Acid Fuzz Sonic Boom


Acid Fuzz

The Sonic Boom is based on the built-in/on-board effects Vox put in some of their professional line of guitars around 1967-68, models like the Starstream, Ultrasonic, Delta, etc... Specifically it’s based around the holy trinity of the “Treble/Bass Booster”  “Distortion” and “Repeater” effects.  I don’t know what kind of acid those guys at Vox/JMI were smoking back then, but they produced some of the wackiest and best sounding musical devices of their time.  Although I don’t think these effects ever got their just desserts until the 1980’s when Spacemen 3 got a hold of them.  If you’ve never had the chance to check out one of these guitars let’s just say they are a real fun trip, very hypnotic and psychedelic, especially when the effects are used together.

However, there were a lot of problems with the Vox effects as I saw them.  Vox used the same exact “T/B Booster” and “Distortion” circuits, part for part, in both their guitars and basses!?  Bad Idea.  So, on the guitars, the booster really only sounds good at the treble end of the knob, say 8-10.  From about 2 to 8 it’s tinny and low volume with no mids.  With the “distortion” on the booster does have a great Velcro fuzz sound.  On the other hand, on the bass guitars the booster only sounds really good at the extreme BASS end of the knob.  Anywhere else on the dial it’s very thin.  As a stand alone booster the Vox T/B Booster is OK, not amazing.  It’s only when you use it with the fuzz and repeater that the real magic happens.  The Repeater is an AMAZING effect, but when you switch it on there is first a very loud “POP” as it powers on, then there is a substantial volume drop while this effect is engaged.  The distortion/fuzz is a great sounding Fuzz Face type circuit, but because Vox wired the guitars signal from the pickups directly to the input of the effect, with the guitars volume after the effect output, the guitar master volume does not have the same clean up interaction with the fuzz.  Kind of a bummer if you like to control and clean up your fuzz that way.  Some of these guitars also came with an E or G tuner, and a palm operated wah.  Yes a built in fu$%ing palm-operated wah-wah controlled by a big chrome “V” that swivels out of the way towards the bridge when not in use.  In fact, the wah was essentially the same circuit as the great sounding and highly $ought after early grey Vox wah pedal with the 250 mH inductor. Same Wah sound used by Page, and many other classis British guitarists of the time.  Of course you still have to operate it with your picking hand while playing, instead of the much more ergonomic foot operated rocker pedal.  The tuner was basically just an oscillator that gave you a barely audible note to tune with.  Maybe useful to have in 1968 as a tuner, or on acid with all the effects on you can hear it and could perhaps use it as a subtle background drone while playing in the same key.  Wacky.  So, the idea with this one is to take the Vox Starstream as a starting point, trim off the fat, keep the really good stuff and make it even better.

So, “Three In One”.  What do these three things do?  Individually and Together?

The “booster” section is a frequency selective volume booster.  In other words a type of filter that boosts only the frequencies around where you select with the range knob. The original Vox “booster” was still only at about unity gain.  Anything below the treble end on a guitar there was actually a volume drop and things got very thin or muddy in a bad way. I’ve modified the booster to maintain the same volume level regardless of the tonal range setting, bumped up the available output volume boost and added a volume control so you can actually dial in both the frequency range you want to boost as well as how much you want to boost it. The frequency range available is much greater than most boosters. The tonal range goes from VERY trebly to WAY DOWN stinky low.  So, you can also use this one with bass and keyboard/organ with great results.  Due to the extreme low-end boost available this is also great for making a vintage bass with low output pickups really sit up and beg.  At high boost volume it grows a little hair down on the low end too. Great for growing some bass balls.

The “distortion” is actually a very nice FUZZ.  Basically the same as the built in “Distortion” in the Vox guitars and the little plug in boxes Vox/Jen made called the “Vox Distortion Booster V8162” and “Jen Distortion Booster PE402”. Closely related to the silicon Fuzz Face and many other YAFF circuits,  it has a bit more definition than a fuzz face, but still has all the rich full fuzzy harmonic overtones you’d expect from a nice fuzz face. It is in short a badass sounding fuzz.  I didn’t think the original Vox circuit needed much help, aside from proper shielding to avoid picking up EMI and radio interference, so I just added a master volume and external bias control so you can get some other flavors of fuzz and varying degrees of headroom.  There’s also more output volume available so you can dial it in just how you like it.

“Repeater”. One of my all time favorite effects. Period. The unique “Vox Repeat Percussion V809”, also released as a Jen labeled unit.  Some describe this effect as a type of delay, others call it a tremolo. It is essentially an oscillator tremolo that produces a sawtooth waveform similar in shape to a right triangle. At slower speeds this sharp ramp up and subsequently sharper drop in volume does produce a sound similar to some analog delays.  The effect gives the illusion of an automatic repetition of the note as if being repeatedly played (repeater) at a constant rate some time after (delay) the initial note is played.  This effect is exaggerated and enhanced when used in conjunction with the fuzz and booster, which really get it spitting.

There are also controls to re-route the order of the booster and distortion allowing for two very different sounds when both effects are engaged simultaneously. Running the distortion first produces a very extreme fuzz sound similar to tacking on an extra gain stage and tone control. This setting really knocks the fuzz up to 11 when you kick on the booster.  Vice versa, running the booster before the distortion produces a very filtered sound like a parked wah and can be used to boost and filter the tone in a similar manner.

I’ve enhanced the repeater’s depth and cut properties and bumped up it’s output volume so you can actually get a volume increase when this effect is on. In addition to the stock “rate” control, the three above aspects all have their own control so you can dial in the exact depth, cut, and volume of the effect.  As the original repeater also cuts a lot of low end from your signal, which is nice and cutting in it’s own way, I’ve added a tone voicing switch so you can toggle between this brighter sound or a full tone. I really opened up the speed range of the repeater and in mode 2 it will go in to a full on ring mod effect which you can tune to resonate in a particular key. Last but not least, the repeater has a dedicated LED that flashes in time with the repeater effect, even when bypassed.  So, you never have to guess where it’s at.  Useful on a dark stage or under the influence…or both.

In addition to the usual input/output and 9V power jacks there’s an effects loop and expression pedal jacks for the repeater rate and mode controls.

It seemed appropriate to move the new pcb construction Sonic Boom 3 in One in to the “One” enclosure from pedalenclosures. It’s perfect for multistomps and designs with many switch/control options. The front is raised and sloped allowing for mounting of multiple stomp switches without worrying about your foot hitting the other controls.

Under the hood it’s quality components throughout. WIMA or similar film box caps, tantalum and long life electrolytic capacitors, nos BC108 transistors for the fuzz and booster, low noise MPSA18’s and the original 2N2646 unijunction transistor for the repeater, etc…A nice compact package you can use with any guitar, bass, or whatever you want to do.

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low frequency oscillator lfo-controlled fx pedal stompbox stomp box guitar effects pedal amplifier amp amplification preamp pre-amp volume/amplification tremolo trem modulation modulate time-based lfo fuzz distortion/fuzz/overdrive dirt grit
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