hufker:
This past Sunday I recorded a concert of Early Music featuring soprano and harpsichord.
The sound was modern (in the best sense) with great imaging.  
The high frequencies were never shrill and the recording turned out very well.
Your work is a big improvement over the original.


Reference on the retrofitted Schoeps CMC6 microphone with an active 60V PCB. 

Barry Hufker:
This is just a note to tell you how much I enjoy the modification you did of my two Schoeps microphones. 
I had the pleasure of recording a recital of music played on the Fortepiano. 
The sound you achieved is lively, clear and detailed.
I am hearing the Schoeps capsules in a way I have never heard them before.
I am also glad to be free of the “tubbiness” in the upper bass which the mics had previously. 

Branic Howard, Open Field Recording:
Your updated Schoeps sound fantastic to my ears.
The retrofitted mic body circuit provides a different lens on what the Schoeps capsule hears.
For me, the most important change is the transient clarity—such beautifully rendered percussive sounds—
I hear a more relaxed and 3D sound stage.
They also have a very well articulated bass. I am excited to use them for years to come!

Retrofitted Schoeps acting like there is blanket removed from the capsule.
Very well defined, no boomy mid lows.

Price list retrofitting microphones