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Trident Audio Developments 78 Series

Analogue Mixing Console
By Hugh Robjohns

Trident Audio Developments 78 Series

Derived from the larger flagship Trident 88 consoles, this new range offers many of the same features for a lot less money.

The Trident brand dates back to the early 1970s and a very influential London recording studio that set up a console manufacturing business. Although the studio and console businesses went their own separate ways, Trident Audio Developments still make products that draw upon that heritage. Currently, Trident offer two hardware channel strips, a 500-series EQ module and the 10-slot Deca-Dent rack and power supply, as well as their flagship product, the Trident 88 large-format analogue console. The subject of this review is a new, more affordable version of that console — the Trident 78. Like its upmarket sibling, it was designed by Taz Bhogal, whose experience dates back to the development of the original Trident Series 80C from 1986. It retains the same core design philosophy and signal path ideas as the 88; the keener price is possible thanks to some logical feature-set simplifications and a more cost-effective semi-modular construction.

Overview

The Trident 78 is available with eight (as on the review model), 16 (as in the main picture), 24 or 32 input channels, and all have the option of moving-coil VU or more affordable LED bar-graph metering in the meter-bridge. Following the traditional in-line concept, each mono channel strip accommodates two signal paths (channel and monitor), and it features six aux sends (four mono, one stereo), a four-band EQ derived from the Trident 80B console, a balanced pre-fade insert and a configurable balanced direct output.

Being an in-line console, the monitor path can borrow the entire equaliser section and the stereo aux send, if desired, and it routes into the stereo mix bus via a rotary fader and pan-pot. The channel path can also be routed into the stereo mix bus and/or any of eight mono sub-groups (in pairs), via a large fader and pan-pot. For mixdowns, the channel line and monitor input connections can be swapped over at the press of a button, allowing the monitor signal to be routed through the full channel path, but the channel and monitor faders can’t be flipped over (as they can on most in-line desks).

The console always features eight mono sub-groups but these can be used as monitor returns if preferred, effectively working the console in the traditional split format. Each sub-group is equipped with balanced pre-fader inserts and can access two mono and the stereo aux sends. They also feature balanced outputs, post-fade metering, and a long fader, but not EQ. By default, the (post-fade) sub-group output is routed to the stereo mix bus via a separate rotary ‘monitor’ fader and pan-pot, but each group module also has its own monitor input connection, which can be selected to replace the post-fade sub-group signal, if required. Each sub-group also accommodates a stereo effects return which feeds directly into the stereo mix bus, and the first six sub-groups also carry the corresponding auxiliary master controls.

A master module houses the master stereo mix fader and simple control-room monitoring and talkback sections. There’s also a pair of external two-track returns, and both main and alt monitoring outputs for two sets of stereo speakers, with talkback to the groups and auxes.

Construction

Whereas the Trident 88 series consoles are built from individual channel strips, with each fader housed in a separate module, the new Trident 78 models are of ‘semi-modular’ construction: each physical module carries four input or four sub-group channels including their faders. The simplified metalwork brings down the construction costs, obviously, but, importantly, it doesn’t adversely affect the operational ergonomics or make maintenance problematic or inconvenient. In fact, the (largely surface-mount, but in critical places through-hole) electronics for each channel are built on independent, vertically-mounted, circuit boards suspended below each module’s panel in the traditional way. Not only does this simplify servicing, but it ensures excellent crosstalk performance between adjacent channels. It also makes everything a little more reachable: the modules are about 14cm (almost six inches) shorter than those of the Trident 88, and the top of the meter-bridge is about 3cm (an inch) lower.

All input and sub-group connections are on D-subs, which cuts costs and occupies less space.All input and sub-group connections are on D-subs, which cuts costs and occupies less space.Another major cost saving comes from the choice of external connections. Whereas the Trident 88 features individual XLR or TRS connectors for every input and output, the Trident 78 is connected almost entirely via AES59 (balanced eight-channel Tascam format) D-subs. XLRs are provided only for the stereo master and main monitoring outputs (both are duplicated on the D-subs). This much less expensive arrangement makes it quicker and neater to install the console, and brings some welcome benefits such as balanced inserts across the console. (Currently, the Trident 88 has only unbalanced inserts.)

The inputs are all transformerless balanced types, while the main stereo, sub-group, aux master, and primary monitor outputs are active and symmetrically balanced. Impedance-balanced outputs are used for the channel direct outs, inserts sends, and the alt monitor outputs. Like its sibling, the Trident 78 can optionally be fitted with Lundahl transformers on the stereo mix outputs. (At the time of writing, the manual and schematics referred to the optional transformers being on the main monitor output. I’m told that this and a number of other errors in the schematics and documentation should have been corrected by the time you read this.) I gather that the next production run of the master/monitor boards will be modified so that the output monitoring is taken post the transformer outputs (where fitted), so that the effect of overdriving them can be auditioned... which seems like such an obvious requirement that I’m surprised it wasn’t already arranged that way. Other production changes are being made to the input modules (see below), and taken overall I’m left with the impression that this console is, to some extent, a work-in-progress.

Power comes from a 2U rackmount switch-mode supply, which accepts 100-240 Volts AC. Terminals are provided to access and link the chassis and audio grounds, and a seven-pin Hirose connector carries the ±18V and +48V DC power rails to the console via a chunky cable. The PSU is cooled by a fan, which is a quiet one, though some might prefer to locate it in a separate machine room. The manufacturers clearly have confidence in their product: a two-year warranty is included (three years if the console is registered within 30 days of purchase).

Input Signal Paths

Having outlined the console structure already, I’ll now highlight some of the more interesting features. For anyone unfamiliar with the in-line concept, the monitor signal path in each channel strip was originally intended to handle the output from the corresponding multitrack tape-recorder channel, so a rough mix could be built up across the console on the channels that weren’t being used for recording. Today, those monitor inputs are more likely to come from a DAW/audio interface. The channel path is used to feed the recording signal to the corresponding track of the recorder, via the channel’s direct out. For mixing, the monitor inputs can be flipped across to the channel paths and routed through to the stereo mix bus via the big faders, and with full access to the aux sends. When tracking, the traditional ‘analogue’ practice was to record the processed signal after EQ, outboard dynamics and fader-riding (helping to overcome the limited dynamic range of the recorder). Today, though, it’s common to record a clean input signal to the DAW, and process this later, either inside the DAW or via the console and/or outboard.

The channel strips include bypass buttons for both the EQ section and the insert return. The channel strips include bypass buttons for both the EQ section and the insert return. The Trident 78 provides some configuration options for the channel direct output, though I feel they could still be improved upon. On the first consoles, jumper links on each input PCB provided post-fade and insert-return options, but both being post-EQ and post-insert (the channel insert point is fixed post-EQ here, whereas it is switchable pre/post EQ in the Trident 88), neither guaranteed a completely clean recorded signal (at least, not without engaging the EQ bypass, which makes it impossible to track clean while building a console mix). I’m told that all subsequent production runs of the Trident 78 (and 88) will offer a third option, which is a pre-fade feed. However, as the insert return connects directly to the fader via the insert switch, in all practical situations I can imagine, these two options are essentially identical.

It appears that the insert-return option is borrowed directly from the Trident 88, where it makes sense, since that console’s unbalanced insert socket has normalled send and return connections (so its insert return is effectively a pre-fade/post-EQ direct output, which always provides a signal of some kind and complements the post-fade option in an obvious way). The D-sub in the Trident 78 precludes automatic normalling across the console’s insert send/return connections, though. So if the insert switch is engaged (via the dedicated switch in the EQ section) but there’s no device patched in to the return, the insert-return option will provide no signal. That could be confusing in the heat of a session, so you’ll either want to get used to using the insert switches, or to connect the desk up to a normalled patchbay (I’m told that some manufacturers also make D-sub cables for this purpose).

I’d much rather see the third direct-out option being immediately post-preamp; this would always allow a clean signal to flow to the DAW/recorder, while starting to build the analogue mix.

Moving on to the mic preamp, this is identical to the Trident 88’s, although it lacks the input transformer option. It’s a discrete-transistor Class-A design boasting low noise, low distortion, a wide bandwidth (>100kHz), and an enormous headroom margin. The gain range spans +5 to +60 dB in mic mode (-20 to +35 dB in line mode) and a maximum of +17dBu can be accepted at the mic input, or +42dBu at the line input. The EIN figure is better than 128.5dBu (20Hz-20kHz, 150Ω source, 60dB gain) — that’s within a decibel or two of theoretical perfection! Illuminated buttons on each channel engage phantom power, invert signal polarity, and select the line input.

The 88 model’s separate line gain control has been omitted; instead the output from the dedicated balanced line-receiver amp is padded down and routed through the mic preamp. This saves the expense of a second variable gain stage and rotary control, as well as panel real-estate, but it doesn’t compromised the signal quality — the 78 and 88’s line input’s tech specs are virtually indistinguishable.

Another button selects what’s displayed on the channel’s meter: the signal at the direct output (to monitor what’s sent to the recorder/DAW), or the monitor return signal (pre-fade). Another button labelled ‘I/P Rev’ swaps the line and monitor input connections, so that the monitor signal is available to the channel path and its long fader and aux sends for mixing, and the line input flows through the monitor path if extra mix inputs are needed.

The four-band EQ is slightly simplified compared with the Trident 88. All four bands enjoy ±15dB boost/cut ranges but, instead of fully tunable high and low shelves, there are two selectable turnover frequencies (8/12 kHz and 60/120 Hz, respectively). The two mid bands are sweepable between 1-15 kHz and 100-1500 Hz, but the Q is fixed. There’s also a switchable 50Hz, 18dB/octave high-pass filter, and a button switches the entire EQ in or out. The whole EQ section can also be switched into the monitor path, if desired.

I’ve discussed the inserts already, but the two consoles’ auxes differ slightly too: the Trident 88 has eight auxes (four mono and two stereo), whereas the new console has six, arranged as four mono and one stereo. That’s a sensible place to make savings, as there are more than enough auxes for most applications, and all are switchable pre/post-fade. The stereo aux (5/6) is also movable into the monitor path, if required, as it’s intended to serve as an artist cue mix.

The monitor path feeds the stereo mix bus via a rotary fader and pan pot, and has a dedicated mute button but no PFL/AFL facility (unlike the Trident 88). The channel mute kills all post-fade sends: the stereo mix, sub-groups, direct out (if so configured), and post-fade auxes. A pair of LEDs above the fader indicates signal levels at -20dBu (green) and +10dBu (red), with an internal jumper to meter either the pre- or post-fade signal. Unlike on many multitrack desks, there’s no destructive solo mode, but a button on each channel selects whether solo is PFL or (post-pan) stereo AFL (there’s no global PFL/AFL mode switching).

Published December 2017