what is a “box tone”?

“Box tone” is a term that is often used to describe the characteristic sound of a particular piece of audio equipment, particularly when it comes to classic analog effects devices such as equalizers and compressors.

The box tone of an effect is often described as the unique timbre or tonal coloration that the device imparts on the audio signal as it passes through it. This can be due to a variety of factors, including the type and quality of the components used in the device, the design of the circuitry, and the way the device processes the signal.

Some audio engineers and producers may seek out specific box tones for their recordings and mixes, as they can add character and depth to the sound. Others may prefer a more neutral or transparent sound, in which case they may choose equipment that has a more subtle or less noticeable box tone.

It’s important to note that the term “box tone” is often used informally and can be somewhat subjective, as different people may have different opinions on what constitutes a distinctive or desirable box tone.

some FlavourMTC coverage from the net

Short review from Bedroom Producers Blog – Variety Of Sound Releases FREE FlavourMTC Passive Equalizer Plugin:

Variety of Sound is one of the legendary old-school freeware VST plugin developers, providing top-tier audio software that easily rivals the quality of paid plugins. Their incredible FerricTDS mkII is still my favorite tape saturation plugin.

If you’re looking for mixing and mastering software with a taste of analog hardware, I highly recommend checking out Variety of Sound’s plugins. It is one of the best freeware plugin collections for Windows-based music producers.

Thread over there at gearslutz gearspace –  A completely new plugin after a long streak of redesigned classics:

This sounds like analogue gear. Incredible.

… it’s a big fat lump of ‘ashish dissolved in a bucket filled with two parts honey and one part roasted sesame on a warm Himalayan afternoon. Dip yer finger, don’t forget to lick it and soon not only sesame opens …

FlavourMTC “Mixbus Tone Control” released

FlavourMTC follows classic “passive” equalizer designs where the EQ circuits itself are not able to amplify signals but a dedicated amplifier stage takes care of it. Those EQ designs are well known for allowing very transparent frequency changes while their amplifier designs do add some icing on the cake quite often.

mixbus tone control – closest to analog

FlavourMTC implements this by utilizing 1^st order shelving filter designs avoiding unwanted resonances and takes advantage of “zero delay” implementations for most accurate higher order filtering and w/o introducing curve warping near Nyquist frequency. The output amplifier stage of the plugin can be calibrated according specific mixing levels, provides a distinct “box tone” and glues everything together. Parts of the plugin are oversampled internally for maximum transparency and sound quality.

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

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.

A more realistic look at the Pultec style equalizer designs

One of the few historic audio devices with almost mystical status is the Pultec EQP-1A EQ and a lot of replicas has been made available across the decades. Whether being replicated in soft- or hardware, what can we expect from a more realistic point of view? Lets have a closer look.

Some fancy curves from the original EQP-1A manual

• In the top most frequency range a shelving filter with 3 pre selected frequencies is offered but just for attenuation. Much more common and usable for todays mixing and mastering duties would be an air band shelving boost option here.
• Also in the HF department there is just one single peak filter but this time just for boosting. It offers 7 pre selected frequencies between 3 and 16kHz and only here the bandwidth can be adjusted. However, the actual curves could have been steeper for todays mixing duties.
• There is no option in the mid or low-mid range at all and also no high pass option. Instead, there is a shelving filter for the low-end which allows for boost and/or attenuation around four pre selected frequencies between 20 and 100 Hz.

All in all, this appears to be a rather quirky EQ concept with quite some limitations. On top of that, the low frequency behaviour of the boost and cut filters is rather unpredictable if both filters are engaged simultaneously which is exactly the reason why the original manual basically states “Do not attempt to do this!”.

Nowadays being refered to as the “Pultec Bass Trick” the idea is that you not only boost in some low end area but also create some sort of frequency dip sligthly above to avoid too much of a boost and muddiness in total. In practise, this appears to be rather unpredictable. Dial in a boost at 3 and an attenuation at 5, just as an example: Does this already feature a frequency dip? And if so at which frequency exactly? One has no idea and it even gets worse.

Due to aged electronics or component variety one has to expect that the actual curve behaviour might differ and also to see each vendors replica implementation to be different from another. In practise this indeed holds true and we can see the actual bass frequency dip at a much higher frequency within one model compared to another, just as an example.

… the more I boost the EQ the more it makes me smile …

A reviewers statement misguided by simple loudness increase?

Fun fact: Like the original device, all current (hardware) replica models do not have an output gain control. Also they increase the overall signal level just by getting inserted into the signal path.

So, where is the beef? Its definately not in the curves or the overall concept for sure. Maybe I’ll take some time for a follow-up article and a closer look into the buffer amplifier design to see if all the hype is justified.

Further Links

Not really demystifying but fun to read:

Demystifying the ‘magic’ of the Pultec EQ

In the VoS plugin line you can find some Pultec style low end performance within NastyVCS: https://varietyofsound.wordpress.com/2010/05/07/nastyvcs-released-today/

Also interesting to read and hear: https://www.sweetwater.com/insync/pultec-shootout-with-sound-samples/

tips&tricks with SlickEQ

Note: Some of the tips rely on features from the GE version.

Mixing against HP/LP combo

A good generic practice when EQing several tracks in a mix is too start by dialing in HP/LP combinations by an  appropriate level and then do further EQing/mixing against those settings. Also using the tilt filter is a good idea to apply very first and rough tonal corrections and then working out the details afterwards with the three EQs.

Preserving low-end energy when high-pass filtering

A cool trick to preserve some low-end energy when high-pass filtering is applied is to boost the low-end while using the EQ-SAT feature. As you can see in the routing diagram the HPF comes after the main EQs and EQ-SAT. This way, harmonic overtones are generated based on the fundamentals before the HPF is applied.

Decoupling the low-end

The low-end EQ features a “Phi” option switch which allows to decouple the low-end by an allpass filter network. The crossover can be freely adjusted with the normal frequency control in this band while the gain control does not have any effect in this mode. This may work great for that mellow bass drums just as an example but in other cases it might loose some definition as a trade-off.

Compare different settings

SlickEQ contains two effect settings slots, A and B. Use them in combination with the automatic output gain control to AB test different settings. Within the plugin you can move settings between A and B but also copy&paste is there to freely copy settings between different plug-in instances. Also, undo/redo comes in handy here.

Adjusting precise values

The gain/frequency displays can also be used to enter specific values and also shortcuts are accepted, e.g. “5k” can be entered to set a value to 5000. And did you know that SlickEQ has mouse-wheel support?

 

 

out now: SlickEQ “Gentleman’s Edition”

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/

Related

• announcing SlickEQ “Gentleman’s Edition”

TDR VOS SlickEQ – video review

Read the whole story at modernmixing.com.

 

released: SlickEQ

TDR VOS SlickEQ is a mixing/mastering equalizer designed for ease of use, musical flexibility and impeccable sound.

Three (and a half) filter-bands arranged in a classic Low/Mid/High semi parametric layout offer fast and intuitive access to four distinct EQ modes, each representing a set of distinct EQ curves and behaviors. An elaborate auto gain option automatically compensates for changes of perceived loudness during EQ operation. Optionally, SlickEQ allows to exclusively process either the stereo sum or stereo difference (i.e. “stereo width”) without additional sum/difference encoding.

In order to warm up the material with additional harmonic content, SlickEQ offers a switchable EQ non-linearity and an output stage with 3 different saturation models. These options are meant to offer subtle and interesting textures, rather than obvious distortion. The effect is made to add the typical “mojo” often associated with classy audio gear.
An advanced 64bit multirate processing scheme practically eliminates typical problems of digital EQ implementations such as frequency-warping, quantization distortion and aliasing.

Beside the primary controls, the plug-in comes with an array of additional helpers: Advanced preset management, undo/redo, quick A/B comparison, copy & paste, an online help, editable labels, mouse-wheel support and much more.

SlickEQ is a collaborative project by Variety Of Sound (Herbert Goldberg) and Tokyo Dawn Labs (Vladislav Goncharov and Fabien Schivre).

Key specs and features

• Intuitive, yet flexible semi parametric EQ layout
• Full featured, modern user interface with outstanding usability and ergonomics
• Carefully designed 64bit “delta” multi-rate structure
• Three EQ bands with additional 18dB/Oct high-pass filter
• Four distinct EQ models: “American”, “British”, “German” and “Soviet” with optional non-linearity
• Four output stages: “Linear”, “Silky”, “Mellow” and “Deep”
• Advanced saturation algorithms by VoS (“stateful saturation”)
• Highly effective and musically pleasing loudness compensated auto gain control
• Oversampled signal path including stateful saturation algorithms
• Stereo and sum/difference processing options
• Tool-bar with undo/redo, A/B, advanced preset management and more

Availability

TDR VOS SlickEQ is a freeware audio plug-in available for Windows and Mac in VST and Audio Units format (both 64-bit and 32-bit). VST3 and AAX formats will follow later.

All downloads are available via the Tokyo Dawn Labs website.

Related Links

• vladg/sound
• KVR page
• forum talk
• SlickHDR – final teaser & release info
• what I’m currently working on – Vol. 12
• sharing the same vision …