Here's a quick overview ... The Alesis QuadraVerb is a 16Hz-20kHz bandwidth stereo programmable effects box with four digital effects (EQ, Pitch Change, Delay, Reverb). The effects can be used in parallel or in serial (or a combination). Specs say the dynamic range is 85dB, less than .1% distortion. Processor speed is 24 MIPS (no Z80 in this baby!). Conversion scheme is 16-bit linear PCM. It's fully MIDI-fied.
In the following description, 'program' could mean 'patch'. I would say 'effect' but there are multiple effects in a program...
Touch sensitive (multi-speed!) programming buttons. Many have integral LED so you know what mode you're in. If you press harder you move the parameter faster.
2x16 character LCD display.
Stores 100 programs. Comes with 90 (in ROM) that you can overlay into the RAM. At any time you can recall one or all the ROM programs into RAM.
Real-time control of 8 simultaneous parameters via MIDI (you pick the controller type and the parameter it controls).
All functions, parameters and volume levels are programmable per program.
Stereo In/Out (via four 1/4 inch jacks).
Effect bypass jack on the back (as well as a button on the front).
You can name your programs (up to 14 characters).
Awesome effects ... a little noisy and "brittle" at times, but hey, it is almost twenty years old. I use it to create the "80s" guitar sound, aka Rhoads, Lynch etc., but it can do much much more.
My major complaint is that it "colors" your sound, even in the "bypass" mode.
The unit has five preset 'Configurations' which are variations on the above theme. They are:
Config 1: QuadMode(tm): 3-bandParaEQ->Pitch->Delay->Reverb
Config 2: Leslie->Delay->Reverb
Config 3: GraphicEQ(11Band)->Delay
Config 4: 5-bandParaEQ->Pitch->Delay
Config 5: 5-bandParaEQ->Reverb
You don't really need to study the configurations to understand the rest of this description, and these five configurations don't make the QuadraVerb as limited as it might look at first glance.
Each effect is impressive by itself. All are full bandwidth. Here's a quick rundown:
EQ - Usually a three-band parametric. The low and high bands are modified shelf-type EQs (you can't adjust the bandwidth, just the frequency) while the mid-band EQ is truly parametric (bandwidth adjustable from .2 to 2.55 octaves). Everything is +/-14db.
You can also get a five-band parametric. In config 4, you lose the Reverb but almost double the Delay time. In config 5 you lose the Delay but you can still get a chorus out of the Pitch section. Again, the low and high bands don't have bandwidth controls, but the middle three do. All are frequency adjustable, like the 3-band EQ.
You can also get an 11-band graphic EQ with delay (you lose Pitch and Reverb, however, the delay time is just about doubled from 'normal' operation). The EQ really is graphic! They use 11 line segments that can each move up and down on the LCD.
PITCH - The pitch can be either a Mono/Stereo Chorus, Mono/Stereo Flange, Pitch Detune or a Phase Shifter. You can vary the depth, speed and waveshape (triangle or square) of the LFO. The waveshape is only available in Chorus mode. You can also adjust the feedback, except in detune mode. It is possible to retrigger the flange at every new input signal event; good for drums and other percussive input sources.
DELAY - Usually 800ms delay in mono. In stereo, it's 400ms each channel. If you use the 5-band or graphic EQ you get 1500ms/750ms mono/stereo. There's also a ping-pong delay, where the delay bounces between the left and right channels.
REVERB - In addition to the two mixed inputs I already discussed, you can set and mix the amount of pre-delay - you can hear some of the reverb before the loudest part of the reverb. You can also adjust the decay time, as well as the separate controls for the low and high frequency decay (for shaping the reverb envelope). There are controls for adjusting the reverb diffusion and density (the manual has some nice graphs to show what these do). Finally, you can have the reverb gated and adjust the gate's hold rate, release rate and release level.
LESLIE - a Leslie simulator is built in. If you use it, you lose EQ and pitch controls, but keep delay and reverb. You can control stereo separation, motor control (on/off), speed (slow/fast), and the level of the high rotor in case you want the treble a little louder/softer than the bass. If you shut the motor off, the Leslie slows down until it stops!
MIX - each effect has its own level control, and there are Effects & Direct (dry) level controls, all programmable from 0-99, per program. This is in addition to the potentiometer on the front panel, which is not programmable.
MODULATION - as I said before, you can control just about everything via real-time MIDI controllers. Up to eight params can be controlled per program. For example, you can control LFO depth via aftertouch, Reverb High Decay via pitch bend, Mid EQ Bandwidth via note number, Leslie speed by an on/off switch, etc. You get the idea.
MIDI - you can assign channel (1-16 or omni, in omni mode it transmits on channel 1), turn program change on/off, SysEx on/off, start bulk or individual dump, etc. The usual stuff. In addition it has a program table, so you can map any of the 128 possible MIDI program numbers to any of the 100 available programs. Possible use would be to leave 0-99 alone and map 100-127 to various programs.
Botton line ... it takes some getting used to. But once you get used to it .... it sounds awesome !!