The secret of sound

The OP-X is rated by many as one of the most organic and lively sounding VA synths available, with a depth and feel that makes it hard to tell apart from a real hardware synth. So what is the secret? Learn more about it on this site.

Separate Voice Design (SVD)   by SonicProjects

Old analog polysynths OB-X Voiceboards >>  click to enlarge In real analog polysynths, each voice was a separate mono synth containing oscillators, filters and envelope generators. They either sat on separate and exchangeable voiceboards like in OB-X and OB-Xa, click on pic above, or side by side on a big wiring board. None of of them sounded exactly the same because of device tolerances and slightly different trimpot settings. The differing settings could often be "auto-tuned" by adding an offset voltage. In most cases, exept for the matrix models, this feature was only available for the oscillator pitch. But even then in was never perfectly tuned. The warm up drift did its own to alter these settings again over time.

Voice differences:

  original           opxvst           tuned

Exactly these technical imperfectnesses, coupled with great sounding filters, gave those old analog beasts that lively, fat, organic and smooth sound.

It makes them sound more like a musical instrument than a perfect sound generator.

OP-X engine structure

Common VA synths achieve polyphony by just cloning one voice algorithm to a variable number. Not so in the OP-X.

The building structure of the OP-X is the exactly same as the one of a real analog polysynth. Each voice is built separatly with a completely independent signal path.

The voices also differ slightly in sound by default. They can be tuned however globally and parameter selective.

The tuning section

      click to enlarge

Like in real analog synths, VCOs, VCFs, ENVs and portamento times of each of the six voices are slightly and individually (!) detuned by default. Four buttons let you tune or again untune each of these sections individually for accuracy or analog feel, in any combination.

The VCOs' detuning can be altered too with the variable spread knob which also works in polyphonic mode. This gives you a level of control you have never experienced before! You will even start to miss it in your real analog synth.

Even more control

You want even more? You don't like the default detuning? No problem. Have a look at the OP-X PRO. It allows you to alter the default detuning with virtual trimpots, like a service technician of the old days.

  click to enlarge

SVD in use

Listen to some clips that illustrate the benefits of SVD in different situations and sounds.

Note that there are sounds that sound better tuned, first of all snappy brass or precise basses. With the OP-X you always have the choice and you can play with the settings.

Sweeps

Maybe the most obvious of all. Slightly differing rising and falling times make the sound lively. Exactly equal times can sum up to stiff sounding resonances.

SEM Sweep:

  with svd           without svd

Pads

First of all pads with high resonance settings sound lively and rich with slightly detuned cutoff settings. The filters of e.g. old Prophet synths never were tuned exactly the same.

Prophet Pad:

  with svd           without svd

Solos

While the pitch spreading has become a standard feature in VA synths, cutoff spreading is missing. But, first of all with high resonance settings, stacked solos sound much more gentle and smooth with slightly spread cutoffs.

Prophet Solo:

  with svd           without svd

Portamento

Slightly different portamento times from voice to voice were very typical in old analog polysynths. It gave that special "smear" and depth. Note: the OP-X has got polyphonic portamento!

Portamento:

  with svd           without svd

SVD in the every day life

Once you know how the tuning features work you will learn to use them intuitively on the fly and you will ask yourself how you could live without them before. Promised!

download pdf manual

The op-x is built like a real hardware synth      separate voices

The structure of a normal virtual analog synth      cloned voices

The famous filter   ob-x filter

This is the most important part of a subtractive synth. The old discete SEM filter is legendary and holds up to moog with different and unique character.

One of the great things of SEM filters was that they didn't lose gain or fullness even at highest resonance settings. This made them sound extremely sweet, deep and rich. You won't find self oscillation here but you will never miss it.

   click to enlarge

The filter of the OP-X is meticulously modeled after the hardware counterpart with absolutely stunning result. It's rated as one of the best models done ever.

Listen to a comparison:

  op-x model           original ob-x

You want morphable multimode filters like in the old SEMs? Then again have a look at the OP-X PRO!

OP-X PRO product page

Crossmod, Sync and Ring Modulation

While X-Mod and Sync are available in the original, ring modulation is a special gift. Sync is a very weak point in many VA synths, both harware and software.

Not so in the OP-X. The sync sounds exactly the same as in its analog godfather with no shortcomings.

Syncsolos on OP-X:

  syncsolo1           syncsolo1           syncsolo2

Stereo voice pans

This was a popular feature within old analog synths and you won't miss it here as well! Every voice can be panned individually in the stereo field. This means real stereo and sounds fantastic!

   click to enlarge

Polyphonic portamento

Very rarely seen in VA synths, but its there! The times detuning allows the real analog "smear".

In detuned mode the voices are spread bit while gliding because some are a bit faster and some a bit slower. Of course it also can be tuned for accuracy.

Portamento on OP-X:

  portamento1           portamento2           portamento3

Free running oscillators

In voltage controlled analog polysynths the oscillators are swinging permanently. The ons and offs are only determined by the envelopes of the filters and amplifiers.

This causes the oscillators to be never in-phase to each other which contributes to the general livelyness.

In the OP-X, the oscillators are free running too and are never completely in phase, exept you force them to with sync.

Oscillators in OP-X:

  oscillators

Modulation behaviour

A further important point for the general "feel" is how parameters behave on their own and also when they modulate each other. This has been meticulously designed in the OP-X with various custom logarithmic curves.

Take the knob for lfo to pich depth: It was designed to react double logarithmic just in the first quarter for extremely subtle control in this most sensitive area.

Listen to some audio clips: