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Drawmer Tube Station TS1

Tube Preamp & Compressor
By Paul White

Drawmer Tube Station TS1 header image.

A compressor and front end combining pedigree Drawmer performance with ease of use.

Drawmer have a long history of building hybrid tube/solid-state processors, dating back to their 1960 compressor, which is still popular today. However, the 1U Tube Station TS1 is their first foray into hybrid equipment for the more budget-conscious project studio owner. As we have come to expect from Drawmer, there's more to the unit than you might initially imagine and the build quality is every bit as good as their high-end products.

Mono Or Stereo?

The unit combines stereo vacuum tube dynamics with a mic/instrument preamp, and these two sections can be used together to form a well-specified channel strip, albeit only in mono. It can also be fitted with the optional DC1 24-bit digital output card at a relatively low cost, capable of outputting at all the common sample rates from 44.1kHz to 96kHz. The stereo part of the unit comprises the compressor, a variable tube drive stage and an analogue output stage with limiter. The only tube circuitry resides in the tube drive stage where there are separate 12AX7/ECC83 tubes for each channel running at a full 200V HT. Half of each tube is used to handle the treble frequencies and the other half the bass frequencies, so as to reduce intermodulation effects.

Feeding the compressor is a pair of balanced XLR line input sockets, but there's also a mono front end offering mic and instrument-level inputs that, when selected, feed the input to both compressor channels. In order to handle electric guitars and basses, the instrument input has a high impedance (1MΩ) whereas the mic impedance is designed to take normal low-impedance studio microphones and has switchable phantom power plus a phase reverse switch. A button to the right of the Tube Station logo selects either Line (stereo) or Front End (mono) operation. Though the TS1 doesn't claim to have an EQ section, the front end is equipped with a variable-frequency high-pass filter (variable up to 250Hz) and an HF Contour control, which is generally all you need to add a touch of 'air' or enhancement while tracking. The mic amp gain is variable from 0 to 60dB while the same control sets the instrument gain from -20dB to +40dB. All switches are fitted with status LEDs and the input section includes a Clip LED that lights prior to the onset of clipping.

An insert point is provided between the front end and the compressor section and immediately prior to this is a Preamp Output jack, enabling the preamp section to be used in isolation when the compressor section is being used as a stereo line compressor. There's also an insert point in the compressor side-chain making it possible to insert, for example, an equaliser to set up frequency-conscious compression (for de-essing, de-popping and so on).

In order to keep the compressor section easy to use, the circuit has a fixed compression threshold. The Compress control effectively changes the level of the signal feeding the compressor, forcing the signal up against the compressor threshold so that more gain reduction takes place. There's no ratio control to adjust, but the user has full control over attack and release, both of which have fully variable, dedicated controls — Attack 0.5ms to 50ms, Release 0.05s to 5s. An eight-section LED meter tracks the amount of gain reduction being applied, up to a maximum of 30dB. Invisible to the user is Drawmer's enhancer circuit, designed to counter the loss of high-frequency information that can occur during heavy compression. No user adjustment is required — the circuit continually monitors the compressor action and works automatically.

Following on from the compressor is the variable tube drive stage, with its own bypass switch. A single control regulates the amount of tube drive and hence coloration; the stage needs to be bypassed if no tube 'flavouring' is required as some distortion is always added by this section, even at the minimum control setting. A gain trim control follows the tube stage and essentially functions as a make-up gain control to compensate for any level imbalance caused by the compressor and the limiter, though with this fixed-threshold system, more compression equals more level, so perhaps 'make-down' gain would be a more accurate description.

The limiter is set to a fixed threshold 16dB above +4dBu, which corresponds to a decibel or two below clipping for most +4dBu A-D converters. A red LED indicates when limiting is taking place and, as always, the best strategy is to have the limiter LED flashing only infrequently, and then only on the very loudest signal peaks. That leaves the analogue output level control, which goes from 'off' to +16dB. Note that this follows the two LED level meters, which work independently of the analogue output gain control so that they accurately monitor the signal level feeding the optional converter card if fitted. The Bypass button switches out all processing in the compressor section but doesn't affect the input stage settings.

DRAWMER TUBE STATION TS1 rear panel.TS1 rear panel connections.All connections other than the instrument input are on the rear panel, where balanced XLRs handle the line ins and outs as well as the microphone input. The nominal operating level is +4dBu and the line ins/outs may be used unbalanced by grounding the cold conductor. The signal and side-chain inserts are on TRS jacks and power is via a standard IEC mains socket. The optional DC1 digital converter module replaces a rear-panel blanking plate, and in addition to offering 44.1, 48, 88.2 and 96kHz operation (selectable via two switches), it offers both AES-EBU and coaxial S/PDIF outputs, and has a BNC connector for word-clock input.

In Use

I have to concede that all sections of the Tube Station work exceptionally well, but let's start with the Input section, as that's where your recorded signal starts life. As expected, the line and instrument inputs are clean, but the mic amp also performs well, due in part to the wide 12Hz to 52kHz (-1dB) analogue bandwidth of the circuitry. The mic amp is both quiet and transparent, but its usefulness is extended significantly by the Hi Pass and HF Contour controls. Hi Pass works much as you might imagine, skimming away low frequencies without materially affecting what's left. It has more than enough range for standard guitar and vocal work and just about makes it into Britney territory at the 250Hz setting.

DRAWMER TUBE STATION TS1 front panel.The HF Contour seems to function exactly like an 'air' EQ, so, although the manual doesn't confirm this, I suspect it provides gentle, wide-band boost up in the 12 to 16kHz region. Used carefully it can lift out the detail in a vocal or guitar sound without introducing harshness, but it has enough range to go slightly over the top if that's what you want. I found settings up around 50 percent worked best. Although not part of the Input section, the Drive control also works on the tone of the input signal, but in a rather different way to EQ. The effect is reasonably subtle, as it should be, but it adds the thickness and presence to the sound that we've come to expect from tube audio circuitry, and goes a long way towards making any mic sound more like a tube model, especially if you throw in some gentle compression. It's also very effective on rhythm guitar and bass parts.

The compressor is extremely forgiving of careless handling and it is very hard to get a bad sound out of it, though you can coax it into (rather nice) pumping by setting a long attack, a short release and then pushing it really hard. Even when the compression is seriously heavy, the tonal balance of the signal stays reassuringly consistent and, because there are relatively few controls, getting a good sound is not hard. The unit also follows the Drawmer philosophy that if you set the controls midway, the result will probably be acceptable in most situations.

Having a separate limiter is a hugely valuable feature if you work in a digital environment, whether you choose the digital output option or not. The limiter is all but invisible in use unless you deliberately provoke it into over-action, and even then it remains polite but firm.

As a stereo compressor, the TS1 works smoothly and efficiently on pretty much any material, especially if you keep the amount of compression down to sensible levels and don't insist on going for 30dB of gain reduction on every drum hit! The enhancer circuitry certainly works in keeping the high end intact during periods of heavy compression and there's enough attack and release range to get a more obviously compressed sound if transparent gain reduction is too polite for you.

Verdict

Although not radically different in concept from some products already on the market, the TS1 distinguishes itself by the quality of the processing on offer and by its ability to function as a stereo compressor as well as a mono voice channel. The two filter controls do almost everything you'd normally want to do with a full EQ anyway in a tracking situation, and in combination with the Tube Drive section it's possible to coax a whole range of musically flattering characters out of a single microphone. Personally, I'm a little disappointed that the front panel logo wasn't cut out to show the tube glowing within, but that's hardly a good reason for not buying what is essentially a very high-performance unit.

The Tube Station TS1 should appeal to anyone seeking a classy-sounding front end/stereo compressor, while the digital output option makes it an obvious partner for the computer-based studio. Similarly, if the stereo compressor is used on a final mix, the converter can be used to deliver a very high-quality digital signal to any master recorder equipped with S/PDIF or AES-EBU inputs. Though the TS1 may not be the cheapest processor on the UK market, it is nevertheless very cost-effective given its excellent audio performance and its high build standard.

Pros

  • Works brilliantly as a front end or a stereo compressor.
  • Simple yet effective user interface.
  • Variable tube drive.

Cons

  • No light-up logo?

Summary

A simple-to-use yet great sounding front end/stereo compressor built to Drawmer's usual high engineering standards. The digital output option will be welcomed by users of both hardware and computer-based digital recording systems.

information

TS1 £558.15; DC1 digital output option £170.38. Prices including VAT.

Drawmer Distribution +44 (0)1924 378669.

www.drawmer.co.uk

Published October 2002