KVR Audio

chk071 · Post by **chk071** » Tue Dec 05, 2017 3:49 pm

ENV1 wrote:Too bad that opening the chassis would void the warranty, id really like to see whats in there.

aciddose · Post by **aciddose** » Tue Dec 05, 2017 3:54 pm

EvilDragon wrote:
aciddose wrote:If you like that sort of timbre I can highly recommend something like the MKS-70, although it would appear this particular unit utilizes 3xDCO with some odd wave-shaping capability (not certain it uses analog waveshaping at all.)
It's a VCO (why would they do their nomenclature wrong TWICE, on the website, and on the PCB silkscreening?!), since clocking them is not done digitally. Digital is just temperature compensation etc. Same as on Andromeda and Minilogue - frequency control is still voltage, not synced to an external frequency source.

I doubt it's any sort of waveshaping included. Most likely ROM waves fed through a DAC.

Of course, so it's a different type of DCO: rather than the sort where the digital clock is used and filtered by an analog waveshaper, it's an analog clock used to step through a digital wavetable. So the core is probably just an ultra-high frequency ramp generator in that case which is used to produce a clock to step an index.

The thing is though there are two aspects of "analog" effects in true analog oscillators: both the clock and the waveshaping must be analog to get the full range of effects. A DCO is only a reasonable compromise whether the digital part is the clock or the waveshaper. A true analog oscillator + waveshaper are limited and require a lot of PCB space which was obviously at a premium on such a usb-stick synth. Would people be happy with only ramp+pulse+triangle? Possibly not, while in the same space on a chip used for the whole analog waveshaper you can fit several megs of data, ADCs, DACs and other components used in this type of DCO while providing 100s of possible waveforms along with oscillator level + modulation of that level!

That said you won't be getting 100% of the effects a true analog oscillator + waveshaper are capable of either: just that those really aren't very important and can be emulated with satisfactory accuracy with 16-bit wavetables, given enough memory to store a large variation of wavetables and modulate through them.

EvilDragon wrote:
aciddose wrote:while this synthesizer on a USB-stick seems to use a Tow-Thomas biquad, which is related to Kerwin-Huelsman-Newcomb and Sallen-Key biquad filters and a minor rearrangement with slightly different timbre depending upon clamping/OTA structure.
Errr, this is a Polivoks inspired filter, which is a SVF done entirely with opamps, resistors, a single transistor, without a capacitor in sight... not a biquad? In fact, aren't biquad filters purely digital, non-existent in analog realm? Correct me if I'm wrong.

A biquad is a mathematical concept. The analog filter topologies are identical to digital filter topologies: TT, KHN and SK are all biquadratic and it doesn't matter whether the implementation is digital or analog.

See here: https://en.wikipedia.org/wiki/Electroni ... ad_Example

The "Polivoks filter" you refer to is a cheap implementation of a Tow-Thomas Biquad that uses the inherent compensating filter inside particular cheap opamps. The transistor you're looking at is used as a current source where the opamps are being misused in a way as OTAs such that they form combined OTA+capacitor units. The inverting stage of the Tow-Thomas example on wikipedia is dropped by sending the input to the second stage non-inverting input.

The noise performance therefore suffers greatly along with CV feed-through as these opamps were never designed to be used in such a way. It is none-the-less a rather clever mad scientist type of misuse of the opamps which turns a few disadvantages into advantages used with purpose!

ENV1 · Post by **ENV1** » Tue Dec 05, 2017 4:25 pm

chk071 wrote:
ENV1 wrote:Too bad that opening the chassis would void the warranty, id really like to see whats in there.
viewtopic.php?p=6942848#p6942848

I knew that one.

What i meant was a picture that shows everything thats in there, i.e. whether there is a second board underneath the one thats visible or a second layer of parts on the invisible side.

(I was wondering about that in a post yesterday so thats what id like to find out.)

Thanks anyway.

aciddose · Post by **aciddose** » Tue Dec 05, 2017 4:34 pm

For people who have trouble understanding what Tow-Thomas means: The ----- (wrong!) filter was a Tow-Thomas.

edit: I was confused and I'll need to try to figure out which old synthesizer used Tow-Thomas. I know the Alpha Juno uses two in series to get 24 dB but I'm certain there is another one I'm forgetting ...

afta8 · Post by **afta8** » Tue Dec 05, 2017 5:38 pm

fisherKing wrote: nice! will be good to hear some real-world observations (versus the rants on this forum about things no one's seen...).

Uninformed rants are the soul of KVR

egbert101 wrote: Why do I have an urge to knock over your coffee?

lol.. It's tea, I'm English

tedannemann · Post by **tedannemann** » Tue Dec 05, 2017 5:40 pm

tripleflows wrote:I really like this concept of ditching hw UI but getting sounds from analogue path, integrated into DAW.

This! I only care for the sound - I don't need another keyboard, machine, rack and what not in my studio - I love to work completely in the box - but still have an anlog sound without routing stuff on a patch bay or constantly running out of inputs...
Analog sound for the spoiled in the box worker. Target group ist clear, this would be me.

Now it has to deliver.. sound wise.

VariKusBrainZ · Post by **VariKusBrainZ** » Tue Dec 05, 2017 5:59 pm

Many years ago SKnote were going to release a product simlar to this

http://www.kvraudio.com/product/realthing_by_sknote

afta8 · Post by **afta8** » Tue Dec 05, 2017 6:03 pm

Here's a first mess around with it. It doesn't appear to have a presets browser so there are no factory sounds I can browse through. The video is just a looping pattern with control tweakery, second half is in paraphonic mode.

VariKusBrainZ · Post by **VariKusBrainZ** » Tue Dec 05, 2017 6:07 pm

Thats a really nice demo youve done, created better patches on the fly than a certain someone on this forum sells.

I was just itching for you to hit the Random button though

afta8 wrote:Here's a first mess around with it. It doesn't appear to have a presets browser so there are no factory sounds I can browse through. The video is just a looping pattern with control tweakery, second half is in paraphonic mode.

fisherKing · Post by **fisherKing** » Tue Dec 05, 2017 7:03 pm

thanx for the video! a good intro to this thing...

EDIT: just mentioning, stereo balance is heavily leaning to the left in the video...

tedannemann · Post by **tedannemann** » Tue Dec 05, 2017 7:08 pm

This sounds fantastic!

Robmobius · Post by **Robmobius** » Tue Dec 05, 2017 7:29 pm

Niiice video! Thanks.

braj · Post by **braj** » Tue Dec 05, 2017 7:43 pm

How is the latency?

fluffy_little_something · Tue Dec 05, 2017 7:57 pm

As someone said, most of the signal is on the left side.

Does the USB pen become hot after a while?

EvilDragon · Post by **EvilDragon** » Tue Dec 05, 2017 8:00 pm

aciddose wrote:The thing is though there are two aspects of "analog" effects in true analog oscillators: both the clock and the waveshaping must be analog to get the full range of effects. A DCO is only a reasonable compromise whether the digital part is the clock or the waveshaper. A true analog oscillator + waveshaper are limited and require a lot of PCB space which was obviously at a premium on such a usb-stick synth. Would people be happy with only ramp+pulse+triangle? Possibly not, while in the same space on a chip used for the whole analog waveshaper you can fit several megs of data, ADCs, DACs and other components used in this type of DCO while providing 100s of possible waveforms along with oscillator level + modulation of that level!

That said you won't be getting 100% of the effects a true analog oscillator + waveshaper are capable of either: just that those really aren't very important and can be emulated with satisfactory accuracy with 16-bit wavetables, given enough memory to store a large variation of wavetables and modulate through them.

I'm pretty sure the analog waveforms are analog oscillators + waveshapers, and then digital waveforms are a secondary part to the VCO. With high level of integration it's certainly possible to cram that in a chip, ALONG with the digital part, converters, you name it.

Andromeda is an immensely complex synthesizer, yet its whole voice was in one VLSI chip. It just had 16 of them. So I don't see why it wouldn't be possible to have a true VCO (and 3 of them) in space of a single USB stick.

Tone2 I2 vs Trueno Analog