ARP 2600 - Envelope Generators

 The 2600's & TTSH's Envelopes

 

 The ARP 2600 has two envelope generators.

The first is a full four-stage (ADSR) Attack, Decay, Sustain, and Release Envelope. 

 

 

The second EG  is a simpler AR offering variable Attack and Release only. It works really well for making percussive sounds.

The Manual Start button allows both the Envelopes to be retriggered at any time, without using the keyboard. 

 Usually, however, the EG is triggered with a +15V spike of voltage (trigger pulse) from the keyboard. As soon as the key is pressed, the keyboard also begins generating a gate signal.

The cord that connects the keyboard is on the left side of the tolex cabinet. It has six prongs.

 

 

The envelope module also provides both Gate and Trigger outputs for patching to external modular gear.

The S/H Gate jack is an input.

It's wording is rather misleading. 

When nothing is plugged into the jack, the internal clock (that is used in the sample & hold circuit) triggers the envelopes if the switch is in the lower position.

It seems that the 2600’s designers considered the electronic switch, the internal clock and the sample-and-hold units all part of the “Sample-and-Hold module.” Hence the label on the jack below the EG’s. However, it is really the internal clock which is responsible for causing the EGs to fire, not the sample-and-hold unit. (Fundamentals of Music Technology  by Samuel Ecoff)

Thus when the S/H switch is in the lower position, the envelopes will self trigger. Like a LFO.

The rate of the trigger will be controlled by the 2600's internal clock.

If you wish to externally trigger the ADSR or AR envelopes, connect a clock (+10V  pulses) or a +10V gate.

The switch should again be in the lower position.

The eurorack Winter Modular Eloquencer triggers these envelopes perfectly.

I've also had success with the Music Thing Modular Turing Machine. (mk II).

 

 

The internal clock’s connection to the EGs can thus be broken by returning this switch to the upper position.

You can now trigger the EGs with the keyboard.

 

The ADSR EG is normalled ( hardwired) to FM inputs on each oscillator and one of the control inputs on the VCF.

The VCA has two control envelope inputs .. the first normalled to the AR envelope, and the 2nd normalled to the ADSR. 

Thus, the EG’s can be used to raise the filter’s Fc every time a key is pressed. 

 

They can also be used to modulate the VCA.

You of course can override these hard wired (very west coast connections) and modulate the VCOs

or Filter with an AR envelope.

Both envelopes in-fact have their own outputs which to can patch to any place your heart desires.

 

Another module you can incorporate to make the envelopes more interesting is the inverter.

The ARP 1601 sequencer is a great device if you can get your hands on one.

Quite rare these days, though I understand there is a clone available.

 

This is a basic patch for connecting the 1601 with a 2600.

The quantized CV outs of the 1601 are connected to VCO 1 + 2's CV inputs.

The 1601's "clocked Gate 1 Out" is connected to the 2600's S/H GATE input jack

 

A second way to connect is just plug the clock out into the  2600's S/H GATE input jack.

The Clock out is a +10V pulse.

 I have also tested a ARP2500 sequencer with the 2600.

This basic patch works very well.

Clock out of the 2500, to the 2600's S/H GATE input jack.

 

You can also connect the gate outs (of the 2500) to the 2600's S/H GATE input jack.

 

 

 

 This is only a brief introduction but. should get you started. I'll cover more features of the 1601 in later blog posts.