Noise artifacts when changing cutoff

LDT · Post by **LDT** » Fri Nov 16, 2007 1:39 pm

I noticed the following: When I setup something like a single osc playing in the higher range, I can easily find a range where the cutoff produces some artifact noise when moved. Interesting it is though, when I use e.g. the pedal to change the cutoff in the same range, I dont get the problem, so my guess is, that is has to do with the cutoff knob itself (scanning?).

Does anybody know what I am talking about?

Jarkko · Post by **Jarkko** » Tue Aug 11, 2009 12:31 pm

Yes, I know exactly what are you talking about.

I just bought a new shining Voyager Performer, with latest OS (3.4) already installed. It sounds fantastic but this noise is very annoying. I don't hear it when playing normal patches, but if I try to tweak cutoff with very high resonance setting, I can hear them. It is very easy to reproduce if the oscillator is tuned down so that the self-oscillating filter is louder.

This is a minor issue, but the more I think about it, the more it is pissing me off. This was exactly the reason why I bought this VERY expensive instrument instead of some random VA synth in the first place! I don't know what to do, but I need to do something. My choises are:

1. By Voyager OS or LP (RAC) and sell my Voyager

The problem here is that OS is sold out, my local dealer says. LP's RAC sounds exactly what I need, but I just love the Voyager sound..

2. Build some custom CV controllers for filter

I could put up some self-made CV controller to filter input and be happy... Until next digital artficact pops up which cannot be controlled with CV.

3. Wait for OS fix

I don't know if this issue can be fixed with software.

Just Me · Post by **Just Me** » Tue Aug 11, 2009 3:14 pm

My local store has an OS in stock. $2000 would take it. Use a Foot pedal to control cutoff and it won't make that noise.

RL · Post by RL » Tue Aug 11, 2009 6:18 pm

Jarkko wrote:Yes, I know exactly what are you talking about.

I just bought a new shining Voyager Performer, with latest OS (3.4) already installed. It sounds fantastic but this noise is very annoying. I don't hear it when playing normal patches, but if I try to tweak cutoff with very high resonance setting, I can hear them. It is very easy to reproduce if the oscillator is tuned down so that the self-oscillating filter is louder.

This is a minor issue, but the more I think about it, the more it is pissing me off. This was exactly the reason why I bought this VERY expensive instrument instead of some random VA synth in the first place! I don't know what to do, but I need to do something. My choises are:

1. By Voyager OS or LP (RAC) and sell my Voyager

The problem here is that OS is sold out, my local dealer says. LP's RAC sounds exactly what I need, but I just love the Voyager sound..

2. Build some custom CV controllers for filter

I could put up some self-made CV controller to filter input and be happy... Until next digital artficact pops up which cannot be controlled with CV.

3. Wait for OS fix

I don't know if this issue can be fixed with software.

Hi,
the cutoff pot is not a controller to change the filter range. If you want to control the filter cutoff for your music it's better to use a foot controller.
Have fun,
Rudi

Jarkko · Post by **Jarkko** » Wed Aug 12, 2009 12:54 am

Thanks guys. I'll build a custom "foot pedal" with a knob that I can play with. The plan is to just hook potentiometer to TRS cable and put them in a nice box.

Jarkko · Post by **Jarkko** » Thu Aug 27, 2009 12:53 am

Here's a pic of my custom "hand pedal":

.

No more artifacts

psicolor · Post by **psicolor** » Fri Sep 04, 2009 11:54 am

nice!

Do you know, why controlling the cutoff with a controller does NOT produce artifact noise although the cutoff pot does?

Where's the difference?
If it was the scanning, you could turn scanning off afair.

RL · Post by RL » Fri Sep 04, 2009 1:36 pm

psicolor wrote:nice!

Do you know, why controlling the cutoff with a controller does NOT produce artifact noise although the cutoff pot does?

Where's the difference?
If it was the scanning, you could turn scanning off afair.

Hi,
the voltage of the external pot controls directly the filter without processor scanning.
Mittelfranken gruesst Unterfranken

Jarkko · Post by **Jarkko** » Sun Sep 06, 2009 2:09 am

psicolor wrote:If it was the scanning, you could turn scanning off afair.

If I understand this correctly, turning this on/off requires special circuits which are not in Voyager. I believe there are something like this in LP (Real Analog Control, aka RAC).

RL · Post by RL » Sun Sep 06, 2009 4:55 am

Jarkko wrote:
psicolor wrote:If it was the scanning, you could turn scanning off afair.
If I understand this correctly, turning this on/off requires special circuits which are not in Voyager. I believe there are something like this in LP (Real Analog Control, aka RAC).

Right!
when RAC is active you don't hear processor scanning artifact noises.
For this function you need special analog switches and it would be too expensive to offer this for all pots on a Voyager.
Have fun,
Rudi

David Hrivnak · Post by **David Hrivnak** » Tue Dec 01, 2009 12:16 am

I noticed this same problem when I first tried out the Voyager at a music shop. I couldn't believe my ears when I heard that digital aliasing on an all analog signal path. It completely turned me off from getting a Voyager until the Old School came out. I bought one of those, despite the ridiculous name, and I love it beyond belief.

It's unfortunate that people have to invent work-arounds or use pedals to avoid digital artifacts on a Moog synthesizer, but I'm glad you guys have found a way to do so. If any digital synth users out there are considering entering analog land via the Voyager, I highly recommend jumping all the way in with the Old School.

The digital features on the Voyager are a dream come true to many people, and I'm not trying to criticize them. In fact, the "problem" seems to be completely unnoticeable unless you max the filter's resonance and slowly sweep it through the higher ranges. I don't remember the oscillators acting that way at high frequencies. Realistically, that extreme filter sweep is almost never going to happen in a song, and if it does the stepping would almost certainly be invisible in a mix. So I know it's really not much of a hindrance, but it's enough to turn me off. I'm just not interested in anything digital making its way into my sound, no matter how slight or overcome-able it may be.

LivePsy · Post by **LivePsy** » Tue Dec 01, 2009 7:52 pm

The filter cutoff is the only parameter which covers a huge range and has to do it in 256 steps. The stepping when moving the cutoff is unavoidable. If this is a deal breaker with the Voyager, you are missing out on everything else that is great and IMO superior to a LP or OS. Frankly, the front panel control are not the place for performance modulation. Its fun to tweak them of course, but I question that grabbing the cutoff is the best way to manipulate the filter in a performance or recording situation.

B

mayidunk · Post by **mayidunk** » Wed Dec 02, 2009 3:57 am

I have never encountered this on my Performer. Could someone please relate the panel setup that will produce these artifacts so that I can see for myself?

Thanks,
Bob

till · Post by **till** » Wed Dec 02, 2009 7:26 am

If you would like to change the cutoff (or other parameters) within a small an rather precise range, a pedal might not give you enough detailed control.

But if you use the MP-201 you can do it just as you like, by setting the right amount of variation by using fine tuned HEEL and TOE VALUES. Of cause, you could do this by a slightly modificated expression pedal too. Just some variable resistors are needed to limit the range and the starting point.

But actually, you will most likely not hear these artifacts at all in the real world usage of the Moog Voyager. And there is always the chance to get yourself a Voyager Old School if your are a real purist.

LivePsy · Post by **LivePsy** » Sun Dec 06, 2009 7:54 pm

I just built myself a "rotary hand controlled foot pedal" like Jarkko, A real foot pedal is just too imprecise as a controller. But the range of filter cutoff is not the entire spectrum.

I was expecting I'll have to build an active circuit to get the full voltage range, but I rediscovered the obvious on the CP:-251: make a few TRS 1/4" plugs shorting the ring and tip. Plug these into the foot pedal input on either attenuator. This generates +/-5v output controlled by the attenuator knob. You have enough voltage swing to sweep the filter entirely. Or use the 4 input mixer's offset knob if you don't need the mixer.

Bit of new school, bit of old school for the Voyager

B