Grundig GDM 311 Early 1960s - XLR

Original Box / Stand System – Exceptional Condition - XLR Converted

A clever and beautifully engineered microphone from Grundig’s early-1960s catalogue. The GDM 311 was conceived as a compact, professional solution for broadcast, speech, and recording applications, featuring an original transport box that converts into a functional desktop stand.

Behind its understated appearance lies a technically and historically interesting capsule design that reflects Grundig’s close connection to German high end and broadcast manufacturing of the period. read more if you are interested.

This example is presented in mint condition, complete with its original box / stand system, and has been converted to balanced XLR for seamless use with modern studio equipment.

OPTICAL CONDITION

The microphone, grille, finish and body are exceptionally clean, with no notable wear. Logos and markings are crisp, and the stand mechanism functions perfectly. A rare level of preservation for this model.

TECHNICAL CONDITION

Fully functional and tested The XLR conversion has been carried out cleanly

THIS ITEM INCLUDES

• Grundig GDM 311 microphone
• Original Grundig box with integrated stand system

BUILD & DESIGN

• Type: Dynamic (moving-coil)
• Front-address design
• Solid plastic housing
• Integrated transport box that converts into a desktop stand
• Converted to balanced XLR

CAPSULE & DIAPHRAGM – HERITAGE FAMILY CONTEXT

The GDM 311 employs a dynamic diaphragm whose plastic diaphragm structure and voice-coil geometry originate from the same production family used in certain high-end broadcast microphones, including the AKG D19.

The diaphragm material and voice-coil construction are production-equal to those found in the D19 and several other broadcast-grade models. For this reason, these diaphragms are sometimes used by experienced technicians — and myself — in the restoration of such microphones.

This is not a claim of similar sonic characteristics or performance. While the diaphragm construction shares manufacturing lineage, the capsule housing, acoustic loading, and mechanical environment are fundamentally different. In the GDM 311, the diaphragm is coupled to a simpler housing and pressure rings- resulting in a distinctly different tonal balance and behaviour compared to broadcast microphones that employ more complex capsule assemblies.

Successful restoration or adaptation work requires retaining the original capsule rings and carefully, expertly modifying the internal assembly. When performed correctly, this shared production line can help return classic broadcast microphones to life.

The GDM 311 should therefore be understood as an example of shared manufacturing lineage, not as a substitute or tonal equivalent to broadcast legends- but a valuable device.

ESTIMATED FREQUENCY RESPONSE

~50 Hz – 14,000 Hz

• Clear, articulate midrange
• Controlled low end
• Smooth, natural high-frequency roll-off
• Good transient definition for a dynamic microphone

Estimated from practical testing; not factory specification.)

SOUND CHARACTERISTICS

Balanced, controlled, and articulate.
The GDM 311 offers excellent intelligibility and a refined dynamic response, making it suitable for:

• Speech and voice recording
• Vocals with a natural, non-hyped top end
• Acoustic instruments
• Guitar amplifiers
• Broadcast-style applications

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