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Rascal Audio Analogue Tone Buss Summing Mixer

Analogue ToneBuss offers the sound of a classic mix bus combined with musical harmonic distortion.

Although the controversy has somewhat dwindled over the past two or three years, the debate between summing externally and ITB (in the box) remains at the forefront of many audio conversations.

If this is a new concept to you (welcome to the 21st century), you need to be aware that there are a lot more variables than simply “in the box” or “out of the box.” Total analog summing (usually through an analog console) requires that every track independently leave the DAW through a D/A converter. More common than total analog summing is hybrid summing, where a mix is reduced to several stereo pairs (submixes commonly called stems), and then the final summing is done in either a console or a summing box.

There are many different summing boxes out there and although there isn’t a clear leader, everyone who owns one undoubtedly swears that theirs is the best. I’ve tried several of them and while I’ve yet to encounter one that sounds bad, I’ve never felt like they give me a result that isn’t attainable mixing ITB. In my opinion, the problem is that these summing boxes typically sound clean and natural but totally uncolored. This admittedly by textbook standards is desirable, but it isn’t at all what we achieved when mixing albums through old API, Neve, or Trident consoles before ITB mixing was possible. That all changes with the Rascal Audio Analogue ToneBuss summing box, which delivers the classic, pre-IC tone found in the classic consoles that we all love.


Analogue ToneBuss is a simple device with no monitor section, no gain controls, and no metering. It does one thing, and it does it unlike any other product out there: Through the use of completely discrete, Class-A circuitry and customwound input and output transformers, this 2RU box delivers a truly classic analog tone. The inputs and outputs on the ToneBuss are balanced, accessed via DB- 25 connectors. The box is available in either 16- or 24-channel configurations. Channels 1-4 are switchable as either L/R or Mono, and the remaining inputs are in stereo pairs with the odd inputs being hard left and the evens hard right.

The custom output transformers provide identical secondaries that are so closely matched that loading one set of outputs results in the same loading on the other pair. This ensures that what you hear from the monitor pair is exactly what you’re getting from the main output pair.

The front panel includes a bright — and I mean bright! — blue LED that illuminates not only itself but everything in front of it when the unit is powered on. A small piece of console tape over the LED makes it the perfect brightness, otherwise I find that I have to let my eyes refocus for about 2-3 minutes every time I look at the Analogue ToneBuss before I can focus on my computer monitor again. [According to Rascal Audio, this LED has been updated for easier viewing on all future production models: “The new LED is still blue, but diffuse and much less intense –- no blinding now!” — Ed.]

In Use

Like most engineers I know, I love vintage gear. Ironically enough, it’s usually the sonic shortcomings of classic gear that give it the character that our ears find attractive. The phase characteristics and limited bandwidth of some transformers, the sluggishness of some of last century’s circuit designs, and the loading that results from oddly matched impedances within combined signal paths and circuits (all considered flaws by today’s design standards) can coalesce to produce that vintage sound that we know and love. The ToneBuss authentically re-creates this sound.

I found it simple to hook the Analogue ToneBuss up to my Pro Tools rig; the DB-25 connectors (used for both input and output) follow the TASCAM standard, so any cabling wired for a Digidesign 192, iZ RADAR, Lynx Aurora, etc., will interface with the Analogue ToneBuss without any modification. The manual is well written, and it includes descriptions of typical configurations, explaining the benefits of the thru-ports, among other important information. It is also important to note that the Analogue ToneBuss uses balanced, passive voltage summing, so the bus level and impedance are dependent on how many inputs are physically connected to the box. Loading all of the inputs is necessary for optimum sound, and the manual gives a schematic for loading the unused inputs when not making use of all of the Analogue ToneBuss’ inputs.

Before breaking my Pro Tools session into individual outputs, I ran the stereo mix through the Analogue ToneBuss and was actually impressed with the sound of the box when just passing a stereo signal without doing any summing at all. Breaking my mix out through multiple outputs was even more impressive. I had my best results setting inputs 1-4 to center panning, using them for kick, snare, bass, and lead vocal, and then splitting everything else out into stereo pairs (drum kit, guitars, keys, backing vocals, strings, and effects).

I found that driving the inputs harder increases the amount of dynamic saturation. The Analogue ToneBuss actually smoothes out the transients while leaving the overall sound tight and punchy. The resulting sound is big and overall headroom is actually increased with the transient decrease. The ToneBuss melds the signals together in such a way that signals running through the box blend more musically and are easier to balance.

I realize that Rascal Audio was trying to keep this box as simple as possible, but my biggest complaint is that the Analogue ToneBuss makes total analog summing practically impossible, as a DAW output can only be routed to the center or hard left or right — nowhere in between. I’ve been fortunate to have a 16-input version of the Analogue ToneBuss parked at my studio for over a year (and sadly, the time has finally come to either buy or cry). I’ve gone back and forth on many projects, using the Analogue ToneBuss for some and not using it for others, yet here’s the one thing that has always been the case: the Analogue ToneBuss is sonically powerful. Without a question, it colors the sound, and it does so in a very positive, musical way.


The Analogue ToneBuss is a no-frills outboard audio summing apparatus that delivers genuine analog tone. It is the perfect solution for anyone wanting his DAW mixes to possess the sonic richness and spatial definition of tracks mixed on vintage, discrete, Class-A, large-format consoles. It easily configures to any existing DAW, is easy to use, and the results are remarkable.

Russ Long is a producer, engineer, and mixer. He owns the Carport studio in