The MXR 01A is a complex user-controlled device. While able to generate excellent analogues of natural reverberation, the MXR 01A ‘s capabilities offer the user an extreme range of effects.
The technology of digital reverberation has been steadily developing since its infancy in the early 60’s. The MXR 01A is the result of work done by researchers over this time, and in many respects is the most advanced design to date. Front panel controls offer the user access to important reverb variables simply and quickly, in an easily understood format. The programs available are selections of reverberation types most frequently used in the studio, such as plates, chambers and halls.
Decay times may be set over a wide range to produce expansive choral effects at high settings or to simulate small rooms, ideal for adding thickness and body to drum tracks. The MXR 01A may also be used live with remote controls to achieve sustain pedal and infinite decay time effects, as well as- dynamic reverb — a quite unnatural but useful program modification.
Program and option descriptions given in this manual are meant to be helpful in selecting appropriate settings, but there is no substitute for hands-on experience. The user is encouraged to experiment with the programs, discovering the possibilities within. The section on programs in the manual will provide a good starting point for your acoustic journey.
The MXR 01A is an outboard device intended to be used with a mixing console equipped with reverb send and receive controls. The maximum input and output levels are +6 dBV, therefore the mixer used should be capable of handling these levels without distortion.
Input: The input of the MXR 01A is mono, active balanced, with a 20K ohm input impedance. In connecting consoles with stereo sends, connect one send output or mix the sends to mono
before connecting to the reverb. When connecting to a board with single ended outputs, the (-) input (ring on the phone plug connection) should be connected along with the reverb input ground to the ground of the console send, through separate wires. This allows the balanced input to be fully realised. Special attention should be paid to this input in that at long decay time settings, the Zero-One has enormous gain at specific frequencies, and small amounts of noise and crosstalk at the input will result in exaggerated output noise levels. In less critical installations, a mono patch cord will suffice.
Outputs: The MXR 01A outputs are capable of driving full output levels into ‘600 ohm line impedances. The outputs are single ended, with a source impedance of 100 ohms. Shorting the outputs to obtain a mono output is not recommended. In such applications a 1K resistor in series with each output to a common point is advised. In applications requiring a mono output, such connection is desirable, in that higher echo density is achieved.
External Control: The MXR 01A is equipped with two rear panel jacks marked Hold and Stop. These are external controls meant to be connected to momentary, normally open switches, available as accessories. Pressing the Hold switch causes the reverb to extend its current decay time to infinity, and to return to the selected decay time upon release of the switch. This feature is wonderful for keyboard players, as it simulates the sustain pedal on a piano, and is usable with synthesisers. Depressing Hold for extended periods of time is not recommended, as input program material is still being conducted to the reverberator, a gradual build-up of noise and program are likely to overflow the processor, resulting in distortion.
Stop has the opposite function. When depressed, Stop will reduce the decay time to the minimum allowable for the selected program. Using a normally closed switch with Stop will be similar to the previous example of hold, with the exception that the maximum decay time is settable on the front panel. Stop is also useful with extreme settings of decay time in that the excessive reverberant energy can be stopped at will, smoothly and quickly.
Factory Presets: Version 1.1 contains factory presets that are not user alterable. These presets can be installed into the user alterable preset memory while destroying previously contained preset data. Recalling the factory presets is accomplished by pressing the preset 4 button, the decay time increase button and the program # increase button simultaneously.
