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DEMETER VTCL-2B STEREO TUBE OPTICAL COMPRESSOR/LIMITER REVIEW

Audio Media (April 1995)
By Zenon Schoepe

Demeter VTCL-2A Valve Compressor/Limiter

Building on the success of the VTMP-2B valve mic preamp, Demeter's VTCL-2 valve compressor/limiter has all the makings of a modern day classic. Zenon Schoepe investigates.

Released last year, the VTCL-2 offers two fully independent and variable channels which can be linked for stereo operation, and "tubing" courtesy of two 12AX7As, two 12BH7As, and a 12AT7A. Like the original VTMP-2b mic preamp, the VTCL-2 combines valves with components like polypropylene capacitors, metal film resistors, and in this case, Vactec opto-isolators. The power supply has a fully regulated B+ voltage and filament voltage.

Central to activity, and in keeping with the retro look, are mechanical VU meters for each channel. They can be switched to display the input, output or the gain change, with the useful addition of a switch which inserts a +10dB boost into the meter path for the monitoring of -10dB gear. This degree of interconnectivity is increased by each input and output block on the panel sporting XLR, TT, and unbalanced quarter-inch jack sockets, with the option of Jensen transformer balancing.

Switches are provided for stereo linking of the two channels--they can also be bypassed individually. All pots have an expensive, firm feel to them, but are calibrated only for minimum and maximum settings at the extremes of their travel. Fully variable pots are provided for input gain, attack, threshold, release, and output gain. Attack time ranges from 0.5mS to 100mS, release between 200mS and 10 secs; input gain is 40dB with maximum compression of 26dB and a maximum output level of 20dB.

You get the desired effect by driving the signal through the input gain pot and balancing this against the threshold setting, while topping up or winding down the result on the output gain pot. The flexibility in this area is enormous. You never get into the situation where input signal strength or the amount of gain reduction involved compromises what comes out of the unit. You can achieve the desired effect on any signal type and the box is always working within its adjustable gain abilities, with matters helped by a wonderfully quiet signal path. The unit is controllable enough to run with just the occasional peak being squeezed, or the more evident application of major flattening out.

The attack an release times are not the fastest you are likely to encounter on a compressor, but the VTCL-2's maximum times are generally longer than you are likely to find on other boxes. While it is true that a super fast transient can poke its nose over the line before the Demeter slaps it back, in practice, it is not a great problem. The device always manages to stop anything really nasty getting through. And it does it with great panache. In fact, I believe that the speed of the attack and release times contributes significantly to the character of the Demeter. It sounds relaxed and on top of things, rather than constantly breathless and twitchy. If you look at older and even "old-style" modern compressors, none of them sport tyre-burning attack times or skid-inducing releases. They are altogether more relaxed affairs. Whether this is due to the limits of technology or the result of time-honoured listening tests, I don't know, but the results are supremely pleasant.

What the VTCL-2 does (in the same way that the Tube Tech LCA2B does) is make you appreciate what slower attack times in particular can do to the contour of a sound. The temptation is always to opt for the fastest time and wind it back as much as you dare. This box is more creative, and it encourages you to employ smoother and fuller sounds. Bass and vocals benefit from this sort of thickening and it adds a very expensive quality to sources, which were not overly classy to begin with. The fact is that you don't really need ultra-fast attack times for the majority of uses.

In use, it is less possible to be totally invisible with anything but the slightest of dynamics control, but I don't have a problem with that. For this sort of money, you are paying to hear it work and the processing involved adds warmth and depth, simply by inserting it into a signal path on a mild setting.

Inevitably, you will want to wind it up hard, and provided there are no large gaps in the material for the unit to catch its breath in, you can run it on full throttle, nail the gain reduction meter needle hard left to twitch away, and still convince yourself that it all sounds pretty good and together. Consequently, we're talking about dynamics processing as well as the control of dynamics.

Conclusion

In comparison to something like the aforementioned Tube Tech, I have to say that the VTCL-2 has a purer and less valve-like quality. This is not a criticism in either direction, but an indication that the two boxes are distinctly different in character. The Demeter sounds more modern and less blatantly "retro", which could be construed as a benefit or hinderance depending on your opinion.

James Demeter has done a damn good job on this device. Beautifully engineered, it is great fun to use, with instant gratification. It is also closest to what I would regard as a 'modern' valve compressor/limiter in terms of sound, but it doesn't make any other compressor/limiter redundant, it just expands the available choice. If you're serious about this sort of stuff, you ought to hear it.

Specifications:

  • Input impedance: 27 kOhms
  • Output impedance: less than 50 Ohms
  • Total harmonic
  • distortion at 30dB gain: 0.0662 at 1 kHz
  • Bandwidth: 0.06dB at 20Hz
  • -0.34dB at 10kHz
  • -0.78dB at 20kHz
  • -3.00dB at 65kHz.
  • Signal to noise ratio: -110 EIN