First of all I need to thank everyone who gave the prototype a work out and expressed their encouragement at the NY AmpShow in June. It's now time to turn it into a product. The "Zagray!" has been in development since around January 2009 when I first began toying with ideas for a new amp. My objective was to achieve a wide tone spectrum from rich cleans to roaring overdrive in a single channel that would be easy to dial in and tune to various pick-ups and playing dynamics. At the same time it should offer a very high "fun factor" and playability so that amplifier-player interaction will become a musical dialog instead of a manual dispute. An easily controlled musical acoustic feedback was also high on the priority list. The very first physical prototype was tried out in May-July 2009 after a hundreds of computer simulations, this was followed by several circuit modifications, re-designs and tests over the next 10 months. Finally, by the end of April 2010 prototype No.1 was behaving as I envisioned. It was time to build a presentable demo prototype No.2 from scratch in time for the NY AmpShow. This made the Atlantic crossing as checked baggage: The obvious departure from what we are used to see are the the transformers. Both PT nad OT are custom wound toroids, only the choke is standard but it will be replaced by an electronic ripple filter. It will save some 1.5 lb of weight. So, why all the different knob shapes? When I see a rows of identical knobs I get confused. We are visual creatures that recognize patterns. So I grouped the knobs by function and shapecoded them. Thus all chickens heads are tone controls, small round knobs are gain/distortion controls and the big round knob is Master Volume. On the production model there'll be 2 MVs for clean & overdrive modes, selectable via foot switch. What do the chicken head knobs do, from left to right: Bottom - this is a sweepable High Pass filter, use it to tame a boomy/farty cab or filter out low frequency rumble when playing in high gain overdrive, it will tighten up the low end. Bass - use together with Bottom knob: tighten and boost, great on palm mutes. Treble - wide range high end EQ reaching down to high mids prevents any screachy treble and also provides a frequency selective drive to the following gain stages. Bass & Treble are a James stack (sometimes called passive Baxandall), modified to suit guitar frequency range better than a hi-fi version. edit 6/26 Next chicken head, between GAIN and DRIVE, is the mid EQ labeled: Dip<->Hump - turn counter clockwise to create a mid dip, i.e. a rather narrow cut, turn clockwise past noon to get a wide mid boost. At 12 o'clock the frequency response is basically "guitar flat" which is not flat in the hi-fi sense. It balances/equalizes perceived volume of the strings, but not like a compressor. I have chosen wide mid boost in contrast to a narrow one to avoid a resonant quality in tone. IMO narrow mid peaks sound telephone like, more of an effect than tone enhancement. Below the Dip<->Hump we have a 4 position switch for 4 distinct mid center frequencies spaced at 1/2 octave intervals. The impact of switching the frequency is more pronounced the deeper dip is dialed in. The mid EQ can also be modified with two toggle switches: Accent - when EQ is adjusted to dip at earlier then noon setting this switch swaps relative balance of the before dip and after dip frequency bands. Toggle up for brighter rocky emphasis, toggle down for smoother mellow jazzy tone Boost toggle, when in upper position, basically defeats the Dip<->Hump setting. Last but not least of the chicken heads is: Crystal - it could be called brilliance or reverse cut but it's different. It is a high treble EQ aimed to tame high order harmonics produced in high Gain and/or Drive modes but can also be used to fine tune the high end in clean/crunch modes. It's like the difference when pinging a wine glass of fine crystal vs every day glass. On their own they both sound fine, but stand them side by side.... even the wine tastes differently. edit 7/1 SC/90/HB toggle, the one above input socket. I was never fully satisfied with the two input hi/lo system. It only gives 6db difference in amps input sensitivity but doesn't reflect various pickups fundamental tonal differences. So, instead of cutting input signal level by 6db we have the Single Coil / P90 / Humbucker toggle switch. It leaves guitar signal level unaltered but subtly changes amps voicing enhancing each pickup types character. In short, a single coil will sound "more" single coil etc. Of course, it's not disallowed to use a humbucker in SC position. Toggle between Bottom & Bass knobs is an On/Off switch for the Bottom HP filter. It's main purpose is to allow quick comparison of the effect this filter has on the low end when tuning in a speaker cab or finding just the right low end cut off in high gain/distortion settings. The round knobs GAIN, DRIVE In contrast to more conventional design practices both can be turned down to zero and there'll still be quite a lot of sound from the amp. Very dynamic, clean sound with lots of headroom. Diming VOLUME now can take you to power tube break-up/compression with no or very little distortion from the preamp. Turning DRIVE up, with GAIN still at zero, to around noon will gradually add more body to the clean sound and depending on the pickups will go to hairy crunch as you go to late lunch hours. At 5 o'clock tea time it gets sort of warewoolf hairy with a hot pickup. Now, turning DRIVE back to around midmorning coffe hour and turning GAIN up produces a different kind of distortion,a mixture of clipping and compression that gets rougher as you turn the knob past early lunch hours. Between 12 and 4 o'clock a lot happens and the GAIN knob may feel a bit nervous - that where the DRIVE comes back in. Simply put, at high Gain settings DRIVE allows you to fine tune overall gain making it easier to find that G-spot. VOLUME, well there'll be two of them on production model. One for Clean, one for the other extreme. Foot switchable ofcourse. edit 7/3 New freshly recorded video clips uploaded: http://www.youtube.com/vacuumvoodoo these have sound recorded separately to HD replacing cameras soundtrack. About clips on youtube: they don't do the amp full justice. The camcorder mic and sound recording channel are designed to give good reproduction of human speech, not music. It has a nasty peak in the 900 to ca 1500Hz range, that's where lots of harmonics in the overdriven guitar sound are. They get screwed up - over emphasized - by the camcorder. All that can be gleaned from youtube is basic tone range and character of the amp. ...I'll continue in a short while by editing this post. Clicking on "ZAGRAY!" in my sig below takes you to youtube demos.