SR Technology JAM 90 review

  • £329
The top-mounted control panel is superbly well-designed

MusicRadar Verdict

A great little PA-in-a-box for acoustic players; clarity and definition across the full range. May suit jazzers looking for that clean Polytone-like sound.


  • +

    The clean, clear and unadulterated tone.


  • -

    No reverb/delay on jack inputs.

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For acoustic musicians, happening upon an amp with a clean, colourless sound is akin to finding the Holy Grail. An amplifier that audibly translates the identity and individual sonic characteristics of a particular instrument without adding tonal colouration, or a specific edge to the sound, is a rare beast.

And the smaller and more compact the unit the better, as acoustic players tend to travel light and anything that minimises the strain on the shoulders is most definitely where it's at.

Small and stylish

This neat little combo from SR Technology is not only small but also extremely stylish. Solidly built with a plywood case and a choice of a cherry wood stain/black lacquer or carpet-like moquette, the Jam 90 weighs in at 9kg and comes with two inset hand holds, a black steel grille and four heavy duty 'sticky' rubber feet.

It's a simple, straightforward unit with a few little 'extras'. The bi-amp configuration offers a total of 90 watts in output (70 watts low end, 20 watts high end), six channels, and an internal digital effects processor, while the sound emanates from a six-inch Sica (Italian) woofer and a compression tweeter horn.

Spacious layout

The top-mounted control panel should win ratings on its own for its spacious and well-designed layout, and comes with the added benefit of an extremely bright purple power light.

The main area of the panel is fitted with pear drop-shaped rubberised control knobs with white raised plastic sections that are very helpful for a quick check on levels.

At the back of the panel is a raised section, which carries the connections. Channels one and two are XLR sockets with high and low frequency adjustment from -15 to +15dB, together with volume and reverb/delay adjustment, while the unbalanced, high-sensitivity channel three and low sensitivity channel four have standard
6.4mm jack sockets.


These also come with both volume and low and high frequency controls, although sadly with no reverb/ delay option. Channels five and six have RCA connectors for high-level audio signals and are paired with mono RCA connectors on the 'record out' option offering auxiliary outputs for mixers and external effects.

Set next to the RCA connectors is a line-out jack. Below the rectangular grill is the mains socket, together with a power and ground lift switch.


The Jam 90 has exceptional dynamics, balance and good separation across the full range. Tonally, it has a natural warmth and creaminess and plugging an acoustic flat-top into channel three delivers clear, crisp highs, no mid-range muddiness and a bass response that is well defined, yet not too edgy. Chords come through clean and true - in fact the openness and separation is remarkable.

Using a contact transducer mic through the XLR connection gives you the option of
adding some reverb/delay into the mix and produces a rich, spacey and liquid sound with depth and clarity. You can, of course, plug in a vocal mic if you want to sing: PA in a box!

The Jam 90 is one of a small clutch of acoustic amps that delivers a faithful reproduction of the source instrument's sonic identity. Its full, clean sounds and the clarity and separation that the unit delivers is, we believe, unmatched at this price point.

Needless to say, it's a shame that the unbalanced channels don't offer the reverb/delay option. But given its size, weight, simple layout, padded gig bag and general versatility, this could be the perfect partner for any gigging acoustic musician.