Hiwatt

Hiwatt is a British company that manufactures amplifiers for electric guitars and electric basses. Starting in the late 1960s, together with Marshall and Vox, Hiwatt contributed to the sonic image popularly termed "British sound".
History.
Origins of the Dave Reeves Hiwatt legacy.
Hylight Electronics was the brainchild of British audio engineer David Reeves. He attended technical school in the late 1950s, and did apprenticeships at Marconi Company and Mullard. While working his day job, young Reeves also started working evenings in a small room over Plato Music on Crown Passage in Morden from 1964–1968. He fixed things at first, repairing hifi sets and televisions as well. It was during this time that he first conceived the idea to start his own company and invented the Hiwatt name.
Early timeline.
1963 – Local band "The Hylights" amplifier blew up, Dave Reeves said "I could build a better one than that" so he did. He conceived the idea to build more amps from this whilst living in 3a Cotswold road, Belmont, Surrey.
March 1964 – Moved to Morden, Surrey (The maisonette).
Early 1966 – Made redundant (laid off) from Mullard, used £800 separation pay to give him breathing space to develop Hiwatt idea, whilst wiring the amps at 4 Crown Passage, Kingston, Surrey (Plato Musical Instruments Ltd.) and finishing them in the maisonette in Morden.
Late 1967 to early 1968 – Was under contract to build Sound City Amplifiers and with £800 earned from his work, he placed a deposit on 171 Malden Way, New Malden and moved in March, 1968. Then started to build Hiwatt amplifiers in the garage.
Between 26 Jan and 1 Feb 1972 – Moved Hiwatt from the garage on Malden Way to a facility at 16 Park Road, Kingston, Surrey.
First amplifiers.
The first series of units that were produced bearing the moniker first appeared from Reeves work bench in 1964 (based on one early example obtained by Plexi Palace). These first models used ultralinear taps for the screen grids. They were a split-chassis design 50 watt head with the control panel mounted on the top of the cabinet, and a black and gold nameplate that featured small-case, cursive writing spelling out the name "hi-watt". The original HIWATTs owed more of their design and look to the VOX and SELMER counterparts of the day than to the classic look of the British guitar amplifier that HIWATT later embodied. The DR506 (S/N 159) pictured on this site was built in this shop in 1966, based on receipts still in existence.
Reeves apparently created a few early Hiwatt amps using a script logo, but we don't know where exactly in the timeline these fit in. There followed a number of more traditional front-panel head designs, the earliest of which had "HIWATT AMPLIFIER COMPANY" printed on the control panel where the more familiar "CUSTOM HIWATT 100" text would later go. Partridge transformers and Mullard valves were part of the Hiwatt recipe from the earliest days, in large part because Reeves was intimately familiar with them from working at Mullard.
Hylight and Sound City.
Reeves eventually started the Hylight company (the name came from an early 1960s band named "The Hylights" that a friend belonged to), and the name was registered in September 1966. 
The first big order for amplifiers came from Ivor Arbiter's Sound City music store—these became the original Sound City amps. These amps (the so-called "Mark I") were apparently just his current amplifier design, re-badged with the Sound City name. Note that many of these amps still have the "Hylight Electronics" stickers on the chassis inside. He received 800-odd pounds for this batch of amps, but decided to focus on producing amps using the HIWATT name after this.
In an interesting turn, Arbiter took Reeves to court afterwards saying they owned the design and Hylight was using it without permission. During the proceedings, Reeves pointed to the unused holes in the amp chassis and asked the Arbiter engineers what they were for—they couldn't answer, since they were just producing copies of the existing chassis that Reeves had originally designed! The case was decided in Reeves favour shortly thereafter.
Several units later, Dave Reeves starting building amplifiers that more closely resembled the modern day HIWATT. The nameplates had been changed as well to feature a non-hyphenated, bold, all capital letter logo that stated .
At around the same time (1967–68), Dave was made redundant from Mullard ("laid off" in US terms), and got another 800-odd pounds redundancy pay. He used the two sums of money to help put a down payment on a house in New Malden. The new house had a small garage, and this became the new home of Hylight Electronics.
Hylight Electronics originally sold direct to the musicians so that they could put the additional fees charged by distributors and music stores back into the growth of HIWATT. Probably the earliest famous user was Glenn Cornick, then bassist of Jethro Tull, who often played up the road at the Toby Jug. It was at his urging that the first 200-watt (and later 400-watt) amps were produced. Hiwatt heads can be seen on the January 8, 1969 Toby Jug (and subsequent) pictures on the cornick.org website. The May 8 Royal Albert Hall picture in particular looks like a Hiwatt advert!
Certainly one of the most famous guitarists to endorse the brand in the early days was Pete Townshend of The Who. Dave Reeves had made the Townshend connection earlier via the original SOUND CITY heads that Pete used. By February 1970 when the famous "Live at Leeds" concert occurred, The Who stage was full of Hiwatts.
To subsidize its income at the time, HyLight Electronics also started manufacturing amplifiers under the SOLA SOUND name for Macari Ltd., one of the largest musical instrument distributors in the U.K. This arrangement only lasted for a short while as the popularity of the HIWATT amps were becoming more overwhelming on a daily basis.
As the demand for HIWATT Amplification grew towards the end of the 1960s, so did Dave Reeves passion for producing an even more "road-worthy" unit for professional musicians. Much of the credit for getting HIWATT gear into the hands of such legendary bands as The Who, Pink Floyd, Jethro Tull, The Moody Blues, Manfred Mann's Earth Band and others, must go to HIWATT'S original Sales Manager, Peter Webber.
Peter Webber was a former band road manager whose savvy, experience, and connections with many high-profile British musicians made him the perfect choice to promote Dave Reeves premier line of amplifiers. Peter logged endless hours driving the lengths of the U.K., giving bands "hands-on" demos of the HIWATTS, and selling them on HIWATT's superior tonal capabilities and unmatched reliability. The bands initially trusted Peter for his reputation and knowledge, and the deals were closed once they plugged in. In particular, he would regularly take a set of Hiwatts up to a place in London called the Roundhouse, where they became the house amplifiers.
With Peter Webber selling HIWATTS as quickly as the Hylight Electronics garage workshop could turn them out, Dave Reeves knew he needed help. The most critical and time-consuming stage in building the amps was in the wiring of the chassis. (Note that the trademark "right angles and neat bundles" internal wiring was being used in Hiwatts as early as 1969, before anyone external was brought into the picture.) In 1971 Reeves picked up the phone book to find a wirer that would be able to re-create and fine tune his "super neat" approach to wiring amplifiers, and came across the name Harry Joyce.
When Dave Reeves initially visited Harry's workshop in Walton-on-Thames in early 1971, and approached him with the proposition of wiring the chassis for HIWATT amps, Harry was skeptical.
Harry Joyce Electronics was at that time under contract to Gravesby Instruments Ltd. to produce wiring projects for the British Navy which required Harry's "no compromise" workmanship and quality control. Harry had hand-picked his elite crew of wiring technicians who were "fresh" out of technical school and taught them his meticulous format for "military-spec" wiring.
After some prodding by Dave Reeves, Harry agreed to take on the chassis-wiring chores for Hylight Electronics on one condition: He insisted that they not be asked to produce more than forty units per month, to maintain a high standard of quality control. Dave reluctantly agreed, and the legendary marriage between Hylight Electronics and Harry Joyce Electronics began in earnest. Harry's company wired many Hiwatts from this time until early 1984, when Biacrown could no longer pay its bills.
Once the services of Harry Joyce and Co. had been acquired, the next step for Hylight Electronics was to find a "proper" facility for the research, design, assembly and marketing of HIWATT Amplification. Just up the road from New Malden was the town of Kingston upon Thames. Dave Reeves found a site for HIWATT'S new home, a converted bakery complex in a very old building that was located in a small industrial section of town known as ParkWorks. In January 1972, Dave Reeves, Doug Fentiman, began settling into their new address at 16 Park Road. The HIWATT legend was shifting in to high gear.
Building the team.
The next step in getting the production of HIWATT amps out of the garage and into the new facilities at ParkWorks was to find a superior cabinet-making team that could develop a "tank-like" skin to protect the premier electronics that Dave Reeves had developed.
Mike Allen and Danny Edwardson were brought on board to improve upon the current crop of speaker cabinets that were currently being produced in the U.K. The first step was to use a more robust and acoustically sound material for the cabinets construction. This came in the form of 14-ply Baltic Birch, which was a much heavier and dense wood product than most of the other amplifier manufacturers of the day were using. Next, the cabinets were internally braced at no less than 9 points, and the construction was finished using tongue- and-groove joints. The cabinets were finished off with the most resilient and "classic-style" vinyl covering Reeves could find (made by Brymor Ltd.) and the "tough as nails" black, white & grey fret cloth (speaker cloth) covering that was distinctively HIWATT.
To put the cabinets into a small production stage, Reeves enlisted the services of Henry Glass and Co., known as BEESKIT, one of the U.K.'s premier cabinet builders. Henry's meticulous production techniques were a perfect complement to HIWATT'S already legendary road-worthiness, and Reeves fanatical approach to building nothing less than the ultimate guitar amplifier.
Another integral member that was added to the team at Hylight Electronics was Phil Dudderidge, whose specialty was the design and manufacture of public address systems. Phil's knowledge and extensive expertise in working with most of the major acts in Europe at the time, made him the perfect choice to expand the HIWATT name into the realm of sound reinforcement. Soon HIWATT would become almost as well known for their P.A. gear as they were for their guitar amplifiers. Phil went on to form Soundcraft with Graham Blyth.
The design of the amplifiers changed bit by bit through the 1970s, reflecting changing tastes within the industry. Some odd designs briefly surfaced during this period, including the "SAP" model with footswitch and the mysterious DR118. Also, in a concession to modern times, the use of printed circuit boards was started at the end of the 1970s, although the same strict construction and wiring standards were still employed.
Also during this time, some custom amplifiers were produced by Hiwatt for their most famous clients, including Pete Townshend's CP103 (a recreation of the early Sound City-era Hiwatt design) and David Gilmour's linked-input models.
The company changes hands.
In early 1981, Dave Reeves suffered a fatal fall down a flight of steps. Because he was divorced at the time and had not remarried, control of the company fell into the hands of solicitors (lawyers). Although his stated intention had been for his three children to inherit the business, this did not happen. Mary Clifford, the admin for the company at the time, along with other existing employees formed Biacrown Ltd., and continued making Hiwatt amplifiers.
There were some minor innovations to the circuitry produced during this time, including the "OL" (overload) model which had an extra gain stage added. Some were labeled "OL", while many were not. Some had an additional gain control added to the front panel labeled "overdrive".
Technical.
Classic Hiwatt circuits.
Input stage variations:
Phase Inverter (PI) Variations:
Combination I: 
The earliest DRs with 4-inputs used Input 1 and PI 1.
Combination II:
At some point, the circuit was changed to use Input 1 and PI 2 (this version is represented by the Audio Bros and Hiwatt.com schematics). Some 4-inputs may have been made this way.
Combination III:
Finally, the circuit was changed to use Input 2 and PI 2. This change was definitely in all the 2-input heads, and is represented by the widely circulated freehand-drawn schematics in Pittman and elsewhere.
The OL Model (early 1980s):
Biacrown's "high gain" model moved back to the Input 1 circuit (still keeping PI 2), but used the "extra" half triode as an additional gain stage.
The LEAD Model (early 1980s):
This was basically the same as the OL model, but with an extra level control after the extra gain stage, which was marked "Overdrive" on the front panel.
DR103 amplifier.
This is the amp that started it all. The dr103 has proved itself as the cornerstone of such a huge variety of acts that has provided them all with the platform on which to build their own, unique sounds.
Classic ‘British’ tone stands out distinctively, particularly when the amp is cranked up. Dual channel pre-amp with high and low sensitivity inputs and normal and bright options on each. Volume controls for each channel and master volume control. Three-band EQ; bass, middle and treble.
Specifications:
Mains (100 or 117.5 V) 6.3 A (T) slow blow
(225 or 250 V) 3.15 A (T) slow blow
H.T. (all) 3.15A (T) slow blow
References.
Jimi Hendrix can be seen using a Music City amp head on the 1968 Miami Pop Festival footage.