Gyraf Audio G 25 VocalShape Recording Channel

Gyraf Audio G25 VocalShape Recording Channel

The G25 “VocalShape” is our elaborate all-in-one box for vocal recording. It is an all-tube unit, consisting of a preamplifier stage, a filter and an equalizer section, a compressor, and finally a single stage of frequency-selective clipping for control of resonances. Every and all parameters optimized for – and only for – recording vocals.

First of all this is a tube device: All active functions, all amplification stages processing your signal are based on old-fashioned thermionic valves. This means that the unit usually will take 10-15 minutes from power-on before stabilizing into its working conditions. You can off course still use it during this time, but don’t expect too much precision or predict-ability before it’s settled.

So it’s a tube pre-amplifier, followed by a tube equalizer, feeding a vari-mu tube compressor, which in turn drives the output stage containing a single band of passive frequency-selective clipping.

What’s not to like?

Preamplifier

The topology of the G25 preamplifier is very much like our classic G9, in a version optimized for high-gain frame-grid tubes (6N23P/E88CC).

“INPUT” Switch selects between Line, Mic, and Mic+P48. The” GAIN” switch controls the amount of gain applied – ca. 4bB steps.

Mic/Line Inputs are floating transformer balanced, Line load is ca. 10K Ohms, Mic load ca. 2K Ohms. 48V Phantom power can be switched on only to the Mic input – for phantom powering condenser microphones that may need this.

The Instrument input jack on the front is a very-high-Z input that simply interrupts the connection to back panel Mic/Line connectors when a jack is inserted. The addition of this Instrument input was possible without in any way compromising the units usability for vocal recordings – it’s a left-over from early revisions that is kept in place because of popular demand – several of our test drivers insists on its qualities for processing certain instruments. Ymmw.

Mic gain maxes at a bit more than +70dB, plenty for your old beaten-up SM7, and happy with anything louder. Line gain is generally some 27dB under Mic gain setting, Instrument input gain some 17dB under mic. With all knobs set to 12 o’clock, we see some +48dB gain in mic mode, +21dB in line mode

Equalizer

Eq section consists of a first-order HPF @ 50Hz or 120Hz, a High/Low shelving symmetric boost/cut Bax at 6dB/Oct combined with the Linear Tilt circuit from our G23 – adjustable between +/- zero and one dB/Oct at its extremes.

Vari-mu Compressor

Copied from the G10, off course. Fixed ca. 20ms Attack, variable Release some 50ms-1.6sec . Threshold and Ratio functions are combined into one knob labeled unified “Drive”. Gain reduction read-out on meter.

De-resonance/Clipper

This stage, which is integrated into the unit’s output transformer – and thus comes after the “Output Drive” control pot, is our frequency-selective clipping circuit. The topology is a simplified version of the G21 Infundibulum – with a handful of switchable frequency ranges selected for their usefulness for helping vocal trouble. The “ALL” position is simple full-spectrum schottky diode clipping.