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Recording

The Mixer

In the basic recording chain, the destination of every signal flow is an audio interface: a small box, one or two inputs, plugged into the studio Mac, getting one signal at a time into the digital audio workstation (the recording software running on the computer; from here on I'll use the shorthand DAW for the whole flow from the audio interface into whatever software is doing the recording). That works when there's one mic and one sound to record. It stops working the moment there are seven mics on stage and the engineer needs to balance, EQ, and route each one independently to multiple destinations at once. The mixer is what gets used in that situation. It doesn't replace the audio interface; in a studio setup the mixer sits between the mics and the interface. The mics plug into the mixer, the engineer shapes and combines the signals on the console, and the mixer's outputs feed the audio interface, which still gets the result into the DAW. The interface's role shifts from "the only routing point" to "the link between the analog console and the digital recording," and the mixer becomes where the engineering work actually happens.

That description fits an analog mixer, which is what's in our studio and what this reading covers. Every signal path on an analog mixer is a real voltage moving through physical circuitry; the mixer has no concept of digital audio on its own, which is why a separate audio interface is needed to get the output into a computer. A digital mixer is a different piece of equipment: its mixing, EQ, routing, and effects all happen as math on digital audio samples rather than as voltages through circuits. Most modern digital mixers (Behringer X32, Allen & Heath SQ, Soundcraft Si, Yamaha QL, and others) include the analog-to-digital conversion stage inside the same box as the routing, and connect directly to a computer over USB or ethernet. In that setup, the digital mixer is the audio interface; every channel on the console can become a recording input to the DAW without a separate interface in the chain. The routing concepts are the same across both kinds (channel strips, aux sends, subgroups, masters, inserts), so the work you do on our analog Toft transfers directly to any digital console you'll meet in the field. The differences are in feel, in how settings get saved, and in whether the math is happening in copper or in code.

The Toft Audio Designs Series ATB 16-channel console, photographed from directly above. On the left two-thirds: sixteen identical input channel strips, each with rows of magenta, green, and pink knobs and a white vertical fader at the bottom. In the middle-right: eight narrower submaster strips with green knobs and red vertical faders. On the right: the master section with bargraph meters, the auxiliary master knobs, two VU meters, talkback controls, and the blue stereo master fader. The console sits in a warm orange wood frame.
Our studio's console: the Toft Audio Designs Series ATB, 16-channel.
Photo via Retro Gear Shop.

1 · The mixer as the place where flows meet

A mixer (or console, or board, or desk: the words are interchangeable) is the piece of equipment in the middle of every multi-source audio workflow. Each source plugs into its own channel. Each channel has its own controls (level, EQ, routing, sometimes more). The channels combine into one or more outputs that go somewhere: speakers, headphones, a DAW.

The mixer's job is the same in every context: take many flows in, let the engineer shape each one, and send the combined result somewhere. What changes from context to context is what's connected at the input and where the output goes. Live sound and studio recording are two of those contexts. The hardware between them is the same hardware; the patching changes.

Our studio's console is the Toft Audio Designs Series ATB, designed by Malcolm Toft, who founded Trident Audio in 1972 and built consoles for studios that recorded David Bowie, Queen, Stevie Wonder, and many others. The Toft ATB is a modern descendant of that lineage: a smaller, more affordable design for project studios, but with the same channel-strip layout you'd find on a console in a commercial studio. Once you learn this one, the next one will feel familiar.

The board has three kinds of strips, arranged left to right:

  1. Input strips (sixteen on our console). One per channel. Where signals from mics, instruments, and the DAW come in.
  2. Submaster strips (eight). Group outputs that combine many channels into one before sending to the DAW, and that also handle DAW returns.
  3. Master strip (one). The final stereo output of the console, plus the controls that shape what the engineer hears in the room, plus talkback.

2 · The channel strip

Every input on the console is a vertical strip with the same set of controls, top to bottom. Learn one strip and you know all of them. Here's a single channel:

An annotated photo of a single input channel strip on the Toft ATB. From top to bottom, with labels pointing to each control: 48V phantom power, Input/Monitor Reverse, Line, Phase, HF (selectable 8K and 12K), HM (sweep 1K to 15K), LM (sweep 100 Hz to 1.5K), LF (selectable 60 Hz and 120 Hz), High-pass filter 80 Hz, EQ In/Out. Then a section labeled '6 Auxiliary Sends': Aux 1 (pre-fader) and Aux 2 through 6 (pre or post). Then the inline monitor section: Aux 5 and 6 to Monitor, EQ to Monitor, Monitor Mute. Then the pan knob with Solo and Mute buttons. Then the 100mm 'Alps' type fader, with Signal Present and Peak indicators, an Assign to L&R button, and Assign to Groups 1-8 buttons.
A single input strip on the Toft ATB, with every control labeled.

From top to bottom, the controls do this:

Input section. A button labeled +48V turns phantom power on (you met this earlier). A button labeled I/P REV (input reverse) swaps two signal paths inside the channel; we come back to it in section 3. A button labeled LINE switches between the mic input on the back and the line input on the back. A red knob labeled INPUT GAIN sets how much amplification the preamp applies. Same gain knob you set earlier to set peaks at -12 to -6 dBFS in an audio editor like Audacity; here it's setting the level going into the mixer's own internal flow.

Phase reverse and an 80 Hz high-pass filter. Two small switches. Phase reverse flips the polarity of the signal (sometimes needed when two mics on the same source are partially cancelling each other). The 80 Hz filter rolls off everything below 80 Hz, useful for cutting room rumble or wind on vocal mics.

Phase, again

You met phase earlier, inside the XLR cable: two wires carrying the same audio, one flipped upside down, summed at the interface so external noise cancels out (peak meets trough, the math collapses to silence). The phase-reverse button on the channel strip does the same flip operation, but here on the whole signal, on purpose. Two mics on the same source can sometimes produce signals that are partially out of phase with each other (some frequencies cancel, leaving the sound thin and hollow). Hitting phase-reverse on one of the two channels flips that channel's polarity and lets you check whether the sum gets stronger or weaker. Stronger means you'd been cancelling something; the flip fixed it. Weaker means leave the button alone.

Four-band equaliser. Four pairs of knobs. Each pair is a frequency control (which band of the spectrum to affect) and a boost/cut control (how much to change it). High, high-mid, low-mid, and low. Each band can boost or cut by 15 dB. The high and low are shelving (everything above or below a frequency moves together); the two middle bands are peaking (a bell curve centered on the chosen frequency). The whole EQ section can be switched into or out of the signal path with one button.

Same operation, different surface

The EQ you used in an audio editor like Audacity (Effect → EQ and Filters → Filter Curve EQ) and the EQ on this channel strip do the same job: boost or cut specific frequency ranges of the signal. The surface is different. In an audio editor like Audacity, you click points on a curve and the software shapes the audio mathematically; on the console, you turn knobs and an analog circuit shapes the signal as the voltage flows through it.

The other difference matters more: where in the signal flow the EQ sits. The Filter Curve EQ in an audio editor like Audacity changes the audio data on the track when you click Apply (destructive: you can undo it during the session, but if you save and close, the change is permanent). The console's EQ shapes the signal as it passes through the channel strip on its way to the output. Whatever's plugged into the input (the mic on stage, the DAW playback at mixdown) keeps making the sound it was making; only the signal coming out of the channel is shaped. Turn the EQ knobs back to flat, or hit the EQ In/Out button, and the channel returns to passing the signal through unchanged. This is non-destructive: you can change your mind freely, take after take, without ever altering the source.

Six aux sends. Six green knobs, one per aux. Each one is a tap of the signal at this channel that goes out to a separate output on the back of the console (the AUX MASTERS jacks). The level of each tap is set independently of the channel's main fader. Aux 1 is permanently pre-fader (the tap happens before the fader, so the fader doesn't affect the aux level). Auxes 2 through 6 can be switched pre or post: pre-fader (independent of the fader) or post-fader (the fader controls them along with the main channel signal).

A river with taps

Think of the channel's signal as a river flowing left to right through the strip, from the input on top down to the fader and out into the master mix. The aux sends are taps along the river: small pipes that siphon off a copy of the water into a separate channel running somewhere else, without slowing the main flow. Each aux knob controls how much water its pipe carries; turn it down to zero and that pipe sends nothing.

THE CHANNEL'S SIGNAL, WITH TAPS Input EQ aux tap point Fader Master mix Aux 1 knob Aux Master 1 e.g. stage monitor mix Aux 2 knob Aux Master 2 e.g. headphone cue Aux 3 knob Aux Master 3 e.g. reverb send ...and three more
The channel's main flow runs left to right; the aux taps siphon off copies of the signal at independent levels.

The main flow doesn't change because of the taps. Whatever level you set on the channel fader, the signal arriving at the master mix is the same. The aux taps are parallel: they pull a copy off the main flow without subtracting from it. This is what makes one channel useful to many destinations at once. The vocal mic feeds the main mix (audience), and the singer's stage monitor (via Aux 1), and a reverb unit (via Aux 4), all simultaneously. One signal, many places, each at its own level.

Monitor section. A second smaller level control, labeled MON LEVEL, with its own MON PAN. This is a second input on the same strip, with its own way into the master mix, and it's the reason this console is called in-line. We'll unpack the monitor section in section 3.

Solo and mute. Two small buttons near the bottom. SOLO isolates this channel in the control-room speakers (the same solo you used in an audio editor like Audacity, but in hardware). MUTE silences the channel without changing the fader position.

Channel pan. A red knob that places this channel left or right in the stereo image.

Routing buttons. Beside the fader: L-R assigns this channel directly to the master mix; 1-2, 3-4, 5-6, 7-8 assign it to one of the four subgroup pairs (subgroups 1 through 8). The buttons are independent (any combination can be engaged), and the typical case is to use one or the other: L-R for a channel that goes directly to the mix, or a subgroup pair for a channel that wants to be grouped with others first. The pan knob decides the left-right split across whichever pair the signal arrives on.

How the pan knob splits the signal across a subgroup pair

Worked example. You have a mic plugged into channel 1, and you press the 1-2 button on that channel. The channel's signal is now routed to the subgroup pair 1 and 2 (subgroup 1 = left side of the pair, subgroup 2 = right side; odd-numbered sub on the left, even on the right). What happens next depends on the channel's pan knob.

With the pan knob in the centre: 50% of the signal goes to subgroup 1, 50% goes to subgroup 2. Pan all the way to the left: 100% of the signal goes to subgroup 1, 0% to subgroup 2. Pan all the way to the right: 100% to subgroup 2, 0% to subgroup 1. Anywhere in between is a smooth ratio (75/25, 60/40, etc.).

This is what people mean by a stereo bus: two subgroups treated as a left-right pair, with the channel pan knob acting as a level splitter between them. A bus is the point inside the console where many channel signals combine into one; the technical name for that combining operation is mixing (also called summing, which is more literal: the bus adds the channel signals together into one). Sub 1 is one bus, sub 2 is another; treating them as a pair gives you a stereo bus. The master mix works the same way at a larger scale, summing every channel routed to L-R into the final stereo program.

The fader. The main level control for this channel. Where the channel sits in the final mix. The scale beside it runs from minus-infinity at the bottom (fader all the way down, signal fully attenuated, no audio passing through) up past -40, -30, -20, -10, -5, through 0 (a thicker line, usually marked with a small notch), and up to +5 and +10 at the top. The 0 mark is called unity gain, or just unity: the fader is passing the signal through at the same level it came in at, with no change. Above unity, the fader amplifies the signal further (up to +10 dB on this console). Below unity, it attenuates: -10 dB cuts the signal level noticeably; -20 dB cuts it sharply; further down still and the signal is barely audible. The dB scale here is the same decibel scale you saw on the meters in an audio editor like Audacity, with the same warning behavior: small moves near the top of the scale do a lot, large moves near the bottom do relatively little.

The back of the console

Each strip's input and a few of its output jacks live on the back of the console. Looking at the rear panel for the first eight channels:

The back panel of the Toft ATB, showing the input connections for channels 1 through 8. Each channel has, from top to bottom: a LINE jack (1/4-inch TRS), a MON jack, an INSERT jack, a DIR. O/P jack, and at the bottom a large female XLR socket labeled MIC.
The rear of the console, input section (channels 1 through 8). Every channel has the same five jacks.
Image © Toft Audio Designs / PMI Audio Group. Used for educational purposes.

Five jacks per channel. Reading from the top down (the order they appear on the panel):

Every channel has its own copy of all five.


3 · In-line architecture · one strip, two inputs

The Toft ATB is what's called an in-line console. The defining feature: every input strip carries two inputs at once, not one. There's the main input that travels down the big fader (set up in section 2): mic or line on the back, through INPUT GAIN, EQ, the fader, the routing buttons, out to L-R or a subgroup pair. And there's a second, smaller input that travels through the monitor section in the middle of the strip: a separate signal on the back at the MON jack, with its own level (MON LEVEL) and its own pan (MON PAN), routed to the master mix.

Both inputs can be active at the same time on the same strip, carrying two different signals to the master mix.

"Monitor" on this desk is a confusing word

The label MON on the back of the console, and MON LEVEL on the front, both use the word monitor. The word isn't naming the studio speakers. It's naming the source: in the era of multi-track tape, "monitoring" a recorded track meant hearing the playback come back into the console alongside whatever was being newly recorded, so the engineer could keep checking the take against the previously-recorded layers. The MON jack on the back is that playback-return input.

The I/P REV button

At the top of every input strip is a button labeled I/P REV (input reverse). Press it, and the two inputs on that strip swap. Whatever was coming in the MIC or LINE jack now travels through the monitor section; whatever was coming in the MON jack now travels through the channel path with full EQ, aux sends, and the big fader. The most common use is at mixdown, when an engineer wants the full processing chain on the recorded track that had been coming back through the smaller monitor section during tracking.


4 · The submaster section

To the right of the sixteen input strips sits the submaster section: eight narrower strips that handle group outputs, monitor returns, and effects returns.

An annotated photo of the entire group and master section of the Toft ATB. The left two-thirds shows eight identical submaster strips side by side, with labels: Stereo FX Returns 1-8 (with Pan and Mute) at the top, Accurate 12-Position LED Group Meters in the middle, then Tape Returns 1-8 (with Aux 5 and 6 Level, Pan, Solo, and Tape switch), and Subgroups 1-8 faders at the bottom. The right third is the master strip, with labels: Left/Right VU Meters, Aux Masters, Headphone Output, 2 Track Digital Return, 2 Track Returns 1 and 2, Solo Master Level, Headphone Level, Accurate 12-Position LED L&R Metering, Alternate Monitor Select, Monitor Level, Talkback Level, Talkback Mic, Talkback to Auxes, Talkback to Groups, and Main L&R Output (the blue master fader).
The group/master section of the Toft ATB. The eight submaster strips fill the left side; the master strip is on the right.

For this section, focus on the eight submaster strips that fill the left side of the photo. (The two rows of controls at the very top of the section, the L/R VU meters and the row of six green Aux Masters knobs, belong to the master section and are covered in section 5.)

Each submaster strip is built of four labeled sub-sections, top to bottom: a stereo effects return, a bargraph meter, a tape return, and at the bottom the subgroup fader.

Stereo FX Return (top of strip)

A self-contained stereo input for a signal coming from an outboard audio effect unit (a reverb, a delay, a hardware processor), plugged in at the back of the console. Three controls plus a button, top to bottom:

Bargraph meter

Twelve segments running from -20 dBFS at the bottom to +15 dBFS at the top. Same dBFS scale as the meter in an audio editor like Audacity, with the same green / yellow / red zones. The meter shows the level of either the subgroup output going to the DAW, or the tape return coming back, depending on the TAPE switch in the section below.

Tape Return (middle section, with: Aux 5 & 6 Level, Pan, Solo)

The whole middle block of controls (PRE, AUX 5, AUX 6, MON LEVEL, MON PAN, SOLO, TAPE) is one named section. The label "Tape Return" describes what these controls do during playback, when the strip is monitoring the DAW's output coming back into the console. The same controls also work on the subgroup output going to the DAW: the TAPE button at the bottom of this section selects which signal the controls (and the bargraph above) are operating on.

Top to bottom inside this section:

AUX 5 and AUX 6, with PRE switch. The submaster strips each have two aux sends, sharing buses with channel auxes 5 and 6 (the callout below explains why). Use them to send the subgroup off to wherever a stage monitor or a headphone cue needs the whole sub-mix. The PRE button decides whether the tap happens before or after MON LEVEL.

Why share aux 5 and 6 instead of adding aux 7 and 8

An aux send is a bus: a single horizontal conductor that runs the length of the console, with every channel and submaster that wants to contribute connecting to it through its aux knob. Aux 5 is one bus; everything that turns up its aux 5 knob dumps a copy of its signal onto that bus, which ends at the Aux 5 Master in the master section and goes out the AUX MASTERS 5 jack on the back.

Making the submaster aux sends share buses with the channel aux sends (instead of introducing aux 7 and 8) keeps the bus count down. Each new bus would mean another conductor across the console, another Aux Master knob, another output jack on the back.

MON LEVEL and MON PAN. A red knob and a small black knob. This is the submaster's route into the master mix: MON LEVEL sets how much of the subgroup joins the master mix, MON PAN places it left-right in the stereo image. With MON LEVEL all the way down, the subgroup is heading only to the SUBMASTER OUTPUTS jack (the send to the DAW); turn it up and the subgroup also arrives in the master mix. The job of these two controls is the subgroup equivalent of the L-R button and channel pan on an input strip, but at the group level instead of the individual-channel level.

The labels on the front panel say MON, but the destination is the master mix, not the studio speakers. (Section 5 covers the master strip's MON LEVEL knob, which is a different control with a different job: the volume of the control-room speakers.)

SOLO. A white pushbutton. Press it to send just this submaster to the solo bus, muting the other submasters in the control room while you listen. Same job as the SOLO button on the input strip, applied at the group level instead of the channel level.

TAPE. A red pushbutton that selects the source for the whole middle section (bargraph, AUX 5 and 6, MON LEVEL and MON PAN, SOLO). Up: the live subgroup output, summed from whichever input channels routed here. Down: the playback coming back from the DAW through the MONITOR RETURNS jack on the back (covered later in this section). The name TAPE is a holdover from when those returns were a tape machine; most studios now use it to flip between "what's going to the DAW" and "what's coming back from the DAW."

Subgroup fader (bottom of strip)

A 100mm fader controlling the level of this subgroup's output at the SUBMASTER OUTPUT jack on the back: the level the DAW gets. It does not affect the subgroup's contribution to the master mix (which is set by the MON LEVEL above). The fader scale matches the input strip's: minus-infinity at the bottom, 0 (unity) marked with a thicker line, +10 at the top.


Summing: what happens at the destination

Recall the five routing buttons from section 2 (L-R, 1-2, 3-4, 5-6, 7-8). The L-R button assigns the channel directly to the master mix; the other four assign it to one of the four subgroup pairs. When several channels are routed to the same subgroup pair, their signals mix together in that subgroup (the summing operation from section 2's bus callout): the subgroup carries the combined output of every channel routed to it, with each channel's pan position deciding the left-right split between the two subgroups in the pair.

The canonical case is drums. Say four drum mics (a kick, a snare, and a pair of overhead mics for the cymbals and the overall kit) all route to subgroup pair 1-2. Kick and snare are panned center (each splits 50/50 between sub 1 and sub 2); the left overhead is panned hard left (100% to sub 1); the right overhead is panned hard right (100% to sub 2). The four channels become two combined signals on the subgroup pair, and the kit is now a single stereo group inside the console. From here, the kit travels onward together as a stereo pair: sub 1 carries the left side, sub 2 carries the right, and the controls on the two submaster strips set what happens to that stereo pair on its way out. The next callout walks where it goes.

Where the subgroup pair actually goes

From the subgroup, the combined signal goes to two places, each with its own control on the submaster strip:

  1. Out the back of the console, at the SUBMASTER OUTPUTS jacks (subgroup 1 leaves at SUBMASTER OUTPUT 1, subgroup 2 at SUBMASTER OUTPUT 2, and so on). The level is set by the submaster fader at the bottom of the strip. Those jacks typically feed eight inputs of the DAW.
  2. Into the master mix, via the MON LEVEL and MON PAN in the middle of the strip. MON LEVEL sets how much of the subgroup goes into the master mix; MON PAN places it left-right. The signal then joins everything else in the master mix on its way to MASTER O/P.

The two destinations are independent. The DAW can get one level (set by the submaster fader), while the master mix gets another (set by the MON LEVEL). Neither has to follow the other.

So if four drum mics are routed to subs 1-2 only (channels with the 1-2 button engaged, L-R off), the kit reaches the DAW via the submaster faders and reaches the master mix via the MON LEVEL knobs. The submaster strip is doing the work of a stereo-pan-and-level control for the whole drum group on its way into the mix, with a separate fader for the DAW send.

FOUR CHANNELS → ONE SUBGROUP PAIR Kick pan: center routed to 1-2 Snare pan: center routed to 1-2 Overhead L pan: hard left routed to 1-2 Overhead R pan: hard right routed to 1-2 Sub 1 (L) kick · snare · overhead L Sub 2 (R) kick · snare · overhead R Sub 1 fader "drum bus L" Sub 2 fader "drum bus R"
Four drum mics routed to subgroup pair 1-2. Pan position decides how each channel's signal splits between the two subgroups; from here the kit travels onward as a stereo group.

The back of the submaster section

The output section of the Toft ATB rear panel. On the left: MASTER O/P L and R, MASTER INS L and R, 2 TK RET. 1 and 2, ALT SPKR L and R, MAIN SPKR L and R. On the right, in rows: STEREO FX RETURNS 1 through 8 (sixteen jacks), MONITOR RETURNS 1 through 8, SUBGROUP INSERT 1 through 8, SUBMASTER OUTPUTS 1 through 8, and AUX MASTERS 1 through 6. A DC POWER round connector and a DIGITAL OPTION blanking panel sit at the bottom.
The rear of the console, output section. For this section, focus on the right half: the four rows of submaster jacks (STEREO FX RETURNS, MONITOR RETURNS, SUBGROUP INSERT, SUBMASTER OUTPUTS).
Image © Toft Audio Designs / PMI Audio Group. Used for educational purposes.

The submaster section is the right side of the panel. Top to bottom, the four rows of jacks are:

The bottom row of jacks (AUX MASTERS) and the left side of the photo (master outputs, master inserts, two-track returns, speaker outputs) belong to the master section, covered next.


5 · The master section

One strip, on the far right of the console (the right third of the group/master photo from section 4, repeated here for reference):

The same annotated photo of the group and master section as in section 4. For this section, focus on the right third of the image: the master strip. Labeled controls include Left/Right VU Meters at the top, then six Aux Masters knobs, then on the right column: Headphone Output, 2 Track Digital Return, 2 Track Returns 1 and 2, Solo Master Level, Headphone Level, Accurate 12-Position LED L&R Metering, Alternate Monitor Select, Monitor Level, Talkback Level, Talkback Mic, Talkback to Auxes, Talkback to Groups, and at the bottom the blue Main L&R Output fader.
The same photo as section 4. Now focus on the master strip on the right, plus the six Aux Masters knobs and the L/R VU meters at the top.

The master section handles everything that affects the whole console rather than any single channel. Two rows of controls sit at the very top of the section, above the eight submaster strips from section 4; the master strip itself fills the column on the far right.

L/R VU meters. The two round needle meters at the very top, labeled LEFT and RIGHT. VU meters respond more slowly than peak meters: they average the signal over a short window, which makes them a better visual stand-in for perceived loudness than for instantaneous peaks. The needle moves with the music in a way the bargraph segments do not.

Aux Masters. Six green knobs in a row across the top of the section, one per aux send. Each aux send across the desk (the six on every input channel, plus auxes 5 and 6 on every submaster strip) feeds into one of these six masters; the Aux Master knob then sets the overall level of that aux's output before it leaves the back of the console at the corresponding AUX MASTERS jack. Think of each Aux Master as the master fader for one of the six parallel mixes the aux sends create.

The remaining controls run down the master strip on the far right of the section, top to bottom.

Headphone jack. A stereo headphone output (the round HEAD PHONE jack near the top of the strip). The engineer's headphones. The level for this jack lives a few controls down (see PHONES LEVEL below).

Two-track returns. Three pushbuttons that switch the control-room monitor over from the live mix to one of the 2-track return inputs: 2TK DIG RET (from the optional digital card), 2TK 1 RET, and 2TK 2 RET (analog). This is what you press when you want to A/B the mix you've recorded against the live mix coming out of the console.

What "A/B-ing a mix" means

A/B is a comparison move. You have two versions of the same audio, you switch between them (A, then B, then A again), and you listen for what changes. The two versions could be: the live console mix vs. the recorded version of that mix, two different masters of the same song, your mix vs. a commercial reference track, a "before" version of a mix vs. an "after" version with some processing applied.

The 2-track return buttons are the A/B switch built into the console. The live console mix is "A"; press a 2TK RET button and you're now hearing "B" (whatever is plugged into that return). Release the button and you're back at A. Press a different 2TK RET button and you're at C, the next thing under comparison.

The point of A/B-ing is that the ear has a short memory. It's hard to tell whether a mix sounds better or worse if you can't switch back and forth quickly. The button collapses the comparison into something you can hear in seconds, while the impressions are still fresh.

SOLO MASTER. A pink knob that sets the level of the solo bus in the control room. When any channel or submaster has its SOLO button engaged, this knob controls how loud the soloed signal plays in the monitors.

PHONES LEVEL. A pink knob that sets the headphone jack's level (the jack near the top of the strip). Separate knob, separate position, separate function from the monitor level a few controls down.

Master bargraph meters. A 12-segment L/R pair showing the final stereo output. The main metering reference: same dBFS scale as the meter in an audio editor like Audacity, same green/yellow/red zones. Faster response than the VU meters at the top of the section, useful for catching peaks the VU needles would smooth over.

Two outputs from the master section: MASTER O/P and the speakers

The master section has two distinct outputs going to two different places. They both carry the master mix, but they diverge after the master fader, and the controls on either side don't affect the other.

The output section of the Toft ATB rear panel, same photo as in section 4. The left half of the panel holds the master section jacks: MASTER O/P L and R, MASTER INS L and R, 2 TK RET. 1 and 2, ALT SPKR L and R, MAIN SPKR L and R.
The same rear-panel photo from section 4. For this section, focus on the left half: the master section's jacks (MASTER O/P, MASTER INS, 2 TK RET, ALT SPKR, MAIN SPKR).
Image © Toft Audio Designs / PMI Audio Group. Used for educational purposes.

The first output is MASTER O/P (L and R, balanced jacks on the back). This is the master mix on its way out of the console: to the DAW input, or to the front-of-house (FOH) amplifiers driving the audience speakers in a live show, whoever is capturing or carrying away the mix. The master fader at the bottom of the strip sets the level out of MASTER O/P.

The second output is the speaker output, which exits at either the MAIN SPKR jacks (L and R, the main pair of control-room monitor speakers) or the ALT SPKR jacks (L and R, the second pair). This is what the engineer hears in the room while working. The three controls walked next (ALT MONITOR, MONO, MON LEVEL) shape this speaker output; they do not affect MASTER O/P.

The split happens after the master fader. Both outputs carry whatever the fader is letting through, but from that point on the engineer can adjust the speaker side freely (turn the room down, listen in mono, switch to the alt pair) without changing what the DAW is capturing.

ALT MONITOR. A white button that switches the control-room signal from the MAIN SPKR jacks to the ALT SPKR jacks at the back of the console. Two sets of monitor speakers means you can A/B between them ("does the mix translate to the smaller pair as well as the big pair?").

Why two pairs of monitor speakers

A mix that sounds great on one set of speakers can sound thin, muddy, or unbalanced on another. The phrase mix engineers use for "how well the mix holds up across different speakers" is translation. A well-translating mix sounds intentional everywhere: on big studio monitors, on car speakers, on phone speakers, on earbuds. A poorly translating mix sounds great in one place and broken everywhere else.

Engineers check translation by switching between two pairs of monitors during the mix. The classic setup: one main pair (large, full-range, accurate, the reference) and one alternate pair (smaller, more consumer-grade, closer to what most listeners actually own). Yamaha NS-10s, Auratones, Avantone Mixcubes, even a small Bluetooth speaker in the corner: anything that sounds like "real-world listening" rather than "studio listening." The engineer mixes mostly on the main pair, hits ALT MONITOR to A/B against the alternate, fixes whatever sounds wrong on the smaller pair, switches back, repeats.

The button is a workflow tool, not a sound-quality choice. Both speaker outputs come from the same console master; the alternate pair is there so you can hear the same mix through a different physical filter (smaller drivers, less low end, different room interaction) without unplugging anything.

MONO. A white button that combines L and R into a single mono signal in the monitor speakers. The mix itself stays stereo at MASTER O/P; this is just a check, to make sure the mix still works when collapsed (radio play, phone speakers, single-speaker venues).

MON LEVEL. A red knob: the master volume for the control-room speakers (whichever pair is currently selected by ALT MONITOR). The most-touched knob in any control room. Doesn't affect MASTER O/P, only the speakers in the room.

MASTER OUTPUT · FROM FADER TO BACK PANEL MAIN SPKR L · R · back panel ALT SPKR L · R · back panel MASTER O/P L · R · back panel back of console MONITOR CONTROLS · SPEAKER PATH MONO L+R sum? MON LEVEL speaker volume ALT MONITOR main or alt? these controls shape what reaches the speakers; they do not affect MASTER O/P Master fader master mix level front panel master mix (from all the strips)
Signal flows upward from the master fader at the bottom to the three back-panel jacks at the top. MAIN SPKR and ALT SPKR both pass through the three monitor controls (MONO, MON LEVEL, ALT MONITOR) on the way out. MASTER O/P bypasses those controls entirely, going straight from the master fader to the back of the console.

Talkback and master fader

Talkback. A small microphone built into the console (the round grille labeled T.B. MIC), a level knob above it (T.B. LEVEL), and two red pushbuttons below it: TALK TO AUXES and TALK TO GROUPS. Together they're how the engineer in the control room communicates with the musicians in the live room, and how a session slate gets put on a take.

Talkback in practice: two buttons, two jobs

The two talkback buttons look similar but do very different things, and the consequence of pressing the wrong one shows up at the worst moment (during playback of a take you thought was clean).

TALK TO AUXES. The engineer's voice goes to the aux outputs, which are typically routed to the performers' headphones in the live room. The musicians hear the engineer ("hold on, I think we lost the click track"), but nothing gets recorded. This is the everyday button: anytime you want to say something to the band between takes, or during a take if you absolutely have to, TALK TO AUXES is the one.

TALK TO GROUPS. The engineer's voice goes out to the subgroups and the master mix, which means it gets recorded onto whatever tracks are armed. This is for slating the take: at the top of every take, the engineer announces the take number ("Song one, take three") so when you're sorting through forty takes later, every one is labeled at the head of the audio file. The slate becomes part of the recording, gets logged with the session, and saves your sanity at mixdown. Press TALK TO GROUPS, announce the slate, release, hit record.

The film-set equivalent is the clapper board (the slate that snaps shut at the start of every shot). Audio recording does the same job with the engineer's voice and this button.

Master fader. A 100mm stereo fader at the bottom of the strip (the large blue one). The level control for the master mix on its way out at MASTER O/P (the DAW side) and on its way to the speaker output (the room side). Wherever the fader is set is the level that hits both sides of the split downstream.


6 · The console as a creative space

Walking the Toft control by control is a technical exercise, but the reason the console is built the way it is is artistic. The designers had to make choices: how many channels, how many aux sends, how many subgroups, where the EQ sits in the chain, what the I/P REV button swaps, whether the submaster MON LEVEL feeds the master mix or something else. Each choice opens some patching possibilities and forecloses others. A good console is one where the flexibility lines up with the work an engineer actually wants to do.

That work is partly recipe-following and partly invention. The recipes are conventions the field has settled on: pre-fader for stage monitors, post-fader for reverb sends, route the drum kit to a subgroup pair, put the vocal on Aux 1. Knowing the recipes is half the job. The other half is figuring out what to do when the recipes don't quite fit, or when the session calls for something the conventional patching doesn't cover: a parallel compression chain that needs an aux return blended with the dry, a delay that should feed back into a reverb on a different aux, a click track that needs to reach two performers but not a third. Solving those problems is where the engineering becomes design, and where the console becomes a creative instrument rather than a transparent path from source to recording.

The puzzle is small at first (where does this mic go, how do I get this track to the performer's headphones) and grows with practice. Engineers who've worked on the same console for years still find new patches inside it; engineers moving between consoles apply the same routing logic, because the underlying operations (channel, subgroup, aux, master) are the same even when the specific jacks and switches are not. What you're learning here is the routing vocabulary itself. The Toft is one place to learn it, the way one piano is one place to learn the keyboard.

So the question to keep in mind as you walk this desk, and again when you encounter your next console: what does this signal need to do, and what's the cleanest path through the console that gets it there? Sometimes there's one obvious answer. More often there are several, each with its own trade-off, and the choice of which one to use is part of the craft.

Vocabulary


Read more

The console itself ships with a manual that documents every connector, switch, and signal path, including signal-flow schematics for each section. A copy lives on the studio shelf next to the console.

Links and further reading to come.