6. Important Terms
On this page you can find frequently asked questions on mixers.
- What is a 2 track machine?
- What is an Aux-Return?
- What does Aux-Send mean?
- What is an aux-path?
- What is a Pre/Post-Fade?
- What is balanced or unbalanced
- What is ''Direct-Out''?
- What is the Equalizer?
- What is Control-Room?
- What is ''gain''?
- What is the ''high pass filter''?
- What is an ''insert''?
- What is the master section?
- What is the mono channel?
- What does ''mute'' do?
- What does ''parametric'' mean?
- What is the ''patchbay''?
- What is ''PFL''?
- What is ''Phantom supply''?
- What is meant by Pre/Post?
- What are the ''routes''?
- What is meant by ''solo''?
- What is the stereo channel?
- What are the ''sub groups''?
- What does symmetrical refer to?
- What is meant by unsymmetrical?
- What is the sub mixer?
What is a 2 track machine?
This refers to all recording devices that can record on at least two tracks (cassette recorder, MD recorder, DAT recorder, CD recorder, etc.). At the ''tape-ins'' you connect the outputs of the machine and the ''tape-out'' jacks are connected to the inputs of the machine. Of course you can also use the connections for other purposes. On tape-in, a CD player or a synthesizer can be connected for instance.
What is an Aux-Return?
It indicates the inputs and controls which bring a signal from the effects device into the mixer. Meaning the aux-return controls how many effects end up coming through from the effects device. The aux-return is routed directly to the master-out fader and depending on the console, you can switch to those aux-sends that carry a monitor signal in order to hear the effects on stage monitors. If you don't need all of the aux-returns, you can simply use them as stereo inputs. Similarly, one can direct the return signals of an effects device into the normal inputs of a mixer. Once there, the signal can be edited to cause a delay with the reverb effect and you can also send it via the aux-sends to your monitors.
What does Aux-Send mean?
It indicates the controls and ports that carry a signal that from the mixer to the effects device. Also used as a name for the aux-paths, the aux-send ports connect to the inputs of an effects device. You can control all channel-send-controls with the aux-send master control, which allows for quick correction of the effects for all channels.
What is an aux-path?
It allows an already pre-amplified signal, from the mixer for example, to have an effect added to it. Aux-paths, through the use of the aux-sends, allow for multiple channels to use one effect at the same time. A kind of mixer within a mixer. As a rule, a potentiometer is used to determine how much of the signal should pass into the effects unit via the aux path, this allows you to regulate the strength of the effect. Usually used for reverb, delay or chorus, an aux path can also be used to divert a signal for a stage monitor. Aux-paths may also be referred to as effect, FLB, fold back, or monitor.
What is a Pre/Post-Fade?
A term used to describe the route an audio signal takes within a mixer, most commonly applied to aux sends. Pre-fade means that the aux send isn't affected by the main fader level (and sometimes also the EQ) - this is usually used for monitor and headphone mixes, giving the performer a mix that is independent of the FOH or main mix. Alternatively, post-fade signals are affected by the fader level, and this is normally used for effects sends where the level of the effect or wet signal therefore follows the level of the untreated or dry signal.
What is balanced or unbalanced
Describes the manner of a signals transfer from source to destination. Balanced signals require a balanced output at one end and a balanced input at the other end in order deliver their advantage, which is the substantial reduction of any noise induced in the cable. This is achieved by sending the audio signal down two separate cores of the cable, one of which has its phase inverted. At the other end, the inverted signal is re-inverted and combined with the untreated signal, at which stage any interference that has been picked up in the cable will be cancelled out, leaving the original signal in-phase, at twice the strength, and without any interference. Balanced connections are usually made either with XLR or Tip-Ring-Sleeve (TRS) jack connections. A balanced TRS jack connection will have two rings on the connector as opposed to an unbalanced one which has just one. TRS jacks are sometimes known as a stereo jacks, as they can also be used to transmit an unbalanced stereo signal. The main problem when using unbalanced connections is that of combating interference, and although less of an issue in smaller applications, unbalanced cables used in environments demanding longer cable runs can suffer from undesirable buzzes and hums. Almost all microphones and mic inputs are balanced, although line level inputs and outputs vary.
What is ''Direct-Out''?
It is used to send individual channels to a multi-track machine. The direct outs are tapped before the preamps and depending on the manufacturer's preference before or after the equalizers. Sometimes the user is given a switchover option for the tapping point.
What is the Equalizer?
Also referred to as compensator, tone control, or simply EQ, originally it was used to compensate for the weaknesses of microphones, by raising or lowering the frequencies which were not linearly transmitted. As time went on however, the EQ was used more and more often to purposefully change the sound. Depending on the version, equalizers have different numbers of controllers for each individual frequency (see also Parametric).
Equalizers are offered in two primary designs: graphical and parametric. Graphical EQs offer regulators for the individual frequencies; the more regulators, the more precisely the signal can be edited. The side-by-side fader on these equalizers makes it easy to see which corrections were made. Graphic equalizers are most often used for the correction of sound in rooms and on public address systems. Balancing out frequencies which are too weak or to strong.
In studios, EQs are often used to measure the monitor and/or room acoustics. Parametric EQs can be found in mixing desks, external effects devices and are available with different frequency bands depending on the version. You can also edit the frequency bands in a much more targeted fashion with parametric EQ's. But there is a bit of a learning curve because they don't offer the same clarity as a graphic EQ.
What is Control-Room?
This refers to the connections for the control speakers or studio monitors, which can be used to monitor sound signals as an alternative to headphones. Often, these connectors are placed in parallel with the headphone jack, so that the solo and PFL function also works on them. These connections can also be used in live operation to combined the sound from secondary recording rooms with the main signal.
What is ''gain''?
Also called the ''Trim'' controlller, responsible for the preamplification in the microphone-/line-preamp. With this you regulate the different loud signals so that the subsequent electronics receive a strong enough signal.
What is the ''high pass filter''?
It lets all frequencies over a certain frequency ''pass through''. Also referred to as ''Low-Cut'', on mixers it serves to filter out unwanted noise in low frequency ranges.
What is an ''insert''?
Designates a connector that feeds a pre-amplified signal to an effects unit and back to the original channel. In contrast to the aux-path, the editing is done only for the channel in which the insert is used. Mostly effects are connected here, which use the complete signal of a channel for processing, for example compressor, external equalizer or noise gate.
What is the master section?
This refers to the part of the mixer in which all signals converge. Both the signals of the individual channels as well as those of the external effects and playback devices converge here and can be distributed to different outputs or groups. In addition to an optical level display, this section usually also contains the headphone/control room settings and other setting options for the entire mixer.
What is the mono channel?
This type of channel do not mean that signals are only processed mono, it refers to the fact that only one signal, from a microphone of guitar for example, is received at a time. You can edit this signal with the tone control and send it out again via the aux. paths. The pan control determines whether the channel can be heard more left or right in the final sound.
What does ''mute'' do?
It mutes a channel with a switch. The position of the volume fader does not need to be changed which preserves the settings. Sometimes terms like "On'' or ''Off'' are written instead. Afterall the mute function is nothing more than an on/off switch.
What does ''parametric'' mean?
In the context of mixing consoles and equalizers it refers to the ability to use the equalizer to select different frequencies for processing. In the case of a full parametric, it is possible to determine which frequency should be raised or lowered with each filter, you can also control the the quality (also called Q factor) of the filter which determines how ''narrowly'' or ''widely'' the processing will intervene in the frequency spectrum. With a semi-parametric there is no possiblility to determine the quality (Q).
What is the ''patchbay''?
Also called the patch panel, different in and outs can be found on the back of mixers, effects devices and synthesizers and are connected to the front by short ''patch cables''. This enables fast cabling or interconnection of signal paths without having to crawl behind racks and under tables.
What is ''PFL''?
Pre Fader Listening allows you to hear the activated channels through headphones without being influenced by the position of the channel fader. Since the PFL function does not change the other channels (see Solo Function), it will be used as a control during a concert or recording.
What is ''Phantom supply''?
Capacitor microphones need an operating voltage which can be supplied via a battery, power supply or as ''phantom'' power, which is sent via a balanced microphone cable. You can also use dynamic microphones on microphone inputs with activated phantom power without any problem, provided that they have the correct pin assignment (pin 1 = ground, pin 2 = positive, pin 3 = negative). Under no circumstances should you use adapters or other cable bridges from balanced to unbalanced, as this will cause a short circuit. The phantom power is usually in a range between 48V and 52V. Those two numbers can also appear as an alternative label on a mixer.
What is meant by Pre/Post?
Used in combination with the aux paths, they designate the different tap points of the send controller within a channel. If an aux path is tapped before (pre) the respective out/send controller, then a signal is received which is independent of the position of the channel fader. As a rule, stage monitors and headphones are connected to the pre-aux outs/sends, this way their volume shouldn't change if corrections are made to the channel fade. With post switched aux outs/sends it is exactly the opposite. The signal is picked up after the channel fader and the volume of the speakers or in the headphones will change when the channel volume is changed. Usually effects devices are connected to post-aux-sends so that when the channel is made louder or quieter the effect will be adjusted to the same level.
What are the ''routes''?
This term is used as a synonym for cabling or connections. Just as useful is the term ''patching'' (see patchbay).
What is meant by ''solo''?
Pressing this mutes all channels except the one for which this function was activated. It is used primarily during a live sound check but can also be used in the studio.
What is the stereo channel?
In these channels two mono channels are combined to make a stereo channel. As a rule stereo devices like synthesizers are connected to these since they require a joint editing of the left and right channel at the same time. In stereo channels, all controls are designed so that a knob, switch or fader performs the same adjustment for both parts of the signal. Often stereo channels are somewhat simpler than mono channels. In stereo channels, the panning poti is usually called the balance poti and it controls the ratio between the left and right inputs.
What are the ''sub groups''?
They are a type of ''sum volume fader'' which come before the master-volume-fader. Using the assignment buttons in each channel, you can route signals to different subgroups and control their volume together before they reach the master fader. Subgroups are very good for regulating a drum kit for example; Just set all channels to the desired ratio and assign them to a subgroup then raise or lower the volume at will. In this way not all channel faders have to be moved individually, whereby the desired volume ratio may be lost, just the volume fader of the subgroup. Subgroups are also suitable for keyboards, backround vocals or winds.
If the subgroups are equipped with their own outs/sends, then you can direct them to a multi-track machine in a studio and assign individual channels by subgroup directly to the recording tracks. If the sub groups have their own in-jacks, you can apply a single effect to multiple signals which cannot be operated via the aux-path (for example a compressor). Most mixers do not have an assignment switch for each individual sub-group, rather they are listed in pairs e.g. 1-2, 3-4, 5-6, 7-8. If you press the switch, the signal will be equally split to both sub-groups and from there each group can be separately controlled with the panorama poti. As a rule, the odd subgroups are addressed when the pan poti is turned to the left and the evens when it is turned to the right.
What does symmetrical refer to?
It designates a type of signal routing used in electrical conductors. In this case, the original signal is routed twice over its respective conductor, during one of the two the phase angle is rotated by 180 degrees. With this circuitry it is possible to reduce noise and other unwanted interference from the ''outside'' allowing for the use of relatively long cable lengths. Since the noise/interference is on both conductors - the rotated and original one - they cancel out and the signal can be merged again without loss of quality. Therefore, a symmetrical signal lead always needs three conductors: one for the ground, one for the original signal and one for the rotated signal. XLR connectors are the most widely used connection type with this circuit technology and have at least three poles. In addition this technology can be found in various multipin plugs and stereo jack plugs, which also have three poles.
What is meant by unsymmetrical?
With an asymmetrical signal routing only two conductors are used. The consequence is that disturbances - especially with long lines - occur more frequently than with symmetrical signal routing. Common plug shapes here are cinch and mono jack plugs.
What is the sub mixer?
It is usually a smaller and/or simpler mixer which receives and combines different signals in a premix and then gives a stereo or mono signal to the main mixer. It is often used in live operation as a keyboard mixer. It is also used in the studio to expand the capacity of the main mixer.