KVR Audio

DrGonzo · Post by **DrGonzo** » Sun Oct 03, 2021 12:33 pm

Why are sine waves so rare in hardware analogs?

I could in some way understand it 30-40 years back. I can understand why engineers decided on triangles instead (which if my memory serves me right is an altered square wave) back in the day. But today?

Does anyone know of any hardware analogs with real sine waves?

/Carl

chk071 · Post by **chk071** » Sun Oct 03, 2021 12:37 pm

Good question. Maybe because there isn't analog hardware which doesn't incorporate saturation in the signal path, basically rendering sine waves unclean. Or they think that, with self oscillating filters, it's easy to produce sine waves anyway.

Or maybe I'm wrong with both theories.

imrae · Post by **imrae** » Sun Oct 03, 2021 12:40 pm

It's because most analogue oscillators use charging/discharging capacitors to create a triangle or saw "core". This mechanism is easy to hard-sync by shorting to ground, and saw/tri/square/pulse waveforms are derived fairly easily. (PWM is achieved by changing the reference voltage of a comparator on a saw wave.)

Deriving a sine wave from saw/tri is more difficult; it requires a carefully designed and calibrated waveshaper and still the result will be approximate with some harmonic content.

It is possible to get very pure sine waves from a self-oscillating VCF, but this would be an independent "core" - quite difficult to extract saw/tri waves from, and not very responsive to sync.

DrGonzo · Post by **DrGonzo** » Sun Oct 03, 2021 12:52 pm

imrae Yeah the problem with self-oscillating filters is that they are so damn tricky to tune over the keyboard - and of course you cannot layer it with another waveform.

chk071 - yeah! But that saturation might sound bloody gorgeous

Does anyone know of any hardware analogs that use sine waves? The only ones I find are based on digital oscillators. Just curious if anyone succeeded with something like this.

BertKoor · Post by **BertKoor** » Sun Oct 03, 2021 12:57 pm

The classic analog synthlayout is Osc - Filter - Amp.
When using sine as oscillator waveform, there is nothing to filter. It has no harmonics. People might complain the filter works as amp instead.

imrae · Post by **imrae** » Sun Oct 03, 2021 1:00 pm

A classic synth with saw-to-sine shaping is the ARP2600. Amusingly in this SOS review, the writer complains that the Arturia emulation has a worse sine wave than a real 2600: https://www.soundonsound.com/reviews/arturia-2600v

I suspect they modelled one that wasn't quite trimmed optimally. (Or maybe there is no trimmer and it's at the mercy of tolerances? I've never had one to check...)

DrGonzo · Post by **DrGonzo** » Sun Oct 03, 2021 1:00 pm

BertKoor wrote: ↑Sun Oct 03, 2021 12:57 pm The classic analog synthlayout is Osc - Filter - Amp.
When using sine as oscillator waveform, there is nothing to filter. It has no harmonics. People might complain the filter works as amp instead.

But only if the synth has one oscillator and one waveform.

foosnark · Post by **foosnark** » Sun Oct 03, 2021 3:12 pm

VCO2 on the Minibrute 2 has a sine option. It's not very clean though compared to making the filter resonate.

The primary oscillator on the Buchla 208 can crossfade from sine to a triangle, square or narrow pulse. Sines are more important to "West Coast" synthesis where you're likely to be running it through a wavefolder.

Lots of analog Eurorack oscillators offer sines, not all of them though.

DrGonzo · Post by **DrGonzo** » Sun Oct 03, 2021 3:29 pm

foosnark wrote: ↑Sun Oct 03, 2021 3:12 pm VCO2 on the Minibrute 2 has a sine option. It's not very clean though compared to making the filter resonate.

I have totally forgot about the MB2. Yes - I remember now. The sine was quite decent actually. I mean, it felt like a sine and not a filtered triangle.

DMG68 · Post by **DMG68** » Sun Oct 03, 2021 4:45 pm

Novation Bass Station ii

Azbest · Post by **Azbest** » Sun Oct 03, 2021 7:27 pm

Matrixbrute has 3 sine OSCs.

DrGonzo · Post by **DrGonzo** » Mon Oct 04, 2021 5:31 am

Azbest wrote: ↑Sun Oct 03, 2021 7:27 pm Matrixbrute has 3 sine OSCs.

That's really interesting... was actually checking out the Polybrute - but no sines on that one.

/C

lfm · Post by **lfm** » Mon Oct 04, 2021 8:08 am

The new "Prophet" Take 5 has sine
https://www.sequential.com/product/take ... oly-synth/

Very affordable as well, and has same modulation features as REV2.

Very interesting synth and alternative to getting Prophet 5 I must say. Effects are stereo as well.

cryophonik · Post by **cryophonik** » Mon Oct 04, 2021 3:46 pm

Funny, I was pondering this same question recently. It seems that I recall more synths having sine wave oscs's back in the 80s, but I've looked back at some of them and, nope. The closest I've seen in most synths is from filter self-oscillation.

egbert101 · Post by **egbert101** » Tue Oct 05, 2021 12:11 pm

Only problem with the Take 5 (as far as I'm aware) or not a problem for some is that the synth goes into a digital signal path at the end. So yeah, analog until effects.

Hardware Analogs with Sine waves?