ARP 2500 questions- update: IT WORKS! Video inside...

[RobotHeroes]

BTW...The "freaking crazy thing that goes like that" is a step sequencer.

Yep.

That patching matrix looks awesome. Hopefully you get everything patched up(hopefully the modules are working) and get some fresh sounds.

[nathanscribe]

Extremely nice.

[Bitexion]

I'm sure you can make the other modules with lights in them work, if you figure out how to use them in a modular patch.
The "crazy thing with lights" on the right is basically an automated keyboard, you send the output to somewhere like an oscillator, and it will play the 8 steps the knobs on the sequencer are set to in order, at the speed the lights are moving downwards.

I saw another 2500 video just now where a guy used the sequencer on the far right. Seems like they are all mostly working, if you figure how to patch them into a sound. Also keep in mind that on a modular synth, the Envelope Generators are external from the sound path. The sound doesn't go through them, they act as a modulation on the sound. So to control the filter you set the EG output to a filter CV input, and the filter will follow the envelope shape every time EG is triggered, either by keyboard (if keyboard gate is patched to the EG Gate input) or any other module that provides steady timing signals, or even a "trig" button on the EG itself. I picture it as the EG sits outside the patch, just acting on it whenever it is told to trigger.

Ah, I'd love to try out my theories on a monster like that. You may ask me anything about the modules you have, I might know how to patch them up. I have a fairly large modular system myself.

[Esus]

Here's a site with the 2500 owners manual in pdf form:

http://guitarfool.com/synthesizer.html

[LVC_Jeff]

Thanks for the link, I found that myself just the other day and printed it out. Definitely useful for figuring out how the modules work.

Bitexion, thanks for the suggestions. I'm sure once I read through the manual that I'll be able to figure out all the modules, but basic theory stuff like that isn't in the manual.

[Esus]

I'm sure once I read through the manual that I'll be able to figure out all the modules, but basic theory stuff like that isn't in the manual.

Synthesizers.com is a good place to start. Roger Arrick's site has good references to subtractive analog synthesis. There are a lot of good books on Amazon.com as well.
The 2500 was unique in the sense that you "patch" using matrix switches, but the workflow is essentially the same.
You're in an enviable position to have access to such a rare and wonderful machine with relatively little effort and expense.
Good luck!

[Bitexion]

The thing about modular synth manuals is that often they just tell you what all the inputs and outputs are for, but not how to connect them in a useful manner. They kind of expect you know all that theory already.

Most people don't, though. So by all means, don't be afraid to ask

[rjd2]

a few things:

1-lights on doesnt always mean PSU is 100%. LED's can run off a secondary voltage, so dont always assume that ALL voltages are working just cause you get lights on. only way to know for sure is to measure voltage coming off the PSU. im not suggesting you do this, especially if you havent before, im just saying....

2-i dont know if you can patch into specific point on a 2500, but in theory, a modular VCO puts out a constant pitch at its output-the gate of a keyboard turns it on and off via EG/VCA/etc. so holding a kybd note and patching headphones into the VCO output is the simplest way to see if a VCO is working.

[Clavier]

Yeah what Bitexion said. He found it in a museum basement no? Belonged to an old cowboy film star or something like that. The person was into electronics and everyone was giving him the third degree because synths have magical properties that only the elder synth lords could deal with.

I am pretty sure Matrixsynth lurked about and copied the thread and posted it on that repost spam of a blog. Then the wrath of nerds everywhere was unleashed. They probably called the guy a dumb bastard for at least 20 pages.

Actually, It was me who sent the link to Matrix. I had no way of knowing it was going to turn into the bitchfest that it did. I thought that everybody would just join in the celebration of this incredible find. The guy was trying to preserve and restore it, certainly not the worst one could do. His name is Andrew. We spoke on the phone and he was very pleasant and knowledgeable. All he ever wanted to do was get this thing restored to perfect condition electronically, so it could be used to make music again and could be further preserved. The thing was never kept in a 'garage' either. It was kept in a climate contolled office building and covered with dust covers it's entire life.

[minime123]

if the powers not staying on on its own, you dont want to tape the switch down. replace the switch instead. if it works, great. if not, there may be something more serious going on. i wouldnt take any chances with the power supply section...
mini