Posts Tagged ‘EL34L’

Electro Harmonix Guitar Valve / Tubes EL34 s etc..

Tuesday, March 30th, 2010

Electro-Harmonix is a New York based company that makes electronic sound processors. The company was founded by Mike Matthews in 1968. They are most famous for a series of popular guitar effects pedals introduced in the 1970s and 1990s.

EL34EH Electro-Harmonix


Electro-Harmonix was founded by Mike Matthews in October 1968 in NYC, USA.

Himself an R&B keyboard player, he had traded his passion of music for a job as a salesman for IBM in 1967. Shortly afterwards he realized that his job at IBM no longer suited him, and he was interested in trying once again to make career for himself as a keyboard player. Concerned he may not be able to support his (now ex) wife while being unemployed, he aspired to save some money to support her before embarking on his journey to stardom. Partnering with an acquaintance of his, Bill Berko, an audio repairman who claimed to have his own custom circuit for a fuzz pedal, they jobbed construction of their new pedal to a contracting house, and began distributing the pedals under a deal with the Guild Guitar Company Fuzzboxes were in demand following a trail of hits involving their sound, including “(I Can’t Get No) Satisfaction ” by The Rolling Stones two years prior, and recent popularization of Jimi Hendrix. The latter connection resulted in the pedals being branded the ‘Foxey Lady’.

Following the unexplained departure of his partner, Matthews was introduced to inventor and electric engineer Robert Myer through IBM colleagues.

Together the two began conceptualizing a circuit designed to emulate Jimi Hendrix’s use of a distortion-free sustain. While testing a prototype of the Distortion-Free Sustainer pedal, which Matthews did by simply plucking the strings of an electric guitar, as he did not play guitar, he noticed another small box connected to the prototype. When asked, Myer explained this box was a line booster, designed to boost the guitar’s passive signal to an appropriate level for the prototype. Matthews listened as the guitar’s volume increased greatly as the booster was turned on, and asked Myer what was involved in manufacturing the pedal. The pedal consisted of a simple circuit and used just one transistor (This would later become know as the Linear Power Booster (LPB-1), a pedal still manufactured today.Shortly afterwards, Matthews founded Electro-Harmonix to produce this and other pedal designs throughout 1960s, 70s and early 80s.

The first Electro-Harmonix product was the Axis fuzz pedal, which was also sold under the name “Foxey Lady” for the Guild guitar company. While working with Bob Myer on the early Big Muff design, Mike Matthews used a booster circuit Myer had incorporated into the design and marketed it as the LPB-1 or Linear Power Booster in 1969. This massively boosted a guitar signal to provide gain by clipping the signal, dramatically changing the sound. The new device provided a raw distorted sound, full of sustain and harmonics.

Several similar devices followed such as the Treble Booster and Bass Booster. The new devices were extremely popular with guitarists.

Electro-Harmonix stopped making pedals in the mid-1980s, and in the early 1990s started selling vacuum tubes re-branded with their name for guitar amplifiers, which they had also been making since the 1970s. However due to demand, and the high prices guitarists were paying for old 1970s pedals on the vintage market, they reissued the more popular old pedals in the mid-1990s, the Big Muff Pi and Small Clone included. In 2002 they started designing new pedals to add to their range. Company policy is that all reissued effects remain as close as possible to the original, vintage designs. This means however that casings, knobs and especially the old-fashioned mini-jack power plug are not up to modern-day standards. This all changed in 2006 with their smaller and more standardized “micro” and “nano” effect lines.

JJ Electronic Tubes / Valves

Monday, March 29th, 2010

All materials used in the JJ tube  manufacturing process must comply with the most stringent quality requirements. In tube manufacturing, the fundamental requisite for the best production results is to maintain as high mechanical precision for assembly as possible. JJ Electronic uses assembly precision of no more than ± 0.02 mm.

Before tubes are assembled, they are thoroughly cleaned using such methods as the ultrasonic bath, chemical cleaning or annealing in an inert gas atmosphere (hydrogen, nitrogen).



A thorough inspection is performed on every component of the tube internal system before assembly. Assembled systems are then sent to sealing in a glass envelope. During the sealing procedure, the temperature of the glass pass-through joints must be controlled and joints are gradually tempered to relieve the inherent thermal stress.

Next, the assembled glass envelopes are evacuated by mechanical and diffusion vacuum pumps. During this process, the cathode emission coating is activated. All internal parts are heated by a high frequency heater and any spurious dust particles are evacuated. Finally, the getter rings are activated, while they absorb any residual gas inside the glass envelope of the tube.


Every tube is then electrically tested for all parameters which are the key to a flawless operation and a great sound. Specifically, these parameters include: leakage characteristics, internal vacuum level, cathode emission capability, filament voltage and current, anode current saturation level, microphony and others.

Every month, random samples are taken from the production line in order to perform a life time test of 5000 hours under nominal conditions or 1000 hours at maximum specified ratings.

Tube Types

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