Radial Tonebone Classic & Plexitube

Neither the Tonebone Classic or Plexitube valve distortion pedals that are the subject of this review are exactly new pedals, but now that they are becoming more and more widely available, the time has come to drag them out of the shadows and into the limelight.

Although promoted as valve distortion pedals, both are in fact hybrids that combine the control possibilities of a proprietary dual-stage, solid-state front end with a 12AX7 valve for warmth and to generate the even-order harmonics that characterise the sound of a valve amplifier. Power for the pedals is provided by an external 15V DC wall-wart power supply, which fits into a well-recessed receptacle on the pedals, thus avoiding accidental connector damage. There is nothing that new in using low voltages to power valves (a US patent was issued in 1991), but the care taken by Radial Engineering in filtering the power supply and in the incorporation of a ground-plane circuit topology means that the Classic and Plexitube are, despite their ability to deliver seriously high gain, very quiet pedals indeed.

These two pedals are designed to drive guitar amplifiers and not recording systems, so despite their undoubted sonic qualities, the absence of any speaker emulation voicing means that they don’t make convincing guitar recording preamps.

The Classic’s first stage is where the distortion is generated. The incoming guitar signal first hits the Drive control, which operates across three gain ranges — 0dB, +9dB and +20dB — which are selected via the three-position Drive Gain switch. The boosted signal then drives the 12AX7 valve to produce the desired distortion. To my ears, the Classic takes its inspiration primarily from the Fender amplifier family, and at the zero boost setting you’re going to get a lighter distortion that sounds to me like a lightly driven Deluxe. At the medium boost you’ll be into the world of a hard-driven blackface Twin or Super Reverb, and at the +20dB you’re into the frenetic world of an overdriven tweed Champ at full throttle.

The post-distortion equalisation is extremely effective in letting you develop precisely the sound you’re looking for. The three-position Top End switch sets the basic character of your sound, with its Bright, Flat and Dark settings (+6dB at 10kHz, no boost, and -6dB at 1.8kHz) allowing you to compensate for, or enhance, the basic tonal characteristic of your amplifier. In addition, the Filter control overlaps the Top End to allow you to roll off some high end to compensate for an overly bright-sounding amp. Once you’ve got these set up, you can then use the High and Low EQ (±10dB at 4.3kHz and ±14.5dB at 100Hz) to tailor your sound precisely.

As a final tweak you can boost the mid-range by 12dB at 620Hz or 6dB at 390Hz, to give your solo tone a bit more cut or just to fatten up the sound of single-coil pickups. The mid-boost frequencies have been chosen specifically to complement Fender and Marshall amplifiers, and can help compensate for the essentially clean nature of these and other similar amplifiers.

The last control on the extreme left of the panel is Level, which sets the level of the Classic’s output, allowing you to balance the bypass (clean) mode up with the distorted sound, and the last front-panel feature is a large, red LED to remind you when the pedal is in operation.

Radial Engineering got to the Plexitube by essentially putting two of their Tonebone Hot British pedals in a box, in order to please metal players who wanted the ability to switch between heavily distorted but very different tonalities for rhythm and lead. You can think of the Plexitube as having two channels, with channel 1 being the rhythm channel, where the Voicing switch lets you fatten the mids to give a real upfront sound or to scoop them out a bit, or really scoop them out to leave the mid-range of your band’s sound open for any vocals (and guitar solos) to come through. Channel 2 is the lead guitar channel, where the mid-range voicing is either flat, slightly scooped or boosted. Each channel has its own Contour control, which allows you to find the mid-range centre frequency that is best suited to your particular amplifier/guitar combination.

However, you shouldn’t get fixated on the rhythm/lead designation, as either channel can be used for either or both purposes. As each channel has its own Level control, in the Plexitube you have an immense amount of flexibility open to you and you can just as easily set up two vastly different lead sounds or two contrasting rhythm sounds, depending on what you need to be able to do.

You’ll also find that channel 2 has a couple of extra features that differentiate it from its fellow. On the right-hand side of the pedal casing is a recessed preset potentiometer that lets you adjust the channel 2 drive level relative to that of channel 1, which means that you can make it even more distorted should you wish to. On the other side you’ll find a send/return stereo jack effects loop that lets you insert effects units into the signal path. This means that, if you were using channel 2 as your lead channel, you could have a delay sitting there that would come in automatically when you switched to your lead sound, which would disappear when you switched back to rhythm, all with only one footswitch press.

Unlike the Classic, the Plexitube has two footswitches with associated LEDs, with the left-hand one toggling between the two channels, and the other switching between operating and true-bypass modes.

The Classic responds very much like a good Fender amplifier, and if you set up your drive levels carefully, you can get your sound to clean up beautifully when you back off your guitar volume. Once you start experimenting with higher drive gain and varying the mid boost levels, you can get into some seriously tasty distortion sounds. Although, to me, this is very much a single-coil player’s pedal, it also works extremely well with humbucker-equipped guitars, and a Strat Ultra with its bridge humbucker setup sounded seriously tasty with a load of distortion and heavily boosted mid in the equation. One thing that I really liked with the Classic was that, almost no matter how silly you got, it always kept the note definition in there and allowed the basic character of the guitar driving it to shine through.

The Plexitube, by comparison, is a fire-breathing monster. If you’re into the sounds of modified Marshall-type amplifiers, you’ll be in heaven here. Think wall of 4 x 12s when using the Plexitube and you won’t be far out. The gain structure is much hotter than the Classic and it almost feels as though the Plexitube starts out where the Classic tails off. Where the Plexitube really shines is in the interaction between the Contour and Voicing controls. These allow you to get the mid-range boost/cut frequencies just right, and it was interesting to experiment with these settings and various guitar/pickup combinations. Drop tune your guitar and the Plexitube responds admirably, with loads of the bottom end thud that you’d find in a real flat-out 100W Plexi. Again, even under really heavy distortion, the Plexitube kept a high degree of definition in the sound and even fairly wide chords didn’t disappear into mush.

Both pedals have such a huge potential for experimentation and fine-tuning that you’ll probably find yourself playing around for hours to get the sounds just right. Spending time with these pedals is really worthwhile, as you’ll find great sounds almost no matter what you do. Checking out the users on the Radial web site brings up famous players across a wide variety of styles and serves to underline the versatility of both of these two pedals.

If you’re into the ‘cleaner’ distortions of modern country guitarists, Clapton, Stevie Ray Vaughan and Hendrix’s lighter moments, you’ll gravitate towards the Classic, even though it can deliver some pretty tasty saturated sounds. Metal heads, especially those with a penchant for drop tuning their guitars, should head immediately towards the Plexitube, where you’ll find all the heavy distortion voicings that you’re ever likely to need.

If there is a negative in the whole equation, it is the price. Unlike so many products nowadays, these pedals aren’t made in China, they’re made in Canada, and that fact is reflected in the price. However, once you take into account the quality of construction and performance, these Classic and Plexitube pedals represent significant value for money. So if you use distortion pedals and you’re serious about your tone, you really need to try them out at your favourite dealer. You will enjoy the experience.  0