Guitar Amplifiers & Speakers by

Shere Sound England

Origins of RIF During the late 1970's I worked towards making a guitar amplifier that could compete tonally with the best available at the time, but would provide significant savings in weight and cost over comparable valve-based equipment by using solid-state circuitry. My aim was to get equivalent dynamics and tone from the natural behaviour of the circuit rather than a synthesis created in a preamplifier or, as in more recent times, software modelling. Some efforts have since been made using similar ideas, but although some good-sounding solid-state amps have resulted, none so far has successfully emulated the touch-response and overdriven sound of classic valve amplifiers. Touch-response affects the feel of the guitar to the player, and is noticeably different from one type of amplifier to another. Both this and the overdriven sound depend on a complex interaction between the amplifier and speaker, so success meant developing a solid-state power amplifier that would react with a speaker in the way I'd experienced in valve amps, with a similar balance of harmonics in its normal and overdriven spectrum. It soon became clear that none of the techniques usually applied to solid-state power amplifiers would work for guitars. The need to earn a living put a limit these time-consuming investigations, although I made more progress working on developments for Vox in the 1980's. I believe RIF amplifiers meet these requirements, with sound, playing response, and ease of handling aimed at fulfilling the wishes and practical needs of guitarists in every kind of amplified music present and future. I am sure that when you try one, a RIF amplifier will change your ideas about solid-state guitar amplifiers for good. David Petersen : Shere Sound

Bluebottle 38 watt Tremolo / Reverb Amplifier Head

Superb punch, tone and sensitivity in a compact and easy-carry unit. Classic on-board effects to simplify pedal-boards. Cable and footswitch storage. Dimensions: 45cm W 20cm H 22cm D - Weight: 7kg RRP: £375. Specification: Max Output 38W / 16Ω, 45W / Ω. Control panel: Inputs: Normal & Switched, both 500kΩ impedance; Humbucking / Single-coil selector, sensitivity 10mV single-coil, 30mV humbucking with-12dB contour at 100 hz. Volume control, Treble, Bass controls +/- 18dB ( -6dB mid cut at max Bass). Magic-i Tremolo Depth/rate display (remains active with footswitch cancel). Stereo jack for footswitch (Tremolo/Reverb cancel). Tremolo Depth, Tremolo rate, Reverb Depth controls. Mains switch, Power on indicator. Rear panel: Effects Send-jack, Effects Return jack (-10dB series wired); Low/Normal power selector (3.8W – 38W); RIF boost selector; Output jack; IEC mains socket; mains fuse. Cable storage compartment under rear panel. IEC cable, speaker cable and footswitch supplied.

Effects controls, Power switch

Pickup Selector & Main Controls

Magic-i and Footswitch Jack

Loop Jacks & RIF selector Firefly 38 watt Tremolo / Reverb 1 x 12” Combo

RIF's mean, clean, bluesy sound in a single unit (electronics specifications as Bluebottle)

Compactly-dimensioned robust unit with quarter-panel open back for easy storage of cables and accessories. Fitted with Harma Blue Ruby speaker for clear sound, 114dB clean output, and reliable, smooth overdrive performance. Supplied with 2-function footswitch (Tremolo and Reverb) and UK standard IEC cable. Slipcover available upon request, to order only. Dimensions: 45cm W 48cm H 22cm D - Weight 14kgs RRP £525. Speaker Cabinets

Cabinet view showing thin-wall construction & metal grille

Jaybird 50W Speaker cabinet, 15” Jensen C15N driver (also shown on front cover) Dimensions: 56cm W 46cm H 28cm D - Weight 11kgs RRP £399 Companion cabinet to Bluebottle amplifier, with wide range 15” Jensen drive unit (16Ω impedance) for full sound and excellent composure with overdriven input from the amplifier or effects. Quarter-panel open-back design, with twin jacks for easy linking and breakout to external equipment.

Seabird 50W Speaker cabinet, 12” Harma Blue Ruby driver

(same appearance as Jaybird) Dimensions: 56cm W 43cm H 28cm D - Weight 9kgs RRP £379 Similar dimensions to Jaybird cabinet for stacking compatibility, fitted with Harma Blue Ruby drive unit (16Ω impedance) for the warmth and mid-range colour associated with British-made amplifiers of the 1970's. Also available with Harma High Power Sapphire 100 watt drive unit (for enhanced clarity and volume) RRP £389

RRP's include VAT and shipping within UK (Trade terms by agreement)

Technical Notes RIF stands for Regenerating Inductive Feedback,Shere Sound's proprietary method of solving a key problem in achieving valve-like sound with solid-state circuits. All valve amps use an output transformer (OT) to convert the energy in their power valves to a form that can be used by speakers, and it's a significant factor in their sound. RIF technique uses a small transformer to sample the output, which is returned via a special feedback circuit. The amplifier's tone signature is determined by the transformer without affecting its full power capability, emulating this important element of a valve amplifier. A RIF defeat switch is fitted to the rear panel, but most players leave it switched in, giving RIF amplifiers the essential “twang” and cut-through capability until now only found in valve amplifiers. P38 Module The P38 module is Shere Sound's patent-pending speaker-driving circuit. Its low damping factor contributes to RIF amps' supple touch response, while its harmonic spectrum within clean power limit is dominantly 2nd harmonic (5% at 30 watts, with 2% 3rd harmonic – with RIF selected, these figures increase by 2%). As the output limit is exceeded, the balance changes gradually to dominant 3rd harmonic, approximately inverting the clean balance at 40 watts. This wide margin contributes to its valve-like signature. Another unique feature of the module is its power-scaling capability, and RIF amplifiers feature a 10% (Low) or 100% (Normal) switch for flexibility in recording/rehearsal or live performance work without tonal compromise. P38's unusual architecture ensures thermal stability, negligible output DC content, and absence of problems with short / open circuit and inductive loads that plague conventional power stages unless tone-killing protection circuitry is used.

Tremolo, Reverb, Magic-i and Effects Loop. RIF amplifiers feature two effects engineered to the same standard of excellence and originality as the regular sounds. RIF's Tremolo with its unique 'Magic-i' Rate / Depth indicator has a wide range of both, with rich-sounding modulation and good symmetry. Its FET-based circuit is inherently more reliable than the commonly used optocoupler type. RIF's spring reverb can be used for effects ranging from subtle ambience enhancement to large-hall echo, due to employing our regenerating technique combined with a short-tray reverb unit. Both effects can be cancelled using the footswitch with no change of tone or level in the regular sound. For effects, RIF's series -10dB loop can be used with pedals or rack mounted line-level units, being wired post-fade but pre-Tremolo / Reverb effects for best results with distortion pedals, compressors and other dynamics-changing effects.

Input, Preamp and Tone circuits. RIF's sound benefits from a two-stage preamp using new discrete FET/bipolar pair amplifier stages, giving a high input impedance on both jacks. A passive tone circuit gives a wide-range of Treble and Bass swing with a familiar interaction at high settings. The Humbucking / Single Coil selector on the Low / Switched jack optimises its gain and contour for humbucker-loaded instruments. Excellent transparency, sensitivity and touch-response are immediately noticeable properties of this effective new circuitry.

RIF amplifier / cabinet construction. From the outset we've aimed at compact dimensions and low handing/shipping weight over our whole range of products. This is reflected in the use of exterior rated low density ply in our thin-wall cabinets and 2mm aluminium for amplifier chassis. There's no conflict with the requirement for a robust road-ready product, because most transit damage results from weighty equipment that's beyond the safe handing limit for a person of average strength (20kgs). The heaviest RIF unit (Firefly combo, 14kgs) is an easy one-handed lift over distance. This unusually low weight doesn't compromise strength – the unique structural design provides rigidity in the chassis itself and strong support from the cabinet and fixing layout. RIF cabinets have 12mm frames and rear panels with 18mm speaker baffles for solid support of speaker units, fronted with robust metal lattice over easy-breathing speaker cloth, giving good strength, a classic look, and negligible treble absorption. Our low-radiation transformers allow single-coil pickups to stay quiet, even if you like sitting on the amp.

Other Shere Sound products:

Blue Tube Level/Treble/Overdrive Booster RRP £135 Whirligig Vibrato/Tremolo/Phaser RRP £145

For more information / supply, please contact: Shere Sound tel: e-mail:

01843 – 8555038 [email protected]