Groove Tubes The Glory Comp

Mono valve compressor

Groove Tubes The Glory Comp Mono valve compressor

Review by George Shilling

The Glory Comp (GC hereon) is a sister product of the ViPre microphone preamp. A similarly over-engineered all-valve design, this new product is equally robust – it weighs a whopping 37lbs in old money, so care (and strength!) is required getting it out of the box.

Side braces are provided to take some of the rear weight – these attach to 1U of rackspace above the 3U GC. A 1U space is also required below for ventilation – the unit uses about 95 Watts and relies on a large rear heatsink and vents to dissipate this. Groove Tubes founder Aspen Pittman is an unashamed valve obsessive (GT has even acquired the GE valve production line to produce their own tubes) and the GC contains seven valves to handle the program audio. So, preposterously, 5U of rackspace is required for one mono compressor!

The GC’s appearance is striking, with military-style build using huge black knobs with clear pointers, stiff toggle switches, useful rack handles and a super VU meter. The latter is accompanied by a control with positions for displaying Output at various levels, Program Input, Gain Reduction with the option of a double scale for checking heavy compression amounts, Side Chain, and a setting that turns on the internal Oscillator for balancing the large Plate and Cathode trim pots on the front panel. This knob, along with many other rotary controls, is stiffly switched, while Input, Output and Glory knobs have a nice oily damped feel. Conventional controls are provided, along with one or two (such as Glory) that require explanation. But layout is logical and clear, with boldly etched labels and legending. Firstly, there is the large Input pot which is great for fine adjustment, ranging from -20 to +10dB. The Threshold knob is switched from 0dB downwards in 3dB steps. Fine tuning can be obtained by adjusting the Input to drive the compressor input, and I generally found I had to turn the input up past zero for a reasonable amount of compression.

The unit has a huge amount of headroom, so this isn’t a problem. The GC uses a “variable transconductance tube gain stage” for signal compression. This utilises an own-brand valve (easily available at reasonable cost) which provides clean gain reduction up to 20dB in a single valve. And it does this in a smooth linear fashion, lending the GC an unusually suave character for a valve compressor. Compression is frequently quite subtle in character, such is the smoothness of the GC. The knee is such that the selected Ratio is reached 2dB above the Threshold set. Attack is stepped from 1ms up to a quarter of a second, the fastest setting is remarkable for a valve unit. Release ranges from 50ms to 2s. However, there is an accompanying Release Mode toggle switch, and the labelled range refers to Log mode. In Linear mode, the range is 25ms to 1s and this provides a snappier release character, rather than the tapering off of Log mode. The wide range of settings means the GC works well with all kinds of program material. Ratio too is stepped from 1:1 up to 6:1, with plenty of choice in the lower orders. On the far top right the large Output pot has a similar range to the Input. The output circuitry is incredibly powerful, allowing full use of all the dynamic range available at the input to any DAW. Bypass separately hard-wires the input and outut XLRs plus the input and output TRS jacks.

There are CV linking sockets for chaining multiple units, with a toggle on the front for selecting Master or Slave mode, plus a useful Local position for removing the unit from the chain without having to unplug. Two GCs would undoubtedly make a superb stereo mix compressor, and a 5.1 arrangement would undoubtedly be something to behold, with 30U required rackspace! There is even a cal screw on the front for calibrating the link circuit. Connections are also provided on XLR and jack (Outputs, Thru/Mult and Inputs) for external sidechain control of the gain reduction, but internally a pair of EQ controls are available for contouring the side chain. 10dBs of cut or boost (in 2dB steps) is available for the LF and HF bands, and this is most useful on program material with dominant HF or LF content. They are set at 50Hz and 10kHz respectively, which works extremely well, although perhaps the degree of control is over-generous.

The continuous pot labelled Glory has Earth at one end of the scale and Heaven at the other. As the control is turned towards Heaven, low-order even harmonics are added in the 40 to 700Hz range. So there is distortion in the afterlife! The legending alone certainly impresses non-technical clients. Whilst this is subtle on signals with predominantly high frequencies, deep basses tend to exhibit obvious slight fuzz when turned to Heaven. The manual explains at length how this effect is uniquely implemented, but although this can enrich a lifeless signal, I felt there was something slightly contrived about it – mixing a bit of fuzz in with a clean signal is not the same thing as pushing a vintage valve circuit which is straining to cope. A touch of this hairy distortion can be useful, but it never sounds as rich or grainy as a Drawmer 1968 or ADL1500 (respectively). It is fast enough for crunchy drum ambiance, but not as convincing as the Drawmer. Where the GC works best is on acoustic guitars, bass and vocals.

This is obviously a unit for fiddlers and tweakers, unlike, say, the two-knob LA-2A. There is far more to think about here, but the Glory Comp has a character and sound of its own, albeit more neutral than most vintage valve compressors. It sounds as big as it looks, and as proper as the military look suggests, but is incredibly smooth without becoming totally bland.


The ultimate in smooth valve compression


‘Heaven’ is slightly disappointing(!); 5U of strong rackspace required!

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Reproduced with kind permission from George Shilling. Copyright George Shilling.