KVR Developer Challenge 2009

Yeah, right – we did it: “With over twice as many points as the second placed entry, FerricTDS by bootsie, a Windows VST effect Tape Dynamics Simulator plug-in is the clear favourite in this years Challenge. Bootsie wins 30% of the prize fund as the top Windows entry!”

Many, many thanks for your support during the challenge!

In the top bar of this blog there is now an eMail subscription option to this blog available which lets you receive eMails on whats going on here. If you are not a wordpress registered user you can simply type in your eMail address and hit the button. If you are registered and logged in, just hit the button.

In both cases you are able to manage your subscription of course, e.g. setting frequency of eMail delivery or deleting the subscription.

Some folks are asking me from time to time if and when the NastyXTC thingy will ever see the public light. Atm, the short answer still is: I really dunno.
While the original NastyXTC design was mainly a transient EQ sort of thing, I extended it concept wise to become a rather complete “transient workbench” solution in a small but flexible modular effects system. Despite of the amount of work necessary to accomplish this, there are still some essential and fundamental technical concepts not yet really explored by me.
On the other way around, the actual existing design and implementation of NastyXTC was already the blueprint for some other plug-in parts and therefore I rather see it as an unfinished “technology study” (for the moment) but you could spell it “vaporware” as well of course.
However, if this will someday actually show up in a dedicated plug-in release or not remains unclear for still a while.

epicVerb

An important major update for the epicVerb digital reverberation simulator is (almost) done and will be released in the beginning of December 2009. It not only features some bugfixes and major stability improvements but also some re-worked algorithms which supports way more dense and three-dimensional reverberation processing.

Opposed to VCA, Variable-Mu or FET based approaches, opto-electrical compression takes advantage of using a light-sensitive resistor and a small light emitter (a LED or electroluminescent panel) to obtain a gain reduction voltage in the sidechain path. This technique is well-known to add some smoother gain riding characteristics to the signal because of the specific attack and release response which comes from the inertia and inherent memory effect of the photoresistor element.

Program dependency

Typical classic opto-electrical circuit designs do have a significant and highly program dependent impact on the processed sound and this comes mainly from three factors:

1. The adaptive release time characteristic which gets faster at higher compression activity and can be fairly long when leaving the compressors duty cycle.
2. The specific compression transfer curve which features soft-knee characteristics by nature and limits the dynamic range.
3. The frequency dependency and non-linearities which impacts the actual behaviour of things like the compression transfer curve.

Experimental frequency dependent "opto" transfer curves

In addition, opto elements do have an inherent lag time in their attack response which is typically not fast enough to catch short transients but adds up to an overall smooth gain riding impression.

Light and shadow

Opto compression really shines on overall adaptive and smooth gain riding purposes such as for vocals and solo instrument performances, whereas faced with rather complex program material it can easily tend to sound rather quirky. This might be the reason why it is typically not used that often on the mix-bus or if so then just with few amounts of gain reduction.

In digital implementations where the opto element effects are modelled in an explicit fashion this kind of weirdness can be avoided and both, frequency dependency and non-linearities can be applied in a way to better support full program material.

If you are into electronic music making (whatever sort of) then don’t miss this BBC documentary about the legendary “Krautrock” decade in germany:

See all six parts on youtube.

Both maintenance releases are containing important stability improvements, especially for the memory issues that were causing crashes when deleting plugins in some host applications.

Additional changes TesslaSE 1.2.1

• noise model removed
• faster loading times on systems with large amounts of system fonts
• VST vendor tag changed to ‘Variety Of Sound’
• manual updated

Additional changes TesslaPRO 1.0.1

• samplerate compatibility issue fixed (internal filter)
• VU needle renders proper on mono tracks now
• VST vendor tag changed to ‘Variety Of Sound’

Both updates are available through the downloads page here.

Both maintenance releases are containing important stability improvements, especially for the memory issues that were causing crashes when deleting plugins in some host applications.

The Density mkII v2.0.2 update is available through the downloads page here.

The FerricTDS v1.0.2 update is available through the KVR Developer Challenge over here.

FerricTDS - Tape Dynamics Simulator

Inspired by the smooth dynamic shaping capabilities of some high-end reel-to-reel tape recorders, this plug-in simulates three of the most distinctive and much appreciated sonic effects generated by these devices:

• DYNAMICS – gently shaping the overall dynamic response
• SATURATION – adding extra harmonic-related content
• LIMITING – controlling peak performance

Functions at a glance:

• performs gentle audio dynamic treatments
• masters difficult to handle audio material
• adds extra harmonics and saturation effects
• controls outgoing audio peaks

Plug-in specification:

• Win32 / VST compatible
• state-of-the-art digital signal processing
• 4x oversampled core algorithms
• performance-critical parts are written in assembler
• completely SSE-optimized

For more information, please refer to the manual.

FerricTDS is released within the KVR Developer Challenge 2009 and can be downloaded here.

This short article gives a brief introduction on applying waveshaping algorithms not directly in the audio path but via a transformed equation through the sidechain and a VCA instead.

Typical saturation curves

As mentioned earlier before in this article, waveshaping can be seen and applied quite similar to compression techniques via its computation in a separate sidechain path. This way, the algorithm does not work anymore on the audio path in a direct fashion but only on the sidchain part and the outcome then drives the main audio via a VCA. The actual used algorithm has to be properly transformed math wise to work in a sidechain configuration and the transformation depends on if the sidechain operates on log encoded audio or does work in linear scale.

So, why could this be more favourable compared to a direct implementation?

Some experimental transformed curves (linear scale)

One big advantage could be that filter and phase alterings upfront the waveshaping (to shape its frequency response) does not translate back into the originial audio source since due to the VCA only amplitude modulation (by a DC signal) is performed in the end.  Given this method a circuit designer is able to e.g. setup frequency dependent saturation behaviour without the need to filter and compromise the original signal. Even some artifacts of oversampling can be reduced to some extend if its specific use is limited to just parts of the sidechain and not the entire signal chain. However, normally the VCA would be oversampled as well to minimize the intermodulation distortion.

Even more sophisticated waveshaping processing such as combinations with envelope and transient processing or frequency split techniques are now easily possible without touching the integrity of the main audio path.