Digitech RPM1 Valve Rotary Speaker Simulator in excellent condition.

Thoroughly tested and in perfect working order.

When electric organs were first sold, their sound was static and needed some “animation”, so the rotating speaker cabinet was born. The rotating speaker sound became synonymous with blues, jazz and rock & roll, especially when players discovered that they could drive the cabinets’ built-in tube amplifiers into distortion and get a thick, warm sound as well as the swirling rotary effect. (See diagram, page 6) The DigiTech RPM-1 allows you to emulate that classic rotating speaker sound without having to deal with the bulky speaker cabinets that were formerly required. Based on extensive study of rotating speaker cabinets, the DigiTech RPM-1 incorporates speaker emulation circuitry which delivers an authentic sound by recreating the individual horn and cabinet resonances of a real rotating speaker.

There are several features of the DigiTech RPM–1 that make it unique: 1) Where competing products use solid-state distortion circuitry to simulate overdriven sounds, the DigiTech RPM-1 is unique in that it uses a vacuum tube analog distortion pre-amp. The 12AX7A pre-amp stage gives you the authentic, rich, warm overdriven sounds previously attainable only with actual rotating speaker cabinets. 2) Only the DigiTech RPM-1 gives you the flexibility to run mono, stereo, or tri-output mode to simulate the most effective microphone arrangements on stage or in the studio. 3) The DigiTech RPM-1 is a ruggedly built, 1U full rack-mount unit, with AC power. No external power supplies or flimsy plastic cases. 4) While other units are based on modified chorus or phase-shifting circuits, only the DigiTech RPM-1 incorporates patented Intelligent Pitch Shifting technology together with VLSI delay and volume modulation circuitry for maximum realism.

Power Switch Turn on the RPM-1 before your mixer or amplifier, or turn down volume on mixer or amp if you are going to switch the RPM-1 on or off. Input Controls the input level to the RPM-1. Adjust this while playing so that the Clip indicator only flashes on the loudest musical peaks. Turning up the Drive control increases the pre-amp gain, and you may have to adjust the Input after setting the Drive. (See also page 4 for balancing Bypass) Speed Switch (also activated by the left foot switch button) Alternates between the slow and fast rotary speeds. The light will flash in time with the revolutions. Brake (also activated by the center foot switch button) Stops the rotation portion of the effect, leaving the Drive and Cabinet Emulation effects in place. The Brake over-rides the speed control; turn off the Brake to return to the rotating sound. When the Brake is applied, the Horn and Rotor stop at a random position, like a real rotating speaker. By quickly dis-engaging and re-engaging the Brake, you can change the stopped position, to control the harmonic content of the stationary sound. Bypass (also activated by the right foot switch button) Bypasses the RPM-1 effects so that the original “dry” signal is sent to all three outputs. The Bypass is full Stereo - Right and Left inputs remain separated while the RPM-1 is Bypassed. Drive Controls the amount of overdrive provided by the RPM-1’s vacuum-tube pre-amp. The tone will change from clean in the fully counterclockwise position, to a lightly compressed sound with a touch of distortion in the center, to a compressed, full-out overdrive “crunch” in the fully clockwise direction. You may have to adjust the Input after setting the Drive. Horn speed Sets the rotation speed of the horn (high frequency portion of the sound) in both the fast and slow Speed settings.

Rotor Acceleration Because the low-frequency rotor in a rotating speaker cabinet is much larger than the horn, it takes longer to speed up and slow down than the horn does. The Rotor Acceleration control determines how fast the Rotor sound speeds up and slows down - clockwise makes the acceleration time shorter. In the fully counter-clockwise position, the Rotor sound does not turn at all. Spread Emulates the position of two microphones around the rotary speaker cabinet. A fully wide spread setting corresponds to a 180˚ spacing of the mics (i.e. on either side of the cabinet), which gives the most dramatic stereo effect. A fully narrow setting emulates both mics being placed together giving a monaural sound. If you are using the RPM-1 with only the mono output, turn the control fully clockwise.

Balance Adjusts the volume balance between the high frequency Horn sound and the low frequency Rotor sound. This can be used to adjust the frequency balance; counter-clockwise toward Horn is brighter, clockwise toward Rotor is darker.

Matching Bypass and Effect levels When setting up your instrument volume and RPM-1 Input levels, use the Bypass button or the Bypass foot switch to alternate between the Bypass and Effect sounds while you are playing, and adjust the Input control until the two levels are equal. If your instrument is outputting a very hot signal, the 12AX7A tube will be compressing and adding warmth to the signal even at minimum Drive settings. This may be desirable, unless you need to balance the Bypass level; in that case, you should turn the RPM-1 Input control up to maximum and then turn your instrument volume down to balance the levels. Tri-Output mode To use Tri-Output mode, leave the Horn/Rotor Balance control in the center position, and adjust the Spread control to maximum Wide position. Route the three outputs to three input channels on your mixer, pan the L Horn and R Horn outputs left and right and pan Rotor center. This gives you the most flexibility by allowing you to EQ and balance the Left Horn, Right Horn and Rotor sounds independently. Try applying reverb to both Horn outputs while leaving the Rotor output dry.

Rear Panel 

Stereo Inputs Use Right and Left inputs for stereo, use one plug only in the Left input for mono. Outputs Use the Left output for mono, Left and Right for a stereo image of the rotating effect, and LHorn, RHorn and Rotor to simulate two microphones on the horn (high frequency) and one microphone on the Rotor (low frequency). Footswitch Stereo 1/4” phone jack for the DigiTech FS300 Footswitch (included) Continuous Controller For an optional volume pedal - controls the rotor speed, overriding the Speed and Brake buttons when a pedal is plugged in. This input will use most passive volume pedals or a 0–5 V control voltage pedal - plug a standard guitar cord between the pedal’s output and the Continuous Controller jack. Plug the pedal in before you turn on the RPM1, then immediately after turning on the RPM-1, sweep the pedal from its minimum to maximum position to calibrate the response.

Performance Notes 

Note The RPM-1 contains a 12AX7A vacuum tube, which must be warm to run properly. Note the air vents on the front of the case. Make sure that these are never blocked, and ensure that no foreign object enters these vents. Adjusting the Drive The Drive control, Input control and the volume of your instrument all interact to create the distortion sound of the RPM-1. As you turn the Drive control from fully counter-clockwise towards the vertical position, you will notice the sound taking on a warmer or “furry” tone and the overall volume will increase somewhat. This may require an adjustment of the Input level. The exact point at which the distortion starts depends on the Input level and your instrument’s volume. Past the 12 o’clock position, the distortion becomes more aggressive. When you play chords at high distortion levels, you may hear a rhythmic beating sound which is independent of the horn and rotor speed. This beating is the interference distortion sound caused by the interaction between two or more notes being played at the same time. Try playing single lines instead of chords, and you’ll notice that the beating drops off. If you prefer not to have this beating sound, reduce the Drive control. Speed control Organists have traditionally used the speeding up and slowing down of the rotating speakers to add emphasis and excitement to their playing. Usually, you would not leave the Fast Speed setting on continuously, but rather you would toggle the Fast speed on and off to emphasise peaks in your playing. The most interesting part of the rotary speaker sound occurs while the rotor and horn are accelerating and decelerating. Brake The Brake button will gradually bring the rotary effect to a complete stop from either the Fast or the Slow setting. This is useful when you don’t want the rotating effect, but do want the distortion and/or cabinet emulation to warm your sound up. You can change the Speed setting, but with the Brake on, there will be no rotating effect. When you disengage the Brake, the rotor and horn will then speed up to the current Speed setting again, based on the Rotor Acceleration control. Foot switch The RPM-1 comes with the DigiTech FS-300 foot switch, which has three switches on it. From left to right, the foot switches correspond to the RPM-1’s Speed, Brake and Bypass buttons. Using the RPM-1 with Guitar The RPM-1 faithfully emulates the rotor and horn resonances of a real cabinet, which can sound a bit bassey and dark if a guitar is connected directly to the input. It is best to run a guitar through a pre-amp or a guitar processor (such as the DigiTech GSP series), with the RPM-1 in the effects loop, or at the end of the audio chain like a real rotating speaker cabinet would be. If you want to connect a guitar directly, you can use the Balance control like a tone control, more treble on the left (Horn) side, more bass on the right (Rotor) side. For a clean, warm sound, keep the volume control on your guitar and the Input control up near their maximums and the Drive control around 10 to 12 o’clock.

For tube-amp distortion for rhythm guitar, turn up the Drive control. This will give a warm distortion similar to classic tube amplifier / bass speaker cabinet combinations. Keyboard sounds The RPM-1 sounds great on a variety of keyboard sounds, especially when used on a mixer FX send so that you can blend the RPM-1 sound with the direct sound. A touch of distortion will enhance the realism of electric piano sounds, and the cabinet emulation simulates the built in speakers of popular electric pianos. Sampled piano sounds through the RPM-1 with Drive at 11 o’clock, Horn Speed at 8 o’clock and Balance at about 1 o’clock can create a convincing “reed” electric piano. With Drive at 8 o’clock, and Balance closer to 12:00, you can get a compressed, bell-like piano sound. The cabinet emulation will round out and warm up any sound you put through it, so try the RPM-1 with the Brake engaged even when you don’t want a rotating speaker effect. The cabinet emulation has a definite personality to its frequency response, so “realistic” sampled sounds and sounds with lots of high frequency content can be altered, sometimes dramatically. You can experiment with it; try doubling the RPM-1 sound with the straight sound, both for solo instruments and for pad sounds. Turn off any distortion, delay, chorusing or modulation in the instrument to feed the RPM-1 a clean sound. Organ For best results, make sure that your organ sound input is as pure as possible. Whether you are using a combo organ, synthesizer, sound module or tone-wheel organ, turn off any distortion, delay, chorusing or modulation in the instrument. The best sound is achieved by letting the RPM-1 add the rotating speaker emulation to a clean organ sound. You can add reverb or delay with an external effects device placed after the RPM-1 in the audio chain, or through an effects send on your mixer. Organists will often change the timbre of their sound by pushing in and pulling out the drawbars on their instrument while they are playing. This emphasises certain frequencies of their sound over others. If you are not using an organ with drawbars, you can twist the RPM-1 Balance control to get a variation in tone while you are playing.

What is a rotary speaker? 

A rotating speaker cabinet consists of a high frequency compression driver and a low frequency speaker, whose sound is directed through mechanical deflectors spun by motors. The motors can be switched between stop, slow and fast rotation speed. The horn and the rotor create a directional beam of sound, and as they spin, this sound beam is swept around 360°. The sound is always moving in relation to the listener, creating pitch (Doppler) shifts, volume variation, and constantly changing, complex reflections from the inside of the cabinet and the surrounding objects.

Specifications 
DigiTech RPM -1 Vacuum Tube Rotary Speaker Emulator Input sensitivity -10 dBu to + 4 dBu 

Input impedance 470 kOhms 

Maximum output level + 8 dBu 

Output impedance 1.5 kOhms (max.) 

Continuous Control CV in Control Voltage 0 – 5 VDC; Passive - auto calibration 

Dynamic range > 90 dB IHF-A weighted 

T.H.D. + N < 0.1% IHF-A weighted, @ 1 kHz input 

Dimensions 17.5” (W) x 5.5” (D) x 1.25” (H) (not including rack mount) 

Weight 5 lbs 

Power supply consumption 30 W 

Power requirements 117 VAC 60 Hz 

Tube Type 12AX7A 

Over the course of time, the 12AX7A vacuum tube may wear and require replacement. Replace only with a tube of the same number, and refer installation to a service shop or dealer. Avoid dropping the RPM-1 or handling it roughly, as this could shorten the life of the tube. Don’t install the RPM-1 in an unventilated rack, and don’t install directly above heat-producing equipment such as power amplifiers.