A couple questions for the better informed...

The Unknown · Post by **The Unknown** » Fri Sep 02, 2005 1:21 pm

Hi guys.

I have spent the last few days doing a short teacher training course, and will have to deliver a micro teaching presentation, this coming Tuesday.

My subject is Oscillators, and I will be using the Voyager to illustrate their use and versitility. We have a deaf person in our group and to make the session interesting to her, I will be using my laptop as an oscilloscope. I am using the built in mic to pick up the sound, as opposed to running a line in to the computer - don't want to tempt fate by using too much technology!

Having tested this in my studio, I found that the raw waveforms didn't really resemble their associated icons (triangular was close, but more like a sin, sawtooth not sharp, square not sharp and rectangular nothing like it) and was wondering why? Is it because I am getting colouration of the soundwaves from the speaker cabinets and the room, perhaps? Is there something odd about my Voyager? Or is it an analogue, or other scientific issue?

Forgive my ignorance on this, but I don't want to look a fool next week!

Second question: Is the Voyager's ability to morph between wave forms a feature that is unique to it, or can all Moogs (and indeed any other synths) do this? I have come across a good few synths and don't recall seeing this feature before. Again, forgive my ignorance.

Any help greatly appreciated...

OysterRock · Post by **OysterRock** » Fri Sep 02, 2005 1:33 pm

1) The shapes of the wave forms are purposefully "tweaked" to sound better. A ideal square wave (which, by the way, is impossible to truly produce) would sound very bad to the human hear because of the instantaneous changes in audio which have very high frequency content. In other words, "sharp" features on waveforms sound bad to the human ear.

2) There are a few other Moog synths that have this feature: the Mircomoog and the Multimoog. I think thats it, but I my be wrong. I think more synths should have continuos waveshaping, but the vast majority don't.

The Unknown · Post by **The Unknown** » Fri Sep 02, 2005 1:35 pm

Many thanks, mate - a great help!

GregAE · Post by **GregAE** » Fri Sep 02, 2005 8:24 pm

There is another consideration:

If you are viewing the Voyager waves using your computer and a software program, the waves are subject to the electrical limitations of the amplifier, microphone, preamp, the A/D converters and the sample rate - basically every component that the signal has to pass through to get from the Voyager into the computer (the phrase "a chain is only as strong as it's weakest link" applies here).

A couple of ideas:

Take the signal from the Voyager's Mix Out loop. This will give you the highest fidelity waveform, unaffected by the Voyager Filter and VCA.

Keep the observed frequency low, arbitrarily around 100 hz (about G2).

Skip the mic and use the computer's line input.

Lastly, if you can borrow one, a real quality oscilloscope would give you the best possible result.

Greg

Qwave · Post by **Qwave** » Sat Sep 03, 2005 8:28 am

The waveform at the ideal shape is not what we think analogue waves should sound. Most early digital synths had a very perfect waveshape. And such a boring and raw quality of basic sound. So today all major DSP based VA synths use some tweaked waveshapes for a more natural sound.

But even if the waveshape does look wrong, it might be just a phase shifting in the harmonics. This will not change the sound if it is static. But will change the visual impression.

On analogue synths with upward and downward saw wave, (like the oscillator #3 of the Minimoog) the waves look not only inverted, but also a bit different. This is due to limitations and non linear working of nalogue circuits. But this is what made those classic old synths and the real analogue ones from today (like the Voyager) sound classic, bold and unique. And not like those hundereds of freeware softsynths without character.

The Unknown · Post by **The Unknown** » Sun Sep 04, 2005 8:48 am

I am going to use OysterRock's points in the lecture, as these are concise - I only have 30 minutes!

I also plan to make our deaf student my 'sound analysis person', as I am sure she will quickly realise the actual waves are considerably different to their associated diagrams - I will issue these as a handout to all the students.

Once again, many thanks for the input!

Qwave · Post by **Qwave** » Sun Sep 04, 2005 12:24 pm

Hello "The Unknown",
maybe you could give us a link to the hand-out document as PDF?
I think this would be interesting to see for some of us. I am thinking about doing a synth lecture at our local adult edjucation program.

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