The G25 \u201cVocalShape\u201d 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 \u2013 and only for \u2013 recording vocals.<\/p>\n
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\u2019t expect too much precision or predict-ability before it\u2019s settled.<\/p>\n
So it\u2019s 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.<\/p>\n
What\u2019s not to like?<\/p>\n
It all started some 15 years ago, a local mastering engineer whom I respect a lot ordered a G10 compressor for his setup. Then a couple of weeks later, he orders another one. Aargh, how do I explain to him in a nice way that he won\u2019t ever need more than one of these, for any reason..?<\/p>\n
His short answer was: \u201cwell, it\u2019s not for myself \u2013 duh \u2013 but my wife\u2019s a singer. She heard the G10 \u2013 and she has very good taste in compression for vocals..\u201d<\/p>\n
This was probably the beginning of me realizing that we\u2019d have to get that compression in the hands of artists rather than engineers in some form or another. The Dual\u2019ized version, the G22, was a step in this direction \u2013 but still somehow too excluding for anyone but studio techs due to it\u2019s degree of over-engineering and the sheer bulk of it\u2019s 3u 19\u2033 size \u2013 just for the compression part of the chain.<\/p>\n
Then some years ago one of our local studios were recording an album with above mentioned vocalist \u2013 and her vocal recording chain turned into a really<\/em> tall stack of reserved hardware: Quite a few of the available Gyraf units ended up in permanent use there \u2013 but in particular the G21 \u201cMagneto-Dynamic\u201d frequency-selective clipper was shining in its newfound function of controlling voice resonances above a certain level. And the linear-transfer tilting knob of the G23 was just<\/em> right more often than not.<\/p>\n This was the point of no return for Anders Boll, the engineer in charge of those sessions \u2013 he promptly started a campaign of persuading us into compacting that monstrous tower of a vocal setup into something manageable. Initial arguments were like: \u201c..look at this attack-time control \u2013 we NEVER move that, no matter who\u2019s singing.. Can\u2019t we just get rid of that..?\u201d and \u201c..who the f* would ever need fine control over both<\/em> threshold and<\/em> ratio for when recording vocals?\u201d<\/p>\n Turned out that when we followed this approach to its logical conclusion \u2013 optimized circuitry for vocal use only<\/em>, we were able to put together a system that not only was much more compact than the original heap, but also profoundly more user friendly, almost intuitive, in its user-interface. This was the core G25 idea.<\/p>\n Now all that was left was trying out different hardware ideas and control-range optimizations \u2013 we\u2019ve spent the last three years frequently consulting Anders and his visiting artists about functionality, interfacing and expectations for the system. Now here, late 2023, ca. 92 revisions later, we\u2019ve had the resulting G25 in the hands of a small group of independent engineers and artists \u2013 and it turns out that now we finally have it ready to fly..<\/p>\n ..and oh, by the way: \u2013 it turned out that even though we went out of our way to optimize for vocals and only<\/em> for vocals, we still ended up with a box that does so much more. But that\u2019s for you to discover when you have it in your hands one day.<\/p>\n 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).<\/p>\n \u201cINPUT\u201d Switch selects between Line, Mic, and Mic+P48. The\u201d GAIN\u201d switch controls the amount of gain applied \u2013 ca. 4bB steps.<\/p>\n 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 \u2013 for phantom powering condenser microphones that may need this.<\/p>\n The Instrument input jack on the front is a very<\/em>-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<\/em> way compromising the units usability for vocal recordings \u2013 it\u2019s a left-over from early revisions that is kept in place because of popular demand \u2013 several of our test drivers insists on its qualities for processing certain instruments. Ymmw.<\/p>\n 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\u2019clock, we see some +48dB gain in mic mode, +21dB in line mode<\/p>\n 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 \u2013 adjustable between +\/- zero and one dB\/Oct at its extremes.<\/p>\n 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 \u201cDrive\u201d. Gain reduction read-out on meter.<\/p>\n This stage, which is integrated into the unit\u2019s output transformer \u2013 and thus comes after the \u201cOutput Drive\u201d control pot, is our frequency-selective clipping circuit. The topology is a simplified version of the G21 Infundibulum \u2013 with a handful of switchable frequency ranges selected for their usefulness for helping vocal trouble. The \u201cALL\u201d position is simple full-spectrum schottky diode clipping.<\/p>\n The \u201cFunction\u201d switch can bypass this stage or put it into one of two modes: In \u201cCUT\u201d mode, the circuit acts like a subtractive eq, allowing you to turn down parts of the spectrum. In CUT mode, the clip meter is not active. \u201cCUT\u201d is also a useful mode for finding the frequencies that you potentially want to deal away with. Now, if you find something annoying then put the \u201cFunction\u201d into \u201cCLIP\u201d, the de-resonance stage will remove that part of your frequency range, but only when you are above a certain threshold, some set amount of build-up in that spectral area. In other words, you can home in and remove annoyances almost like a dynamic Eq. The \u201cDe-resonance\u201d pot\u00a0 controls how much you activate this function \u2013 it both controls the threshold of onset of the clipping and the ratio of removal. As this function only subtracts, i.e. turn down signal, the knob logically goes from off\/neutral at fully clockwise \u201cturned up\u201d to full-removal at counterclockwise \u201cturned down\u201d. Note that the \u201cDe-resonance\u201d pot works in concert with the \u201cOutput Drive\u201d \u2013 being placed at the output of the unit, reacting to the absolute output level, it\u2019s dependent on both settings. The \u201cCLIP\u201d \/ \u201cResoSculpt\u201d meter is indicating how much energy you are removing from your signal \u2013 but for technical reasons (it\u2019s passive after all..) the readout is an absolute value, not a relative one like the dB GR-meter for the vari-mu compressor. This means that minor movement at lower levels may well indicate more relative \u201caction\u201d than a lot of movement at high operating levels. In other words, don\u2019t get too focused on precise amounts of needle-movement here \u2013 unless you know your source and its operating levels well.<\/p>\n This preamplifier is built around a signal chain entirely based on tubes \u2013 we have chosen this because we think that some of the specific overload characteristics of tubes can be very beautiful when applied to certain types of voice performance and recordings. This means that we intend the unit to enable you to experiment with the less-than-clean border areas at high operating levels.<\/p>\n Output impedance is ca. 150 Ohms floating transformer balanced. This unit was originally made for use with our local recording studios, which means that we have optimized for \u201cconservative\u201d operating levels around +4dBu \u2013 at this point you still have some 14dB up to the point where the unit starts to sound really hot, which happens around 15Vpp AC output \u2013 and then some again before it starts sounding unusably bad.<\/p>\n This means, however, that you should consider checking your levels if you\u2019re running a modern-day DAW, which often comes factory set to extremely-high levels like +24 or +28 for 0dBfsd. Those kinds of levels are aimed at keeping a good safety-margin before running into digital-clip, but at the same time it\u2019s common practice (for a good reason) to try getting as close to clip as possible.<\/p>\n A good level for use with the G25 (and for most analogue gear in general) is somewhere around +10dBu to +15dBu analogue for 0dBfsd (full scale digital)<\/p>\n The G25 comes preloaded with four new-old-stock tubes:<\/p>\n Pre-amplifier and EQ stages are built around 6N23P tubes \u2013 one for each section. At this time (ser. no. ca. #001-050) these will be Russian military 1980\u2019es production. Expected to last very long.<\/p>\n The vari-mu compression stage is built around a PCC189 (6ES7) \u2013 most probably a late-1960\u2019es Philips, or a 1970\u2019es Mullard. These can last ridiculously long too.<\/p>\n The output driver stage, which also feeds the frequency-selective clipping circuit, is based on a PCC88 \u2013 in this case made by Tesla in CZ before the world went insane, and should last probably as long as the vari-mu PCC189. \u201cProbably\u201d here because I\u2019ve only used these for 7-8 years, and I haven\u2019t yet had to replace one (!)<\/p>\n Contact Gyraf Audio for instructions on eventually replacing tubes when that time comes. Your local guitar amplifier repairman, if decently into tubes, could help with that also.<\/p>\n The G25-A is a not-yet-finished specialized version intended as power supply and hardware extension for the legendary Campbell Transmitter \u201cAstrud\u201d tube microphone. The Astrud connects through an additional 7-pin XLRf connector located on back panel. Astrud will be available only on special order and by appointment with mr. Campbell<\/p>\n Do not open this unit: When powered, there are high \u2013 potentially lethal \u2013 voltages present inside, including mains voltages. Refer servicing to qualified personnel.<\/p>\n You can safely remove the four rubber feet if you wish to mount this unit in a tight rack \u2013 please save the feet AND screws for future use, do NOT use longer screws than the supplied M3x6. NOTE: The feet are the ONLY part that can safely be removed. Do not loosen any other screws!<\/p>\n This unit operates from 220-230V AC, consumes about 34W, and the mains fuse is a 315mA slow-blow type. For the US-version, marked \u201cCE 115VAC\u201d above the power input connector, the operating voltage is 110-120VAC, and the fuse is a 630mA Slow-blow (\u201cT\u201d) type.<\/p>\n Warren Huart, on the G25 Eq section: (note that in this video there\u2019s also a long\u2019ish interview with Jakob Erland on general Gyraf units at 0-13min)<\/p>\nPreamplifier<\/h2>\n
Equalizer<\/h2>\n
Vari-mu Compressor<\/h2>\n
De-resonance\/Clipper<\/h2>\n
Technical:<\/h2>\n
Tube types:<\/h2>\n
G25-A<\/h2>\n
Important notice:<\/h2>\n
LINKS:<\/h2>\n