Voyager Osc Calibration Help

[nightcrier]

Greetinge Moog Warriors! Has anyone ever been able to calibrate the oscillators on a Moog Voyager. I can no longer keep them in tune from the lowest key to the upper and have no idea who in the Detroit or surrounding area might be able to help. Glad to pay, just need some direction here. Thanks in advance!!

[mcguyver]

I had asked Nick Montoya who used to run the repairs at Moog while I worked there and I believe he gave me these same instructions that were posted here from a response from Amos (also of Moog)

Amos at Moog once posted this:

Osc 1 tuning & scaling info

Here is the info you should need in order to adjust the tuning of oscillator 1 on your Voyager

"First you will need something with which to prop up the chassis so that you can open the back panel while you work. I recommend a stack of books or similar, about 3” thick. Raise the panel to its full upright position and slide your prop under the back so that the panel will rest in a vertical position. Now you can remove the five screws from across the back panel and open the synth.

I have attached a diagram which has the relevant adjustment points highlighted in a lovely shade of blue. There are two multi-turn trimmers (RT1 and RT2), which are tall and boxy with a brass turnscrew at the top, and there is one single-turn trimmer (RP9) which is a squat boxy item with a recessed plastic turning adjustment. The latter, RP9, is the adjustment for the keyboard tracking of oscillator 1. This is the first thing to adjust.

Here is how to set up the Voyager for proper tuning: Go to the Edit menu and select “Init. Defaults,” press Enter, cursor to Yes and press Enter. This will set all of the oscillators to (what should be) unison tuning, all set to Squarewave. By default only oscillator 1 will be turned on.
Next, go back to the Edit menu and select “Pitch Bent amount” – set the pitch bend to Off. This ensures that pitch bend does not inadvertently affect your tuning.
Go to the Mixer section of the control panel and switch off Oscillator 1, and switch on oscillator 2. Do not adjust the oscillator 2 or 3 “fine tune” controls; leave them be so that your tuning is not thrown off by accident.
Hook up your synth to a tuner and use only the master Fine Tune control (lower left of the control panel next to the Glide rate knob) to adjust the master tuning until oscillator 2 is in proper tune. We tune to the low “E” on the keyboard, and then test the keyboard scaling by playing the “E” two octaves up on the keyboard. Generally if this interval is set correctly, then there is very little error across the rest of the keyboard.
So, once you have determined that oscillators 2 and 3 are properly tuned, set the switches in the mixer section so that oscillators 2 and 3 are both turned off and only oscillator 1 is on.

Play the low “E” and check the tuner; is Oscillator 1 in tune? Also, you could turn on oscillator 2 and listen for beating between the oscillators. If Oscillator 1 is not in tune at low E, then we need to make a few adjustments before setting the keyboard scaling. First, adjust the multi-turn trimmer RT2 until oscillator 1 is bang-on pitch at low E. it can help to set the Gate switch on the control panel to On/Ext. so that the note will continue to play while you make adjustments.
Next, set the Oscillator 1 Octave switch on the panel to 2’. Play the same low E key on the keyboard and check the tuning. If it is not in tune (should be E5, I think), adjust the multi-turn trimmer RT1 until oscillator 1 is exactly in tune at the 2’ octave setting. Now switch back to 8’ on oscillator 1 and play the low E key and adjust RT2 if necessary to tune in E3 on your tuner. You may need to go back and forth a time or two between the above steps; when you are finished you should have an oscillator that is in tune at all of the octave settings when playing the same low E key. A note: if the tuning is OK on all lower octaves but it is not correct at the 1’ setting, you can adjust the single-turn trimmer RP11 to correct this.


OK, so now Oscillator 1 is in tune and can be scaled to the keyboard. Turn on Oscillator 2 and listen to be sure that oscillators 1 and 2 are still in unison on the low E. Do not adjust the tuning of oscillator 2! If the two oscillators are not quite in unison, adjust RT2 until they are.
Now play up two octaves on the keyboard; it will probably sound wretched. Very carefully, as it’s quite sensitive, adjust the single-turn trimmer RP9 until oscillators 1 and 2 are in unison again. This will, unfortunately, have some effect on the Osc.1 Range adjustment, so you should play the low E again and see if the oscillators have drifted apart a bit. At this point you might want to switch off oscillator 2 and listen only to oscillator 1 as you fine-tune the adjustments. You will want to alternate between playing the low E and the E two octaves above it… use RT2 to adjust the low E to be in tune, and RP9 (with the utmost delicacy as it is so fiddly) to scale the keyboard such that the high E is in tune. Through all of these adjustments, do not change the panel knobs in any way apart from switching the various oscillators on and off using the mixer section.

This completes the calibration of oscillator 1.

Osc 2 tuning and scaling info

Follow the same procedure as with Oscillator 1 to set up the Voyager for proper tuning: Go to the Edit menu and select "Init. Defaults," press Enter, cursor to Yes and press Enter. This will set all of the oscillators to (what should be) unison tuning, all set to Squarewave. By default only oscillator 1 will be turned on.
Next, go back to the Edit menu and select "Pitch Bend amount" and set the pitch bend to Off. This ensures that pitch bend does not inadvertently affect your tuning. Before you begin to make any changes to the tuning, be sure that your Voyager has been turned on and running for 30 to 60 minutes, so that it can reach a stable operating temperature.

Next, connect your Voyager audio output to a tuner and use only the master Fine Tune control (lower left of the control panel next to the Glide rate knob) to adjust the master tuning until oscillator 1 is in proper tune. We tune to the low E on the keyboard, and then test the keyboard scaling by playing the E two octaves up on the keyboard. If this interval is set correctly, then there is generally very little error across the rest of the keyboard.

Go to the Mixer section of the control panel and switch off Oscillator 1, and switch on oscillator 2. Do not adjust the oscillator 2 or 3 Frequency controls; leave them be so that your tuning is not thrown off by accident.

Play the low E on the keyboard and check the tuner; is Oscillator 2 in tune? Also, you could turn on oscillator 1 and listen for beating between the oscillators. If Oscillator 2 is not in tune at low E, then we need to make a few adjustments before setting the keyboard scaling. First, adjust the multi-turn trimmer RT4 until oscillator 2 is exactly on pitch at low E. If you turned on Oscillator 1 also, you can adjust RT4 until there is no beating between oscillators. If this is confusing, turn off Oscillator 1 and listen only to Oscillator 2. It can help to set the Gate switch on the control panel to On/Ext. so that the note will continue to play while you make adjustments.

Next, set the Oscillator 2 Octave switch on the panel to 2'. Play the same low E key on the keyboard and check the tuning. If it is not in tune (should be E5, I think), adjust the multi-turn trimmer RT3 until oscillator 2 is exactly in tune at the 2' octave setting. Now switch back to 8' on oscillator 2 and play the low E key, and adjust RT4 if necessary to tune in E3 on your tuner. You may need to go back and forth a time or two between the above steps; when you are finished you should have an oscillator that is in tune at all of the octave settings when playing the same low E key.

A note: if the tuning is OK on all lower octaves but it is not correct at the 1' setting, you can adjust the single-turn trimmer RP20 to correct this.

OK, so now Oscillator 2 is in tune and can be scaled to the keyboard. Turn on Oscillator 1 and listen to be sure that oscillators 1 and 2 are still in unison on the low E. Do not adjust the tuning of oscillator 1! If the two oscillators are not quite in unison, adjust RT4 until they are.
Now play up two octaves on the keyboard. Very carefully, as it's quite sensitive, adjust the single-turn trimmer RP21 until oscillators 1 and 2 are in unison again. This will, unfortunately, have some effect on the Osc.2 Range adjustment, so you should play the low E again and see if the oscillators have drifted apart a bit. At this point you might want to switch off oscillator 1 and listen only to oscillator 2 as you fine-tune the adjustments. You will want to alternate between playing the low E and the E two octaves above it; use RT4 to adjust the low E to be in tune, and RP21 (with the utmost delicacy as it is so fiddly) to scale the keyboard such that the high E is in tune. Through all of these adjustments, do not change the panel knobs in any way apart from switching the various oscillators on and off using the mixer section.

At this point, Oscillator 2 should be in tune.



Osc 3 tuning and scaling info

Here is the info you should need in order to adjust the tuning of oscillator 3 on your Voyager.

See the diagram for oscillator 3 tuning trimmer locations. There are two multi-turn
trimmers (RT5 and RT6), which are tall and boxy with a brass turnscrew at the top, and there is one single-turn trimmer (RP16) which is a short square item with a recessed plastic turning adjustment. The latter, RP16, is the adjustment for the keyboard tracking of oscillator 3.

Here is how to set up the Voyager for proper tuning: Go to the Edit menu and select "Init. Defaults," press Enter, cursor to Yes and press Enter. This will set all of the oscillators to (what should be) unison tuning, all set to Squarewave. By default only oscillator 1 will be turned on. Next, go back to the Edit menu and select "Pitch Bend amount" and set the pitch bend to Off. This ensures that pitch bend does not inadvertently affect your tuning. Before you begin to make any changes to the tuning, be sure that your Voyager has been turned on and running for 30 to 60 minutes, so that it can reach a stable operating temperature.

Next, connect your Voyager audio output to a tuner and use only the master Fine Tune control (lower left of the control panel next to the Glide rate knob) to adjust the master tuning until oscillator 1 is in proper tune. We tune to the low E on the keyboard, and then test the keyboard scaling by playing the E two octaves up on the keyboard. If this interval is set correctly, then there is generally very little error across the rest of the keyboard. Go to the Mixer section of the control panel and switch off Oscillator 1, and switch on oscillator 3. Do not adjust the oscillator 2 or 3 Frequency controls; leave them be so that your tuning is not thrown off by accident.

Play the low E on the keyboard and check the tuner; is Oscillator 3 in tune? Also, you could turn on oscillator 1 and listen for beating between the oscillators. If Oscillator 3 is not in tune at low E, then we need to make a few adjustments before setting the keyboard scaling.

First, adjust the multi-turn trimmer RT6 until oscillator 3 is exactly on pitch at low E. If you turned on Oscillator 1 also, you can adjust RT6 until there is no beating between oscillators. If this is confusing, turn off Oscillator 1 and listen only to Oscillator 3. It can help to set the Gate switch on the control panel to On/Ext. so that the note will continue to play while you make adjustments.

Next, set the Oscillator 3 Octave switch on the panel to 2'. Play the same low E key on the keyboard and check the tuning. If it is not in tune (should be E5, I think), adjust the multi-turn trimmer RT5 until oscillator 3 is exactly in tune at the 2' octave setting. Now switch back to 8' on oscillator 3 and play the low E key, and adjust RT6 if necessary to tune in E3 on your tuner. You may need to go back and forth a time or two between the above steps; when you are finished you should have an oscillator that is in tune at all of the octave settings when playing the same low E key.

A note: if the tuning is OK on all lower octaves but it is not correct at the 1' setting, you can adjust the single-turn trimmer RP14 to correct this.

OK, so now Oscillator 3 is in tune and can be scaled to the keyboard. Turn on Oscillator 1 and listen to be sure that oscillators 1 and 3 are still in unison on the low E. Do not adjust the tuning of oscillator 1! If the two oscillators are not quite in unison, adjust RT6 until they are.

There's one bit missing from that procedure. From the Moog forum:
Quote:
Note on Osc 3 tuning: Osc 3 has the tendency to sync with Osc 2. You may find it helpful to de-tune Osc 2 before tuning Osc3. Go to “init parameters” and turn Osc 1 off. Then, turn the Osc 2 Freq knob fully counterclockwise and turn the Osc2 Octave switch down to 32'.
Without that it'll appear you've got oscillator 3 in tune but it's quite likely to drift again within a couple of days.

Some general comments after having tuned my Voyager multiple times:
• Parts of the power supply that are live at mains voltage are exposed when you open the rear panel of the synth.
• Trimmers have very limited lifespans, typically something like 200 cycles, so don't adjust them any more than you absolutely have to.
• The process is very time consuming. There was a comment on the Moog forum that it takes an experienced engineer about 30 minutes; first time I tried it took me about 3 hours and I began to think I'd never get it right...
• The comment about the keyboard scaling trimmer being ridiculously sensitive is the absolute truth: turning it enough for the movement to be visible will send everything massively out of tune and it's not easy to get it back again.
• When you open the rear panel of the synth the change in temperature affects the tuning. So you really need to open it, make some changes, close it back up and wait for the tuning to stabilise before you check it.
• A stroboscopic tuner, like one of the Korg Pitchblack series, is a big help because they're very accurate.
• A proper non-conductive trimmer tool is a good idea: I use CK ceramic ones.
It's easy enough to find the trimmers: they're all clearly labelled as in the instructions and are located towards the bottom left of the board.

from: viewtopic.php?t=32485

I also need to tune/calibrate mine, it's unfortunately had to sit in its box for years but now I have space again to have it out. All of my presets are off because the oscillators have drifted lol.

[nightcrier]

Perfect - exactly what I was looking for. Thank you for sharing!

[nightcrier]

I was able to get a PDF right from Moog Music tech support with the latest calibration process (last updated in 2020). Very cool - also found a tech service here in Michigan to do the calibration for me (Vintage King - a great restoration company). Looking forward to getting this bad boy up to parr...then sell it! Thanks for all the help.