THE SG2100 IS SESSION'S offering to the growing band of players who are going stereo. It's an interesting, if limited, alternative to buying two amps. Its stereo function is confined to power amps only, the whole pre-amp section staying mono.

The pre-amp section is excellent, as existing Session owners will expect. It uses a single high impedance input, switchable between two channels. The Accutronics reverb spring, coupled with a drive circuit which takes full advantage of it, sounded wonderfully spacious and can be used to an extent to counteract the characteristic speaker damping and harmonic thinness inherent in solid state amp construction — and evident here.

Channel A contains the filth. Its preset EQ, used with the distortion set to fairly heavy, produces a classic obese hooligan sound reminiscent to me of the Marshall demo booths of yore.

The EQ rocker switch on this channel can be flicked over to bring in the bass, middle, and treble controls in channel B to affect channel A as well. But it's hard to improve on the preset for the traditional heavy sound. Channel A has a "Variable Overdrive Harmonic Filter"(!), which sounds very like a treble roll-off in practice, simply sharpening or dulling the distorted edge.

Channel B is less inspiring on its own, and the lack of valve-type harmonics becomes apparent quite quickly. The EQ controls are sensibly centred, though I found myself, as usual, looking for a wider range of adjustment.

The two GC100-212 cabs which arrived with the head were covered in the same dull grey mixture cloth, which will probably look filthy after a little while on the road, and didn't really do the amp justice; they were constricted in the bass and favoured high-mid rather than breathy treble.

Q & A soloing is easy and noiseless with the channel-swapping footswitch, though a lazy foot could delay the changeover. Similarly, a respectful distancing for back-up work alters easily to an attention-grabbing, solo level.

No such luck with the reverb switch. Taking out the reverb failed, and merely produced a sustained grunt and squeal. A little slip-up in quality control, chaps? The reverb worked happily without the footswitch, and the clean sound available from the amp by mixing channels A & B together was quite stunning. Backing off the distortion does reduce the level available from channel A, however, so this could be of limited use on large and noisy stages.

All the front panel controls, including the master volume, operate before the single fx send, which is unfortunate, as it leaves wide open and very sensitive the two power amps, accessible via the two fx returns.

Switching power on and off can produce enormous bangs, and any juggling with fx link leads must be done with power off. Mechanical switching fx units, now largely extinct, are unusable without a stereo volume pedal between fx units and fx returns. The power-down period after switching off is quite long, so really the unit would benefit from a standby switch or a power amp gain control.

The stereo effect is achieved by plugging whatever stereo floor or rack unit you choose between the mono fx send and the twin fx returns. Using a stereo chorus, for example, the out-of-phase modulation is delivered by the power amps, each handling a speaker load of four to 16 ohms, to separate speaker cabs. It is perfectly possible to use a mono fx between send and only one return — here, some of the cross-channel leakage effects can add an extra dimension to the sound.

There is limited control of the stereo image by means of a Wide In/Wide Out rocker switch. A stereo chorus sounds broad and full at Wide In, but reduces in effect and level at Wide Out, indicating some phase cancellation. The most attractive leakage effects on mono units occurred at Wide In; an old MXR Phase 100, carefully switched on when the amp wasn't looking, showed a small phase difference between power amp one and two when hooked up to tape deck meters from the rear-mounted monitor outlets, which is probably related to leakage and the comb filter effect of the phaser hitting favourite frequency ranges in the power amp input impedances. The stereo here managed to take out much of the passé flavour of phasing and revive it as a useable colour; movement without delay. Switching to Wide Out knocked out the phase difference, and made the unit sound merely boring again.

Noise levels in the power amps, as in the pre-amp, were reasonably low, which was fairly crucial considering their flat-out state. At a possible 100 watts a side, depending on speaker impedance, there is bags of sound available, so quite possibly, with speakers split on stage, you won't need much monitoring. However, it is useful to be able to control the monitor levels independently from the monitor outlets, and any controversy over your monitor level in a colleague's perception can be damped quickly.

The head is a timely, if timid, step into stereo, and at this stage probably only represents an economic advantage over separate amps. It is less flexible in terms of separately variable eq and level, and there are situations, like telly or daytime Radio 1, where stereo is no use and mono-ing down will simply cancel out-of-phase chorus or flanging.

I'd like to see the stereo split extended further back into the pre-amp section, perhaps with the option of splitting pre-amp channels side to side — Q & A soloing would then get very dramatic.

Whatever, try it out carefully; a dirty jack or crushed lead in the fx chain can produce a horrifying noise. One more thing. Next time, could I have some speaker leads please, and an English mains lead? Oh, and a reverb switch that works?

SESSION SG2100: £295

CONTACT: Musimex, (Contact Details).