Korg/ARP Odyssey. LFO Envelope retrig problem.

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Korg/ARP Odyssey. LFO Envelope retrig problem.

Postby Broadwave » Thu Oct 01, 2015 2:52 pm

I think I may have discovered a bit of a problem with the LFO repeat of the envelopes :(

If you create a short sharp envelope patch, and switch the ADSR LFO REPEAT on, what you *should* get when playing the keyboard is an initial trigger of the ADSR followed by repeats from the LFO - you should end up with a cleanly triggering psudo-step sequencer effect when playing melodies.

It would seem that both mine and a friends Korg Oddy is not cleanly triggering from the initial keyboard strike - it's very hit & miss and not at all like the genuine Odyssey's behaviour, in fact it's a bit of a mess.

I can only put it down to different keyboard circuitry (digital scanning), an omission in the triggering path, or possibly that the Square LFO output providing the gate signal is inverted. Unfortunately it seems to be a fundamental circuit error and obviously not something that can be fixed with a firmware update, and I very much doubt if there'll be a recall... So it looks like I'll have to fix it myself :roll:
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Re: Korg/ARP Odyssey. LFO Envelope retrig problem.

Postby Jabberwalky » Thu Oct 01, 2015 3:20 pm

Does it happen when controlling via cv/gate?
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Re: Korg/ARP Odyssey. LFO Envelope retrig problem.

Postby meatballfulton » Thu Oct 01, 2015 3:33 pm

Considering the repeating envelopes are a key feature of the Odyssey, that's a shame. Good luck with the mod.
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Re: Korg/ARP Odyssey. LFO Envelope retrig problem.

Postby Broadwave » Thu Oct 01, 2015 6:48 pm

Jabberwalky wrote:Does it happen when controlling via cv/gate?


I had a sudden rush of hope when I read this... :( No, sadly it makes no difference - an external trigger doesn't reset the LFO either, which I'm pretty sure it should, so that's probably a good place to start looking. I just hope Korg hasn't deviated too far from the original circuit - tracing it all back with SMDs is going to be a PITA, especially if it's a muli-layer PCB.
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Re: Korg/ARP Odyssey. LFO Envelope retrig problem.

Postby Broadwave » Fri Oct 02, 2015 9:59 am

UPDATE - Think the problem is with the LFO repeat switch - I believe Korg, for whatever reason, has wired the switch up to disengage the keyboard triggering when using the LFO - Why??!!
I've also found that the square wave output from the LFO is inverted! Luckily, it's an easy fix :roll:

Considering how many Oddys Korg have sold, I'm surprised that no one's picked up on such a basic flaw.

I've contacted Korg with a full explanation, so I'm just waiting for a response - fingers crossed.
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Re: Korg/ARP Odyssey. LFO Envelope retrig problem.

Postby Jabberwalky » Sat Oct 03, 2015 8:46 pm

Strange. Korg definitely did it correctly with the older synths like the Minikorg700/800dv. The repeat function retriggers the envelopes when you hit a key. It's also possible to have them retrigger by themselves when in Hold mode. I'm not too familiar with the Odyssey but it seems the LFO is not synced to key, but free running. Are you sure the original had a LFO reset on key?

From the Korg site

Image

The typical use is to set both ADSR and AR to “KYBD GATE” so that the envelope operates when you play the keyboard. Next, switching this to “LFO REPEAT” will make the envelope trigger repeatedly at cycles of the LFO. If the ADSR repeat switch in the center is set to “KYBD REPEAT,” the envelope is triggered by the LFO only while you hold down a key, but if it is set to AUTO REPEAT, it is triggered even if a key is not being held down; depending on the settings, this can produce continuous sound as if it were driven by a step sequencer.
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Re: Korg/ARP Odyssey. LFO Envelope retrig problem.

Postby Broadwave » Sun Oct 04, 2015 6:36 am

Jabberwalky wrote:Are you sure the original had a LFO reset on key?


Absolutely, I had one for 30 years and I also repair/refurbish ARP Oddy/Axxe & 2600s ;)

I'm pretty sure Korg have messed up the LFO Repeat switch wiring, so that it disengages the Keyboard Trigger when the switch is down - which it shouldn't do.

It's so tempting to do a DIY repair, or at least open it up and take a closer look, but I just don't want to invalidate the warranty. Meanwhile, mine's sadly packed up ready for a return and refund :(
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Re: Korg/ARP Odyssey. LFO Envelope retrig problem.

Postby meatballfulton » Sun Oct 04, 2015 1:41 pm

Makes me glad I didn't jump on one. That was one of the features I used a lot when I owned my Odyssey decades ago. Oh well.
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Re: Korg/ARP Odyssey. LFO Envelope retrig problem.

Postby Reginator » Sun Oct 04, 2015 3:05 pm

So, the LFO envelope retrigger is the second problem with the Korg Odyssey. I reported earlier to Korg about the CV out not sending PPC vibrato and this was the email response from their tech support (extracted from Korg To Release Odyssey thread):

Reginator wrote:"I heard back from the development team and unlike the original Odyssey, the PPC vibrato on the new Odyssey is not added to CV out.

Unfortunately, we do not have schematics to provide or can authorize or encourage users to open the product and make modifications."


It's a bummer when their advertisement says, "The distinctive synthesis of the ARP Odyssey has been reproduced from the circuit level up", but's it's not an entirely accurate statement.
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Re: Korg/ARP Odyssey. LFO Envelope retrig problem.

Postby Broadwave » Sun Oct 04, 2015 8:00 pm

Reginator wrote:I reported earlier to Korg about the CV out not sending PPC vibrato


Not just vibrato, but PPC bend and +/- 2 Oct transpose should also be present on the CV out :roll:
Considering David Friend was on-board, I'm shocked that basics like these have slipped through.

I'm not slagging Korg off, they did an admirable job, but they should have got it right.
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Re: Korg/ARP Odyssey. LFO Envelope retrig problem.

Postby Reginator » Mon Oct 05, 2015 9:37 am

Agreed
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Re: Korg/ARP Odyssey. LFO Envelope retrig problem.

Postby bochelli » Tue Oct 06, 2015 9:07 am

Broadwave wrote:
Jabberwalky wrote:Are you sure the original had a LFO reset on key?


Absolutely, I had one for 30 years and I also repair/refurbish ARP Oddy/Axxe & 2600s ;)

I'm pretty sure Korg have messed up the LFO Repeat switch wiring, so that it disengages the Keyboard Trigger when the switch is down - which it shouldn't do.

It's so tempting to do a DIY repair, or at least open it up and take a closer look, but I just don't want to invalidate the warranty. Meanwhile, mine's sadly packed up ready for a return and refund :(

Is Korg selling these with a 2 year warranty ? ive yet to see inside one .
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Re: Korg/ARP Odyssey. LFO Envelope retrig problem.

Postby Yekuku » Tue Oct 06, 2015 8:08 pm

bochelli wrote:Is Korg selling these with a 2 year warranty ? ive yet to see inside one .

AFAIK Korg gives 1 year warranty in the US. Retailers can give up to 3 years, like Thomann.
This guy opened up a KORG Odyssey , maybe you will find it useful:
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Re: Korg/ARP Odyssey. LFO Envelope retrig problem.

Postby Broadwave » Thu Oct 08, 2015 6:21 am

I went to Dawsons yesterday and messed around with another Odyssey - same problems, so it definitely wasn't just mine that was off kilter. While I was there, I also noticed that the Pulse Width wasn't calibrated correctly on both VCOs. With the PW sliders fully down, the square waves should be a perfect 50%... they're not. I had to nudge the sliders up about 5mm to get them right. Again, I don't know if it was just this one I tried, or if the problem is right across the range.

I've got my refund and bought a second hand Roland V-Synth instead.
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Re: Korg/ARP Odyssey. LFO Envelope retrig problem.

Postby ppg_wavecomputer » Thu Oct 08, 2015 12:00 pm

When reading all this, I am utterly happy to own an original white-face Odyssey. No need to be bothered with this type of flaws...

How do they get away with this? Hoping all original Odyssey owners from the days of yore have turned geriatric in the meantime, faulty memory and all?

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