Golden Age Audio GA-251 Tube Microphone  From Golden Age

The Telefunken ELA M 250/251 was made for Telefunken by AKG after Neumann discontinued its OEM production of the Telefunken U-47. The Golden Age Premier GA-251 is inspired by this truly classic mic model.

The GA-251 shares the same design goal that was set for the GA-47: to offer the classic qualities and advantages that a vintage unit in perfect condition would provide and doing so at a very low price point. Having gone through a number of prototypes that was compared to great sounding vintage units in different recording settings, everyone involved agreed that the goal was reached.

Its a great pleasure for me to present the second mic in the Golden Age Premier line, the GA-251!

Bo Medin, October 2018

FEATURES

 ♦ High End, no compromise components and build quality

 ♦ Point-to point wiring with silver-plated wires, no printed circuit board used

 ♦ Solid wood microphone box, tweed style system flight case.  Every mic, box and psu has a badge with the serial number

 ♦ Hand Made in small series,

 ♦ 50 units at a time

 ♦ All soldering points made with Mudorf Msolder Supreme SilverGold solder (Sn88, 6Cu, 1,8Ag, 9,5Au)

 ♦ Capsules selected with very tight tolerances

COMPONENT SPECIFICATIONS

CAPACITORS AND RESISTORS

The coupling capacitor is made by Solen from France. It is a high balanced film capacitor made from MKP material with pure oxygen-free copper connections. It has a very delicate and balanced sound.

The capsule capacitor uses NOS Siemens antique grade polystyrene capacitor to reduce loss.

The tube cathode bypass capacitor uses an ELNA OFC Cerafine high end hifi capacitor from Japan with oxygen free copper connections exhibiting a very sweet and delicate character, not the least for vocals.

The other capacitors are of the low loss polystyrene type.

The resistor used for setting the capsule voltage is a high quality DALE 1% metal film resistor. The result is a very stable and consistent operating level leading to better consistency between different GA-251 units.

The plate resistor uses a non-inductive resistor of the United States IRC audio with pure copper connections. The sound level is rich and full bodied.

CAPSULE

The GA-251 uses a 34 mm K251 style capsule. Being a dual-sided one, it provides both cardioid and omni polar patterns.

In order to get a good consistency between units, for each production run of 50 pcs GA-251 units, approximately 200 capsules is evaluated in order to find 50 capsules with specifications that lie within the tight tolerances.

Specifications:

Backplate material: Brass

Capsule diameter: 34 mm

Membrane diameter: 34 mm

Membrane material: 6 micron gold-coated mylar

The sensitivity of the front and back side of the capsule do not differ more than 0,3 dB. The sensitivity between different capsules do not differ more than 0,5 dB.

The tight manufacturing tolerance will lead to a very good consistency between different GA-251 units.

The capsule is specially designed to complement the electronic circuit of the GA-251 to achieve a frequency response curve with a nice balance between the high, middle and low frequencies.

POWER SUPPLY STRANSFORMER & ELECTROLYTIC CAPACITORS

The vintage style power supply PSU uses a high power R-style transformer with a low noise level and minimum stray field.

A simple but effective circuit uses dual-stage filtering for the filament voltage.

The High voltage is also precisely filtered and stabilized using an ON semiconductor zener diode.

The polar pattern switch is placed on the power supply so that the recording engineer can change the polar pattern between Cardioid and Omni remotely.

A ground lift switch will help to solve mains power related noise issues that can appear in some cases.

TUBE

The GA-251 uses a NOS Phillip 5480W super low noise pentode tube connected in triode mode in order to decrease the noise

The tube has the following character:

- balanced sound response 

- a smooth and warm sound character and low noise level

- long lifespan

The GA-251 amplifier features a new proprietary circuit designed around the NOS 5840W tube

MIC INTERIOR

The electronic circuit is built with point-to point wiring, All soldering points made with Mudorf Msolder Supreme silvergold solder

All of the inside wire use pure silver wire and decrease the loss during the circuit transmission, also it can ensure the sound quality is transparent

All components which are connect to electrical ground is connected to the ground plane on the circuit board. All other component connections use point to point wiring which results in virtually zero loss and crosstalk

MIC BODY AND GRILL

The mic body is made of brass, the grille is made of iron.

The grille, which is a critical component affecting the sound character, is similar to the one in the 251

POWER SUPPLY TRANSFORMER & ELECTROLYTIC CAPACITORS

The vintage style power supply PSU uses a high power R-style transformer with a low noise level and minimum stray field

A simple but effective circuit uses dual-stage filtering for the filament voltage. The High voltage is also precisely filtered and stabilized using an ON semiconductor zener diode

The polar pattern switch is placed on the power supply so that the recording engineer can change the polar pattern between Cardioid and Omni remotely

A ground lift switch will help to solve mains power related noise issues that can appear in some cases

MIC CABLE

The cable is specially produced using 99,99% pure oxygen-free copper, Teflon insulation, tin foil and 98% kitmesh, ie with a very high braided density of the cable shield

It has a very open and smooth sound

The mic connector is an aviation style plug providing solid connections and a long life

OUTPUT TRANSFORMER

The GA-251 transformer is specially designed with a 10:1 AMI style dual bobbin transformer

It is made from permalloy steel sheet from USA and enamelled wire from Germany

It offers a wonderful sound character with a high resolution and great balance between the low, middle and high frequency bands