Tuning Issues With Korg Arp Odyssey

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TCLGuy1
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Tuning Issues With Korg Arp Odyssey

Post by TCLGuy1 » Mon Oct 29, 2018 11:23 pm

Are there any Korg Arp Odyssey owners out there that can confirm that this is normal?

If I tune oscillator 1 at C3, then C4 will be 8 cents sharp and C2 will be 8 cents flat. C5 will be 16 cents sharp, C1 is 16 cents flat  and so on. Behavior is the same for oscillator 2. I contacted the dealer that sold me the unit and they in turn contacted Korg.

Via the dealer, here's the response from Korg:

“When I conducted a tuning test for the Odyssey that we have here in the office, I came up with very similar results.
The reissue Odyssey was built using the same specs / schematics as the original Odyssey from the 70’s so it comes with the same “charm” and “characteristics” as the original.”


Pitch drift to the tune of 8 cents per octave seems like an excessive amount of “charm”. :despair:

Any thoughts, ideas?

Thanks!

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Post by Dcramer » Mon Oct 29, 2018 11:40 pm

:hihi: as if Korg reproduced it so accurately.

Korg makes me laugh, I remember one of there staff being completely confused when I asked about the Korg MS-50, he had no idea they’d made such a device.

Probably what’s going is your oscillator is out of scale;
In the old days, such instruments had a little trimmer that would let you offset the pitch and alter the ‘scale width’ so that all the octaves were in tune.
Some newer instruments might have a little setup routine that does this for you like the bassline oscillator on my son’s Akai Rthym Wolf, you put it in a certain mode with the updated software and it scales the octaves automatically.
I’m not sure how the Karl Odessy works but I’m sure there’s a way to do it.
It’s either in the manual, or the service manual. :tu:

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Dave Peck
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Post by Dave Peck » Tue Oct 30, 2018 12:00 am

That is not TUNING, it is the 1 volt per octave CALIBRATION.

This calibration is something that commonly needs to be adjusted from time to time on just about any analog synthesizer, so that the keyboard will cause the pitch produced by the oscillators to accurately track the keyboard, so playing up or down an octave on the keyboard causes the pitch of the oscs to go up or down exactly one octave, and not a little bit more or less than an octave as you are currently experiencing on your synth.

That's what the small holes on the front panel in the osc sections are for. There are small trim pots under these for adjusting the 1 volt per octave calibration.

If you don't know how to do this, you can either read up on it and give it a try yourself, or it may be better to have it done by someone who knows how to do this - and have them show you how to do it so you can do it next time. You may need to do this once or twice a year if you really want to keep it tracking very accurately.


....and btw, the dealer & the guy from Korg should have realized what the issue was. That response you received from them about this was ridiculous.

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Post by Blairio » Tue Oct 30, 2018 1:01 am

when I took delivery of my Moog Grandmother a couple of weeks back, it had some interesting calibration issues. Scale quantization seemed ok if you just played C2, then C3 then C4. However random notes were out in between. Also the mod wheel was on even when it was off (if you see what I mean), and some pot ranges and centre points were out.

Luckily running the key board calibration routine sorted the bum notes out, and some Moog Support supplied sysex files ( one each for high, low and centre points of travel) sorted the pots and wheels out.

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Post by TCLGuy1 » Thu Nov 01, 2018 3:19 pm

Thanks everybody - still looking into how to calibrate this sucker!

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Dave Peck
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Post by Dave Peck » Thu Nov 01, 2018 5:14 pm

In your opening post, which mentions "8 cents" etc., this leads me to believe you probably have a digital tuner, is this correct? If so, there's a pretty easy way to do this calibration.

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Post by TCLGuy1 » Thu Nov 01, 2018 6:55 pm

Dave Peck wrote:In your opening post, which mentions "8 cents" etc., this leads me to believe you probably have a digital tuner, is this correct? If so, there's a pretty easy way to do this calibration.
Yes! Let me know.

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Post by Dave Peck » Thu Nov 01, 2018 7:41 pm

DISCLAIMER - If you somehow misunderstand these instructions, it won't break anything, but you COULD make it worse, and then you'll need to have someone else do the calibration anyway.

Here's what you do:

In the OSC1 section there is a small round trim pot near the top, to the right of the two frequency sliders. In the OSC 2 section, there are two if these. They may be under small plastic caps. You'll need to remove these caps and access the small trim pots located below the caps, recessed into the metal front panel. These trim pots are tiny 'knobs' that you turn, using a small screwdriver like a jeweler's screwdriver. The purpose of these is to adjust how the osc pitch tracks the keyboard.

1. Turn the synth on and let it warm up for about 20 minutes.

3. Odyssey VCF freq slider all the way up, High pass filter cutoff all the way down, VCA initial gain up, VCO1 sawtooth osc in audio mixer up. Set the octave switch to the middle. Set the VCO1 frequency sliders both to the middle. You should hear a constantly droning sawtooth from osc1, on a mid-range pitch. You should not hear anything else.

4. Play the bottom 'C' on the keyboard and make a note of the exact frequency displayed in your digital tuner.

5. Now play up one octave and note the frequency again. You WANT it to be exactly double the first frequency. That's what you're about to adjust.

6. Make a note of whether this higher octave note is sharp or flat, and then use a small screwdriver to turn the small OCS1 trim pot a little bit. Make a note of which direction you turned it. Don't try to get the pitch correct at this point, just turn the trim pot a bit (maybe a quarter turn).

7. Now play the bottom key again and note the frequency (it may be a little different now), and play up one octave again and see if the jump is closer to the exact double you are trying to achieve.

8. If it is closer, but still off in the same direction as before (still sharp), turn the trim pot a bit more in the same direction you turned it previously. If it is off, but now it's off in the other direction (i.e. was sharp, is now flat) it means you turned it too much on the previous try and you should turn it part way back again.

9. Go back to step 4 and repeat.

After a couple of tries, you'll have it adjusted so it plays exact octave pitches when you play octaves on the keyboard.

Then shut off the blue OSC1 slider in the audio mixer and turn up the OSC2 slider and do the same, using the OSC2 trim pot.

Note that there is an additional trim pot in OSC2, which is a secondary adjustment for OSC2's tracking when you play two notes at the same time (pressing two keys simultaneously on the Odyseey keyboard causes OSC1 to play the low note and OSC2 to play the high note). Don't adjust this unless you have to.

Let me know how it works!

BTW - you should let the synth warm up for several minutes whenever you turn it on, because the pitch WILL drift during this warm-up period, and the keyboard tracking can be off during this warm up period. This is normal. But after that, it should stay quite stable and you should not have to re-calibrate the trim pots again for a long time, if ever.

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Post by TCLGuy1 » Thu Nov 01, 2018 11:31 pm

WOW! Thanks Dave for the detailed instructions!

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Re: Tuning Issues With Korg Arp Odyssey

Post by bambrose » Fri Feb 21, 2020 6:58 am

Thank you for such a precise and clear instruction @Dave Peck
Took me all of ten minutes to get perfect tracking after having read through your post

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Re: Transpose adjustment

Post by fbertran5 » Tue May 12, 2020 7:58 am

Dave Peck wrote:
Thu Nov 01, 2018 7:41 pm
DISCLAIMER - If you somehow misunderstand these instructions, it won't break anything, but you COULD make it worse, and then you'll need to have someone else do the calibration anyway.

Here's what you do:

In the OSC1 section there is a small round trim pot near the top, to the right of the two frequency sliders. In the OSC 2 section, there are two if these. They may be under small plastic caps. You'll need to remove these caps and access the small trim pots located below the caps, recessed into the metal front panel. These trim pots are tiny 'knobs' that you turn, using a small screwdriver like a jeweler's screwdriver. The purpose of these is to adjust how the osc pitch tracks the keyboard.

1. Turn the synth on and let it warm up for about 20 minutes.

3. Odyssey VCF freq slider all the way up, High pass filter cutoff all the way down, VCA initial gain up, VCO1 sawtooth osc in audio mixer up. Set the octave switch to the middle. Set the VCO1 frequency sliders both to the middle. You should hear a constantly droning sawtooth from osc1, on a mid-range pitch. You should not hear anything else.

4. Play the bottom 'C' on the keyboard and make a note of the exact frequency displayed in your digital tuner.

5. Now play up one octave and note the frequency again. You WANT it to be exactly double the first frequency. That's what you're about to adjust.

6. Make a note of whether this higher octave note is sharp or flat, and then use a small screwdriver to turn the small OCS1 trim pot a little bit. Make a note of which direction you turned it. Don't try to get the pitch correct at this point, just turn the trim pot a bit (maybe a quarter turn).

7. Now play the bottom key again and note the frequency (it may be a little different now), and play up one octave again and see if the jump is closer to the exact double you are trying to achieve.

8. If it is closer, but still off in the same direction as before (still sharp), turn the trim pot a bit more in the same direction you turned it previously. If it is off, but now it's off in the other direction (i.e. was sharp, is now flat) it means you turned it too much on the previous try and you should turn it part way back again.

9. Go back to step 4 and repeat.

After a couple of tries, you'll have it adjusted so it plays exact octave pitches when you play octaves on the keyboard.

Then shut off the blue OSC1 slider in the audio mixer and turn up the OSC2 slider and do the same, using the OSC2 trim pot.

Note that there is an additional trim pot in OSC2, which is a secondary adjustment for OSC2's tracking when you play two notes at the same time (pressing two keys simultaneously on the Odyseey keyboard causes OSC1 to play the low note and OSC2 to play the high note). Don't adjust this unless you have to.

Let me know how it works!

BTW - you should let the synth warm up for several minutes whenever you turn it on, because the pitch WILL drift during this warm-up period, and the keyboard tracking can be off during this warm up period. This is normal. But after that, it should stay quite stable and you should not have to re-calibrate the trim pots again for a long time, if ever.
Thanks a lot.

And could you please explain how to adjust the Transpose with the two external trimmers (above the transpose switch)?

When I change to 2 octaves up or down the tuning is not exact (but quite) as in the middle position (once done all of the VCO's adjustments you've explained)

Thanks again.

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Re: Tuning Issues With Korg Arp Odyssey

Post by Dave Peck » Tue May 12, 2020 4:19 pm

It looks like the Korg is a little different from the original Arp Odyssey here - on the original, there's just one trim pot for the octave switch, and you just adjust it so that changing the switch position gives you exactly 2 octaves up & down (you do this AFTER you adjust the 1V/oct tracking in the osc sections, of course).

I don't have the Korg, I have the original rev II Arp Odyssey. Not sure what the second trim pot on the Korg version's octave switch would be for, you'll have to track down the Korg Service manual for that info.

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Re: Tuning Issues With Korg Arp Odyssey

Post by fbertran5 » Fri May 15, 2020 5:07 pm

Thanks a lot.

Best regards.

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Re: Tuning Issues With Korg Arp Odyssey

Post by Dave Peck » Fri May 15, 2020 6:12 pm

If you are comfortable with the idea of opening your Korg Odyssey, it may be worth looking at the PCB to see if there are any markings on the board at these two trim pots to tell you which one is for the octave cal and what the second one is for....

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Re: Tuning Issues With Korg Arp Odyssey

Post by fbertran5 » Sat May 16, 2020 12:25 am

I'll do it.

There's no Korg service manual and I've sent an email to Korg asking what these two trimmers are for, with no answer yet.

Regards.

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Re: Tuning Issues With Korg Arp Odyssey

Post by KSS » Sat May 16, 2020 3:38 am

On the original ODYs, there are two trims for the Up/Dn 2Oct switch. T3 and T4 on the A1 Bd. You can read abou them in the ARP Ody service manual.

T2 is labeled "normal", and actually sets the down 2 oct position. T4 is for the up 2 oct position. The calibration for the Korg ODYs probably coincide with those for the originals, and the service manual has step-by step instructions.

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Re: Tuning Issues With Korg Arp Odyssey

Post by fbertran5 » Sat May 16, 2020 6:30 am

Finnally I've found out !!!

The Korg has a Mode switch (little one between the Portamento slider and the Transpose lever (2 octaves switch).

This Mode switch selects whether the portamento is enabled when you use the Transpose lever.
(Up = disabled.
Down = enabled).

The trimmer on the right adjusts the Transpose lever when the Mode switch is disabled/up and the trimmer on the left, when enabled/down.

Both trimmers must be adjusted to use one mode or the other.

Regards.

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Re: Tuning Issues With Korg Arp Odyssey

Post by Dave Peck » Sat May 16, 2020 1:25 pm

KSS wrote:
Sat May 16, 2020 3:38 am
On the original ODYs, there are two trims for the Up/Dn 2Oct switch. T3 and T4 on the A1 Bd. You can read abou them in the ARP Ody service manual.

T2 is labeled "normal", and actually sets the down 2 oct position. T4 is for the up 2 oct position. The calibration for the Korg ODYs probably coincide with those for the originals, and the service manual has step-by step instructions.
Ah, that's right! But only for the 'white face' rev I version, model 2800. I used to have one of those, but now I have a black & gold 'rev II", model 2813. The 2813 only has a single trimmer, R23, for the octave switch.

I remember that the original had the portamento AFTER the octave switch, so you could flick the switch and get a long slow slide, but the 2813 doesn't work like that. I prefer the original setup. Nice to see that the Korg allows both options, very smart of them! (I also think their inclusion of all three filter types was a brilliant idea!)

fbertran5, sounds like you got this octave trimming procedure sorted out?

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Re: Tuning Issues With Korg Arp Odyssey

Post by fbertran5 » Sat May 16, 2020 3:35 pm

Hi Dave,

Yes, everything's fine and in tune.
Thanks.

I had an Arp Ody rev3 in the past and I can tell, imho, that the Korg sounds quite the same or the same.

But let's see its reliability with time 😁😁😁

Regards.
Francesc.

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Re: Tuning Issues With Korg Arp Odyssey

Post by KnobTurner » Sat May 16, 2020 5:45 pm

My Memory Moog would go out of tune, I had to learn how to open that sucker and tune the oscillators manually.
Nice to see some of the newer synths have this feature build in.

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