Why are Valve or Tube Mic Preamps So Revered?
A much sought-after addition to a recording setup, home or professional, is a tube pre-amp/channel strip. This is generally added to inject some colour, or character to the vocal sound recorded, bringing a sense of analogue warmth.
Even within DAW recording set-ups, a classic preamp software plugin is usually regarded as a 'must-have'.
Placed between the microphone and audio interface, this piece of hardware adds it’s own sound to the signal, which of course, is down to user/recording artists preference, but a handy tool in modifying your tone for certain recordings. On some units there are additional controls available for crafting the sound. These generally include a High Pass Filter, Compressor, and EQ section to the “Channel Strip”.
In times of past, the term “Valve Pre-Amp” was synonymous with “expensive”, but fortunately today there are some good, well-built options offering such functionality at a reasonable price.
This makes it much easier for many more recording enthusiasts to be able to add such hardware to their setups without breaking the bank!
We’ll take a look at a few of these units here and explore just what they have to offer.
First up in my pick of affordable devices are the ART Tube MP series. Coming in two flavours, lets have a look at the original black, Tube MP first.
Built in a rock solid, all metal shell this unit provides an extremely versatile tube preamp for use with Microphones, instruments or line level sources. On the top panel, there are both XLR and ¼” jack connections, with this the same for outputting the amplified signal. Continuing the simple design, there are two rotary controls controlling the input signal gain, and overall output volume. A handy LED above the input control will also change from green to red if clipping occurs, avoiding spoiling your recordings!
Between the input and output rotary controls are 3 additional switches offering further control to your signal. these include a +20db gain switch, phantom power for condenser microphones and a phase reverse for when using more than one mic at once, such as top & bottom snare drum to avoid phase problems. The valve section itself, is built around a 12AX7a valve, providing superior warmth and fatness to whatever is ran through this little monster.
For such quality and wealth of features, it’s a pretty unbelievable unit for under £40!
The second we'll look at is the Studio V3. This is essentially the Tube MP’s big brother and comes as a classic channel strip to fit stusio racks.
It offers the same feature set found on the original model, but with some added professional features. Most noticeable is the inclusion of the “Variable Valve Voicing” preset dial. This provides a range of tonal presets developed by top studio engineers for instant access of recommended tone for whatever instrument, or source is being connected to the device. The 2nd addition to the V3 is the OPL (Output Protection Limiter). This controls and maintains the output peak signal precisely and accurately. This serves in providing protection to whatever is coming after the tube mp in the audio chain, such as audio interface input stage. Finally, the V3 includes a VU meter on the front panel, allowing visual monitoring of your signal, whilst looking great too!
On the upper end of the “affordable” scale, the Presonus Studio Channel is well worthy of a mention as an introduction to a full “channel strip” style tube based preamp.
Like the ART Tube series, this unit has both XLR & ¼” jack inputs for connection either microphones, guitars or line level sources. This provides great flexibility to what can be pumped through this beast. In all, this unit is comprised of a Class A tube preamplifier, a VCA-based compressor and three-band parametric EQ.
On the input section as well as offering gain control, there is a separate tube drive control allowing control of the overall warmth coming from the valve to the signal. The standard options of Phase Reverse, phantom power, -20db pad and a HiPass filter are also there for controlling your input stage.
Next up in the strip comes the VCA-based compressor. This is fully variable through easily controlled rotary knobs and has a super fast attack whilst retaining a smoothness of sound for controlling whatever you pass through it. This enables you to record hot levels, without the fear of clipping your signal.
A 3 band parametric EQ comes next, enabling you to pull out problem frequencies with ease, as well as boosting any enhancements required to your sound. The Mid-Band also features a variable Q, allowing you to control the width around the centre point of the frequency you’re cutting or boosting. On the Highs and Lows, you can choose between peak/dip or shelving options for controlling the frequencies dialed in.
The compressor and EQ section can be bypassed from 2 easily accessed controls, whilst the large VU meter in the centre of the unit provides great visual feedback as to exactly what is happening.
This unit really provides a massively versatile tool for use in the studio, allowing control in crafting almost any instrument or signal you may encounter. Allowing you to control the amount of warmth from the Tube control is superb, something not found on many other units.
For under £250, this is a great addition to your studio setup in enhancing the tools you have available.
These two units are simply representative of the fantastic range of mic preamps now available at prices that would shock the old recording studio managers. For more background information and reviews, the above links offer guides and comparisons of the various mic preamps available.
Andy Atkins has been writing about music gear for over 5 years and has been published in several trade and consumer titles. He consults for a major UK retailer of musical equipment as well as writing for several big brand names, particularly around guitars, recording and live performance. His latest favourite toy is a Blackstar modelling amp.