ThrillseekerXTC mkII released

ThrillseekerXTC – bringing mojo back

ThrillseekerXTC mkII is a psychoacoustic audio exciter based on a parallel dynamic equalizer circuit. It takes our hearing sensitivity into account especially regarding the perception of audio transients, tonality and loudness.

The mkII version now introduces:
• Plugin operating level calibration for better gainstaging and output volume compensated processing.
• A reworked DRIVE/MOJO stage featuring full bandwidth signal saturation and a strong
focus on perceived depth and dimension. It provides all those subtle qualities we typically associate with the high-end analog outboard gear.
• Special attention has been taken to the mid frequency range by introducing signal compression which improves mid-range coherence and presence.
• Relevant parts of the plugin are running at higher internal sampling frequencies to minimize aliasing artifacts.

Available for Windows VST in 32 and 64bit as freeware. Download your copy here.

Getting the most out of the SPL Tube Vitalizer

In this article I’m going to share some analysis insights but also proposing an easy to follow 3-step approach for finding the sweet spot while processing any kind of material with this device.

Preparing for winter season: room heating with style

So, having now a Tube Vitalizer here on my desk (at least for some time), I was surprised about the lack of usable online reviews and background information. One just finds the usual YT quality stuff which might be entertaining in the best case but also spreads misinformation ever so often. To save those influencers honor it must be said that the Vitalizer concept is really not that easy to grasp and its quirky user experience makes it not easier. The manual itself is a mixed bag since it contains some useful hints and graphs on the one hand but lots of marketing blurb obscuring things on the other. Time to clean up the mess a little bit.

What it actually does

While easily slotted into the “audio exciter” bucket, some more words are needed to describe what it actually does. Technically speaking, the Vitalizer is basically a parallel dynamic equalizer with an actual EQ curve behaviour which aims to mimic equal loudness contours as specified in ISO226. Rather simplified, it can be seen as a high and low frequency shelving EQ to dial in a basic “smile” EQ curve but one which takes hearing related (psychoacoustic) loudness effects into account. It does this also by generating curves differently based on signal levels, hence the term “dynamic EQ”. And wait, it also adds harmonic content galore.

Taming the beast

To obtain an equal loudness contour the main equalizers center frequency must be properly set depending on the tonal balance of the actual source material. This center frequency can be dialed in somewhere between 1k and 20kHz by adjusting the Hi-Mid Freq knob which defines a cross-over point: while frequencies below that point gets attenuated, the higher frequencies gets boosted. However, this attenuation is already a signal level dependent effect. Opposed to that, the LF EQ itself (which actually is not a shelving but a bell type curve) has a fixed frequency tuned to 50Hz and just the desired boost amount needs to be dialed in. The LF curve characteristic can be further altered (Bass soft/tight) which basically thickens or thins out the below 100Hz area. Finally, this EQ path can be compressed now with the Bass Comp option.

A typical EQ curve created by the Vitalizer

On top of the main EQ path, the Tube Vitalizer offers an additional HF boost and compression option which both can be dialed in to complement the LF behaviour in a very similar fashion but in the high frequency department. Internally, both are in a parallel configuration and mixed back into a dry signal path. The according Process Level knob can be seen as a kind of dry/wet option but only for main the EQ part. The upper HF part is mixed back in separately by the Intensity dial.

Gain-Staging is key

For the EQ section as a whole, the Drive knob is the ticket for proper gain-staging. If compression can be dialed in properly for both compressors (as indicated by the blue flashing lights) input gain is in the right ballpark. One might expect to hear actual compression going on but it appears to be a rather gentle leveling effect.

Gain-staging for the output stage has to be concerned separately which might become an issue if the tube stage is activated and operates in shunt limiting mode. Now you have to take care about proper input levels since the Attenuators for both output channels are operating after the limiter and not beforehand.

Tube stage limiting: input (red) vs output (blue)

Which directly leads us to the additional harmonic content created by this device. First of all, there is always additional harmonic content created by this device, no matter what. One might expect the device to not show any such content with the solid state output stage but it actually does. The tube output stage just increases that content but signal level dependent of course and 2nd order harmonics are always part of that content. A serious additional amount of harmonics gets added as soon as the HF filter gets engaged by dialing in Intensity (and LC Filter mode activated!) but this sounds always very smooth and natural in the top end, surprisingly.

Delicious content

Also impressive is the low noisefloor for both output stage modes, tube and solid state. The first one introduces pretty strong channel crosstalk, though.

Workflow – Finding the sweet spot in 3 easy steps

Initial condition:

  • Drive, Bass, Bass Comp and Intensity set to 0
  • Device is properly gain-staged

1. Set Process to 5 and now find the best fit for Hi-Mid Freq for the given source material. For already mixed 2bus stuff you can narrow it down to 2-3kHz most likely.

2. Dial in Bass (either left or right depending on source and taste) and some compression accordingly.

3. Only then dial in some further HF content via Intensity and some compression accordingly. Adjust HF Freq so it basically fits the source/taste.

Workflow – Tweaking just one knob

My good old buddy Bootsy told me this trick which works surprisingly well.

Initial condition:

  • Left most position: Bass
  • Right most position: Bass Comp, High Comp, High Freq
  • 12-o-clock position: Drive, Intensity
  • Hi-Mid-Freq set to 2.5kHz

Now, just dial in some (few) Process Level to taste.

He also recommends to drive the input to some extend (VU hitting the red zone) using the Tube stage in limiter mode while always engaging LC Filter mode for HF.

What loudspeakers and audio transformers do have in common

Or: WTF is “group delay”?

Imagine a group of people visiting an exhibition having a guided tour. One might expect that the group reaches the exhibitions exit as a whole but in reality there might be a part of that group just lagging behind a little bit actually (e.g. just taking their time).

Speaking in terms of frequency response within audio systems now, this sort of delay is refered to as “group delay”, measured in seconds. And if parts of the frequency range do not reach a listeners ear within the very same time this group delay is being refered to as not being constant anymore.

A flat frequency response does not tell anything about this phenomena and group delay must always be measured separately. Just for reference, delays above 1-4ms (depending on the actual frequency) can actually be perceived by human hearing.

This always turned out to be a real issue in loudspeaker design in general because certain audio events can not perceived as a single event in time anymore but are spread across a certain window of time. The root cause for this anomaly typically lies in electrical components like frequency splitters, amplifiers or filter circuits in general but also physical loudspeaker construction patterns like bass reflex ports or transmission line designs.

Especially the latter ones actually do change the group delay for the lower frequency department very prominently which can be seen as a design flaw but on the other hand lots of hifi enthusiast actually do like this low end behaviour which is able to deliver a very round and full bass experience even within a quite small speaker design. In such cases, one can measure more than 20ms group delay within the frequency content below 100Hz and I’ve seen plots from real designs featuring 70ms at 40Hz which is huge.

Such speaker designs should be avoided in mixing or mastering situation where precision and accuracy is required. It’s also one of the reasons why we can still find single driver speaker designs as primary or additional monitoring options in the studios around the world. They have a constant group delay by design and do not mess around with some frequency parts while just leaving some others intact.

As mentioned before, also several analog circuit designs are able to distort the constant group delay and we can see very typical low end group delay shifts within audio transformer coupled circuit designs. Interestingly, even mastering engineers are utilizing such devices – whether to be found in a compressor, EQ or tape machine – in their analog mastering chain.

out now: SlickEQ “Gentleman’s Edition”

SlickEQ_German

Key specs and features

  • Modern user interface with outstanding usability and ergonomics
  • Carefully designed 64bit “delta” multi-rate structure
  • Three semi-parametric filter bands, each with two shape options
  • Five distinct EQ models: American, British, German, Soviet and Japanese
  • Low band offers an optional phase-lag able to delay low frequencies relative to higher frequencies
  • High pass filter with optional “Bump” mode
  • Low pass filter with two different slopes (6dB/Oct and 12dB/Oct)
  • Parametric Tilt filter with optional “V” mode.
  • Six output stages: Linear, Silky, Mellow, Deep, Excited and Toasted
  • Advanced saturation algorithms by VoS (“Stateful saturation”)
  • Highly effective loudness compensated auto gain control
  • Stereo, mono and sum/difference (mid/side) processing options
  • Frequency magnitude plot
  • Tool-bar with undo/redo, A/B, advanced preset management and more

SlickEQ is a collaborative project by Variety of Sound (Herbert Goldberg) and Tokyo Dawn Labs (Vladislav Goncharov and Fabien Schivre). For more details, please refer to the official product page: http://www.tokyodawn.net/tdr-vos-slickeq-ge/

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compressor aficionados (9) – D.W. Fearn

Doug, when and how did you arrived in the music business?

I have had an interest in electronics ever since I was a kid growing up in the 1950s and 1960s. I built a crystal radio  receiver when I was 8 and my first audio amplifier (tubes, of course) when I was 10. I passed the test for an amateur radio license when I was 12 and that experience of communicating using Morse code was excellent training for  learning to hear. I built a lot of my own radio equipment, and experimented with my own designs.

The high school I attended had an FM broadcast station. Most of the sports and musical events were broadcast, and I learned about recording orchestras, marching bands, choirs, and plays. Friends asked me to record their bands, which was my first experience working with non-classical music.

Another major factor was that my father was a French horn player in the Philadelphia Orchestra. As a kid, I would attend concerts, rehearsals, and sometimes recording sessions and broadcasts. I learned a lot about acoustics by walking around the Academy of Music in Philadelphia during rehearsals.

It would seem logical that my musical exposure and my interest in electronics would combine to make the career in pro audio I have had for over 40 years now.

I was a studio owner for many years before starting the D.W. Fearn manufacturing business, which started in 1993. [Read more…]

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Chris, you are the man behind the Canada-based Quantum-Music studio. What was your journey towards this venture?

My father (Alain Dion) was an internationally renown live sound engineer and technical producer (Nat King Cole, Sting, Celine Dion, Cirque du Soleil, and many locally-famous artists). Therefore, I grew up in an environment where high fidelity audio was the standard. My father hated everything that sounded less than perfect. Unconsciously, he trained my ears. I owe him a lot for that. Nowadays, every time we see each other, we spend much of our time talking about which compressors, consoles and techniques. [Read more…]

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Dave, some of your Cranesong devices are already legend – how did that affair once started?

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modeling the distortion in Thrillseeker VBL

It’s so important to get the non-linear modeling right if we would like to have a sort of analog feel in the digital domain. I can’t stress this ever enough since it still seems to be a common practise in todays audio plug-in design to just throw in a static waveshaper, oversample it and hope this will make everything alright. Not! Even worse, in a recently released plug-in I saw the static waveshapers curve not being continuous again and I’m not going to talk about the sound.

But what should one expect to hear if the analog modeling is just done right? Only by driving the gain of the unit but way before we notice the obvious distortions there appear different by-products caused by circuit side-effects. Depending on the actual device, circuit and components, it might be that the signal starts just getting thicker and more mid-focused, as an example. Or, the signal might appear much deeper and bigger in other cases.

Whatever it might be in particular, I do call this the “Mojo” of the device – it’s not the primary intention of the device but turns out to be a sort of an added sugar. Such effects are highly frequency, transient and gain structure dependent and this is what makes the processed signal to be much more vibrant and alive. Furthermore, the obvious harmonic distortions are not introduced abruptly but they emerge gradually.