OS Osc 3 sounds different that 1 & 2

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muksys
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OS Osc 3 sounds different that 1 & 2

Post by muksys » Tue Apr 16, 2013 10:26 am

So, couple of weeks ago I had the scope hooked up to my OS and looking for exactly where a true saw and square wave were on all 3 osc's. As I was going through them I noticed that Osc 3 sounded different than 2. I began A/Bing them and what I found was that Osc 1 & 2 sound the same (good n' beefy), but Osc 3 sounded thinner/nasally-er. There is a considerable amount of low-end loss. Now, from what I gathered from the previous owner was that the the 3rd Osc had "died" and was sent to Moog for repair.

My question is, has anyone else experienced this? I'd be ok with a subtle difference between the Osc's (duh, analog), but this is pretty extreme / very noticable. It had the warranty extended, which, thankfully, transfers to different owners, so I will send it in if it can be corrected, but I'm just curious what others have experienced. Has anyone else noticed this when sending their Voyager in for repair of a dead osc?

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CZ Rider
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Re: OS Osc 3 sounds different that 1 & 2

Post by CZ Rider » Tue Apr 16, 2013 12:03 pm

No difference here, all three sound pretty much the same to my ears.
Of the three Voyagers I have here the only difference like you noted is one of my Voyagers the noise is much lower volume than the others. Thought there might be a trimmer inside, but I have never seen any Voyager service procedures for tuning or adjusting this. About time Moog made this available to Voyager owners. Would be nice to have the tuning/alignment information. No need for simple adjustments to be done by the factory.

I do notice if I dial in the same frequency and same waveform on all three oscillators, and try to get that rolling out of phase close detune. The Voyager oscillators lock up to each other. Can see that on a scope and three oscillators locked up, sound thinner than just one by itself. The Voyager oscillators on mine are really prone to locking. Anyone else notice this?
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Portamental
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Re: OS Osc 3 sounds different that 1 & 2

Post by Portamental » Tue Apr 16, 2013 12:21 pm

I ran a battery of tests on the OS when I go it. Some results are shown here. The 3 oscillators sound exactly the same to me.

CZ Rider wrote:The Voyager oscillators on mine are really prone to locking. Anyone else notice this?


No. It was always difficult to tune the three oscillators to unison by ear. I did achieve it using my software scope though. No beating whatsoever. Just a big fat wave of increased magnitude since waves of the same frequency simply add up.

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Re: OS Osc 3 sounds different that 1 & 2

Post by stiiiiiiive » Tue Apr 16, 2013 12:55 pm

Portamental wrote:Just a big fat wave of increased magnitude since waves of the same frequency simply add up.

When in phase, a geek'd say ;)

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Re: OS Osc 3 sounds different that 1 & 2

Post by muksys » Tue Apr 16, 2013 1:28 pm

Thanks for the replies. Not sounding promising. I have some audio recorded that ill up later today.

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CZ Rider
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Re: OS Osc 3 sounds different that 1 & 2

Post by CZ Rider » Tue Apr 16, 2013 1:41 pm

Portamental wrote: No beating whatsoever. Just a big fat wave of increased magnitude since waves of the same frequency simply add up.

The OS oscillators may be different from the other Voyagers? When the Voyager PE/RME oscillators lock up it is as if all the life/motion in the waveforms just stops. Has to be the same frequency and all saws or squares, but easy to lock together.
Here is a small MP3 example:
Voyager oscillators locking together MP3 download 686K
Annoying sample, but the 3 oscillators start out locked up. At around 5 sec. I change the frequency on one oscillator to stop the locking. Nice 3 oscillators slowly interacting with each other. I turn the frequency to get a very slow roll, and at 11 sec. two oscillators lock, then all three lock at 14 sec. Very noticable snap when they lock up and on the scope they offset in a negative direction. Can see the lack of any motion from three oscillators when looking at the wave file.
Image

I noticed this when trying to make a drone with the Voyager. Was trying to emulate that slow chorus type sound I get with a Minimoog. The oscillators kept locking up to each other. There was an interview with the original Minimoog tech team. And was noted when they tried to improve the original Mini power by cleaning it up, the oscillators locked. And FWIW even the Moog huge sounding 901's will lock together at high frequency. But I think the sound is terrible, like this awesome motion of oscillators interacting, simply grinds to a halt.
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Re: OS Osc 3 sounds different that 1 & 2

Post by Ledbetter » Tue Apr 16, 2013 2:15 pm

I haven't noticed this with my Voyager, purchased in January, 2013. I'll check it out tonight with an oscilloscope.
Last edited by Ledbetter on Tue Apr 16, 2013 10:05 pm, edited 1 time in total.
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muksys
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Re: OS Osc 3 sounds different that 1 & 2

Post by muksys » Tue Apr 16, 2013 2:40 pm

CZ Rider, I've noticed this as well. When I tried to get a real slow osc beating (like on any old synth with VCO's). I'm pretty sure the analog boards in all Voyagers are identical. The only difference would be the Panel PCB which uses different routings for the Mod Bus (which is all accessable already from the Breakout connector). I'd be curious what is causing this (a cap/transistor combo?). Not a super big fan of it though.

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Portamental
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Re: OS Osc 3 sounds different that 1 & 2

Post by Portamental » Tue Apr 16, 2013 3:25 pm

I choose the OS (I was a total newbie back then) over the CPU Voyager for the seemingly true analog (discrete) nature of its electronics, and for the fact i did not succeed finding a model D back then.

Now if I understand the inner working of the Voyager... I would venture to say the Oscillator locking is easily explainable. Knobs are scanned, then numerically converted into digital number of fixed resolution then back again to analog for the all analog path. My thoughts.

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Re: OS Osc 3 sounds different that 1 & 2

Post by muksys » Tue Apr 16, 2013 6:37 pm

okok, so I retract anything that I said in this tread. I just got home and tried to recreate both things.

1. I couldn't get the massively obvious tonal differences between Osc 3 and 1-2. One thing I did learn is that when all 3 are completely CCW (TRI), Osc 1&2 sound the same, but 3 has more midrange harmonics and is slightly quieter (I have all 3 at 5). If I raise the volume of 3 to 7 or so, it sounds more like 1&2, but still with a midrange harmonic boost.

2. That thing about causing Osc's to "lock" was total BS. I know that happened to me with something and when CZ Rider mentioned it, I was like, Oh yeah! That totally happened. But, really, it didn't. Not with my OS anyway. Although, it's totally bugging the poopookaakaa outta me right now on which synth it was that DID do that!

So, nonetheless, I believe most of what I said was either wrong/useless or not fully true. Sorries

EDIT: and that's precisely why I got the OS over the Performer. I've been slowly dumping the synths with LCD Screens and opting for straight control. It's easy to fix a bad component. Not so much that digital stuff.

CZ Rider, that sounds like an issue that needs some fixin!

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Portamental
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Re: OS Osc 3 sounds different that 1 & 2

Post by Portamental » Tue Apr 16, 2013 6:47 pm

For your last post, my appreciation of you went up one notch or three.

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Re: OS Osc 3 sounds different that 1 & 2

Post by CZ Rider » Wed Apr 17, 2013 12:10 am

muksys wrote:CZ Rider, that sounds like an issue that needs some fixin!

Just tried it again with both RME's and a PE. At first I could not get the oscillators to lock, then realized I had not given enough time for the RME to warm up and stabilize. Both RME's lock up easily, the PE was a little more difficult to repeat, but those would also lock up.
Just to be clear, these were all three oscillators set to saw waves, 8' range in close unison and playing high notes like one would with a Minimoog lead. Once warmed up, the oscillators do have a tendancy to lock together when set this way in the high octaves. Can see and hear this locking in both file/pic I posted above. The only thing that could be causing this on my end might be I use power conditioners in this studio, and the AC power is too clean?
Doubt this has anything to do with the digital front end on the Voyager. The Minimoog oscillators locked too, when they tried to upgrade the original type "dirty" power supply. The dirt kept the oscillators from phase locking when set to the same frequency. This was one of the reasons I chose to keep the original 910 power supply on my Moog.


Quote from Jim Scott;
"A problem which has plagued many synthesizer designs is "oscillator locking." In a setup where two or more oscillators are ganged in unison to produce a richer pitch source, it is essential the they have absolutely no tendency to "grab" onto one another momentarily and sound in perfect synchronization. The oscillators must be free to roll. past one another at their difference frequency rate without one "pulling" the other at each pass. If they do grab, the sound is dirtied in an unpleasing manner. Now it happens that the MiniMoog power supply is a bit noisy, not so much as to have any affect on the sound, but just enough to disturb the oscillators out of any tendency to lock. This was discovered after the Mini had been in production for a while and someone got the great idea to replace the power regulator board with a new, clean, integrated circuit design. The oscillators locked. The modification was abandoned."
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Re: OS Osc 3 sounds different that 1 & 2

Post by metron » Wed Apr 17, 2013 11:56 am

I spent a little time A/B/C ing the oscillators on my OS last night and found the same thing mentioned in the original post. 1 and 2 are very very close sounding and 3 is a bit different. It's definitely subtle but there is no doubt it sounds a little different, more or less depending on the wave shape. If we have 2 OS synths doing the same thing, I'm inclined to say it's normal. Perhaps due to the additional circuits around the third osc for using it as an LFO? I'm not too worried about it. I think that the sound of 2 oscillators is often better than three plus the third is a pretty badass LFO.
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Re: OS Osc 3 sounds different that 1 & 2

Post by Ledbetter » Wed Apr 17, 2013 11:12 pm

I used the iPad app Oscope to evaluate Osc 1 and Osc 3 on my Voyager SE. The triangle wave form from Osc 1 was symmetrical above and below the mid point. The wave form shape from Osc 3 is sharper below than above, like a row of McDonalds golden arches. Also, Osc 3 is slightly louder than Osc 1. The sound of Osc 1 is hollower than Osc3, which seems to have more midrange harmonics. In other words, Osc 1 has more fundamental tones, less harmonics.

Turning Osc 1's waveform control dial just slightly clockwise seemed to make the two sound more similar. The oscillators would never "lock up," whether or not after playing some high scales.
Last edited by Ledbetter on Thu Apr 18, 2013 7:43 pm, edited 1 time in total.
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muksys
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Re: OS Osc 3 sounds different that 1 & 2

Post by muksys » Thu Apr 18, 2013 5:50 pm

I recorded a demo of the 3 oscillators at each true wave (as it is represented on the pot.) There is a noticeable difference at the tri and saw wave's. Square sounds identical. Pulse is a bit brighter.

I took screenshots of all of the waves to make a crappy table for viewing during the boring audio. It's not the bestestes of quality, but it does the job. You can see a big difference in between the tri and saw waves.

Image

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