Allen & Heath's GL4000 is designed to be equally adept as an FOH desk, a dedicated monitor console, or fulfilling both roles simultaneously.

The GL4000 is designed to cover the three operations you are most likely to undertake during a gig: front-of-house mixing, monitor mixing, and multitrack recording. As such, the desk could be useful in areas of the market where budget and space might not justify a dedicated monitor mixer on stage, still less a mobile recording truck. It could also provide a flexible set of capabilities as a fixed console in a multi-purpose venue, where the requirements changed from day to day.

HEADLINING...

The desk can be configured as a dedicated eight group FOH desk or a 12-bus monitor desk, as well as a system that will handle three functions at once. It is also capable of patch and mute automation via MIDI. The direct outputs on input channels enable it to handle larger multitrack formats than the eight groups would imply.

The GL4000 is available in channel sizes of 24, 32, and 40, which includes four stereo channels to the right of the master section. A non-modular design, the GL4000 has an optional add-on expander in two versions: 8M has eight mono channels and 4SM combines four stereo and four mono inputs. The maximum size of the desk is 48 channels, and appropriately configured meterbridges are available for the various sizes. Larger configurations can be obtained by using the optional Sys-Link bus expander, which enables desks to be linked via two multi-way cables.

There is also a choice of power supplies. RPSD is a 1U supply with the ability to connect a backup supply as well; RPS11 is a beefy 300W supply in a 3U casing.

FEATURING...

Working down a mono input channel, the first three facilities are 48V phantom power, phase reverse, and a mic/line selector switch, which also functions as a 20dB pad on the XLR input when no jack is inserted. The mic/line gain control below it has a range of -14dB to +40dB line or 6dB to 60dB mic, when the pad is not active. A low cut filter, continuously variable from off to 400Hz at 12dB/octave, is next in the chain. It should be noted that the send jacks fitted to input channels derive their signal from the output of the low cut filter and not directly from the inputs, as implied by the preliminary literature. The arrangement shown in the schematic (send post low cut) would seem the better of the two possibilities. The send and returns found on every input channel are balanced.

The EQ section is four-band with sweeps on each. The overall range is 20Hz to 20kHz, with plenty of overlap between bands and an LED indicated EQ-in switch. The two mids are fitted with switchable Q from 1 to 2.4 — a very up-market touch.

It is worth mentioning at this point that the four stereo input channels are very similar to the mono. The main differences are the inclusion of a stereo input section with width control and stereo PFL for line input, followed by a simplified EQ section with shelving HF and LF, plus two fixed bell curve mids.

There are ten aux sends, each with as much as 6dB gain over nominal level. Three pre/post switches are provided, covering auxes 1-4, 5-8, and 9-10 respectively. Aux 10 also has a switch to route it to a direct output, which could be used for multitrack recording or spot effects. Like input channels, aux busses are also equipped with send and return points.

Pan and routing are straightforward. In between these two are the large mute button and the LED indicated PFL, plus a four segment input level meter. The operation of the mute switch is worthy of some detail, as it affects mute and solo status, and is part of the console's automation system.

When a channel is off, the Mute switch itself shows red. There is also an adjacent safe/preview LED. When this is on, it means that the channel cannot be affected by mute groups, patches or solo-in-place. It also indicates channel mute assignments when in preview or edit mode. In order to understand this better, it is necessary to leap momentarily over to the mute master section.

Below the 4-pin lamp connector is a 3-digit patch display, which is used to show the active patch number as well as solo status, console setup, and MIDI information. Under this is the solo switch. This puts the desk into solo-in-place mode, thereby allowing the mute buttons on each channel to determine solo status. A snapshot of this setup can be taken for later use. There is a shift key below the solo-in-place, which prevents accidental operation (and red faces) during shows. In addition, there is an 'edit safe' mode, which enables channels to be safeguarded from the action of mute groups, patches etc.

Beneath this is the patch panel for storing and recalling mute patches, followed by various monitor facilities and the eight mute groups themselves. Mute groups can be previewed without affecting the status of channels.

Group channels and the L/R channels accommodate the four matrix send controls and ten aux masters, which are on faders, as well as the group/main output faders. All the outputs are equipped with mutes and 4-segment level bar graphs. Auxes are on balanced XLRs, with the matrix outputs on jack. This can be reversed with the Out Rev switch on each channel.

The mono output channel includes an engineer's listen wedge facility. In this mode, the output remains silent until a PFL or AFL is selected (PFL overrides AFL). Other facilities on this channel include the two-track return, talkback section, and matrix sends.

FINALE

Suffice to say, not every function has been mentioned in this summary, but by now readers should have the impression that this is a comprehensively equipped desk. It is also admirably compact: a 24-channel version is a little over 1m wide and even a 48-channel system is under 2m.