Gyraf Gyratec XIV

Stereo valve equalizer

Gyraf Gyratec XIV Stereo valve equalizer

Review by George Shilling

Gyraf are a Danish company who have been quietly making valve-based outboard equipment for over 15 years; it is five years since Resolution last looked at any of their products. Their high quality hand-built processors are one of those best-kept secrets, beloved by aficionados, although prices are really rather reasonable for what you get. Designs are steadily developed by designer Jakob Erland who is based at Feedback Recording in Denmark’s second city of Aarhus. Erland is obviously a good old-fashioned boffin with the curiosity to experiment, and the knowledge to adapt circuitry to achieve excellent sonics. Designs are tested extensively in the studio there, and Gyraf steadfastly keep solid state electronics out of the audio path in all their products.

The Gyratec XIV (or G14) is a stereo Parallel-Passive Equalizer, essentially providing a single set of controls covering two channels of five band parametric EQ. There are no high or low pass filters, and no shelving bands. All frequency controls are switched, with a choice of eleven frequencies on each band, with a varying amount of overlap between bands, but no exact duplication of frequencies anywhere.

The most obvious comparison for the XIV is Manley’s Massive Passive. But the Gyraf approach is slightly different. Like the MP the Gyratec is passive, but Gyraf boast that there is no solid state op-amp drive as found in the MP. The EQ comes immediately after the input transformers. The signal is then fed to a minimalist all-tube gain and output stage – Erland says he wanted ‘the organic nature of the tube processing itself to shine through’. Like other Gyratecs the XIV uses commonly available valves, in this case two 6DJ8/ECC88s.

The impressive looking 3U black box is sturdily built and beautifully etched with the legending. There is no obvious provision for heat dissipation, but the two valves have plenty of space to breathe in the large case. Bakelite-style knobs follow the Gyraf house style, a sort of macho retro-cool. All switches are rotary. Large rack handles usefully protect the front panel, while rubber feet are attached to the base – these can be removed for rack mounting. The rear is simple and neat with IEC mains socket with integral fuseholder and XLRs for audio connections.

There are very few other dual channel EQs which use just one set of controls, but this is something of a revelation, just tweaking and listening, rather than trying to match two channels. All matching has already been done at the unit’s assembly stage. On the front panel, the frequency bands start with the lowest on the left.

The top row of knobs select frequencies. Below these is an oversize rotary switch which selects boost, defeat or cut, alongside a small Q control for each channel. At the bottom are the Level knobs for making boosts or cuts. These are continuous potentiometers. The tactile feel of these is not great, by Erland’s own admission. But these are custom items with an unusual value/stack, so Gyraf were tied to the one supplier capable of making these to the required standard. I am assured that their quality and life expectancy is excellent, but it does feel as if one is turning rusty oil-soaked bath taps! Main controls at the right are a large Level trim knob with a boost of about 5dB available – this has a rather more pleasant knurled feel, and Power and In switches reside here also. The power light dims in bypass mode, and this is a true hard-wire bypass.

Internal assembly is worth a peek. A pair of ECC88 valves are centrally mounted, and four Lundahl transformers are apparent. The interior is fairly sparse, but most remarkable is the neatly arranged forest of carefully matched capacitors behind the frequency knobs. Inductors are made in-house to get the quality and tolerances within spec. Making this unit operate in perfect stereo undoubtedly mean a lot of fine-matching to achieve accuracy.

Unusually for a unit designed for mastering, there is no calibration on boost and cut knobs, and these are potentiometers rather than switched controls. This lack of legending is something of a feature of Gyraf equipment – the EQ section of the GII recording channel doesn’t even indicate the actual frequencies selectable! Maximum boost for each band is about 10-12dB but this depends on the Q setting. There are other characteristics that won’t be apparent from staring at the front panel. As with all passive EQs, there is no ‘adding up’ of adjacent bands when similar frequencies are boosted, (although there is a distinct tonal change). Furthermore, the maximum available Q is higher at the upper frequencies of each band compared with the lower frequencies, and is sharper in cut mode than in boost mode. In practice, nothing seems odd, it all works beautifully, and any ‘limitations’ seem to pretty much stop one from being able to make things sound at all bad! With 55 frequencies to choose from, from 35Hz up to 22kHz, there is plenty of scope for seasoned tweakers, but setting a wide Q and adding a couple of notches of brightness or bass is just as satisfying.

I am absolutely sure that you have never used an EQ as smooth, silky and satisfying as this. Choosing a few good frequencies and making a few small tweaks can feel like a monitoring upgrade, it really is that amazing. I normally love finding offensive frequencies by boosting then flipping to cut, but often, the boosts sound unexpectedly good. This is true sonic sweetening, without getting sickly. Highs are crystal clear and exceptionally smooth, lows are hugely effective without resonating or booming. Full boosts never sounds nasty, but subtle boosts can work wonders too. The ability to bypass each band easily is always useful. The lack of Level calibration is little problem in practice, even when mastering, and the Gyraf website helpfully provides some slightly shaky hand-drawn recall sheets.

As a program or mastering equalizer this really is beyond dreams, but furthermore the XIV makes an amazing general purpose recording EQ, even if one is just using one side in mono. The valve circuitry undoubtedly adds a certain amount of sonic magic. But that is not to say the unit sounds at all gloopy or crunchy or unnaturally hyped in any way. The valve contribution adds to the wonderfully silky and open sound without any overblown distortion or colouration. Using the G14, it feels as if you’ve gone from colouring in with crayons to painting the Sistine Chapel ceiling.

Pros: Arguably the finest sounding EQ - ever; No faffing around matching channels

Cons: No high pass, low pass or shelving bands

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