Hello
I have a weird problem in my Voyager synth. the filter creates this really weird lfo to the wave. It sounds like there is some modulation going on. I closed any other parameteres such the LFO’s and check all the OSC. its coming from the filter ENV. and its change the frequency with the ATTACK, DECAY, SUSTAIN knobs. from left till the top.
does anybody had the same problem?
thanks
The filter is designed to go into self-oscillation at certain settings. It’s not as much a problem as it is a feature. Moog filters have always done this, AFAIK.
Did it suddenly start doing this after a while of not using the synth?
You must have the env tied to the filter through a modulation bus somewhere if the env controls are affecting the filter. There are many ways for this to happen and it is a standard routing.
Thank you all for your replies.
I know that the filter can create aself ocsilation and about the option to get the Env control it theough the lfo bias. But that is not the issue. All the bias are closed. The lfo rate can be set anywhere and steel the filter create weird modulation in some conditions. I found out when exactly it happens and i made a short video to explain it.
By the way all the presets are sound different since it started. They are not “clean”.
http://www.youtube.com/watch?v=GK7ITDjdkxk&feature=youtube_gdata_player
I don’t think it is self oscillation, I think the rate is the attack time + the decay time.
If you leave the attack and decay at a setting where it is oscillating and does the sustain level affect the sound?
Also try reducing the envelope depth to zero and does the effect go away?
That doesn’t sound normal.
If there is absolutely no pot mapping going on, then I agree with EricK; that’s not normal behavior. Sounds like an op amp might be going into self oscillation somewhere in the VCA.
Eventually after talking with moog I have decide to take the synth to the lab. Before that I reset all the mapping and factory reset but that problem won’t go.
Thank you all for your replies
I’ll post later what was the problem and how it has been fixed.
Levi
I realized something interesting
After playing a new voyager at the store.
I think somehowon my voyager, the Vol Env and the Filter Env connected together.
In the new synth I tried at store, they act seprately.
On my voyager, when the vol attack is high and the filter attack is low, the filtershort attack will repeat itself again and again for the whole lengh of the vol attack, and that sounds like a Filter Lfo.
Somebody has any idea? Cause my lab doesnt have a clue till now.
Did you try a master reset? It may very well be pot papping, but I don’t think that the filter env is a destination. There are a limited number of options with pot mapping.
Levib, can you confirm that there is no pot mapping active ?
Assigning the Volume Envelope Attack knob to Cutoff in one map, and the same knob to Resonance in a second map could produce somewhat similar results…
Also, from your description in your last post, it looks like the filter envelope might be looping (not possible in a properly functioning Voyager, but available on some other synths).
If that’s the case, then there might be some CMOS logic gate in the envelope circuits that has failed. Logic chips failing in a Voyager seems more common than not… One other member here, named Spav, has recently had to replace a few CD4052 analog signal switches chips in his Voyager.
Hi thealien666,
I made a mapping reset and the problem still exist. You described it better then me- the filter envelope actually looping! And should not behave like that.
Can you please explain me what are the CMOS logic gate in the envelope circuits? So I can focus my tech engeenir who trying to fix it. I’ve been at the lab today for an hour And we didn’t find the reason for the problem.
Thank you 
I made the mapping reset if that’s what you mean. When the 3.5 OS Released I updated the synth too. Is there any other reset to try?
If you get the same result with the init sound (EDIT menu) then there is definitely a hardware problem on your Voyager.
Rudi
I don’t have access to the specific schematics for a Moog Voyager, but relying on past implementations of envelopes circuits in Moog synths, there was sometimes a CD4007 (used as threshold detector) used to have the circuit go through the different envelope stages.
One thing that I’m sure of, is that there are some CD4052 (digitally controlled analog switches) chips in there for the different CV routing, and those have failed in another member’s Voyager recently (he is still investigating the cause of their failure, and suspect the switching PSU sequencing might have damaged those sensitive CMOS chips by the power rails). But he did not have the problems you show, however.
If you have access to a certified tech (which I am not btw, I’m just an electronic hobbyist) he should contact Moog Music support and ask them if he could get a copy of the service manual for the Voyager. That way, he could have the schematics in front of him and have a better idea where to look for possible failures.
TIFWIW.
Levib
If it is just the Volume envelope causing you problems then get your guy to check the operation of U7. If it is the Filter envelope check the operation of U29.
One word of warning when getting devices off this board is that it is multilayered so be very careful not to damage the plating in the holes as you can destroy the board.
There are no service manuals for the Voyager they are currently in the process of producing them.
Hi
So my voyager is in the lab and the problem isn’t solved yet 
We can’t find the source for it but still trying
I wonder if anybody knows where can I get 3.4 OS
I would like to get back to this version.maybe it will fix the problem.
I do not remember this happening before I made an upgrade to 3.5.
Here’s the link for the 3.4 version (but it will not fix your problem I guess):
http://www.moogmusic.de/Version_3_4.zip
Some update about the situation:
the lab couldnt piont the source of the problem and we suggested that it could be one of the switches.
so all these switches been replaced:
U37. U39. U73. U51. U36. U28. U29.U32. U7. U24, U55
unfortunately, the problem still exist. the filter still creates this weird LFO looping.
I even tried returning back to Ver. 3.4, and of course it didnt change a thing.
this is not a natural behavior. I checked a new voyager on store and it acts right.
I’m kinda hopless… don’t know what to do.
It’s a new synth from store, only two years old since I bought it, and its been in the lab for 3 times already… and still do