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Trident Audio 4T Celebration

Recording Channel By Hugh Robjohns
Published February 2005

Trident Audio 4T CelebrationPhoto: Mark Ewing

Despite its vintage design credentials, this new recording channel has some interesting new tricks up its sleeve.

John Oram has now been involved in the design of mixing consoles and related products for 40 years, and to celebrate that fact he has launched the 4T Celebration channel strip. This new product offers a very interesting range of facilities, with Oram's famed sound quality, at a very attractive UK price for a limited period. This isn't the first time John has made a special product to celebrate his years in the business. He launched the Hi-Def 35 equaliser five years ago to celebrate his — you guessed it — 35 years in the industry.

The 4T Celebration is manufactured entirely in the UK and built to high standards, which would normally force a high price. However, Oram has been able to manufacturer it in large volumes thanks to a very significant order from a well-known US retail chain. This has brought the price back down to the current very competitive level.

This 1U rackmounting channel strip incorporates a mic preamp along with both DI and line inputs, a three-band equaliser, and a compressor/limiter. That might sound pretty typical for the genre, but the 4T goes on to offer some unique and very useful features including a stereo input, a stereo output, some natty source-routing modes, and headphone monitoring.

Peering Around The Back

My engineering background means that whenever I pick up a new product, I always start examining it from the back. The connectivity of a product tells you a lot about it long before you start working through the front-panel controls. The 4T starts off on the right-hand side with the main input: an XLR socket and a TRS quarter-inch socket, wired in parallel.

I really do mean 'wired in parallel' too — if you switch phantom power on, it appears at both the XLR socket and the TRS socket. Since the same input connectors are used for both mic and line inputs, this potential appearance of phantom power might well upset some line-level devices with electronic output stages, especially those with ground-compensated outputs.

It is very unusual to find this situation. Normally a couple of DC-blocking capacitors are used to isolate the TRS socket connections from the phantom power applied to the XLR socket. So when plugging things into the 4T, care is needed to ensure phantom is switched off.

The phantom-power supply is completely separate from the main PSU that supplies the rest of the machine's electronics, and even has its own miniature toroidal transformer. However, I noticed that, as with most preamps, the phantom voltage takes quite a while to discharge if there is nothing connected to the input socket to help drain the supply's reservoir capacitors. So if you disconnect a mic, switch off the phantom, and then plug in a line output, there may well still be the best part of 48V on the terminals which will discharge through the output stage of the connected source.

While I'm nitpicking, it is interesting to note that the XLR socket is mounted upside down — a necessity brought about because of the internal construction of this unit. However, since there is no latch on the socket this isn't a practical problem, although I found myself continually having to rotate the XLR connector in my hand as I tried to plug things in!The rear-panel connections include a stereo input on RCA phonos for mixing a stereo monitoring signal in with the mic or DI inputs.The rear-panel connections include a stereo input on RCA phonos for mixing a stereo monitoring signal in with the mic or DI inputs.Photo: Mark Ewing

Side-chain I/O & Stereo Linking

Moving on from the input connectors, we have a pair of quarter-inch sockets which provide an external link buss for the dynamics side-chain. Again, it's usual to require a pair of sockets for this function, and they are clearly marked Link In and Link Out. There is no front-panel facility to activate the side-chain link, so I presume it works as soon as the cables are plugged in. The Technical Specifications & Features leaflet that is supplied with the product makes absolutely no mention of these connectors at all!

Next we have a pair of phono sockets which provide the unit's stereo input, although care is needed when plugging a source in, as the left input channel is on the right phono socket (as viewed from the rear), and vice versa. Finally, we have the stereo output connections, with both XLR and TRS sockets. Again, these are wired in parallel and the XLRs are upside down. In this case it is more of a problem, though, as the release catch on the female XLR cable connector is underneath the plug and quite hard to get at. Like the stereo inputs, the left-channel output is provided on the right-hand pair of sockets. To the left of the rear panel is a mains-voltage selector, a fuse holder, and an IEC mains inlet.


The front panel is very simple, with a brushed-metal finish, dark-red labelling, and elegant knurled knobs. At the extreme left is the DI instrument input section, comprising a quarter-inch unbalanced input socket, a gain control, an EQ Magic control, and a white button labelled Direct. The input circuitry presents an unusually high 10MΩ impedance, making it ideal for use with piezo pickups on acoustic guitars as well as with conventional magnetic pickups, and the input can accept signals up to a massive +15dBu.

The EQ Magic control is a clever constant-power design that either boosts the top and bottom while cutting the middle, or boosts the middle while cutting the top and bottom (turnover frequencies are 100Hz and 10kHz), all the while maintaining the apparent loudness. The control has a centre-detent at the flat position, and it is a very useful facility for creative tonal tweaking of a DI'd guitar.

Equally useful is the Direct button, which routes the DI input directly to the output stage (appearing equally on both outputs, effectively panned centre) instead of passing it through the EQ and dynamics processing. This enables the user to modify the guitar DI signal with the EQ Magic control, while leaving the EQ and dynamics facilities for the exclusive use of the microphone signal, if required — a great solution for a gigging solo musician who wants a simple, compact, but very flexible and high-quality solution.

The next front-panel section is the main mic/line input. As already mentioned, the two rear-panel sockets are wired in parallel and there is no mic/line switching as such. The transformerless input stage, which is identical to that of the Trident S20 and S40 units (derived from the Trident TSM console, but based on the ubiquitous SSM2017 chip) is able to accommodate input signals up to a massive +23.5dBu, yet still manages an EIN figure of -127.6dBu. Up to 60dB of gain is available via a detented knob.

Also provided are a white polarity-reverse button, and a red phantom-power button. The mic/line input signal always passes through the entire EQ and dynamics processing chain, and appears equally on both output channels (in other words, it is effectively panned centre again).

The stereo input is equipped with a level control and a white Mon button. This facility can be used for a number of different purposes, but perhaps most obviously it allows a stereo backing track to be mixed with a microphone and/or DI input. The stereo signal is passed straight through to the stereo outputs via the level control, where it is combined with the DI and mic/line signals (which appear in the centre of the stereo image). Again, this is useful for the gigging musician, who can use the 4T to process and control not only a DI guitar and vocal mic, but also the backing track from a CD player, computer, or whatever as well.

In a home-studio setting, the stereo input can be used to monitor the output from a computer workstation. Pressing the Mon button removes the stereo signal from the outputs and routes it to the headphone monitoring section, where it is mixed with the main output signal as a cue feed. In this way the user can hear their own performance live (and without any latency) along with the replay cue tracks from the workstation.

Signal Processing

The 4T's signal processing is, as you would expect, also derived from previous Oram products and designs. The three-band EQ is derived from the Trident Series 80 console, but has only one swept mid-band instead of two.

Trident Audio 4T CelebrationPhoto: Mark Ewing

The top and bottom shelf sections have switchable turnovers (50Hz or 150Hz for the bass and 7kHz or 12kHz for the treble), with a ±15dB range on the gain controls. The swept mid-range section spans 100Hz to 10kHz with the same gain range, and a red button (with associated green LED) switches the entire EQ section into the signal path. All the gain controls have centre detents at the unity-gain position, and all the knobs have a heavy, solid feel to them.

The dynamics section is based on Oram's solid-state Sonicomp design — a favourite of Al Schmitt, apparently — with rotary controls to adjust the Threshold (from off to -25dBu), Attack (0.1ms to 40ms), and Release (0.05s to 3s). The ratio is determined with a white button, offering 4:1 compression or 30:1 limiting. A red button (with associated red LED) switches the dynamics section into the signal path.

Finally, the output section features a level control (±15dB), a headphone socket, a VU meter, and a white button to select either output-level or gain-reduction metering. A nice feature here is that the meter illumination changes colour depending on the mode: blue for level and green for gain reduction.

The maximum output level is a massive +28.5dBu, so there is plenty of headroom even when driving professional A-D converters. Sadly, though, there is no separate level control for the headphone output, which may be a frustration to anyone using the 4T as the front end to a workstation.

In Use

As we have come to expect from products carrying the Trident badge, the unit performs very well and has excellent specifications. The sound character on the mic input is very slightly on the warm side of neutral, a quality revealed most clearly by sources containing complex transients — the classic 12-string acoustic guitar test, for example — and I would say that the effect is musically flattering, if not always very exciting.

The DI input worked very well, and I was able to achieve some excellent results recording an acoustic guitar fitted with a high-quality piezo pickup (if such a thing really exists!). The EQ Magic facility is superb, allowing a nice range of tonal shaping to be performed very simply and effectively, and I liked the flexibility to route the DI signal straight to the output or through the main EQ and dynamics processors.

Both the EQ and dynamics sections worked entirely as advertised, and were very effective and easy to set up. The EQ had sufficient flexibility and range to cope with every source I tried, and the compressor was rather more versatile than I was expecting. I feared that, with only two fixed ratios, the unit would easily be caught out, but in fact it appears to have a broad, soft-knee slope, and so careful adjustment of the Threshold control can provide less heavy-handed gain reduction if required. With most contemporary vocal styles, though, a ratio of 4:1 is pretty much ideal anyway, and I found the dynamics section actually worked very well almost regardless of the source.

To nitpick again, the instruction leaflet leaves out a lot of important operating details that have to be fathomed by trial and error, and I would have preferred a separate headphone level control — although panel space is rather tight and I can't think of any other facility I would sacrifice to provide the space. However, the flexibility of routing the DI and stereo inputs is excellent and makes this a very versatile, and probably unique, product. If the 4T's innovative feature set appeals, you won't be disappointed with the performance.


  • Good-quality sound.
  • Versatile EQ and effective dynamics processing.
  • Stereo replay/monitoring input.
  • Useful EQ Magic control on DI input, with flexible routing options.


  • Lots of key technical information missing from instruction leaflet.
  • Phantom power appears on TRS input socket.
  • Lacks a separate headphone level control.


An innovative product with several unique features which extend its versatility well beyond that of most channel strips. Brimming with Trident heritage, this is a quality product which addresses several different markets and applications superbly well.


£1086.88; promotional pricing for a limited period, £652.13. Prices include VAT.

Trident Audio +44 (0)1474 815300.

Published February 2005