GDS Amplification

18W History

A Timeline of the 18 Watt Amplifier (and GDS Amps)



Marshall designs the 18watt amplifier based on the design of the Watkins Dominator.


Marshall releases the 18 Watt amplifier in a 1-12 and a 2-10 combo. A few 2-12 combos are also built. Early 18watters had a deeply recessed speaker baffle and squared off control panel opening. These early 18 watt amps were advertised as distortion-free!


Marshall revises the cabinet with a flush speaker baffle.


Marshall builds a 20W variant of the 18W design. Minor changes include solid state rectification and the offering of a head version in Lead, Lead and Bass, and PA versions.


The 18 watter is discontinued due to lack of interest. High-powered amps with 50 or 100 watts ruled the stages.


PCB amps begin to take hold of the market.


Solid state amps are the norm and tubes are losing ground fast.


Tube amps from small boutique companies such as Mesa begin to gain ground in the market for great tone. Tube amps from the early ’60s begin to regain value as guitarists realise how much they miss great tube tone.


More small boutique amp companies begin to build great tube amps based on circuits from the early days of rock and roll. Fender’s Deluxe, Bassman and Champ are popular circuits to build.


Guytron is born using a two channel preamp with Channel A taking some cues from the 18 watt design.  There are also some 18W ideas in the phase invertor and in fact even though the original Guytron GT100 is a 100 watt amplifier, it can get fantastic 18W-type tones but at any volume level.


April 17: Graydon Stuckey starts the Yahoo 18watt group. Intended for discussion of the 18watt Marshall circuit to figure out how the amp was designed and how it could be built today. “Charter members” included Mark Durham (dec. 7/26/07), Richie Hall, Ron Ott, Dave Kiley, James Grove, Lee MacMillan and Mark Draycott. Within a few weeks, the group had expanded beyond anyone’s expectations and real progress was being made reverse engineering the 18 watt amp.


Summer: GDS Amplification starts to build chassis for the 18watt Yahoo group. The first run of chassis is sold out in two weeks. The 18watt Yahoo group numbers over 100 members. Mark Durham coordinates reverse engineering of original Radiospares transformers by EMC and Heyboer. These designs based on the original Radiospares trannys are exclusive to GDS Amplification by an agreement between Durham and GDS Amplification. GDS begins to offer chassis and transformers for sale to the general public.


Autumn: GDS Amps develops a head variant of the 18W chassis and begins selling head versions alongside the combo version.


GDS Amps develops a Single Channel variant of the 18W chassis called the S/C.  The new S/C has only one input, and a volume and tone control from the normal channel of the 18W.  This proves quite popular and many are sold as complete amplifiers and as kits.


GDS Amps purchases the assets of Guytron Guitar Amplifiers and sets up production in GDS’ shop.  Additional development on Guytron products such as the GT20 head and the GT40 in both combo and head is finished and by Christmas of 2008, the entire line of Guytron amps is in production.