Need more warmth and welly in your bottom end? Roger Brown checks out the TLA valve pre-amp and compressor, to see if it really packs the power to deliver...

The growth of affordable digital recording systems, from DAT to d-to-d, means more and more of us are getting used to treating sounds entirely in the digital domain. The ease of editing this offers, and the digital integration of effects into a sound, has made this route the most attractive and creative for the purposes of manipulating data.

Products like Yamaha's Promix 01 and Alesis' Quadrasynth and Quadraverb2 make it all seem so natural, that some of us have begun to wonder if we will need to soil our fingers on the likes of valves, tubes and analogue tape recorders ever again.

While the ability to shunt digital data around means this form of recording is likely to become the norm, both at home and in the professional studio, some of us are growing a little worried. Digital is all very well for manipulating data, but even at 16 bit resolution it is still missing some of the aural information which goes towards adding ambience to a sound. The cleanness of CD quality sound is a mixed blessing, as the limits of 16 bit resolution remove the background noise that is an essential part of this ambience.

Just as the clean, static nature of sample and synthesis synths has prompted manufacturers to start producing modem analogues such as the Bass Station, so the missing link in digital recording is being addressed by the release of products such as T L Audio's Valve Pre-amp/compressor.

The T L Audio Valve Compressor combines classic valve techniques with low noise, solid state circuitry, offering controllable compression on two, independently adjustable channels. Both channels offer unbalanced and balanced line level inputs, and there is a mic input with switchable 48V phantom powering. There is also a front panel auxilliary input which accepts mono or stereo guitar or keyboard inputs, making it an ideal unit to run a bass or guitar through and into your desk, to add the live warmth and punch of a valve amplifier.

Basically, these are the two main ways to use the TLA, as an instrument preamplifier and as a main compressor from your mixer's stereo outs, for recording direct to tape or compressing the signal for your monitoring or PA system in a live situation. The input includes a switchable high pass filter, operating at -3dB at 90Hz, to remove unwanted low frequency noise. The TLA utilises a triode valve as a second stage voltage amplifier to obtain that classic valve sound and overdrive characteristics.

Out of the box

Two XLR input sockets are provided on the rear for mic and line inputs, with 48V of phantom power available on each channel. The mic input is suitable for low impedance (150-600Ω) microphones, with a gain control of +16dB to +60dB. Ihc line signal inputs boast an effective gain range of -10dB to +35dB, allowing the valve stages to be fully driven from line signals in the -20dBu to +20dBu range. There are also unbalanced line inputs at the rear, and one on the front of the unit for immediate insertion of a mono guitar or bass or stereo keyboard.

The TLA also generously provides an insertion point on a sidechain circuit, to allow an equaliser or other processor to be used for frequency-conscious compression. The sidechain processing is solid state, while the compressors employ a second triode valve stage for that full bass sound. The compressors work as a stereo pair, but the stereo ganging may be bypassed for comparison of each side.

Wonderfully retro illuminated VU meters monitor either the output signal level or applied compression, and add as much warmth to the front end appearance of this unit as its circuitry does for your basslines. Output is via balanced XLR or unbalanced jack sockets, with the output level being switchable between +4dBu and -10dBu, the latter level being best for small mixing consoles or portable tape recorders.

On the job

This unit really docs the job when it comes to adding that all-important warmth to a mix or input. Patched into your mixing desk's outputs, it adds an overall roundness to the sound and a marked punch to bass kicks and synth lines. The compressor is particularly effective at adding loads of controllable low-end without ending up with an extremely dry sound, as so often happens with digital compressors.

Listen to the samples and demo track from this month's sequencing tips. The whole mix was run through the TLA prior to the (digital) recording stage, and added an impressive amount of thump to the bottom end.

Compression was set at 1:2. with a fast attack and fast release, and the 90Hz high pass filter activated to trim unwanted noise. It certainly added loads of bottom end welly and compressed the signal without producing a tight 'radio' mix. Compression ratios are between 1:1.5 and 1:3, so we're not talking overcompression here, simply nice, warm, dynamic presence.

The TLA has a nice retro look about it, its front cooling grille and amber VU meters restoring that valve amp warmth and presence to digital recordings. It would be equally at home in a live or studio environment, ruggedly constructed but boasting enough refinement to sit comfortably amongst a host of digital synths and effects.

As a tool for sculpting either your input signals or compressing a whole mix it is absolutely wonderful, and its highish price is worth every last penny. Spending so much on a pre-amp is hard to justify, but I would urge anyone who is serious about their sound to check this little baby out. It is simply one of those units with a Rolls Royce quality about its sound, which has to be heard on a piece of music or instrument you know well to be fully appreciated. Once you have heard it, you'll be boring all your friends with talk of valves and triodes!