Published On: Thu, Dec 12th, 2013

Marshall SL5 Slash Signature Combo Review

Small is beautiful? Phooey, say Marshall and the guy in the top hat, putting their heads together to cook up a practice amp that sticks up two fingers in the face of portability. Review by Huw Price

Description: Twin channel switchable 5W/1W valve combo with 12″ Celestion Vintage 30, reverb and footswitch. Made in China

Price: £589

Contact: Marshall – 01908 375411 –

Until recently most people’s idea of a practice amp would be something small, light and low in volume, but things are changing. We reviewed Tony Iommi’s Laney practice amp, and it turned out to be a 15W bruiser that would be loud enough for many of us to gig with. The SL5 from Marshall’s Signature Series certainly ticks the low-wattage box with 5 Watt and 1 Watt settings, but it’s got a 12″ Celestion Vintage 30 and weighs in at a hefty 20.5kg. Not that we’re complaining; the problem with small-box amps is that many sound small and boxy. For practicing, most of us want the best possible tone at low volume, so low-wattage amps in full-sized cabinets usually deliver good results.

The SL5 was conceived and designed closely with Slash, and Marshall says Slash was ‘intimately involved’ at every stage. It’s tempting to picture Slash sitting in Milton Keynes with Marshall’s technicians, soldering iron at the ready and taking his turn to put the kettle on. Slash himself says ‘it’s just not always possible or practical to have a Marshall half stack – let alone a full stack – in your bedroom.’

Many will empathise, having endured arguments on that very theme. It seems touching that global superstars are not exempt. So here it is: a portable tube amp that promises the essence of Marshall’s monster AFD100 in a smaller package.

The SL5 is an all-valve combo featuring three preamp valves and a single EL34 running in Class A (we should point out that all single-ended amps run in Class A). It’s common practice to select an EL84 or 6V6 output valve when a designer is shooting for around 5W, so it’s interesting that Marshall opted for an EL34 – the valve that has become almost synonymous with the ‘Marshall sound’.

The SL5 has no shortage of features. There are two channels – clean and overdrive – and the clean channel gets its own Volume control. The overdrive channel has Gain and Volume and both channels share the tone controls. It’s the classic Marshall array with Treble, Middle, Bass and Presence.

Unusually, perhaps, the SL5 is also equipped with digital reverb, and there are two inputs. The high sensitivity input is suggested for low output guitars and the low sensitivity input is for ‘normal’ output guitars. The high sensitivity input provides an extra 6dB of gain and regardless of your pickups, it’s useful if you wish to drive the amp harder.

On the back panel there’s a switch to set the power level to 5W or 1W; the SL5 must be in standby mode to do this. A jack socket is provided for the footswitch, which overrides the front panel to swap channels and activate the reverb. There are two speaker outputs, 8 and 16 Ohm, but they can only be used one at a time. The onboard speaker connects to the 16 Ohm socket.

Screen shot 2013-12-12 at 13.02.27

Since this is Slash’s amp we reached straight for a ’50s LP replica. One strum and there were smiles of recognition all round. The SL5 is like a bonsai Marshall – small but perfectly formed. The two channels are very different, with the clean channel having plenty of headroom and a warm, fulsome tone. The overdrive channel is voiced with definitive Marshall bite, and even with the gain down low the sound is never entirely clean. Turn the gain up a couple of notches and the SL5 bursts into life. From here things move progressively from heavy rock to blistering gain, and the middle control exerts a strong influence on the character of the tone.

The reverb control enhances the slightly uninspiring clean channel and adds a bluesy vibe to mildly overdriven sounds, but we’re not convinced that reverb is appropriate for high-gain guitar tones. It tends to muddy the issue when avoiding muddiness is the priority.

Sheer volume often hides a multitude of sins or, in the case of heavy guitar amps, nasty harmonic distortions, but the SL5 doesn’t display any fuzziness or odd beating overtones and chord inversions ring true and clear even with the gain cranked up. We also like the way that the SL5 cleans up from the guitar volume; it retains a sparkling clarity and you can use the guitar’s volume as a ‘virtual gain control’.

To explore the SL5’s full palette you must investigate both inputs. Hitting the overdrive channel from the low sensitivity input opens up the lower gain range. Similarly, feeding the clean channel from the high sensitivity input livens things up and the sound even takes on a throaty overdrive when the volume is maxed out.

Many amps seem to lose bass and clarity when they’re switched to low power mode. Not so the SL5: the tone remains remarkably consistent, which suggests that there’s more going on than simple pentode/triode switching. There’s still enough volume available to drown out an acoustic guitar, but it’s definitely more ‘neighbour friendly’ than the surprisingly loud 5W setting.

Marshall amps have been around long enough for the term ‘classic Marshall sound’ to mean different things to different generations. The SL5 is less about the ’70s and more about the ’80s and beyond. It’s a crunchy, grinding plug-and-play rock amp that works brilliantly with humbuckers for rhythm and lead alike. Bright single coil pickups may need quite a bit of treble rolled off on the overdrive channel, but there’s still great tone to be had with a bit of tweaking.


The SL5 justifies its ‘practice’ tag on low wattage alone, because in all other respects it’s a regular guitar amp. It also costs a lot for a 5W amp – in fact you could buy various giggable 15W or 20W combos for the same or even less money, and on that basis buying a power break for your regular amp may be a more cost-effective option. Having said that, the generously-proportioned closed back cabinet does wonders for the sound. Better still, rock players will find everything they could ask for in a low-wattage Marshall valve amp, and the tone is good enough for the studio as well as the ‘bedroom’. So long as you don’t need an amp you can lug around on public transport, it’s ideal.

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