Z-5 Analog Abstract Generator

[norty303]

I chose a trombone because it just had the one switch

[laserist]

You got nothing to be ashamed of. My angle on this whole thing translates to tubas like this: Someone worked out all that tubing, the flow of air, the lengths, volumes, bends in tubing, and keys, and that just three of those keys will allow a full scale to be played. That was clever, but as any horn player knows (including some people like me who never played one but wished they had been around one long enough to at least try), it takes nothing away from the skill of the player because without those keys the number of competent players worldwide can be counted on the fingers of both hands. In short, I'm talking about the kind of thought that goes into designing any instrument. And as that is what DZ is clearly intending to do, he'll do ok. I imagine that when brass instruments originally got their three keys there were horn players screaming blue bloody murder about all the dilettantes now enabled to play a horn, but given all the extra good music that resulted, we're lucky their argument didn't win. And in really good hands a natural horn still sounds damn good too. Adolph Sax got a pasting from his critics too, but fortunately they ended up silenced by so many saxes outnumbering their cries.

The thing to take from all that, if nothing else, is that for a thing to be really simple, a lot of thought must go into it. This is true for music, physics, pretty much anything. Appearing simple, and actually being so, not the same thing at all. If it were, we'd all be thinking up stuff like E=mc2 every day, and we aren't.

EDIT: I can play a keyboard and an electric bass, but I can't play either without looking at times. As far as I know, most concert pianists spend a lot of time glancing at the keyboard too... I think there may be many buskers who can bellow out a tune without looking at their guitar once, but most bands I saw live would look at their instruments whenever things got tough to play. Kind of hard to play well if you're fighting against natural use of one of the vital senses in an effort to look cool. Stevie Wonder could pull it off, largely because he had no choice.

I never said don't look at the controls - I said if you need lables - you're holding yourself back. If you don't understand the distinction - I can't help you...

[norty303]

I said if you need lables - you're holding yourself back.

What a load of nonsense.

If you need to know what a control does to 'get you off the ground' in the learning curve, then you are only holding yourself back by not using labels.

[AshMcFadden]

I can see that I really do need to post a front panel diagram of the P-4 and walk you through the flow using the users' manual, which, unfortunately, is in Ireland. A couple of the things you brought up that "don't make sense" would make perfect sense, then. I'm going to see if I can get a friend to invade my house, find the manual and post it to me here in America.

[AshMcFadden]

Agreed - labels will get you off the ground. Then you work up to playing the instrument by Braille.

[AshMcFadden]

Doc,

I should mention that ARP didn't hold with my theory that LFO rates and all VCQO frequencies should be controlled by knobs and amplitudes should be controlled by slidepots. That was my own idea, based on something I read in an electronic music magazine I was getting in the 1970s. I think that was one of my few truly original ideas in building the instrument, along with my way of inducing perspective rotation in X or Y axis. And, by the way, unless I miss my guess (which I may have), you got the instrument locked-up because you failed to realise that the X or Y rotation VCQO is what drives the perspective rotation and if the switch for that VCQO is in "hold", nothing's going to rotate.

Clear as mud yet? I've found a front-panel JPG which I'll post here later and try to talk you guys through the flow, but I still need to get my hands on my original Users' Manual to explain things like "The Zero Position" you use to get everything unlocked when you've finally driven the VCAs into a clip and have nothing but a little spaghetti squiggle off to one corner of your projection field.

[AshMcFadden]

David,

I will be in America in March. Sounds like fun! Let me see if I can arrange a travel schedule (and financing for the trip).

Ash

[AshMcFadden]

This is the front panel configuration I drew for the P-4 in 1982. I'll refer to it in following posts.

[Revmutt]

Looking at this, one has to wonder whether patching out the ILDA connection so all the relevant points have input jacks one can just connect to ones modular synth and go. One friend and synth designer has done this, another friend and I have planned to do this.

Obviously having a specific instrument laid out to do this is preferable but if one wanted to experiment and happen to have a bunch of modular synths..
Tommy

[AshMcFadden]

First off, as with any complex endeavour, a modicum of knowledge about the physics of the situation is mandatory. The user should be familiar with what an Oscillator, a Quadrature Oscillator and a Low Frequency Oscillator are and what they do when presented, for instance, on an oscilloscope or projection screen.

Start with "The Zero Position". This is not a new form of contraception; it's the way to get home when you're lost on the P-4.

Position Image Offset (far right) sliders and Rotation Offset controls (top centre) to the centre of their travel to match up with the "0" labels on the front panel.

Upper left, turn X, Y and Z rotation switches to "out". Position the FM gain knobs above those to full lefthand rotation (off) and all three rate controls to off at 12:00 (top dead centre).

VCQO sliders both down (off). VCQO rate controls to top dead centre (off). FM gain knobs full left (off). LFO 1/2 switches to LFO 1. Sin/Normal switches to Sine. Sin/Sq switches to Sine.

Moving to the right, the VCA input should be switched to the centre position (DC). The FM/P-4 output was originally included for onboard FM tape recording PC cards and isn't necessary on newer equipment using ADAT or newer image recording schemes. Master Gain to 9:00. X Gain and Y Gain to 9:00. Image Size slider to about 1/4 the way up. Image B input slider down. VCA gain knob to the left left 9:00 position.

Moving to the right, Image A/B / C slider to the left (A/B). Image A/B inversion and proportioning slidepots both down. Image C slidepots also both down.

Both LFOs Frequency, Symmetry, Offset and Gain knobs set to about 12:00.

Up to Perspective rotation. Set the Orbit Size, Aspect Ratio and Zoom knobs all far left (off). Orbital/Stationary stitch to Orbital and X/Y switch set to X (most commonly used).

Orbit FM Gain down (left), Orbit Size slidepot down (off), Rate to top dead centre (off) and Hold switch off (switch up).

In this "Zero Position", you will have the laser dot centered and nothing else happening.

Now, for image generation. Start in the lower left corner. That's where basic image generation occurs. I say "basic" because there are many complex images that can be created by modifying the original image using X, Y and Z rotation and orbit at high speeds. We'll leave those for later. Raise the slider for VCQO1. You should see the dot rotate left or right, depending on whether you turn the VCQO's Rate knob left or right, creating a circle.

Now, raise the slider for the number 2 VCQO to create a simple Lissajous pattern. Note how both VCQOs can rotate right or left. Play with the Sin/Normal switches and Sin/Sq switches until you understand how to output a sine or quadrature waveform and how to switch from a square wave to a sine wave in either mode.

Move to the right and play with the VCA Master Gain, X and Y gains (for proportioning) and the Image Size slider. You've got four VCA's onboard and this is where you can find ways to get into trouble by driving things into a clip. Get things proportioned so that you have a nice Lissajous pattern you can ramp up and down in size using the Image Size slider.

Turn the VCA's input switch from DC to LFO1. Play with the LFO1 Gain knob to get the image to zoom in and out in time with the LFO. Remember, you have both positive and negative outputs from each LFO, so the Symmetry, Offset and Gain knobs will produce different results depending on whether they're twisted left or right. Use the LFO's Rate knob to synch the image to your favourite music and play for a while with the LFO controls.

So, now you have an image centered on your display screen. At the upper left, turn the X rotation switch to "in" and rotate the image right and left using the Rate knob. Stop the X rotatation and try the same thing with Y and Z.

OK, now you know how to rotate the image in three axes. Restart just the X rotation, move right, raise the Orbit Size knob and watch the image leave the centre of the screen and appear to run around in a horizontal circle. (The Stationary/Orbital switch should be self-explanatory.) Now, raise the Aspect Ratio and Zoom knobs together, slowly, and just play with things until you see how the relationship between Zoom and Aspect Ratio allow you to make the image fade into the distance on one side of the horizontal circle and come closer on the other.

The same works for Y. Just remember that you can only use aspect ratio on X or Y, but not both, and tailor your X/Y knob positions. You can get a Lissajous pattern generated by the two VCQOs to rotate (stationary or orbital, but stationary to start with) in all three axes, speed up the rates on the rotation pots and create whole new images.

Try rotating an image, esp. in the Z axis, while adjusting the Rot Offset sliders. Things get complex, ornate and pretty really quickly.

Get things settled down again in the centre of your projection screen and bring up the slider gain on the Orbit control. Depending on whether you turn the Orbit rate knob right or left, the image will offset and orbit either direction. The square/sine switch can produce an interesting four-images-at-once effect.

Now, lower the VCQO image size sliders, input a digital image into Input B on the back of the panel and raise the Image B gain slider. If the image isn't oriented properly, you can use the Image A/B silders just to the right of the Image B gail slider to flip it so it's properly proportioned. Now, go back and try all the same tricks with your digital image, from using the LFO to drive the VCA to the rotations and the orbit mentioned earlier.

Auxiliary Image C input is "straight in" through the Image C sliders. If you pan from A/B to C, you'll have the image proportioning sliders and the master VCA gain available to proportion the C image, but it's strictly an auxiliary input, say for putting up a sponsor's name while you're using a different digital input for image B. Rotation, LFO modulation, etc. aren't available for the C input.

The Image Offset and joystick controls to the right should be self-explanatory.

Whew! That's as much of the P-4 manual as I can type from memory. I'm sure I've missed some things and questions will be cheerfully (I hope) entertained.