No Pain, Loads of Gain
Tech 21 SansAmp Rackmount Tube Amp Emulator
Tech 21 have taken their popular SansAmp foot pedal guitar preamp and repackaged it in studio, rack-mount format. Paul White takes a look at what else it has to offer.
It sounds like valves, it plays like valves, but in reality, it's a very cunning piece of solid-state circuit design... it's a SansAmp, but it seems to have grown a 19-inch rack case, not to mention a number of other enhancements. Paul White checks out the SansAmp's new clothes.
The original SansAmp pedal unit was simple in concept, but has established itself as a serious recording tool for guitarists. Essentially, it is a guitar preamplifier that uses a combination of variable controls and switched presets to create a range of clean and dirty guitar sounds, complete with speaker emulation, that can be recorded directly into a mixing console. The concept is not new — Rockman must take credit for the original idea — but the SansAmp pedal, along with the UK-built Sessionmaster, is one of the few non-valve units around that sounds similar enough to a miked tube amp to be taken seriously in the studio. Indeed, despite the frustration of the tiny DIP switches used to select the preset tone combinations, the SansAmp pedal remains in production and continues to be popular.
The SansAmp rackmount is based on the same circuit ideas pioneered in the pedal model, but the switches have been replaced by more conventional controls which allow a far wider range of control over the sound. There's also a Live switch, which appears to bypass or modify the speaker simulator, allowing the unit to be used as a preamp with a power amp and guitar. A Bypass Loop is provided too, and this offers an easy way to switch between the SansAmp rackmount and another preamp such as a SansAmp Pedal, a second rackmount unit or whatever else you have in your rig. Apparently the Live switch can also be used in conjunction with the Bypass Loop to voice the SansAmp pedal for use in a live rig, though not having one to try, I can't confirm how well this works. Any on/off footswitch terminating in a quarter-inch jack may be used to operate the Bypass Loop facility, and a suitable switch with status LED is included in the price.
When it comes to studio use, the unit has three different output sockets, offering +4dBu or -10dBv line outs on jacks, as well as a level-trimmable, balanced XLR output. The instrument input is on the front panel where it is easily accessible, though there is a second input on the rear panel which can be switched to work at either instrument or line level. Despite a claim on the brochure that the unit has an external power supply, this UK version is powered directly from the mains, which is a welcome convenience.
Not all the controls have familiar names, but they work logically enough once you've played with them for a while. First off is the Pre-amp gain control, which allows the input gain to be matched to the guitar. This should be set as high as possible without the guitar sound becoming noticeably distorted when the remaining controls are set to produce a clean sound.
What comes next is a pre-overdrive EQ comprising three separate bands labelled Buzz, Punch and Crunch. I would have felt on more familiar territory with bass, middle and treble, but essentially, these controls affect the way the overdrive works in the low, middle and high end of the guitar spectrum. These are followed by the Drive control which interacts with the setting of the previously-mentioned tone shaping controls to regulate the severity of any overdrive effect called up, while a further two-band hi/lo equaliser after the overdrive section allows further shaping of the sound. An output level control completes the complement of controls, though the power switch is charmingly labelled Active, to continue the tradition of thinking up new names for otherwise familiar knobs and buttons.
I spoke to Andrew Barta, the designer of SansAmp, and he explained that he'd approached the design by building a guitar amp in miniature, using FETs, right down to the push-pull output stage. This was then reproduced as a thick-film hybrid circuit to cut down on manufacturing and to afford some measure of protection against copying. It may be that this same hybrid is used in the SansAmp rackmount; a small, encapsulated block is evident on the circuit board, along with several additional dual op-amps employed to handle the active equalisation and various buffering functions.
Tonally, the unit seems far more flexible than its pedal counterpart and the pre-overdrive tone shaping has a profound effect on the nature of the overdriven sound. By backing off the drive control to around its minimum setting, the result is a clean tone which can be modified using the Buzz, Punch and Crunch controls, in exactly the same way as a three-band EQ.
With more Drive wound in, the sound takes on a raunchy overdrive which can be fine-tuned using the aforementioned Buzz, Punch and Crunch controls and the two-band EQ. Careful juggling of the controls produces a wild variety of overdriven tones from the raunch of ZZ Top to creamy sustain, buzz-saw metal or good old fashioned rock with a nice dash of second harmonic overtone. There are no effects on board so a little reverb is needed to complete the illusion, but in the majority of cases, the SansAmp Rackmount substitutes for a miked guitar amp admirably.
An effective unit, to be sure, but quality comes at a price, and with a retail tag of £425, one could justifiably ask why there is just one channel when a clean/dirty arrangement would be welcome in the studio and particularly live. I know the Bypass arrangement helps achieve this, but it assumes that you already have another suitable preamp. You might also ask why valve emulation costs more than some of the excellent units which use real valves, though the counter argument here is that the comprehensive controls do allow you to squeeze just about any tone imaginable out of the unit.
For those who know and love the SansAmp pedal unit, how does the Rackmount compare? For me, it's far easier to get the right sound, it's far more versatile and it seems rather quieter when set to produce the more aggressive styles of overdrive. It is also able to produce a wider range of clean sounds with lots of tonal variation, and whichever way you look at it, the unit is a technical success. Now you just have to ask yourself if you can justify the price!
SansAmp Rackmount £410 including VAT and footswitch.
Klondyke Trading Company, (Contact Details).
Review by Paul White
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