Rupert Neve Designs 5025 Dual Shelford Microphone Preamplifier

Two channels of the finest microphone preamplification in the world
Our best-selling Shelford Channel is the definitive evolution of the original technologies in Rupert's classic modules like the 1073, 1064 & 2254, thoughtfully advanced and refined for the 21st century studio.

Originally released as a limited edition and back by popular demand, we are now offering the Dual Shelford Mic Pre: a two-channel version of our flagship preamplifier that has become an indispensable tool for countless engineers and musicians. The Dual Shelford offers the sonic excellence of two Rupert Neve Designs Shelford mic preamps in a single rack space with an internal power supply; simply put, these are two channels of the finest microphone preamplification in the world.

The Transformer Gain Mic Pre
Like Rupert's designs from his time in Little Shelford, the Dual Shelford Pre uses a custom step-up transformer on the microphone input that provides the first 15 dB of gain. This specially-designed transformer, along with its careful integration with the surrounding class-A circuitry, is critical to the amplifier's bold, mid-focused magic that can be heard on thousands of classic recordings.

While the majority of the harmonic richness found in Rupert's designs is a product of the output transformer and surrounding class-A amplifiers, this step-up input transformer also imparts a unique musical enhancement of its own. The technical reasons for this are primarily a result of the reactive impedance characteristic of the input transformer and how that interacts with the connected microphone, resulting in subtle, non-linear harmonic enhancement of the lows and an unmistakable sweetness in the high frequencies.

While creating the input stage for the Shelford Channel and Dual Shelford Pre, the goal was not merely to recreate the classic designs, but to advance them: combining the unmistakable sound of the vintage technology with wide-bandwidth frequency response, consistently excellent amplifier performance at any gain setting, and extremely low noise operation.

To achieve this, the custom transformer designs were carefully optimized and complete MuMetal shielding of the input transformer was implemented. The resulting preamplifier is flat from below 10Hz to above 60kHz, resulting in the purest possible tone and the very highest levels of versatility.

What is Silk?
The Silk & Texture circuit on the Dual Shelford Mic Pre allows you to fine-tune the amount (and type) of harmonic content in the output stage. This means your signal can be adjusted from quite transparent to settings that produce nearly 10x the amount of sonic color as Rupert's vintage modules - and in two very unique modes. No matter what sound you're looking for, Silk can help get you there.

Silk Red
When you apply Silk Red, you're enhancing harmonic content generated by the highs and high mids of your source. This adds a sparkly sheen to the top end, and is often ideal for sources including vocals, snare, strings, pianos, and other acoustic instruments.

Silk Blue
With Silk Blue, you're enhancing harmonics generated by the lows and low mids of your source. This tends to "beef up" a signal from the bottom up, making it a great choice for drums, bass guitars, heavy electric guitars, male vocals, and synthesizers.

The Dual Output Level Transformers
Complementing the Silk circuit are the custom-designed output transformers, which use Rupert Neve Designs' distinctive dual output topology. These offer both Main (+26 dBu) and -6dB (+20 dBu) outputs, allowing the engineer to drive the preamps fully into classic transformer saturation without clipping converters and other devices later in the chain.

The main outputs are designed to capture a more pristine sound at high levels, avoiding any nonlinear coloration of the output stage. The -6dB outputs allow an engineer to fully drive the Shelford - adding dynamic tone with these same nonlinear "colorations" - without clipping most professional interfaces. On drums, vocals, guitars and other instruments, these outputs let you easily hit the transformer's "sweet spot" of nonlinear harmonic content, bringing a recorded performance to life in a way that other preamps simply cannot match.

Features

Mic Gain
This 12-way precision rotary switch controls gain from 0 to 66 dB in 6 dB steps.

Trim
This rotary switch provides further continuous gain adjustment over a range of +/- 6 dB.

48V
This push button switch engages phantom power on the microphone input.

Polarity
This push button switch inverts the polarity of the signal path. It illuminates when engaged. (The symbol "phi" is often used to denote opposite polarity.)

HPF / HPF Freq
The HPF switch engages a 12dB per octave high pass filter. The HPF FREQ potentiometer is variable from 20Hz to 250Hz, and can be used to filter out unwanted low frequencies, or in conjunction with the EQ to help shape source material. Note that engaging the HPF to S/C switch moves the HPF from the primary signal path to the compressor side-chain signal path.

Silk / Texture
Pushing the Silk button cycles the Silk modes from Red to Blue to Off. Silk reduces the negative feedback on the output transformer, adding harmonic content as the texture is increased. Red Silk accentuates the musical harmonic saturation from the mid and high frequencies, while Blue Silk accentuates harmonics from the low and low-mid frequencies.

By manipulating the Texture control, the amount of Silk can be changed from essentially absent, to roughly 4-5% THD (mostly second order) depending on how hard the output transformer is being driven.

VU Meters
The VU Meters are calibrated to display average (RMS) output levels.

Peak LED
Red indicates near clipping of the output stage.

Dual Tap Output
In addition to the Main full-headroom output, the -6dB output creates a rich harmonic character while reducing the risk of clipping the next device in the chain.

Gnd Lift
This switch separates the direct connection from audio signal ground to chassis earth.

Universal IEC Power Input
Works worldwide, accepting voltages from 100-240VAC.