drefahlaudio.com - gallery

Scroll down for some samples of our work...

Neumann M7 - the core...

The legend starts off in 1932 with the revolutionary Neumann CMV3 condenser microphone, and continues with the CMV5, U47, M49, CMV563 or UM57. Most excellent microphone capsules are derived from this unique design even today.

Here shown after rediaphragming, for another half century of outstanding performance

Spheric-shape omni capsule with new drefahlaudio custom diaphragm. While the original would have been much expensive to replace, its performance could be restored at much lower cost in this case. Other than the metal original, the replacement diaphragm withstands excessive sound pressure and air blasts without damage.

The mysterious Klangfilm "Bike Lamp"...

This Bavaria Film version with cardioid-mode M7 capsule was completely overhauled, custom reskinned, the tube circuitry tuned and completed with a DN221-T power supply unit.

Now its sound can hardly be distinguished from the equally legendary Neumann U47/48, while perfectly matching with state-of-the-art audio equipment, at both lowest inherent noise and interference.

KK56 small double-diaphragm capsule and KK49 after drefahlaudio reskinning. The result: Fully restored frequency response and reliability, superb front/rear balance for perfect omni and figure-of-eight pattern.

Audio demo KK56 reskinned


Not only vintage capsules greatly benefit from professional reskinning...

This Brauner Phantom Anniversary with heavy closemiking issues was restored to full reliability, while exactly maintaining original frequency response and its much valued vocal sound.

Thiele M4 capsules, reskinned to form a perfectly matched and acoustically symmetrical pair. The reskin also significantly improved sensitivity and frequency response, which is usually heavily affected by material ageing.

Also the typical look with its unique aluminium clamping rings was fully maintained, for authenticity's sake...


Sony switchable condenser capsule, the core element of several mic legends such as C-37, C-38 or C-800. Left: with the gold coating washed off by inexpert cleaning. Right: with fully restored sensitivity and performance after in-situ recoating.

All important parameters are monitored already during processing...

...which is not only a prerequisite for superb audio performance, but also for long-term reliabilty under all imaginable recording conditions.


After processing, all capsules pass a practical test on the mic, as well as an audition under real-life conditions for optimum musicality and reliability.

Special measures are taken to guarantee full reliabilty for vocal closemiking, where aged or contaminated capsules often exhibit massive problems. At the same time, full reliability even under adverse atmospheric conditions is ensured.

The AKG CK12 is the heart of AKG's top vintage mics like the C12, C24, C12A and early C414 series.

The capsules shown belong to the famous "Elam" M250, before and after restoration. Acoustic properties were fully maintained over the entire frequency range, perfect directional patterns included.

Drefahlaudio mic power supplies from the DN221 series are highly valued by professional users worldwide.

The remote-control powering unit DN-RC is available for tube and solid state stereo microphones like AKG C24 to 422 and all Neumann SM models, offering lowest feasible noise and interference.

Single and dual-channel units are available for practically every tube mic known.



Neumann CMV5 with VF14 tube circuitry, as we received it (left). The right pic shows the same mic after refurbishment , including a complete circuitry overhaul, noise and distortion optimization, removal of the old coating, repolishing of all metal parts and a durable seven-layer finish.

With its new PSU and cabling, the mic was again fully up to its reputation as the "mother of U47".


Neumann's U47 were often modified to Nuvistor circuitry since the original VF14 tube became hardly available. For this purpose, the tube, tube socket and elastic suspension were removed and replaced with a plug-in solution supplied by Neumann.


The same mic, shown after our VF14 rebuild. All previously removed parts were remanufactured, and the circuitry precisely retuned to original specifications.

By the use of selected passive components from our stock, noise could be reduced to a level even better than with many modern solid-state mics.

This heavily worn 47 was to be restored cosmetically in the first place, but also its internals were brought to original specs at the same time.

It would have been an eyecatcher in any showcase after, but of course it returned to everyday studio work to prove its excellence as the most regarded vocal microphone ever.

The Thiele M4 is undoubtedly one of the fanciest vintage microphones in terms of appearance, but its technical properties could never fulfil the high demands of professional recording.


After our modification - which comprises external powering, capsule refurbishment, full circuitry revision and new cabling - it will compete even most valued tube microphone classics. An eyecatcher and a convincing recording tool at the same time...

Not only tube-based, but also solid-state vintage mics benefit from our services. Here a refinished and matched Neumann-Gefell MV692 stereo pair, with reskinned UM70 tri-pattern capsules and custom power supply.

For these series, we also provide low-noise 48V conversion with or without XLR connector piece.

Typical wear traces of a Neumann KM84 after 30 years of studio life. The new pad slider (lower) can be operated without a tool, and is durable enough to sustain the rest of the mic's life.

As spare capsules for the KMi series have become unavailable, we decided to include these in our diaphragm services as well.

A rare 1950s version of the U47, slimmed down to a lightweight for boom use by CCC Film Berlin. We prefer to leave the appearance of such historical pieces completely untouched, restoring to full performance internally only.

This one could tell countless stories for sure, from Edgar Wallace through to Russ Meyer...

Sometimes there's just bits coming in...

..which are then reassembled to such fine items like a flawlessly working Neumann KM88.


Another field of our activities: the conversion of high-quality measuring mics into recording tools. In this case a Neumann-RFT MV101 tube, now in use for orchestra recording.

With our dedicated DN221-T or -M powering units, mics like the MV101 will deliver outstanding sonic purity and dynamic capabilities.

Another sample from our reconversion range: Neumann M49a downgraded to FET circuitry in the seventies, then rebuilt to original AC701k tube circuitry.

The AKG D12 kick drum legend....

Unfortunately, many of these mics cannot handle low frequencies any more and suffer from drastic output level loss when aged.

By our repair, cleaning and adjustment procedures, many of these great mics can still be helped and returned to good output and powerful low-frequency response.


- end of gallery -
(C)2007 Images by Peter & Frederick Drefahl

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