Hi all,
Is there a way to get a sine wave tone (like the gnd one on the MD) on the a4?
Merry Christmas!
Just via an oscillating filter !
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Lowpass the triangle wave with tracking on so you just here the fundamental?
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Is there a reason the A4 doesn’t or couldn’t have a sin wave osc?
It doesn’t make sense to include a sine wave osc on an analog or VA synth since you can get a since wave by:
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Using the triangle wave with the filter set to 100% keyboard tracking and a cutoff frequency that filters out all overtones, or
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switching off the oscillator and turning up the filter resonance to the point where the filter starts self-resonating.
On the A4, the second filter gives you the cleanest sine-like wave when it starts self-oscillating, the ladder filter is a bit more dirty IMHO.
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fastish CV sine LFO out to input .
this doesn’t help with the sine, since you can’t key track the LFOs, but you can get some neat sounds by using the input track as the source track for the cv track. or copy and transpose the input track and use that as the source track for the CV.
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Having a proper sine wave is in my top 3 wishes for the A4, so key for laying DnB/Jungle basslines
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You should be able to get a perfectly nice sine out of the A4. Just route the triangle wave through both filters combined as a 6-pole low pass filter and you’ll have nearly no overtones left.
Subtractive synths generally don’t offer a sine wave since it would make the filter totally irrelevant.
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exactly
your original post should be in a “tips” post for people to reference…I’ve personally used both of those methods before to create what I call “sine-like” patches…each one has it’s own character too…the self oscillating filter route will give you some neat sonic characteristics when playing it live instead of the sequencer…i.e. sliding between notes etc etc…
and you are dead on about the sound quality on the different filters too, the ladder gives it a bit of a dirty quality whereas the second filter is very clean…the only thing that may trip some people up when going that route is the “tuning”
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that is what I was thinking…
Thinking about it what I kinda meant was it would be great to have sine wave sub oscillator (as well as a regular one but not as important)
Most DnB bass lines are not that subby in themselves but just have a sine wave an octave or two down
Of course this is still possible, but at the cost of an oscillator
I wouldn’t mind a sine wave as a selectable option…only because then I wouldn’t have to design one myself…and as you stated, having one as an option for a sub-oscillator would be nice.
A sine wave option for the sub osc sure is nice. The reason that this isn’t included on most analogue synths as an option on the sub osc is that it’s much simpler to only include square and pulse waves. This also applies to the saw and triangle.
The sub osc on the A4 is pretty limited anyway; there’s not even a way to set the level of the sub osc relative to the primary osc.
However, you can get pretty much the same result by using the second filter in 1-pole high-pass mode with the resonance turned way up and its keyboard tracking set to 32. The only slightly tricky thing you need to do is to “tune” the cutoff frequency for this filter in such a way that the frequency of the sine wave generated by the self-oscillation is exactly two octaves down.
If you don’t trust your ears, you can temporary turn the oscillators off and use a guitar tuner for this.
The nice thing of doing it like this is that you can use both oscillators including their subs to get a really fat top-end with a lot of movement. A bit of sync can also work well for these type of bass sounds.
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I happily agree with all the various ways of creating a sine wave sound, the reason to have one is to merely not have to create that sound with filters and the like and use those bits and bobs to effect. I assume it would be free!
It would be simple to add to a VA synth, not so easy for a synth that has real analog circuitry. 
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That doesn’t really make sense. If you had a sine wave oscillator it wouldn’t automatically cause higher frequencies to be attenuated, it would just create a peak at its own frequency. Much as I like self-oscillating filters, I still want the attenuation functionality…
Of course you wouldn’t need to do any attentuation if your synth had only a single oscillator since with no harmonics there’d be nothing to attenuate, but the A4 and most other synths have 2 or more oscillators. Even synths like the Minibrute, though having only one oscillators, get a lot of different tones by using it to drive multiple shapers so you can get some timbral complexity.
it would add a bit more price to the machine too. likely the most influential reason for not including it.
plus its an elektron machine. the not so obvious route. its all about the tweaks and tricks 
My understanding is that pure sine waves are difficult to engineer with analog oscillators. It would probably be somewhat sine like over some bandwidth but would be unreasonably non-sine like in other regions.
I have used F2 in 12dB high-pass tracking self resonance has a sub oscillator with some success.
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This is the main reason they are not included in analogue synths. A perfect sine is something of a theoretical construct. They don’t really exist in nature. Most analogue synths that do offer them go about it by pre-filtering a triangle wave. Hence terms like “triangle-core” when referring to how an oscillator is constructed. I’m pretty sure I read somewhere that the A4 uses triangle core oscillators… or am I imagining that
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Again all this stuff is true, In the tag line:
The Analog Four is a polyphonic analog synthesizer with state-of-the-art digital control.
Not sure but couldn’t the DSP route a sin wave to the oscillators?
Is my thinking plain wrong? a PipeDream? or Stupid thought?