VFE (VonRutter) White Horse: This is an optical comp pedal from a small-time builder who has mostly been known (so far) for taking "clone" circuit designs and combining or mutating them in novel ways. However the White Horse is really its own developed circuit, it's not just a clone.
For starters, it has many more controls than a typical opto pedal. There are five knobs, a 3-way toggle switch, and four internal switches. Additionally, it can be used as a clean boost, a dirty boost, or an overdrive (but not all at the same time). The Sustain knob controls the amount of pre-gain going into the compression/drive circuit, which increases the amount of compression or drive. The O/B/C switch toggles between Overdrive, Boost, and Compressor functions. The Blend knob controls the mix of the effected and clean signals. Release controls the release time of the compression envelope. The Threshold knob does essentially control the threshold where the comp kicks in, but more particularly it limits the opto element's reaction to the gain provided via the Sustain knob. So the Sustain and Threshold knobs are much more interactive here than they are on most other comps. Level controls the output volume. As for the internal DIP switches, the first one (nearest to the LDR opto unit) doubles the LDR effect, increasing the attack time and the comp ratio; the middle two control the attack time from fast to slow; and the last one (nearest the output jack) allows more bass to pass through.
With that switch engaged, the low frequencies are ruler-flat down to 10 Hz. Switched to the other position, it doesn't actually lose the low end, it's just more of a mid-hump, entirely usable and pleasant for all instruments. There is a bit of high-frequency rolloff in both positions--not enough to make it particularly dark or dull sounding, but enough to bother people who want a really bright sound. The tone is very clean and uncolored, except that it can tend to distort at some settings. I was able to find a range of settings that did not have distortion, but it took a while of experimentation to get there. That's the down side inherent to breaking out so many controls from an otherwise simple circuit. I think part of the problem is the amount of gain available via the Sustain knob, and part of it results from low headroom at the input. So higher-output instruments may have trouble with distortion from this pedal. The settings that will or won't distort for you will depend on your specific instrument and your playing style, so you'll have to experiment. Start with the Sustain around 10:00 and the Threshold around 11:00, and go from there.
If you like the sound of a clean opto comp but don't want to spend time tweaking knobs, then stick with the basic BYOC, BBE, Demeter, etc. It's even possible that my favorite non-distorting settings on the White Horse are essentially the same as the preset values built into those two-knob pedals; but if you like tweaking your sound then this will be a more interesting pedal for you. There is almost no noise, and the action is smooth and natural--unless you have the Sustain set high. At high Sustain, your whole signal will be very compressed, so that when it releases there will be a massive swell of noise and volume, which then ducks back down when you hit another note. It can do a decent job of peak limiting, but I wouldn't recommend it for heavy hitters.
The overdrive has a warm, furry, compressed quality, and the Blend knob is a very good feature here for retaining more of your dynamics and articulation. The Boost section starts off as a clean boost with the Sustain knob at a low setting, and it gets dirtier and more driven the higher you turn up the Sustain. At max Sustain, it's fully a screamy distortion. Personally I don't like that max distortion sound, but the more medium-range dirty boost is very good for pushing the input of a tube amp. My only complaint about the OD and Boost features is that they can't be used at the same time as the compressor, and you have to totally change your knob settings when going back and forth between features. It's hard enough dialing in the perfect distortion-free compression, that I don't want to mess with those knob settings at all. So the versatility is good and welcome, but don't expect to be able to switch between comp and OD "on the fly", during a gig. VFE does custom-make dual-effect pedals, so I'm tempted to order one with two White Horses in it, for different settings. I do like this comp a lot, once it's dialed in.
The housing is the small MXR/Keeley size. The parts are very good quality, and the white knobs and DC jack are a nice touch, but the paint job and lettering are home-made looking. It runs on normal Boss-type 9VDC, and the footswitch is true bypass.