Getting a classic sound using valve gear

Achieving a big budget sound is something of a holy grail for the ‘bedroom producer’. It always seems so tantalisingly close, and yet remains just out of reach. You can work hard to get a great sounding mix in the box, but compare it with your favourite classic recordings and it may well feel like something is missing. So what exactly is the factor which makes that small difference between an ‘amateur’ and ‘professional’ sound, for want of better terminology?

Of course it is difficult to quantify, but generally we are talking about the richness and depth of the sound – qualities that old-school analogue studios had in spades, but ones that the clinical nature of digital sampling can never quite achieve. That’s because the sound that we now take for granted in music production was something of a happy accident, a ‘side-effect’ of the technology that was developed for use in recording technology, perhaps most notably that of the vacuum tube, or valve.

Vacuum tubes are a type of diode that work by heating a filament, the cathode, surrounded by a positively charged anode, in a sealed glass enclosure. Thermionic emission transfers electrons from cathode to anode, and in this manner current flows through the component in only one direction. Because the anode can only attract a finite number of electrons at any given moment, if there is a sudden swell of current into the cathode, the component will provide a sort of limiting effect, ensuring that energy spike is not transmitted to the rest of the circuit.

Therefore the main effect of the tube on the signal is ‘soft-clipping’; primitive audio compression which provides some protection from overload and a degree of ‘smoothing’ to the sound. But there is a side effect as well: they added second-order harmonics, imparting ‘colour’ to the sound signal and training us all to expect richness, warmth and depth in our music. When the drive for cheaper, more practical devices kicked in, made possible by new innovations in solid state technology in the 1950s, the colouring effects of vacuum tubes were often simulated in new circuit designs, this time with the faster transients and wider range that transistors afforded us.

Work of ART

Nowadays, there are a number of choices for tube amps for our studios, and they might just deliver the sound you’re looking for. At the more affordable end of the scale, ART produces some great units that shouldn’t be overlooked in any studio. One of my favourites is the ART Tube MP Studio V3, a small-footprint preamp designed for use with instruments and microphones, and doubling as a great-sounding DI box. ART uses a technology it calls Variable Valve Voicing to give you some degree of control over how much the characteristics of the valve are applied to the signal. For around £60, the ‘authenticity’ it gives your sound is impressive; and perhaps the best bang for your buck.

At around £160, the ART TPS II is another one to check out, giving you two channels in a 1U rackmount enclosure, something you could make the case for re-tracking your stereo bus through for that vintage valve tone. But the ART unit that is most recommendable is the ART Pro MPA II at around £280, a great-sounding dual-channel unit. In all cases, there are some who argue the ART tube amps are all improved by upgrading the tube inside, and perhaps this represents the best value route to high-end valve sound.

If you have a little more to spend, the Universal Audio 710 Twin-Finity (pictured) is hard to look past. I have a lot of faith in this US manufacturer – its UAD processing system and range of plug-ins are arguably the beginning of the end of outboard solutions to the digital problem, but Universal Audio still makes great outboard gear itself, and this mic and instrument preamp sounds incredible. By utilising both tube and solid-state amp designs in the same circuit, it is possible to get a wide range of tones out of this unit. At around £650, it’s worth every penny in the studio, and if you’re looking for more channels, its big brother the 4-710D is a great buy at around £1,500. It is a shame that TL Audio is no longer producing its excellent Ivory tube preamp, but I would recommend finding a used unit to audition as they were really fantastic preamps at their price point.

Then there’s the SPL Goldmike Mk2, another unit that has its fair share of supporters. The Avalon VT-737sp, a truly amazing sounding channel strip comprising a tube preamp, equaliser and compressor is the most expensive unit I’m going to recommend at around £1,700. Once you hear this gem, you’ll want a rack full of them in your studio to track everything through.

Ultimately then, there are a lot of options at every level for utilising vacuum tube preamps in the modern project studio environment, and they provide a great way to recapture that pleasing ‘analogue tone’ that is so often lost in modern, DAW-bound recording.

Joel Elwar is technical manager at Studiospares, a major UK-based supplier of pro-audio equipment to trade professionals and end users.