…doesn’t feel finished yet. Frequently it doesn’t sound like it’s doing anything. I also really wish it was a parameter instead of a switch. Strangely, it seems to be behave like a modulation when you assign an LFO to it.
Discuss.
Hey Anigbrowl, sounds like you haven’t set it up right. Follow what’s below and tell us what you think.
- Manually enter a Note Trig with INF duration and press Play
- Leave OSC 1 at default settings
- Switch OSC 2 Waveform to PULSE and turn TUN down -44
- OSC 2 Page 2 switch AM1 On
- OSC 2 Page 1 turn TUN up slowly
- OSC 2 Page 2 turn AM1 Off
Oscillator 2 is modulating the Amplitude of Oscillator 1 with a positive value. And if you were to modulate the Amount you would assign OSC 2 TUN as a LFO Destination.
Well, this is sort of my point - I shouldn’t really need to make signficant adjustments to osc2 PW before I can hear anything, it’s a little strange that it doesn’t do anything to the sound when the PW is set to 0. It’s not like any other implementation of AM I’ve used. Contrast, say, the way it sounds on the Nord Modular (G2 Demo link) if you just run two saw/square oscillators into a LevMod module.
I get the impression that Osc1 is being modulated with a function of the pulsewidth value rather than the output of the oscillator itself. In fact, I’m almost certain of it, because I get the exact same results if I select an oscillator type of L/R/N/Gnd and twiddle the PW, even when I have no input signal - PW shouldn’t really affect incoming audio, and it certainly shouldn’t make a difference when the incoming audio has an amplitude of zero because it’s meaningless to talk about changing the duty cycle in such a case.
The manual mentions:
AM1 (Osc1 AM) engages Amplitude Modulation on Oscillator 1, which means that its signal is switched on/off (multiplied) by the pulse wave of Oscillator 2. This introduces new harmonics with frequencies being the sum and difference frequencies of the harmonics of the two oscillators. The result is related to ring modulation and can give metallic, hollow, or disharmonic sound qualities. Note that the waveform and pulse width of Oscillator 2 also affects the result, even if that oscillator is not heard.
I can hear that changing the waveform makes a difference but it isn’t exactly clear what, and when external audio is the oscillator source then it seems to treat the AM source like a triangle wave. This also means that you can’t get effects where you run (say) speech into one oscillators and want to AM the other with it. You can modulate the incoming speech signal with the other oscillator, but you can’t use the speech as a modulator. Likewise it sort of limits what can be done with setting Osc1 to do feedback and setting that as a modulator for Osc2 
I can live with not having the audio or exact oscillator as a mod source, but the lack of AM effects when the pulsewidth is set around zero just seems weird to me. I’ve noticed a few other people commenting on it over at the old forum, which is actually what prompted me to post here.
Yes I think you are right, it’s not using the wave but the pulse-width. Have you contacted support about this? I’m also a bit dissapointed with the AM.
I was really stoked when I read the manual it had AM, but was not expecting this weird implementation
The example I used doesn’t even use OSC 2 PW. PW is set to 0 and AM works as expected.
That’s Pulse waveform not Pulse Width.
Hey Anigbrowl, sounds like you haven’t set it up right. Follow what’s below and tell us what you think.
- Manually enter a Note Trig with INF duration and press Play
- Leave OSC 1 at default settings
- Switch OSC 2 Waveform to PULSE and turn TUN down -44
- OSC 2 Page 2 switch AM1 On
- OSC 2 Page 1 turn TUN up slowly
- OSC 2 Page 2 turn AM1 Off
Oscillator 2 is modulating the Amplitude of Oscillator 1 with a positive value. And if you were to modulate the Amount you would assign OSC 2 TUN as a LFO Destination.[/quote]
Anigbrowl is right, it is weird…
why does this work with all waveforms, except the SAW?
also, modulating the AM amount is exactly not possible the way you describe. it’s either on or off. if you modulate OSC2 TUN, you modulate the modulation frequency, but that’s expected.
well, actually you can control modulation amount, but in a quite strange way, namely, you can use the SAW wave as modulator, and use its pulse width parameter for that.
it would be great if Elektron could chime in on why this is designed like it is.
also it would be amazing if ring mod was possible.
could it be that the PW weirdness with the SAW waveform has the purpose to compensate for a missing modulation amount parameter?
That’s true that I misread you about pulse wave instead of pulse with, but it’s also true that when you are using a saw or triangle wave and pulse width is 0 you don’t hear any AM. This is very much not what I expect, though. It is disconcerting to ‘switch on the AM’ and not hear any effect for many configurations.
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That’s true that I misread you about pulse wave instead of pulse with, but it’s also true that when you are using a saw or triangle wave and pulse width is 0 you don’t hear any AM. [/quote]
Hey Anigbrowl, I thought you might have misread not only my instructions but also the manual and I can see your point and perhaps it is valid but I also see it as a design implementation that it is to work with only Pulse and Transistor Pulse. A good analogue for instance a Minimoog Voyager Old School it doesn’t have patch recall even though it’s still a Minimoog Voyager. The A4 even though analog does in fact behave some what differently to other true analog devices.
The above could not be more true and is exactly why, after staying away from the A4 for a long time and coming back to it as it’s own thing, it is quickly becoming my favorite machine - even over the OT. It doesn’t behave “like” any other analog I’ve ever played. It has a “thing” and learning it is the key to finding out all the amazing things you can do with it.
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That’s well put.
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From the manual:
AM1 (Osc1 AM) engages Amplitude Modulation on Oscillator 1, which means that its signal is switched on/off (multiplied) by the pulse wave of Oscillator 2.
[…]
Note that the waveform and pulse width of Oscillator 2 also affects the result, even if that oscillator is not heard.
Regardless of what waveform is selected, it’s always the oscillator’s Pulse wave that AM-modulates the other oscillator. In other words, this modulation simply means that the Pulse signal switches the other oscillator’s signal on and off.
If the Pulse wave has around 50% pulse width, the effect is normally easily heard, since the modulated waveform is chopped up quite a bit. But if the pulsewidth is at or near its extremes (0% or 100%), it results in either unaffected or completely muted sound, since the signal stays either on or off. This is why it’s not always obvious what the AM does, if you just engage or disengage it and listen. Therefore the manual says that the pulse width setting affects the result.
So what is the pulsewidth when Pulse is not selected as the waveform? Is it the same as the PW knob says, so that it would be the same as if Pulse were selected?
In fact, no! It is more confusing than this. And therefore the manual says that the waveform choice also affects the result.
For instance, the pulse waveform is also used internally to create the PW-modulatable “double saw”. In order to have a normal Saw waveform in the middle of the PW knob setting, the actual pulse width of the Pulse wave changes from 0% to 100% and back to 0% when turning the PW knob with Sawtooth as the chosen waveform. This is different to the 0%-to-100% behaviour when Pulse is selected. (The reason is that the mid position of the PW knob should always give the normal version of the waveform selected. Selecting between basic waveforms shouldn’t have to include setting the PW parameter differently.) A side-effect of this is that turning on the AM might sound identical if the PW is set to mid position when Saw or Triangle wave is selected.
That’s well put.[/quote]
Yes, the AM is an example of something that isn’t instant gratification. Find the useful combinations of all the dozens of parameters that affects the sound of this complex modulation, don’t expect magic to happen just by switching it on! 
(The AM modulator might be a bit restricted and illogical due to all this, but note that the AM-modulated signal is whatever waveform selection done on the oscillator page. It’s not restricted to the oscillator waveforms, it can also be the Ext inputs, the Neighbor synth track, or the filter feedback path!)
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Yep - I played with the AM stuff exclusively this morning and both my “harsh/weird” sounds and drum sounds are taking on a whole new depth of dimension.
This box DOES NOT, in many ways, act the same as any other analog synthesizers. It can mimic certain sounds that some classics are known for, but the joy to be had here is to learn the mystique of the A4 and create your own palette of sounds - many of which will be “new” from an “analog”.
I, too, was disenchanted the first time around with the A4 - I will admit it.
I approached it as just another analog 2vco, 2vcf, 2lfo, 2eg machine and found it didn’t do what I thought it would. Things came up and it went away for a while.
This time around, I went immediately at it as something I was completely unfamiliar with and needed to test it out on a basic level to see how all the “parts” interact. This is becoming a very fun machine to make sound with.
Others would benefit from the same approach. Learn from us oldsters.
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Thanks for posting /mr. That was an insightful response even though I must admit I had to read it two or three times. 
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Damn, I just hit some button combo to lose my reply! (func+cue?) 
I noticed that it worked with external audio and that modulating PW was getting some nice sounds, now I know why.
Hmm, like so much elektron gear, it makes sense while i’m using it, but I’m not really verbally understanding what’s happening. …For me that’s a good thing as it motivates me to explore.
Pitch and tuning make a difference too don’t they? Seems like throwing some autobend in (and the different sync options) has interesting results.
I dunno, it seems I can get pretty ring modish sounds using both AM1 and 2. Next time i’m in front of the a4 i’ll try specifically and make a note of what’s going on.
i’m no expert but i think ringmod is quite well defined…
basically you do AM, but then cancel out the original signal that’s being modulated, leaving only the harmonics produced by the amplitude modulation.
Currently the closest I can get is by using the 2nd filter in notch mode to cancel out the signal’s fundamental. But a lot of the original harmonics are still present… so no true ringmod.
However, it already gives some really interesting sounds!
It would be great if it was possible to cancel out the original signal entirely.
Not sure if the architecture would allow such an add-on to be possible via software update. Just wondering. It’s already pretty cool as it is!
and yea thanks /mr for clearing things up!
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It’s done by the hardware, so no, Software Update - you can’t touch this ™.
The notch method you describe is a creative idea. In fact, pure ringmod is not always more useful than AM (ringmod+original). Some synths, like the Yamaha CS-30/50/60/80, have a continuously variable ringmod amount - from unaffected, via AM, to pure ringmod - and it’s far from every sound that sounds best with the ringmod maxed out. Sometimes it’s nice to have a little tonality left in the otherwise atonal and metallic sound.
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This reminds me. What’s up with the phase? I can’t get it to work right. LFOs should cancel out when set opposite right?