ARP 2500 - The 1027 sequencer

The ARP 1027 sequencer

It's the 50th anniversary of this magical synth. So I'm exploing the different modules. A sequencer is one of the essential components of any modular synthesizer. The ARP 2500 is no exception

Also called the Clocked Sequential Control Module, this is essentially three 10 step sequencers, though you can set it to be any number of steps (between 2-10) you wish.

If you wish to get more than 10 steps, use a sequential switch.

It's quite a large module occupying 2 units.

There are 3 rows of pots providing three sets of CVs  for each step.

The sequencer has an internal clock so can step along automatically.

When run fast at switching rates in the audio spectrum, the 1027 can generate sound in the form of very complex wave forms.

The 3 voltage outputs are labeled A, B, & C.

The Clock
The illuminated ON & OFF switches can start & stop the clock and thus the sequencer.
Set the switch to "Trig" .
You can also start & stop the clock with external pulses that are imputed to the ON & OFF inputs.

The pot labeled "Pulse Repetition Frequency" controls the speed of the internal clock.
It can be run at very low or high frequencies. ... between
20 pulses/minute to 400 pulses/second.
The clock speed can also be controlled with an external CV via the "VC trig" input.


The sequencer produces a 10V gate pulse every time it makes a step.
The pulse width can be varied between 5% to 95%.
The width can be adjusted either manually or with a control voltage.

VC Width & VC Freq.
Apply control voltages here to have external control.
The Clock Out is also a source of 10V pulses,
You can use this to clock external gear.

Pulses applied to the ON or OFF inputs will start & stop the clock.

 
Input Sensitivity :  "ON", "OFF", inputs are +8 volts.
                            VC Width & VC Freq inputs are 0-10 volts 

If the clock is turned off, you can manually step and reset the sequencer with the pink Step/reset buttons.
You may also do the same thing with external CV .... 10V pulses applied to the "S" and "R" inputs.
If you are trying to clock the sequencer from an external source such as another sequencer
plug 10V pulses into the "S" input.


Finally, notice the ten "POSITION GATES" outputs.
A 10V pulse is outputted at each ... corresponds to the current step the sequencer is on.
If you wish to change the 10 step sequence to 8, connect the 9th gate out into the "R" input.
If you wished the sequencer to count to 5, and then reset, connect the 6th gate to R.

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To skip a step, connect the position gate output(s) to the "S".
The sequencer will then skip those positions.

There are cable jacks at the back of the 1027 module to connect with other modules such as:

1028 - Sequencer slave

1026 - Preset Voltage

1050 - Sequential mixer

 

 

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Electrical Specifications
Output Impedances : 1Kohm all outputs
Output Position Gates : 0 to +10V.
Input Impedances : 100Kohms minimum , all inputs
Input Sensitivity : "S", "R", "ON", "OFF", inputs are +8 volts
                           VC Width & VC Freq inputs are 0-10 volts
Pulse repetition frequency (without external control):
                         20 pulses/minute to 400 pulses/second.
 Power requirements: +15 V @ 150ma, regulated to +/-0.1%
                                 -15 V @ 75ma, regulated to +/-0.1%
                                 +12 to 15V @ 100ma, unregulated for the lamps.