Re: Arturia Arp 2600 Keygen Software
Cre Wallace
Nevertheless, the bias toward Moog survives to this day, as demonstrated by the host of digital imitations of the Minimoog. But perhaps this is about to change, with the almost simultaneous release of two ARP 2600 software synths. This month, we'll look at the first of these. It's the fourth software-based emulated synth to emerge from Arturia, and as with their previous emulations, it aims to produce a sound as close as possible to that of the hardware instrument, whilst also sympathetically extending the original's feature-set with more modern facilities such as polyphony and MIDI capabilities. It's called 2600V, and as I've done with my previous reviews of Arturia's software emulations, I put it up against the original hardware synth to see just how close the emulation was.
Then I came to the triangle waves. As you can see from the last two graphs on the next page, 2600V generates a 'shark's tooth' waveform, while my ARP produces something thoroughly triangle-like. In listening tests, 2600V 's sound is a little brighter and less 'bottomy' than the ARP's, although the difference is subtle. However, I've seen the waveform before; it's very similar to the triangle wave produced by Arturia's Minimoog V (printed in my March 2005 review of that product), and even though it's not identical to 2600V 's, I couldn't help but wonder if Arturia were recycling some of their technology, even though 2600V supposedly models a different synth.
Happily, 2600V 's pulse waves sound reasonably accurate whether static or modulated although, as on other software synths I've used, its square waves are too 'pure'; they're recreations of a near-perfect square wave rather than the imperfect, not quite 50-percent waves of a real analogue. The final audio source is a noise generator that approximates that of the ARP 2600, but with a wider range of colorations.
There are a further two additions which I've separated from the others, because the manual describes them incorrectly. Firstly, it tells you that you can modulate the 'widths' of the sawtooth, triangle and pulse waves of VCOs 2 and 3, but in fact the sawtooth waves are unaffected. Secondly, it says that you can sync VCO 1 to either of VCO 2, 3, or 2 and 3. In fact, only VCO 2 is available as a master.
One idiosyncrasy of 2600V 's oscillators is that they go sharp when you apply audio-frequency FM. This is not in accordance with FM theory so, when notified of this behaviour, Arturia stated on their web site, "FM modulation may not produce such a pitch deviation, neither with a DX7 nor with an ARP 2600" and undertook to correct the fault. But when I tested this on my original ARP 2600, I found that it did exhibit the same behaviour as the current version of the software synth; increase the modulation depth, and the pitch goes sharp!
Arturia's marketing information states that 2600V has two filters: one that emulates ARP's 4012 filter, and one that emulates the ARP 4072, but this is not the case. Furthermore, the manual makes much of the equivalence of 2600V 's 12dB-per-octave low-pass filter and that of the original synth, but that can't be right, as both the 4012 and the 4072 were 24dB-per-octave low-pass devices. Fortunately, tests show that the 24dB-per-octave setting on 2600V does indeed roll off the signal at approaching 24dB-per-octave, so make of the marketing and manual what you will.
To get a feel for 2600V 's filter, I first tested my ARP 2600. Measurements showed that the front-panel sliders adjust the cutoff frequency from 9Hz to 19.4kHz. With CVs applied to the control inputs, the top end shoots off the top of the audible scale. Furthermore, the self-oscillation at maximum resonance behaves as you would expect. It produces a low-ish output (as set up) of 500mV at 9Hz, around 1000mV throughout the audio range, and it falls away to 140mV at 19.4kHz.
I then tested 2600V 's 24dB-per-octave filter; Arturia claim a frequency response of 10Hz to over 21kHz for this. Making the filter self-oscillate and patching the VCF output to the main output, I found the range to be 32Hz to 18.6kHz. This is almost two octaves short of the claimed specification at the bottom end. Furthermore, the upper frequency of 18.6kHz appears to be an absolute maximum, and no amount of controllers applied to the filter's CV inputs will cause it to exceed this.
While taking these measurements, I noticed that the amplitude of 2600V 's filter oscillation is rather weird, with its highest output at the lowest and highest frequencies, and with a significant dip at mid-range frequencies. If, as I did with my ARP 2600, I set up 2600V 's filter to generate an output of 500mV at its lowest frequency, the output was just 60mV at 1kHz, but 190mV at 18.6kHz. This is not the normal response of an analogue synthesizer's resonant filter.
More improvements lie in the minimum contour times. The first graph above shows the click generated by passing white noise through the ARP 2600's VCA when controlled by the ADSR with all values set to zero. The second trace shows the result obtained from 2600V. As you can see from the third trace, which superimposes the previous two, the durations are similar, but the software synth's amplifier begins to 'close' much more rapidly. The result is a more precise click than that obtained from the analogue synth.
There is another significant change in the VCA section. On the ARP 2600, the horizontal slider at the top applies a permanent 'Initial' gain to the VCA, famously prompting 2600 user Joe Zawinul to ask, "how do you switch it off?" This is replaced on the software synth by a Global Volume control, which is very useful, although not quite as sensible as it seems, especially if you want to play external signals though the filters and effects.
Hidden away behind the left speaker grille lie two additional effects: chorus and delay. The chorus is a single modulated delay line whose output is directed equally to the left and right channels, no matter where the output from the main signal path is panned. It's no substitute for the lush textures of a triple-delay chorus, but it's acceptable if used subtly. The basic delay unit offers independent delay times (from 1ms to 3s) and feedback (from zero to 100 percent) for each of the left and right channels, without cross delays. The nice touch here (and nowadays a common one) is the ability to synchronise the delay to MIDI Clock. Ratios are available from one-eighth to nine times the currently set MIDI tempo.
I have criticised Arturia in the past for attaching faulty effects to the outputs of their software synths and, unfortunately, this time is no different. This is because, if the delay is 'wet', merely the wet (ie. pitch-shifted) part of the chorus is passed to the delay. Only if the delay is completely 'dry' (ie. 'off') does the chorus wet/dry mix work correctly.
If you wanted to get silly with an ARP 2600, you could present external signals to its inputs and see what happened. However, there was just one place where ARP intended that you should insert such signals. This was the Preamplifier, with its associated Envelope Follower. These are recreated on 2600V, and using them proves to be simple. In my case, it meant loading 2600V as a VST instrument under my chosen VST host (Plogue's Bidule), whereupon it appeared with two audio inputs as well as two outputs. I could then direct the output from other software synths to these inputs, patching the output from the Preamplifier and/or the Envelope Follower to the destination(s) of my choice.
A Ring Modulator lies alongside the Envelope Follower. Strangely, while Arturia's panel has the Audio/DC legending found on the ARP 2600, the switch to which this pertains is missing. Testing showed that 2600V modulator is 'AC coupled' (the Audio setting) which means that the carrier and modulator frequencies are not present in the output. Given a single option, I would select this one, but it would be nice to have the choice.
In essence, the Tracking Generator allows you to create four control waveforms using a variety of tools available in the Edit window provided for each. You can then smooth these if desired, and direct the outputs to the destination(s) of your choice. You determine the frequencies of the outputs using the Freq knobs and, as elsewhere, these can be synchronised to MIDI Clock.
In other words, the Tracking Generator is nothing more nor less than four programmable LFOs. While this may seem a bit advanced in an emulation of a 1970s monosynth, the philosophy is not outrageous. On a smaller scale, this is what ARP did when they added an LFO to the ARP 3620 keyboard, thus freeing up one of the 2600's oscillators and extending the modulation capabilities of the complete system. Which brings us to...
The 3620 was quite a sophisticated piece of equipment. In addition to the LFO, it offered a two-octave up/down switch, a pitch-bend knob, portamento with a momentary on/off switch as well as a footswitch on/off input, single/multiple triggering, auto repeat, and dual pitch CV outputs.
For aesthetic reasons, Arturia have sited many of these functions elsewhere on 2600V. Most noticeably, the LFO has migrated to the centre cabinet, where it has grown an extra output (a sawtooth wave) and MIDI-synchronisation capabilities. However, the output from the LFO is very strange. Notwithstanding the fact that it goes up to 100Hz (despite the manual saying that it has a maximum frequency of 20Hz), its waveforms exhibit 'stepped' shapes and complex spectra. Counting the levels shows that the LFO is quantised with just three-bit resolution, but when you apply it to a destination, it does behave as it should, with smooth sines and correctly rendered triangles, squares and saws.
The first few (built in 1970/71) incorporated the simple, monophonic 3601 keyboard and appeared in a blue-painted metal case with a wooden carry handle. Despite their cachet as the earliest ARP 2600s, these 'Blue Meanies' were hand-built, notoriously unreliable, and difficult to keep in tune.
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