There are quite a few rarities in the rack processors family. The MXR Omni decidedly is one of these. It was produced in small quantities at the beginning of the eighties, before the MXR family exploded in a handfull of companies (ART and Alesis amongst others). Traditionally at the head of the game, MXR had launched into the production of analogic and digital rack units at the time.
The OMNI could be the american equivalent of the Ibanez UE400. It offers a range of MXR pedals with a dedicated footswitch giving individual or global bypass. As with the UE400s, the OMNI does not work without this footswitch but it can be connected to the central unit using a simple mono jack cable. The digital encoder allowing communication between the rack and footswitch of the unit in the picture was dead. It is not always easy to find obsolete components like this one today and the last available ones are expensive. But the investment was worth its while.
The effects are well thought out with a compressor, a distortion, a 3 band EQ, an analog delay, an analog chorus/flanger and a bypassable effects loop (unlike on the UEs...). The relative position of the EQ and the loop in the effects chain can be modified to a certain degree and the unit has stereo outs for the modulation and the delay. Furthermore there is a master volume offering more than unity gain. The effects are not straight copies of the usual MXR pedals and certainly aren't as great. The bypassed tone is slightly muffled. The compressor doesn't give the punch of the Dynacomp, the distortion lacks attack and output, and the 3-band eq frequencies have not been chosen wisely, but the flanger definetly is great. Thankfully, the old school and clean printed circuit allows all sorts of reversible modifications...

Produced during the same period as the OMNI from the previous article, the MXR Dual Fifteen Band EQ is a bog standard stereo graphic eq. It has balanced ins and outs and is mainly aimed at PA use. It can be used for guitar but doesn't offer remote switching (the IN/OUT switch is a "true bypass").
30 years ago, this type of unit was often used to modify or "improve" the response of guitar rack preamps. Nowadays, we are wise enough to simply get another preamp and the Dual Fifty is quite simply obsolete for guitarists.
Dating back to times when the digital delays weren't yet all that great, the Ibanez AD202 offered high quality analog delay for the guitarist in a 2U rack package (the REAL professional analog delay of the range was the AD302 with balanced ins and outs). This unit features no less than three bucket-brigade delay chips and sounds very clean for this type of technology. On top of the usual delay range, mix, regen, and modulation width and speed conrols, we get a very handy tone control for the delayed signal.
The tones are exceptional and as clean or as grungy as needed thanks to the tone control. The only low point is the fact that the delay time can be set when in Flanger mode. This is a shame because the flanging tones can be greatly affected by such a control (usually called "manual"). But fear no more because allowing the delay time knob to work on the AD202 is as simple as soldering a jumpre on two pins of the mode selector.
The Ibanez AD202 is without a doubt one of the best units for anybody enamoured with vintage delays and modulations and you quickly forget its cumbersome 2U format once you plug it in.
This unit is one great departure from the usual Peavey production and that may be why the rarest Peavey logo is used here (the one generally employed for the studio gear). The Valverb is a 100% valve reverb and tremolo unit that was more or less a part of the famous Classic range. Only a few units were distributed in Europe and a 1U tweed cover rack case could be ordered to match the amplifiers.
The Valverb offers unconvincing trem tones that quickly create a far too great loss in volume. This is due to an inadequate oscillator design which can be improved to a certain extent. The modulation speed and depth ranges are good nevertheless. On the contrary, the reverb is smooth and deep, and can be tailored thanks to its 3 band eq and mix control. There is a lot to play with here and classic surf tones or more traditional ambient can be obtained easily. It doesn't sound like a Fender 6G15 but it is a great effect in its own wright and will compare favourably with many onboard reverbs.
There aren't many analog guitar reverbs in a 1U rack format (TubeWorks and Torque models exist) and this is the only full tube one that I know off. Could this be the first collectable Peavey unit ever?
Who said digital delays sounded cold? The Ibanez HD1500, like many units with average digital specs (by today's standards) offers some great warm tones. The Ibanez HD range is diverse and each unit has its advantages and disadvantages. The 1500 and 2000 produce a great polyphonic pitch shift (and not harmonizing despite their name). In fact, the effect is much clearer and stable than that of a Digitech Whammy, and the detuning amount can theoritically be controlled by a pedal (although I still have to design that one).
The HD1500 also feature an effects loop placed in its feedback path. This means that one can add modulation to the delayed or pitch shifted sounds, or whatever special effect you can think of (overdrive, treble cut or emphasis, reverb, another pitch shifter, etc...). This unit can be as wild as you want it to be! Low delay time settings can give some really great flanging tones but the modulation is unfortunately not wide enough for my tastes.
There is no MIDI feature (footswitching is done through a standard jack) and it is not possible to store the settings of the delay time. The unit is therefore less suited for live applications but the HD1500 is a great buy be it only for its delay tones. Or its pitch shifting tones, or its feedback effects loop... Well you get my drift: I like it a lot even though the noise floor is pretty high.
The Roland RE-3 Space Echo is the least famous unit of the sought after Space Echo range. Truth be told, it bears very few resemblance to the famous tape echos and gives a limited selection of digital effects. Dating back from the end of the 80s, it is a specialized unit offering only delays and reverbs with or without pitch modulation.
The RE-3 nevertheless has some advantages. It is very easy to use, with all its parameters controlled by traditional pots. It offers 5 different effects (only one at at time): 3 types of delay + reverb, and two stand-alone reverbs. 5 presets can be recalled by MIDI for each effect, or they can be switched by a standard footswitch. The tones have pretty much nothing to do with the Roland tape echos and spring reverbs, but they are very good in their own wright with great clarity and depth. I would qualify them as "eighties studio quality". The modulation control on reverbs and delays (strangely called "Warmth") can give some very natural tones with low settings, or wild and seasickness-inducing warble when you go too far.
One of the greatest advantages of the RE-3 is that it works perfectly in the effects loops of Soldano Hot Rods, ROS or SLOs which are too hot for your average effects processor. Great reverbs and delays on a Soldano at a low price! How would have thought of that?