It was not long after beginning to study music that I became fascinated with the sonic possibilities of signal processing. My primary instrument being the guitar, it was natural to first explore signal processing through effects pedals. Eventually I also became interested in synthesizers, and software for signal processing, but still today I love analog pedals of yesteryear and the sounds they offer.
Over the years, I have looked closely at the pedals I have owned - more from a standpoint of what they can do and how they can be used, than the finer points of circuit design. But I have also spent some time comparing models that differ only on such finer points.
Here are some brief thoughts on some of the pedals I have studied, just my humble opinion as a lover of pedals.
Boss AC-3 Acoustic Simulator
The Boss AC-3 is obviously marketed towards turning your electric guitar into an acoustic. If you play live with a band, it can maybe do this passably. Listening in detail in a studio environment, you will be underwhelmed or disappointed. The options available through tweaking the knobs seem encouraging, but no.
Surprisingly, there is a better use - as a 'preamp' for an actual acoustic guitar. The AC-3 is full-on digital, and the tonal possibilities are limited. There are better choices of course, but if you have one lying around...
Boss CH-1 Super Chorus
The current version Boss CH-1 pedal is digital, but the original version was analog, and this is the one I have tried. Boss is usually pretty solid in their design concept, the CH-1 meets expectations in that regard. The stereo output configuration is nice, allowing for spatial chorus effects like a JC-120, or a vibrato effect with a dummy plug in the second output. As for the sound - it is a workable analog chorus with little or no personality. It can get the sounds one would expect. That might be exactly what you want, I usually want something more. I prefer the Boss CE-3, CE-2, and Ibanez/Maxon CS-9, to name a few.
Boss HR-2 Harmonist
The Boss HR-2 was the first intelligent pitch shifter in pedal format, released in 1994. It tracks pretty well if you put it first in the chain or use the detector input direct from your guitar (if you want it later in the chain). That said, it is not always perfect. And being a pedal from the 90s, it does not have the fidelity of a modern pitch shifter. But it has its own personality and is easy to use. You can add one or two independent harmony voices - up or down a 3rd, 4th, 5th, 6th, or octave - in the key of your choice, that can be output separately (via A and B outputs) or together (using just the A output). There is also a detune setting for each voice, and they are different, so you can use one or the other, or both together for a deeper detune effect. Overall, the HR-2 offers a good range of traditional to experimental sounds.
Boss OD-1 OverDrive
The Boss OD-1 was the first Boss compact pedal, way back in 1977. It is a classic, but I can see why some people hate it. It doesn't sound modern or transparent, it can sound old or boxy. But I love it, and in a sea of drive pedals, I always come back to it. I especially like the low drive settings and its usefulness driving other pedals or an amp.
Boss OD-3 OverDrive
The Boss OD-3 offers a good sound, it is a pretty obvious attempt by Boss to make a more 'transparent' overdrive, in contrast to earier models. Shocking is the absence of high end - even with tone knob fully clockwise, it is still kind of muffled. Maybe it is a different story with single coils and a Rangemaster.
Boss PH-1r Phaser
The Boss PH-1r is an update of the Boss PH-1, with an added resonance control. It is a 4-stage design released in 1980, in the shadow of the MXR Phase 90, which was already popular. The design goes beyond the simplicity of the Phase 90, and its sounds go beyond as well. All of the Boss pedals I have kept are the earlier ones from the 1980s made in Japan - the PH-1r is a great example - well-designed and built, and of course 100% analog.
Boss PH-2 Super Phaser
In the world of phasers, the Boss PH-2 is one of my underrated favorites. It's a great design with two modes (10- or 12-stage), pretty innovative in the 80s. It can get a wide range of sounds, including some weird ones in Mode II. It just sounds good - and a little different from many of the others out there.
Boss PH-3 Phase Shifter
The Boss PH-3 is an all-digital Swiss army knife of a phaser, with a switchable number of stages (4,8,10, or 12), built-in tap tempo, external pedal control, and rise, fall, and step modes. The sounds from the special modes are sometimes interesting, but not really what I am looking for in a phaser. You have to hand it to Boss on the design - they took it in a new direction. Overall, the sound is heavy and not organic, which may be preferable to some players. To me it sounds a little fake.
Boss XT-2 Xtortion
A clever name, a cool sparkly red color, and distortion sounds, most of which are not good. This is the second worst Boss distortion pedal I have tried, the PW-2 is the worst. I had my XT-2 modified into a noise machine, which was an improvement, before I eventually sold it. For me, the only hope was at the very bottom of the drive range, where the sound could be an odd kind of Fender-ish light crunch.
BBE Mind Bender
A good concept - a Boss VB-2 clone and Way Huge Blue Hippo Chorus clone in one box, all analog, well-built with
high-quality components, and true bypass. Unfortunately, it it lazily implemented with an on/off switch to go
between them, and no effect level knob for the chorus. The vibrato sounds very good, true to the VB-2. The chorus is unusable,
unless you like things absolutely soaked in chorus. It sounds like it is set at 50/50 with the dry signal.
I've never played the Way Huge Blue Hippo, maybe it is just being true to the original. For multiple modulation functionalities in the same price range, check out the BYOC Mega Chorus and Vibrato, a truly brilliant pedal with many tweaking options.
DOD Phasor 201
The DOD Phasor 201 is one of the first phasers known to mankind, from back when it was spelled 'phasor'. It is a really nice sounding one, inherently light compared to many models due to its 2-stage design. As such, it is easy to keep it from getting in the way of your tone.
DOD FX22 Vibrothang
The DOD FX22 Vibrothang is a blend of phaser, tremolo, and secret sauce that yields some interesting sounds in the general range of a Uni-vibe pedal. But most prominent is the tremolo. The phaser is not too whooshy and it is always synchronized with the tremolo as they share a speed control. It doesn't do as many different things as the knobs might suggest, and tweaking it is not that easy. But it's all worth it once you get it right.
DOD Overdrive Preamp 250
The DOD Overdrive Preamp 250 is one of those few classic pedals that everyone who plays the electric guitar should spend some time with. It has some unique sounds, at both low and high drive settings, and it works well alone as an overdrive/distortion or driving an amp. The original gray version (LM741 op amp) is the best, but the 2013 reissue (gold color) also uses the LM741.
Fender Starcaster Chorus
The Fender Starcaster Chorus is analog and has the same basic design as the Boss CE-5 Chorus Ensemble (which was analog, then digital), with the exception of being mono and having more useful hi- and lo-cut filters. The sound is comparable - a wide range of tones from flangey to wobbly. Like the CE-5, it is not the silkiest chorus out there, and it has not a lot of personality, but it can make that somewhat harder chorus sound that holds up well when more attack is needed, and it never mushes out. The effect level control allows for as much subtlety as you want. The hi- and lo-cut filters can affect the tone a lot, a very nice feature. They only affect the chorused sound, not the dry signal passing through, which is ideal. Rolling off more highs yields a softer, mellowed chorus sound found on a lot of other models.
Henretta Engineering Green Zapper Auto Filter
This is a great sounding auto filter - analog, true bypass, very small and with no knobs. It does have two trimpots inside to adjust frequency range and sensitivity, which you can optimize for your guitar, playing style, how dramatic of an effect you want, etc. The Green Zapper may leave someone looking to tweak a little wanting, but the sound, the size, and simplicity of the design make this pedal ideal for live use, or if you are just looking for some good auto filter sounds without a bunch of weak ones. It can be set and forget, but adjusting the trimpots is actually very easy, and provides different sound options.
Ibanez PH10 Bi-Mode Phaser
The Ibanez PH10 (manufactured by Maxon) is a colorful and mostly unsung phaser from the mid-80s. It doesn't have overblown sounds. It seems to have a lighter wet/dry ratio, and a small mid boost that helps propel the effect with cleaner sounds. When you turn it up it gets plenty phasey, but the lower settings aren't overcome with whooshing, and chords don't mush out. It is switchable between 6 and 10 stages, somewhat unusual for phasers of the era. The feedback does not self-oscillate, but yields some strange hollow, flange-like tones at higher settings, especially in 10-stage mode, and some really nice subtlety with the feedback down. The PH10 has a slower sweep speed than most phasers - 25 seconds at the minimum setting, glacially slow compared to some others. This can create some cocked wah-type sounds with the depth set lower and the feedback set higher.
Maxon CP101 Compressor
The Maxon CP101 is an optical design that sounds good, and is fairly quiet as compressors go. As a faithful reissue of the 1970s original, it is buffered, not true bypass. It is designed to be a transparent smoothing-type compressor, with a fixed ratio of 4:1, and little or no tonal shift or coloration. With the sustain all the way up you can get a little squash, more than an Orange Squeezer, less than a DynaComp. You can make it more dramatic by goosing up the input level, but that is probably not how you would want to use it.
Maxon PT999 Phase Tone
The Maxon PT999 is a 4-stage phaser design originally released in 1974, reissued in identical form today. It came out around the same time as the MXR Phase 90, and by appearance (one knob for speed) is very similar. The sound is excellent, and without the coloration of the Phase 90. For me, the lack of coloration and distortion make it better than the Phase 90 with clean sounds, and actually with most other sounds too.