Q1) Are your pedals clones of other pedals? If so, what pedals do they clone?
A1) None of the AXiom line of pedals are direct clones. They were all designed from the ground up to address the weaknesses and shortcomings common to many effects of their types. They do tend to be "inspired" by classic pedals, however, and they do contain critical sections of circuitry that are the same or similar to iconic, industry standard defining effects. This is so they can authentically capture the tone and response of the classic effect types they represent while eliminating the weak points of the old designs and expanding on their capabilities.
All musicians have pedals that they absolutely love and couldn't live without - some of these effects have become industry standards and have defined the sound of entire genres of music. But all musicians also, at times, have wished for a little more - that their chorus had just a bit more depth or a better stereo spread; or that their distortion had more bottom end without getting loose and buzzy; or that their favorite compressor didn't hiss so much; or that their overdrive could sound more like a real cranked tube amp when they wanted it to. These are the sorts of things that the AXiom line address - built on the shoulders of industry standards but to a higher standard at the same time.
Q2) What is the difference between the Overdrive Preamp OP-1 and the Distortion Preamp DP-1?
A2) The Overdrive Preamp OP-1 is very much in the traditional overdrive pedal family. It goes well beyond the traditional overdrive pedals' level of gain and frequency control but, tonally, it's in the same camp. The OVERDRIVE stage is a classic Tube Screamer style circuit and the PREAMP stage is designed to take the place of a tube preamp (but, in this case, voiced specifically to work in cascade with the PREAMP). You can use either stage alone by turning the other stage down, in which case the OP-1 becomes a classic overdrive pedal (with a very powerful tone control section) or you can use the stages together like an overdrive pedal pushing a tube preamp.
The Distortion Preamp DP-1 is firmly in the distortion pedal family but also has a character that allows it to take on amp-like tones rather than the buzziness and fizziness distortion pedals are often prone to. At light gains it can cover overdrive-like sounds, but at high gains it's brutal. The MORE section of the DP-1 extends the range of the DISTORTION control. With the MORE control turned down and using only the DISTORTION control for gain, the pedal acts like a very versatile traditional distortion pedal - with the ability to get as loose or tight in the bottom as you'd ever need without altering the tone via the classic/modern switch. MORE takes that basic tone and adds heaps of gain to it while preserving the picking clarity these types of pedals are known for... and without becoming shrill.
In comparison, the Overdrive Preamp is a bit smoother, less compressed and with the PREAMP control dialed up it's like a classic tube preamp being pushed by an overdirve pedal. In fact, with a cab emulator or IR you might not need an amp at all (that's how the OP-1 demos on this site were recorded). The Distortion Preamp is "rawer" and more agressive, like a modern high-gain metal preamp - though, if you dial the MORE control back, it turns into a classic 1970's/'80s style distortion pedal. Both the OP-1 and DP-1 are capable of doing clean through light break-up to very highly saturated tones. Broadly speaking, one could consider the OP-1 as more ideally suited to blues, hard rock and tube preamp emulation, and the DP-1 better for high-gain metal and shredding - though both are very versatile in how they can be dialed in and each can cover a broad variety of applications.
Q3) Does the Fuzz Preamp FP-1 use germanium or silicon transistors? How did you choose the transistor type?
A3) Like many things in the music industry, there is a huge amount of hype and misunderstanding surrounding fuzz pedals. In the mid-1960s the original fuzz pedals used germanium transistors and some of them sounded great... some of them didn't. Germanium transistors are very inconsistent. That's why people would go through batches of old germanium fuzzes trying to find a good one. By the late '60s fuzz pedals were switching to silicon transistors because they were more consistent and stable, but in today's climate of "everything old is better" they're often accused of sounding harsh. In reality, silicon transistors did sound different, but it wasn't the silicon technology itself that made the difference, but rather the gains of the individual transistors and how they biased in the original circuits. Silicon transistors generally have higher gains than germanium, bias to higher voltages in a fuzz configuration, and when they were substituted into circuits designed for ge rmanium transistors they didn't always work well. The same could be said for germanium transistors substituted into fuzzes designed for silicon. Don't forget that Hendrix preferred and recorded what many consider to be his greatest guitar performances on Electric Ladyland and Band of Gypsys with silicon transistor Fuzz Faces (Voodoo Child, Machine Gun, etc).
If the circuit is designed for it, silicon transistors sound every bit as good as germanium transistors but with better consistency, temperature stability, and the ability to use standard 9V dc power supplies instead of requiring an adapter. Yes, there are differences, but those are largely due to gain levels at the input stage (in a traditional Fuzz Face or Tone Bender 1.5), bias points and (to a lesser extent) frequency responses. The AXiom Fuzz Preamp FP-1 was designed with full awareness of these electronic parameters to work with silicon. In fact, it manipulates those parameters to sound like either silicon or germanium fuzzes. It's a case of adapting more modern technology, with its technical advantages, to capture the characteristics of older technology, but without the disadvantages. The FP-1 can produce the warm, clear, mid-focused sound of germanium fuzz along with the aggression, bite and "explosive" compression of silicon too - that was part of the whole point in designing the FP-1 in the first place.
Beyond the FUZZ section, the FP-1 preamp section is inspired by the AXiom Overdrive Preamp OP-1. The GAIN control is designed to add the gain and clipping of a tube preamp while biasing the fuzz transistors for more warmth or bite accordingly. So, using the FUZZ and GAIN stages together is like a fuzz pedal pushing a crunchy tube amp. Furthermore, the BASS and MID controls were designed purposefully to work with the preamp stage to produce an authentic overdrive of its own. That's right, dial the FUZZ control back and trim the bass and mids to taste with the BASS and MID controls and the FP-1 becomes a moderate gain overdrive pedal.
Q4) What do the BASS and TREBLE controls on the AXiom Stereo Chorus-Vibrato SCV-1 do? Are they just tone controls?
A4) Producing an excellent sounding chorus effect isn't simply a matter of applying modulation to all frequencies. Choruses must be properly "tuned" by selectively applying the effect to a specific frequency band and then mixing that effect with the uneffected signal. All well-designed chorus effects do this and the frequency range over which chorus is applied goes a long way to making a chorus sound the way it does. The not-so-well loved choruses often just don't get it right (and usually get forgotten in time).
Applying too much chorus effect to treble frequencies tends to make choruses sound shrill and thin. Applying too much chorus effect to bass frequencies puts too much "warble" on the fundamental notes and sounds "sea-sickening" before long. The key to great chorus is applying the effect to the right frequencies - the right blend of chorus on the fundamentals and higher harmonics (but not too high).
The BASS and TREBLE controls on the AXiom Stereo Chorus-Vibrato SCV-1 allow the user to adjust how much chorus is applied to the low and high frequencies. You can adjust it for solid, unwavering fundamental notes while still applying chorus to the higher harmonics or trim the high frequency chorus to avoid shrillness without affecting your overall tone. This allows the user to tune the SCV-1 optimally for rhythm, lead, bass or acoustic guitar.
Q5) Is the Omega-Vibe OV-1 a Uni-Vibe clone with more controls?
A5) It has more controls but, no, it isn't a direct Uni-Vibe clone. The Omega-Vibe uses a phasing section based on the original Uni-Vibe, with identical frequency notches and peaks, as that's part of creating the classic sound, but the OV-1 has different input, output and oscillator sections, and it implements the frequency sweep by different means. Therefore, it can authentically reproduce the sound of a pulsating lamp-based Uni-Vibe but it can also do much more.
The Uni-Vibe (and clones) use an incandescent lamp to create a low-end throb and asymmetrical double pulse that is a defining characteristic of "real" Uni-Vibes. Until now, the only way to reproduce that double pulse is either by cloning the Uni-Vibe directly or making a digital model. None of the phaser-based vibes on the market can do it.
The OV-1 uses a sophisticated oscillator section that allows the user to create just about any practical frequency sweep characteristic one would want - including that authentic asymmetrical double pulse throb that only "real" Uni-Vibes can do. The difference is the OV-1 produces this same effect while consuming only a fraction of the current (so you can run it off a 9V battery) and with a vastly expanded control section. You can set the OV-1 to accurately reproduce the response of a 1960's or 1970's Uni-Vibe or even mimic the characteristics of a new or aging lamp and how the lamp is biased internally.
Q6) If the Omega-Vibe runs on 9 Vdc how can it have as much clean headroom as Uni-Vibe clones that run on 18 Volts?
A6) The original Uni-Vibe circuit needs a higher voltage to properly run its incandescent bulb. The signal into the phasing section, however, isn't centrally biased at the transistors and it suffers from headroom issues. This generally wasn't an issue in the late 1960s with vintage output pickups but it doesn't hold up too well today with even slightly hotter signals (the same could be said of many phasers and choruses of the 1970s). The Omega-Vibe has its gain structure configured differently so it has more headroom than a traditional vibe, produces the same pulsing modulation, yet runs on a much more convenient 9 Vdc.
Q7) What exactly is harmonic tremolo and how is it different from regular tremolo?
A7) The "standard" tremolo effect is obtained simply by swelling volume up and down repeatedly (or in the extreme case shutting the volume completely off and on). You can get a similar effect by pulsing your guitar's volume knob up and down as you play. When it comes to "standard" tremolo what makes all the difference in how the volume pulses up and down. Does it ramp up and down linearly or follow more of a sine wave oscillation (usually associated with "swampy" tremolo)? How quiet does it go when the volume dips down and how loud is it when it pulses fully on (i.e. the "depth")? How fast does it oscillate - slowly like the tide rolling in and out, or fast like a flutter? Is it "choppy" or "smooth? Yes, tremolo is a relatively straight-forward effect but for tremolo fans the devil is in the details... and those details do make a difference.
Harmonic tremolo refers to the unique tremolo effect found on some very late '50s and early '60s Fender amps. Harmonic tremolos work by filtering the signal into two separate high and low frequency bands and applying volume modulation to them 180 degrees out of phase with each other. The result is a very rich, very smooth tremolo effect that has an almost phase-shifter or Uni-Vibe quality to it. This type of tremolo was found only on high-powered Fender amps for a few years (during the Brownface/Blonde era), presumably because it was so complex to implement (requiring 4-5 preamp tube stages). For many, though, it is the ultimate tremolo effect.