Date: Wed, 20 Apr 1994 05:37:28 +0100 From: D.A.C. Crowell To: Marc Wilhite Cc: analogue@magnus.acs.ohio-state.edu Subject: Re: Finding an ARP 2600 On Tue, 19 Apr 1994, Marc Wilhite wrote: > Im considering the thought of trying to find an ARP 2600. I'd like to > get some purchasing advice. Are there any special types of models to look > out for (there are like three different ARP Odysseys)? Whats a fair price > to pay for one in very good to excellent condition? Any particular quirks > to look out for? All advice is ofcourse appreciated. Ahh, one of my fave synths, the 2600. You're gonna love it...anyways... AVOID: the "blue meanie", if you find one. These are the first model version 2600s, called thus by their weird case color. They break at the drop of a hat, if you even find one in working order. AVOID: the initial version of the keyboard. Try to find a unit that has the later, two-voice (Model 3620) keyboard, distinguished by the addition of patchpoints and an LFO control on the keyboard module itself. LOOK FOR: The later versions of this unit. These can be distinguished easily by their white and orange graphics. Reasoning here is because earlier ARP 2600s used potted subassemblies, making servicing a complete bitch unless you could/can find replacement modules. GET: a copy of Mark Vail's "Vintage Synths" book. In there is a long piece by Timothy Smith with some _excellent_ mods and hotrodding to _majorly_ improve the performance and audio quality of the 2600. PAY: no more than $1000 on the street for one that looks as if it just came out of the box. More rational prices will be between $500-$750 for this thing, especially if it's a later model with the 3620 keyboard. This one may well be one worth checking with someone like Wes Taggart @ Analogics or Chris Youdell @ Analog Modular Systems and paying a higher price in order to get a unit that's been refurbished and fully re-specced. Happy hunting! D.A.C. Crowell Audio Design and Programming KnowledgeMedia/The Aerodyne Works Champaign, IL, USA. (dacc@tigerden.com) ------------------------------- From pulverm@smtpgate.lante.com Tue Sep 13 14:30:42 1994 Date: Tue, 13 Sep 94 12:55:53 CST From: Mark Pulver To: crh3@Midway.Uchicago.Edu Cc: analogue@magnus.acs.ohio-state.edu Subject: Re: Arp 2600 Questions Text item: Re: Arp 2600 Questions >> First: Is it possible to use an external keyboard and control the 2600 through the CV gate? Yes. Plug a CV out into the "KBD CV" jack on the far left side, (it's labeled as an output). Plug a GATE source into the S/H GATE jack just below the AR generator and flip that slide switch down. Alternately, plug the GATE into the GATE jack under where it says "Keyboard Gate/Trig" and leave the switch up. >> At first glance it appears that this should be the case, but when control voltage is sent to 2600 the signal gate does not shut off. Verify that you have a patch setup that is supposed to be affected by the VCA... Try this: On the AUDIO sliders in the VCF section, set VCO1 UP, all others down. In the VCA section, (second from the right), set VCF and AR slider UP, all others down. In the Mixer section (rightmost), set VCF DOWN and VCA UP. Set the VCF freq to something to the right of halfway and leave VCF resonance full left. At this point, you should be able to trigger a sound when you hit the MANUAL START button above the AR generator. If that works, then try your external GATE trigger, if that's not happening, then it's time to check your trigger source. The 2600 is looking for a step of +10v to fire the trigger, Moog triggers are switch based triggers, (you'll have to build a circuit to convert them to voltage triggers), and I dunno about the Korg. Bottom line here is that you may have to break out a soldering iron in order to use your current gear as a GATE source. >> Second: I fail to understand how the envelope follower works on this thing. The basis of the EF is that of a popular effect in the mid seventies the "Auto Wah". The EF will kick out a voltage that is proportional to that of the level of the inbound audio signal. Using a guitar as an example, run the signal into the preamp, then into the MULTIPLE. Run one line to the EF and one to the VCF. Over on the Mixer section, move the VCF slider full UP and the VCA slider DOWN, (this will bypass the VCA and allow for the guitar signal to pass ungated). Open up the VCF and crank up the preamp gain until you hear the guitar. Now run a cord from the EF output to one of the VCF CONTROL ins, (the right set of sliders). Crank that slider up and run the VCF freq down while playing a "chunk" riff on the guitar. There should be a point where the VCF starts "gating" based on the amplitude envelope of the guitar, i.e. hit it hard, and the VCF opens up and allows more upper harmonics, hit it soft and the VCF closes up and soften things out. Playing around with this concept should get you thinking about other things that you can do with it... Just keep in mind that the output of the EF is a voltage that's tracking the amplitude of the source. So use a kick drum in place of the guitar and patch the EF output into a VCO and let the VCO pitch swing when the kick get's hit. Instant SynDrum! >> Third: What do the voltage process do? how do they work? and how can I use them to make cool sounds? There's a lot of power there, 'specially in the inverters. Run your pitch CV source into the KBD CV jack. Now run a cord from the inverter output of the second slider (from the top, the left side says KBD CV, the inverter out is the jack at the end of the triangle), to the KBD CV jack of VCO 2. Move this slider full right. In the filter AUDIO section, bring up the slider for VCO 1 and VCO 2. Play a riff on the keyboard, you should hear the VCOs tracking in opposite directions. The lag processor is an analog time delay... Multiple your CV source, run a line to the KBD CV jack and the ENV FOLL jack at the left of the bottom slider (where the LAG processor is). Run a line from the output of the lag processor to the KDB CV jack of VCO 2. Bring up the levels of both VCO 1 and VCO 2 in the AUDIO section of the VCF and play a line on the CV souce. While doing this, move the lag processor slider to the right. As you move it more to the right, you should start hearing a glide effect, but in VCO 2 only. Know that in a 2600, all inputs are DC coupled which means that you can run an audio signal through the LAG processor just as easily as running a CV signal straight into the AUDIO section of the VCF. For example, running a VCO in LFO mode through the LAG processor and then into the FM CONTROL section of another LFO is kinda fun. Running ADSR signals through an inverter, through the LAG processor and then off to the filter CONTROL section is kinda cool as well. Experiment with everything, and try to visualize what's producing a CV versus what's producing audio. Think of what an inverter does, and then go from there. Take the noise generator and run it straight to the GATE input, (bring the noise level WAY down). Run a sawtooth VCO into the EXT CLOCK IN jack ont he Sample & Hold... Welcome to modular synths dude! From pulverm@smtpgate.lante.com Tue Jan 17 10:06:45 1995 Date: Mon, 16 Jan 95 22:52:59 CST From: Mark Pulver To: mrf546t@nic.smsu.edu Cc: analogue@magnus.acs.ohio-state.edu Subject: Re: trying to find arp 2600 Text item: Re: trying to find arp 2600 >> i'm looking for an arp 2600. any advice or information would be appreciated. When looking for a 2600, look deep, and be sure of what you buy... There's a lot behind that front panel, and it's all tied together with less than average quality jacks. The 2600 (as you may know) is a "normalized" machine in that it's default signal path (VCOs -> mixer -> VCF -> VCA), is defined by jacks in the front panel that are normally closed. If these jack have gotten corroded over the years, the signal path will be broken or distorted. They can be replaced, but considering the time involved in doing so, it calls for a reduction in the selling price. When checking out a 2600, you really should take someone along that knows what to look for in the box. I can tell you patches to set up and jacks to check and sliders to move, but there's a lot in the box, and a lot to check out. If you can find someone local to the machine you want to buy, or local to you to travel with you to check out the machine, it'll save you tons in the long run. Don't let me deter you from buying one... I've had two, and I'd buy a third tomorrow... *** a bit later... man, I'm getting philosophical at my old age... lemme tame this down a bit... There are four basic models of the 2600 mainframe and three different keyboards. The first mainframe is known as "the blue meanie" which was a protoype, and is now basically a collectors item, and only wanted for that status. The box is all metal, blue, and doesn't track too well. The next mainframe in history is known by it's black face with white lettering and the *absence* of fine tuning sliders on the VCOs and filter. I know this machine as a "rev 1". The lack of fine tuning sliders makes this a bad choice for a machine... The next up in line is the "rev 2" which is a black face, and has fine tuning sliders. In my opinion, this would be the first box to get. The reasoning has to do with the internals of the machine, in that the VCOs and VCF are *not* sealed in epoxy. Know that some of these machines were known to have a copy of the Moog ladder filter in them... read that as "sounding fatter than Grandma after Thanksgiving dinner". Then came the "rev 3" (the final mainframe rev I might add). This box is black faced with orange graphics and white lettering. This machine has the most stable oscillators of the bunch. Keyboards... Basically, there was a one voice keyboard, a two voice keyboard, and then a two voice keyboard with what Arp called "PPG". One thing to point out is that the LFO in all the 2600s is a function of the keyboard, there is no LFO per se in the mainframe itself, (though all VCOs can be switched to a low frequency mode). The one voice was pretty straight forward, nothing fancy, LFO depth is a slider, pitch bend is a knob, and the keyboard has a +/- two octave switch on it as well. Comes in handy. The two voice keyboard is basically the same as the one voice 'cept it has a separate CV out for the second voice. This is usually patched to one of the VCOs so that you can play two note harmonies from the keyboard. It still has a slider for LFO depth and a knob for pitch bend. The PPG era was a nightnmare in my opinion. Someone at Arp decided that having 1/2" square white rubber pads for bend up, modulation, and bend down was a good idea, so Arp dropped it in across their whole line of keyboards. The Odyssey, the 2600, and I think the ProSoloist all got them. The concept is that you press on a pad to bend up or down, and to add modulation. The pads are kinda stiff, and you really have to crank on 'em to get a stretch bend or a massive LFO kick outta 'em. The pads don't stick either, which means that your LFO depth goes to 0 when you let go... Personally, I'd stay far away from any Arp gear with this stuff on it, but then again, you may like it... try before you buy. Anyway... The PPG retrofit to the two voice keyboard was the final keyboard made for the 2600. I had a rev 2 (it was stolen many moons ago) and I now have a rev 3 with a "normal" two voice keyboard. I love the box... It's one that I use every time I power up the gear. If there's anything more specific I can tell you, please don't hesitate to ask. 'Till then... Good hunting!