Hiwatt, DR103 Custom 100W AP Guitar Amp Head, 1979


DR103 Custom 100W AP Guitar Amp Head
Serial Number: 
The Story Behind
Hiwatt, along with Marshall and Vox, are largely responsible for shaping the sound of British rock during the 1960s. Bands such as Pink Floyd, the Moody Blues, the Rolling Stones, and The Who have all used Hiwatt amps to help create their legendary sounds.
When Marshall amplifiers became popular on the music scene in the mid 60’s, clone and copy makers soon followed with their own versions of the famous Marshall Super Lead design. It needs to be noted that Hiwatt was not one of these companies. In fact, what may appear at first as a simple variation and copy on the Marshall SuperLead in what was the form of the Hiwatt Custom 100 DR103 head, further examination quickly reveals that the design itself was actually far from it.
British audio engineer Dave Reeves founded Hiwatt in the mid-1960’s. To raise enough money to get his company up and running, he contracted with Ivor Arbiter’s Sound City music store to build a line of amps bearing the store’s name. By the late 1960s, however, Reeves had fulfilled his contract with Sound City and began focusing on building his Hiwatt-branded amps. In the late 1960’s and early 1970’s, Reeves found he could no longer keep up with production. So he commissioned famed amp-designer Harry Joyce to wire chassis for him and this partnership lasted successfully up until Reeves’ untimely death in 1981.
Hiwatt amplifiers were marketed as high-end amplifiers, and indeed their quality in construction, from use of premier Partridge transformers to exquisite attention to detail being made in the electronic wiring and assembly, quickly further enhanced Hiwatt’s reputation. The person responsible for this was Hiwatt’s Chief Technician Harry Joyce, who oversaw the construction of these amplifiers and built and signed many of them himself. Harry Joyce was a military-certified wiring technician, and as a result, all Hiwatts produced during the Harry Joyce era were produced at military-spec levels. Military specifications required that products being made be wired in such a way that components would be easily accessible and that the wiring itself would remain "clean". This was to allow for quick and efficient repairs of military equipment while "in the field". Looking inside a Hiwatt chassis, this attention to "Mil-Spec" is plainly evident.
This attention to detail was also the primary reason why Hiwatt production was limited to only 40 amplifiers per month. As a result, Hiwatts are much more scarce compared to Marshalls and obviously fewer musicians know about them due to their limited availability.
The most famous Hiwatt within the line was the Custom 100 DR103 amplifier. Its 100 watts of output compared to a Marshall Super Lead is quite different to say the least. The Hiwatt DR103 is notably louder and can also run much cleaner than 100 watt Marshalls when needed and they also have tremendous headroom available. Overdrive is certainly available when the Hiwatt is pushed, but it must be acquired by use of the higher-gain "brilliant" channel  and certainly a high-output pickup helps further. The "normal" channel is voiced to stay clean and powerful at all levels. An additional benefit to the Hiwatt DR103’s tone and design was its inclusion of tone controls that actually seemed to respond with a much wider range than other amplifiers of the time. Bass response could be bassy, mids added strong punch and a wide range of the treble and presence controls would deliver all the upper frequencies and sibilants desired.
Similar to the Marshall Super Lead’s four-input design, the Hiwatt DR103 also features four inputs for both "normal" and "brilliant" channels, with preamp levels available for both. The channels can also be linked together like a Marshall, but it is important to note that the higher-output channel inputs on the Hiwatt are the ones located on the bottoms, while the lower gain inputs are on the top. This applies for both the "brilliant" and "normal" channels. This is backward from Marshall’s design. It is also important to recognize that both the Marshall Super Lead as well as the Hiwatt DR103, while both called "dual channel" designs, are not the same as today’s channel-switching amplifiers. Two independent channels were built into these amps and could be used either one at a time or both together but they could not be switched. To serious "old school" players that know "cleaning up" the signal can occur by simply altering picking attack and/or by rolling back the guitar’s volume control a bit, this isn’t considered a big issue. As a result, both Hiwatts and Marshalls that lack channel-switching are still popular and widely used today.
The Hiwatt DR103 design is also based around the use of four EL-34 power tubes and four 12AX7 preamp tubes. The transformers are set up so that the amp can be used with various line voltages around the world and speaker impedance can also be set to 4, 8, or 16 ohms with two speaker outputs wired in parallel.
This is a fine example of a Hiwatt DR103 Custom 100 valve amp, Standard "AP" (All Purpose) model designed for guitar from 1979. 

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