Rupert Neve Designs 511 500 Series Mic Pre with Silk

Input Section

Input signals may be derived from Mic or Line sources (make sure 48V is off for line sources!). The input has a 10K Ω non-reactive input resistance that handles a full 22dBu signal without the need for a pad. The pre-amp is a TLA non-reactive design that precludes the loading of microphones with limited driving capability. A primary gain control provides 66dB of gain in 6dB increments for easy recall, with a +/- 6dB trim for fine adjustment. For condenser microphones and powered DIs, there is +48V phantom power. A transient-optimized HPF continuously covering the range from 20-250Hz is included to tame rumble and proximity effect.

Texture

One of the key developments in the 511 is the Red Silk / Texture control from the Portico II Channel. Building on the “Silk” mode found in the Portico Series mic pre-amplifiers, Texture is designed to adjust the actual amount of harmonic music content from the source material, in effect, providing wide range of tonal options for the preamplifier. Like the original Portico Silk, the Silk Red / Texture works by reducing negative feedback on the output transformer and adjusting the frequency response to more closely resemble Mr. Rupert Neve’s vintage designs. With the 511, the Texture control allows these techniques to be pushed further than previous designs, adding about 10 times the desirable THD of the original silk control at its maximum setting.

With that said, we have taken great care to ensure that the musical integrity of source material itself will not be compromised by these harmonic controls (these are not to be confused with controls from other manufactures that may “incinerate”, “demolish” or “destroy” source material), and we believe they can be confidently utilized to fit the personality of any song, instrument or engineer.

Low Noise, Low Distortion Operation

Much care was given in designing the 511 to produce as little noise and non-harmonic distortion as possible. Carefully implemented signal paths and Class A operation are a large part of the 511′s sweet, whisper quiet performance. For more information, go to Mr. Rupert Neve’s Design Notes.

Mic Gain

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

Trim

Continuously variable +/-6 dB level control.

+48V

Engages phantom power on the microphone input, as supplied by the 500 series rack.

Polarity

Push button inverts the polarity of the signal path, and illuminates when engaged. The symbol “Ø” is often used to denote opposite polarity.

High Pass Filter

The high pass filter is continuously variable from 20-250Hz and engaged by the HPF switch, which illuminates when engaged. It is a valuable aid in any signal chain, but particularly so in a microphone preamplifier. Signals below the selected frequency are attenuated at a rate of 12db / octave, getting rid of proximity effect, building rumble, air handling, motor hum, etc.

SILK / TEXTURE

Pushing the Silk button engages the red Silk circuit, which reduces the negative feedback on the output transformer, adding harmonic content as the texture is increased. Red Silk accentuates the saturation in the mid and high frequencies, similar to that of the red silk mode on the Portico II Channel. By manipulating the Texture control, the amount of Silk can be changed from essentially absent, to roughly 10 times the amount of coloration / distortion found in Silk from the original Portico Series. With Silk / Texture engaged, the distortion characteristic and harmonic content of the unit are very reminiscent of many of Rupert’s class-A vintage designs.

Level Meter

An Eight-segment LED bar-graph meter displays output level (pre-Silk). The color range proceeds from green for lower level signals, yellow for intermediate signals, and red for high levels. When the 511 is clipped, the highest red LED will hold longer depending on how far above the clip threshold the signal was.