1946 to 1969
1946 - James B. Lansing’s contract with Altec expires and he goes on to create his own company, Lansing Sound. Later the name was changed to "James B. Lansing Sound". Still later, it was shortened to "JBL Sound".
1946 - Paul W. Klipsch patents a speaker that will soon be called the Klipschorn, a large folded-horn loudspeaker designed for corner placement. The enclosure housed a three-way design: separate drivers— a woofer, squawker, and a tweeter, handling the bass, midrange, and treble portions of the audio signal, respectively. It remains in continuous production to the present day, with company production headquartered in Hope, Arkansas.
1946 - Sylvania is credited with introducing the first commercial germanium diode, the 1N34, in 1946. It is still in production (in different case styles).
1946 - JBL produced the D101 15-inch loudspeaker and the model D175 high-frequency driver. The D175 would be in the JBL catalog through the 1970s. Both of these were near-copies of Altec Lansing products. The first original product was the D130, a 15-inch transducer for which a variant remained in production for the next 55 years. The D130 featured a four-inch flat ribbon wire voice coil and Alnico V magnet. Two other products were the 12-inch D131 and the 8-inch D208 cone drivers.
1947 - The Williamson Amplifier design is published in the UK, which uses a high quality output transformer and 20dB of global feedback to produce a THD rating of 0.1% at 10 watts out.
1947 – In September, RCA releases the 12AX7, a dual triode design (which combined two triodes of the high gain 6AV6 type in one envelope). Hi-mu tubes, like the pre-octal Type 75, and small 7-pin units like the 6AT6 and 6AV6, had existed previously for the past two decades, primarily as detectors and first audio stages in radio receivers.
1948 - JBL business operations were taken over by William H. Thomas, the treasurer of Marquardt Corporation, who represented Marquardt on Lansing's board of directors, and assisted Marquardt in taking over. The company would again be largely private by the next year, and this would prove tumultuous for the original founder, James Lansing.
1948 - Columbia Microgroove Long-Playing record (using actual vinyl, rather than the earlier shellac compounds) is introduced in June as what has come to be known as the ‘LP’.
1948 - ‘Audio Engineering’ magazine is launched, later to split into AUDIO magazine and the Journal of the Audio Engineering Society.
1949 - RCA introduces the 45 RPM 7-inch record in February, their answer to Columbia’s 33 RPM 10- and 12-inch vinyl LP. RCA’s idea of making a “better” short-playing time 78 RPM disc is eventually relegated to the specialty market of singles, and Columbia’s LP will win out for longer playing albums.
In the beginning of this format war, for example, the famous Benny Goodman 1938 Carnegie Hall re-release in 1950, the first million-selling LP, was actually available in a 6 x 45 RPM stack produced by Columbia, intended for a fast record changer produced by their primary competitor. RCA had released new players which played only 78s and 45s but not 33 rpm discs, which could be considered a foreshadowing of VHS vs. Beta, or HD-DVD vs Blu-Ray or Eureka-147 vs IBOC digital broadcasting.
1949 - General Electric publishes the design of a 6SC7 preamplifier designed to accommodate the new GE VR (Variable-Reluctance) cartridge which had an output of 50mV. It features passive EQ and three turnover points - F2, F3, F4, with no F1 (50 cycle) turnover. The design uses a 68K plate load on the first stage, and a 33K plate load on the second stage, each with a matching (68K or 33K) R/C decoupling from the B+. A 200K resistor is the series feed into a combination (pre-RIAA) equalization network. Low plate voltages are recommended. The 6SC7 is a dual triode with an amplification factor (mu) of 70.
Why were both cathodes grounded in this design? Separate pins for the two cathodes were not available - they shared the same connection pin. In the RCA metal 8-pin series of octal tubes (introduced in 1935) pin 1 is already used in grounding the shell. And since the 6SC7 was originally intended for as an old-style phase splitter, where one triode is feeds the other stage via a shared and floating cathode connection, the single pin constraint posed no issue..
Since cathode resistors could not be used to bias either triode (and using only one would cause serious interaction between the stages), the recommendation was made for low plate voltages which assist in self-biasing (also known ‘contact bias’). Very high value grid resistors were also specified for the same reason.
The miniature 9-pin glass 12AX7, with it’s mu of 100, was one year old and not yet widely adopted. In this mono era, demanding that designers use two separate octal tubes (such as 2 6SF5s, mu=100) or two 7-pin miniature tubes (6AT6, mu=70 or 6AV6, mu=100) would have been seen as extravagant—when the intention was to promote easier adoption of the VR cartridge against other competitors who required less amplification.
The smaller 7-pin tubes were uncommon in the larger console phonographs that would have been an ideal match for this high quality VR cartridge. And the glass-envelope 6SN7, introduced in 1941 (glass case meaning that pin 1, formerly the metal shell, was now free to use as the second independent cathode) only offered a mu of 20, wholly insufficient for a phono preamp.
Audio Engineering magazine Jan. 1949 references the original GE technical note, and both are referenced in RDH4 (1953) on p. 736. The circuit also appears in the RCA 1950 tube manual RC-16. p. 276.
A similar circuit appears as the stand-alone, commercially-available GE UPX-003 Phono preamplifier which went through a number of iterations, eventually involving active EQ, and the similar Fisher PR-6 Phono preamp with slight changes, such as a 100K plate load for the second tube stage.
The octal 6SC7 tube was replaced by a 12AX7 as time went on, allowing a broader array of design choices since both cathodes of the 12AX7 were pinned out and could be biased with separate cathode resistors. Japanese manufactuers sold their own near-clones of this design, and arguably it culminated in the stereo Shure M-65 of 1962. See https://www.audioasylum.com/cgi/vt.mpl?f=tubediy&m=240540
In October 2024, Darlington Labs acquired a 1949 GE Model 45 radio-phonograph for our collection from the Albany, NY area. It includes two GE Variable Reluctance cartridges which are user-switchable via two separate interchangeable headshells (one for 78 RPM and one for 33 RPM), an integral 6SC7 magnetic phono preamp with semi-RIAA equalization (differing from the published schematics referred to above) and incorporating a separate, very-heavy monoblock 4 x 6V6GT Push-Pull-Parallel Pentode monoblock output amplifier mounted separately in the bottom of the cabinet, driving two 10-inch permanent magnet speakers. Other units in this series included one or two Jensen speakers, some of which may have had field coils. Two FM bands are included - the original 42 to 49MC and 88 to 108MC. A sticker on the back states proudly in fancy type: "FM: The Armstrong System". Zenith and General Electric were early licensees of the Edwin Armstrong FM system.
Notes in the service manual indicate modifications developed by another engineer inside GE, on a early electrostatic photocopy, and installed by the owner in April 1957, including a 6-position phono EQ selector, full Baxandall tone control (introduced in 1952) replacing the original stepped bass and treble, and changes to the negative feedback loop adding phase compensation and broadening the HF bandwidth. Other notes indicate that various engineers were testing and competing with their various improvements in what was likely a standard unit for these gentlemen, given their employment and position. (Especially astute readers may know that HC Lin worked at GE up to 1956 when he published his famous direct-coupled transistor preamp and amplifier, taking a position with a different firm north of Boston just before the article was published in “Electronics” magazine in September 1956).
It is somewhat amusing that the 6AK5, a sharp-cutoff pentode introduced in 1940 and used in the above tuner, which was among GE’s earliest in the new ‘high-band FM”, is still today widely used among low-cost, low-quality Chinese headphone amplifiers and line amplifiers, configured as a triode. Even though it is a sharp-cutoff, more linear than a remote cutoff, the triode curves are marginal..
1949 - An Improved Williamson amplifier design is published (in America, the article is called ‘The Musician’s Amplifier’ in Audio Engineering).
1949 - D.E.L. Shorter, of the BBC Research Department, confirms that the human ear’s response to higher-order harmonics is significantly increased. This means that proper and scientifically-valid testing of distortion residuals must be “weighted” according to the ear’s natural response. Shorter propses an N^4 weighting, a second-order function which means that harmonics above the second must be increased in value by 12dB for each doubling of frequency, before summing the result in a weighted average. The prior recommendation from the Radio Manufacturers Association in 1937 proposed an N^2 function, or 6dB increase per octave. Shorter’s evaluation of the initial 1937 proposal found it directionally accurate but incomplete, and his enhancement will be further confirmed and supported by another BBC scientist in 1961 , E. R. Wigan (see our 1961 entry).
1949 - James B. Lansing commits suicide on September 4, 1949, possibly due to deteriorating business conditions, difficulty in paying supplier invoices and significant issues in shipping products. He was noted as a better engineer and inventor than a businessman. The company thereby passed into the hands of Bill Thomas, BL's vice-president.
Lansing had, remarkably and perhaps fortuitously, taken out a $10,000 life insurance policy, naming the company as the beneficiary, a decision that allowed Thomas to continue the company after JBL’s untimely personal death. Shortly thereafter, Thomas purchased the widowed Mrs. Lansing's one-third remaining interest in the company; he thereby became the sole owner. Bill Thomas is credited by many with revitalizing the company and spearheading a period of strong growth up through the late 1960s.
1951 - AES Standardization of vinyl playback EQ. It is quite similar to the future 1954 RIAA standard but without the 50Hz turnover. CCIR also publishes its equalization standard.
1951 - WFMT-FM signs on in December as a commercial FM fine arts broadcast station in Chicago, IL. Bernard and Rita Jacobs took over WOAK-FM and changed the format to 8 hours of classical music per day, with Bernard as chief engineer and Rita as primary host. WFMT, in it’s new incarnation, was one of the hundreds of new entrants to the FM band. In the next few years, most major metropolitan areas of the US would have their own commerical FM Classical or “Good Music” stations which offered a blend of Classical, Jazz, and light popular music. Bernard sold the station to WGN in 1968, who in turn donated it to the WTTW foundation. However, WFMT remained commerical in operation, airing ads which were exclusively read “live” by the on-air announcers.
WFMT outlasted classical competitors WEFM 99.5, WXFM 105.9, WFMQ 107.5, WJJD at 104.3 and WNIB 97.1 who all converted to popular formats by the 1990s. WMFT has had very high standards of technical reproduction, featured minimal audio processing, and its reputation encouraged Sony to partner with it in introducing CDs to air in a 1982 demonstration, DAT in 1987, and MiniDisc in 1992. They were an early pioneer of Dolby SR noise reduction being employed on their wired Studio to Transmitter link, whose location at the time made it impractical to reach via line-of-sight for a high-quality composite or dual-mono aural FM STL until the transmitter moved in 1995 to allow an all-digital path for the STL.
1952 - Magnetic reproducers commonly provide 10mV to 100mV output, tracking at 6 grams to 30 grams
1953 - Over 1,000,000 transistors were manufactured; in 1955, 3,500,000 transistors were manufactured, and by 1957, annual production had increased to 29,000,000 units. (http://semiconductormuseum.com/MuseumStore/TransistorMuseum_Brief_History_of_Early_Semiconductors.pdf)
A February 1953 ad from the Radio and Television News magazine states, “For the first time in history, Germanium Junction Transistors are commercially available...”. The CK722, dropping in price from over $20 in early 1953 to $1 in 1955, is likely the best remembered commercial germanium transistor.
1954 - The advent of the RIAA standard in 1954 simplified the reproduction of brand new records, and simplified the design of reproduction equipment. It would be mirrored worldwide.
1954 - Stereo reproduction via open-reel tape is introduced to the consumer market with 7 inch reels running at 7.5 inches per second, with the professional 1/2 track format (two channels taking up all space on the tape, meaning it only played in one direction; there was no “side B”). These will later be joined by 1/4 track (side A/side B) and 3.75 ips 1/4 track options, all of which will be superceded by the improving Philips Cassette format.
Today, a handful of labels are again offering pre-recorded tapes, often through specialty tape manufacturers, focusing on 10.5” reels, 15 ips, 1/2 track. Typical prices are $300 for an album or $450 for a ‘2-LP’ set. Restored and modified open reel decks are becoming more popular among high-end consumers.
1954 - Acoustic Research, Inc. (“AR”) was founded in 1954 by Edgar Villchur and his student Henry Kloss. The AR-1 was the first commercially-successful speaker using the acoustic suspension principle which allowed extended low-frequencies from a smaller-than-expected enclosure.
The primary disadvantage was one of low efficiency, which was offset by the higher-powered tube amplifiers coming of age at this time, such as the Dynaco Mark II and other units using the Ultra-Linear output transformer winding, which provided more than double the output power versus the previous standard of a triode or triode-connected push-pull pair.
1954 - RCA publishes its famous Passive Equalization Phono Preamp design using a 7025 (an enhanced 12AX7) in its Receiving Tube Manual. The circuit retains popularity among DIY’ers and hobbyists, and is often referred to simply as the “RCA Tube Manual circuit”.
1955 - Heathkit PAM-1 preamp is introduced using the EF86 pentode input tube, bearing notable similarly to the Quad and other British preamps which also preferred the EF86 input. The PAM-1 is a companion to the W3M and W4M monoblock amplifiers which are ultralinear Williamson designs.
1955 - Saul Marantz introduces the Marantz Consolette Preamp - it is the first (mono) version of what would become the famous Marantz 7 stereo preamp in 1958.
1955 - McIntosh C8 Preamp (refined version of prior C108 preamp). One of the most complex commercial preamps dedicated to catering for the myriad of pre-RIAA equalization standards. Still considered a standard by many record collectors today.
1955 – Public demonstration of the world’s first all-transistor hifi system. http://www.ieeeghn.org/wiki/index.php/First-Hand:The_World's_First_Transistor_Hi-Fi_System. Richard (Dick) Shea of GE demonstrated his team’s 1-watt, 5-transistor (2N43s) ‘integrated amplifier’ containing a preamp, integrated volume control and power amplifier stage, all contained in a compact aluminum prototype box. This box, together with a turntable containing a GE VR-1 Variable Reluctance cartridge, was perched incongruously atop a 12” Altec Model 601 Loudspeaker in ported wooden enclosure at the front stage lip of the auditorium.
After his presentation, Dick advised the audience to be quiet, and cued up the record. The high-sensitivity loudspeaker and clean 1W of audio power filled the Irvine Auditorium in Philadelphia with the opening music of a Bach chorus, and thunderous applause ensued. One presumes that the GE team drove down the 4 hours from their Syracuse facility to the IEEE conference in Philadelphia hand-carrying gear in tow. This system had been specially designed as one integrated unit from cartridge to loudspeaker with RIAA equalization and maximally linear operation of all transistors. well before any commercially-available solutions existed, and, indeed, before most participants at the conference believed that it could be done.
The relatively poor transistors of the time meant that they were generally relegated to small-signal applications such as hearing aids (R. Shea was hearing-impaired, and his team also created the world’s first transistorized hearing aid).
Regarding high sensitivity of loudspeakers, and what the 1-watt above would do, installers of theater systems in the 1950s and 1960s would reportedly often connect the headphone output of a portable AM radio with about 0.25W (250mW) output to one or more large speakers like the Altec VOTT (Voice of the Theater) and fill a movie theater with very loud and dynamic sound, for their own background music and enjoyment while conducting needed installation procedures and setup.
1955 – A portable-oriented 3 transistor preamp is published by R. Shea in the first (1955) edition of ‘Transistor Audio Amplifiers’. It used 2N43 and 2N44 transistors and was different somewhat from the one publicly demonstrated, and mentioned above. This first edition of the book was supported by grants from the US Air Force Army Signal Corps and the Navy Bureau of Ships, so it’s not surprising the focus is on portable applications. A preamp design for 10mV input for 1 volt output, 60K input impedance, with F1 and F2 turnovers on RIAA curve and F3 taken care of by cartridge loading is specified, with noise at -50dB at 50 cycles, and 64dB overall gain.
1956 - Dynaco PAM-1 is introduced, the mono predecessor to the more well-known PAS-2 and PAS-3.
1956 - H.C. Lin publishes his design for a direct-coupled Transistor Power Amp using Germanium transistors. It used no interstage or output transformers and appeared simple and elegant. Lin worked for General Electric who promoted it. The design appeared, uncredited, in the GE Transistor Manual starting in 1957 (Third Edition) with enhancements in subsequent editions. Bootstrapping of the VAS was added in 1958 and the bias network gained more stability. Frequency compensation was lessened as the semiconductor complement improved.
RCA promoted a competing design using an interstage transformer-coupled driver for germanium PNP 2N2147 outputs, series stacked for higher power models (what Threshold called “Cascoded” in their 800A of 1975). This design was adopted by Fisher as well as Heathkit in 1963 for their new solid state offerings. While the RCA interstage transformer design arguably offered greater bias stability that the HC Lin, reliability still remained poor, with occasional repeated failures.
Designers converted the original Lin topology (which specified 2 Ge PNP outs, the only type practical in 1956) as soon as more reliable Silicon power transistors appeared in the mid-60s. Sherwood, for example, stuck with vacuum tubes in their S-5000 series until going all-silicon-transistor with their S-9900 and S-9500 in 1965. Dynaco followed, bringing out their famous Stereo 120 silicon solid state amp in 1966, based on a Si NPN HC Lin topology, when its only preamp was still a vacuum tube unit (the new PAS-3X, modified to drive the lower input impedance of a transistor amplifier.) Their all-transistor silicon PAT-4 preamp was introduced in 1967, wowing reviewers including JGH of Stereophile (at least for a few months).
Outfitted with the new, expensive, but relatively reliable silicon NPN output transistors, the H.C. Lin topology would begin to rule supreme into the mid-1970s, easily displacing the RCA Germanium interstage design. The last widely-known interstage transformer design was likely Radio Shack’s 1971 Realistic STA-120C receiver, replaced by the STA-120D in 1972, the D version went “full-HC-Lin” and dispensed with the transformer.
The Lin design, while initially “quasi-complementary” by necessity, was enhanced twice. I.M. Shaw in July 1969 added a power diode in series with the lower half collector (functionally the emitter). Later that year, Peter Baxandall (of feedback Tone Control fame) in December implemented a more elegant arrangement by use of a diode, resistor and capacitor in series with the lower driver. Both were published in the British “Electronics and Wireless World” magazine. Either method substantially improved the crossover characteristics and lessened crossover distortion.
By 1969, RCA was recommending a modified HC Lin topology with a differential BJT input stage, and dispensing with the traditional output coupling capacitor. This topology was used in the Harman Kardon Citation 12 and many other designs throughout the 1970s. RCA incorporated the “Baxandall Diode” improvement by 1971, but manufacturers were slower to adopt. The 1971 30-watt Marantz 1060, Sherwood 7100 series and many others didn’t add the diode until the mid 1970s or sometimes at all. As PNP Silicon power transistors became available, true complemenary outputs were added, negating the need for a Baxandall diode, and were almost always coupled with a differential (un-degenerated) BJT input stage, direct coupled outputs and a bipolar power supply.
Some manufacturers, such as NAIM and Bendini, stuck with Quasi-Complementary into the 1980s and 1990s, believing that NPN and PNP matching was not as good as a Baxandall-diode-assisted all-NPN design. Cost consideration may have also played a part, as PNP Si outputs remained more expensive for many years.
This topology - differential BJT input, single VAS, a complementary driver stage, and complementary outputs - remains the most common discrete solid stage design in production today. Enhancements were added such as active current sourcing replacing the bootstrapped VAS of the 1950s, current mirrors, and others. See Audio Magazine, June 1988, “An Informal History of Solid State Amplifiers” by Dan Sweeney. It contains an interesting overview of development from the mid 1960s to the mid 1980s with representative schematics.
1956 – Fisher introduces the first Hi-Fi transistor product (TR1 preamp). This battery-powered preamp used 2N109s, which was one of the first transistors to be made available commercially by RCA (in 1955) with an apparent focus on high-quality audio. http://web.archive.org/web/20080221051908/http://users.arczip.com/rmcgarra2/fisher.html
JGH himself reviewed the unit in the December 1956 issue of High Fidelity magazine. http://web.archive.org/web/20070208044956/http://users.arczip.com/rmcgarra2/fisher_review_12-56.gif
J. Gordon Holt discussed his first audition of the TR-1 in Stereophile Vol. 7, No,. 3, p. 4 (spring 1984) in 1958. “I remember being completely bowled over by the sound. It did some things far better than any tubed component I had heard, and I was so impressed by those things that I did not at first detect the things the TR-1 was doing worse than tubes. I am confident that I would run screaming from the room were I to listen to it today, though a lot of its shortcomings were doubtless being masked by complementary shortcomings in the loudspeakers of that day.”
Specs were 20Hz to 20kHz +/-1dB, noise -60dB (re: 2mV in via low impedance cartridge). It also offered microphone settings. Advertised as “No microphonics and zero hum”. It employed capacitor coupling between all three stages and used active and passive feedback and a 13.5 to 15V rail, battery powered or from a remote AC supply. JGH continued: “Soon the TR-1 was joined in a proliferation of more sophisticated and better sounding solid-state components, some of which did many things well enough that I, and the audio community at large, was confidently predicting that Lee Deforest’s little glass bottle, the clumsy old vacuum tube with its finite life and its wasteful generation of heat, would be dead and gone within 10 years (e.g. by 1968). Twenty-five years later, the vacuum tube is not only still with us, it is enjoying a renaissance among audio perfectionists.” said J. Gordon Holt in 1984. The front cover read “Stereophile’s Almost All-Tube Issue”.
JGH ultimately had a similar experience in reviewing the Dynaco Stereo 120 amp solid state amp in 1966, the Dynaco PAT-4 solid state preamp in 1967, and the Sony CDP-101 CD player in 1983; all received rave reviews at the time which were later toned down, then discredited, as the new and heretofore unknown distortions became known and able to be described by reviewers and listeners.
Darlington Labs after a long search acquired one of these units in January 2024.
1957 - The Tektronix 575 Transistor Curve tracer is released and is current in the Tek catalog until 1971. Approximately 14,000 units are produced. This unit itself contains 40 vacuum tubes and two germanium TO-3 transistors. Darlington Labs uses two restored models in our FET and semiconductor matching process, in addition to other methods of quantification, preselection and binning. The build quality is exemplary, including extensive ceramic turrets and silver plating. It serves as a daily reminder of U.S. historical design ingenuity and build quality.
The top section header of the “Future Products” tab of our website is the interior of one of our Tek 575s. The background of the top section of the “Our Technology” tab of our website shows a panel separator (the two TO-3 Germanium transistors are on the other side, the panel being used as a heat sink) and the turret construction is visible below as you scroll down the page.
1957 – Quad ESL speaker is released by Peter Walker (later referred to as the ESL-57, and later modified as the ESL-63)..
1957 – In late 1957, the Stereo LP is introduced with Westrex 45/45 cutting system. “The first trickle of stereo discs at the end of 1957 became a flood of them during 1958. By 1962, they were commonplace.” See Stereophile Vol. 8 No. 6, ‘Letters’, p. 16, where J. Gordon Holt gives a personal account of stereo LP release dates and availability.
1958 - The BBC publishes a research paper that defines the following goal for monaural reproduction:
“It is assumed that the ideal to be aimed at in the design of a sound reproducing system is realism, i.e. that the listener should be able to imagine himself to be in the presence of the original source of sound. There is, of course, scope for legitimate experiment in the processing of the reproduced signals in an endeavour to improve on nature, however, realism, or as near an approach to it as may be possible, ought surely to be regarded as the normal condition and avoidable departures from this state, while justified upon occasion, should not be allowed to become a permanent feature of the system.”
1958 - Higher quality magnetic reproducers for the new Stereo LP discs operate with substantially less tracking force than their mono predecessors. Stereo LPs now contained vertical as well as horizontal modulation, and sufficient compliance was needed to handle the vertical motion. The new system chosen was called the ‘Westrex 45-45’, referring to degrees in angle of cut in the groove wall, not the speed of rotation; where each stereo channel was placed on an opposite groove wall.
This system was roughly compatible with mono record players, although excessive use of mono cartridges would tend to wear the difference component more greatly than the sum component, creating “swishy” distortion when later played on a true stereo cartridge and playback system.
1958 - The GE VR-II cartridge is introduced, which was designed to be an improvement to the RPX Variable Reluctance cartridge. This was the "broadcast standard" in the US in the 60's until the Stanton 500's series took over. A detractor of the GE notes, “at which point, vinyl everywhere breathed a sigh of relief...especially the first few seconds which were always cued to death.”
1958 - GE publishes their 3-Transistor magnetic phono preamp (whose basic design continues thru the 1959, 1962, and 1964 Transistor manuals) featuring the new GE PNP low-noise germanium 2N508 transistor in a direct-coupled feedback arrangement with 2N322 acting as an output follower. A 5K potentiometer serves as the emitter load and output level control.
1958 - A hybrid Transistor/Tube Preamp GE design is published by Dwight Jones of General Electric using a 2N508 input with a 12AX7 second stage. One version of the Sherwood S-1000 amplifier used a similar circuit.
1958 - The Marantz Model 7 preamp is introduced. It is still revered today and widely copied in DIY form. An extremely similar circuit appears in Audio Research’s SP-3 in 1973, and launches Conrad Johnson in 1977 with the PV-1 (sans tone controls). The Valve Amplification Company (VAC) introduced a hand built reissue of Marantz 7 in 1996.
1959 - Altec Lansing replaces their 604D model with the 605A Duplex at about the same price. The 605 features measured specifications which were superior to the latest prior version of the 604, and the 605As were used at EMI Abbey Road to record many of the Beatles' LPs. A senior Motown engineer reports this facility used them as monitors for many years.
However, some studios found the sound of the 605 different from the standard 604s that there was some market backlash; given the dynamics of the marketplace, this increased market acceptance of competitor JBL. Capitol Records replaced their Altec 604s with JBL D50 Monitors. Altec later re-introduced the 604 as the "E" version Super Duplex (the 605A was the first referred to as Duplex). The market for large studio monitors was beginning to diversify at least in the US.
1959 - McIntosh introduces their C-11 preamplifier.
1959 – Harman Kardon Citation I preamp, with 9 tubes, is introduced. Feedback is used around each stage, with passive RIAA in between, designed by noted engineer Stu Hegeman who favored wide bandwidth via video pentodes, output stage pentode operation and significant quantities of feedback. The Citation IV, a downscaled, more inexpensive version of the Citation I, used many of the same concepts.
1959 - Harmon Kardon introduces the Citation II power amplifier, a wide-bandwidth design. The Citation II sold for $159 in kit form or $229 assembled.
1959 - The Lafayette KT-600 stereo tube preamp is introduced, principally designed by Stu Hegeman, finished up by Aaron Newman of Lafayette. The LT-30 (KT-300 as a kit) was a mono version of the same unit. Supposedly Stu was having issues finishing up the details on the KT-600 Preamp and KT-550 pair, and they turned to an internal engineer (Stu was working as a consultant) could finish the job and they could start recouping their investment. Hegeman ended up consultng for H/K and designed the famous Citation I-V, and solid-state Citation A preamp (1962) and Citation B power amp (1964).
1959 - Fisher phono preamp tube designs employ a grounded cathode (i.e. contact bias) in the second stage of their 12AX7 circuit and thereby eliminate one cathode bypass capacitor.
1959 - Dynaco Stereo 70 amplifier, a 35W/channel tube design using EL34 outputs in ultralinear, driven by a 6AN8 combination pentode driver/triode phase splitter, is introduced.
1959 - The Marantz Model 8 stereo amplifier debuts.
1959 - Fairchild develops a planar semiconductor production process, which is used first for high reliability transistors including the first planar unit (2N1613) suitable for audio. This process is later used for monolithic ICs, being instrumental in ushering in the continued miniaturization of electronics.
1960 - McIntosh’s C-20 preamp is introduced, lasting three years in the line. It is the predecessor to the C22, which will come out in 1963 and last until 1972.
1960 - The Marantz Model 9 monophonic amplifier is introduced
1960 – In January 1960, Fairchild announced commercial release of the first silicon planar transistor technology with the 2N1613 device (which is available in quantity in April 1960). This technology was rapidly adopted by most other transistor manufacturers.
1960 – The Sherwood S-5000-II integrated amplifier is an example of a phono preamp featuring combined active and passive RIAA EQ. Their arrangement, with their use appearing to date back to 1953, employs feedback around the second tube gain stage, where it implement the 3180uS/318uS correction (50Hz pole and 500Hz zero). The 75uS (2122Hz) rolloff is accomplished passively at the output. It uses two sections of a 12AX7, each with 270K plate resistors. Republished in Richard Shea, Amplifier Handbook 1966, McGraw Hill, p. 17-35 to 17-38.
The long-lived Tim DeParavicini 3 x 12AX7 EAR 834P design uses a similar shunt feedback to V1, the drawback being the high-impedance summing junction, which potentially can be quite susceptible to noise and hum pickup, often self-induced from a nearby unshielded power transformer. Some Chinese clones of the EAR 834 (for example, the LIttle Bear T-10 which we examined) included a 10 foot black ground wire and tell you to “clip it onto a nearby metal heating radiator.” That one didn’t even include a fuse in the AC line. Buyer beware.
1961 - Marantz releases the revised Marantz 8B stereo power amplifier, featuring upgraded output transformers of Sidney Smith’s own design and a sophisticated global feedback system with multiple capacitive trimmers to assure symmetrical HF response in the two halves of the phase splitter. Art Dudley auditioned a stock, working model in 2012 for Stereophile.
1961 - Lafayette introduces the KT-550 power amplifier, largely designed by Stu Hegeman, with a similar driver circuit to the unique Harman Kardon Citation II power amplifier.
1961 - E. R. Wigan, of the BBC Research Department, publishes a two-part article in Electronic Technology that builds upon the prior work of D.E.L. Shorter, also of the BBC, in 1949. Wigan’s new paper (split over two months) further confirms that the human ear’s response to higher-order harmonics is significantly increased. This means that proper and scientifically-valid testing of distortion residuals must be “weighted” according to the ear’s natural response. Shorter proposed an N^4 weighting, a second-order function which means that harmonics above the second must be increased in value by 12dB for each doubling of frequency, before summing the result in a weighted average. The prior recommendation from the Radio Manufacturers Association in 1937 proposed an N^2 function, or 6dB increase per octave. Shorter in 1949 evaluated the 1937 proposal, found it directionally accurate but incomplete, and enhanced it as indicated above.
Unfortunately, despite more than 87 years of scientific testing, certain self-styled “authorities” such as Audio Science Review, flatly refuse to either acknowledge, or perhaps even understand, the intricacies involved with audio testing that will be a genuine help to the consumer. The ASR SINAD factor is completely unweighted, and despite our laying out the case in great detail (and bringing receipts) in the summer of 2021, in a review of our original MM-5, the proprietor of said website remains either uninterested, uninformed, or perhaps monetarily-biased, because the units that do well in his testing are almost all high-feedback, op-amp based, conventional designs that are heavily advertised by ‘deep pockets’ large audio firms. some of whom appear to be financially incentivized via his site.
1961 - Stereo FM radio broadcasting commences in the U.S in June, using the Zenith/GE system which is backward compatible with conventional monaural broadcasting. It features full channel separation across the entire frequency range (>20dB, in comparison to competing systems, one of which is reminiscent of joint-stereo MPEG encoders and only encoded difference information in the low frequency and midrange, but not treble).
It is later adopted in Canada and Mexico with similar specs as the U.S.A, and in Europe with 50uS pre- and de-emphasis, rather than the 75uS used in North America.
This will pose a particular problem for fringe area listeners as the stereo system, compatible though it is, is 23dB noisier in stereo than mono when tuners are not pushed deep into high-RF-signal quieting. Balanced against that often-cited issue by stereo reviewers is the practical consideration that the new system continues to allow co-existing 57 KC and 69 KC SCA subcarriers—often background music or ”storecasting” for commercial establishments—which effectively pay the heat, lights and electric bills at many fledgling FM stations. FM didn’t become widely profitable until into the 1970s, and indeed, top 40 continued to be played on AM into the early 1990s (helped out partially by AM Stereo).
Detractors of the Zenith/GE FM system would be wary to remember that with another system requiring SCA to be abandoned to accommodate stereo, the FM band itself may have failed, as did the original 42-50MC FM Band.
This noisy fringe issue will eventually contribute to demands for increased modulation through sophisticated compressors, limiters and more accurate stereo generators. The idea being that with higher effective modulation, the inevitable background hiss will be less prominent. This difference will become more troublesome for 75uS regions as music gains greater high frequency content. Europe with its 50uS pre-and de-emphasis curve will be less affected.
Robert Orban will pioneer innovative ways to deal with the issue beginning with his Orban Optimod 8000 system in 1975. This is an upgrade by some to the recently-released Durroughs DAP-310 tri-band processor or the CBS Volumax and Audimax processors feeding the line level input of the external stereo generator, with their overshoot-generating 19kHz sharp filters causing the overall modulation level to be lowered about 3dB in order to keep the overshoots from the exciter’s 19kHz sharp-cutoff low-pass-filter (needed to prevent aliasing with the 19kHz FM pilot, similar to the brick-wall digital filters used in digital A/Ds) within the FCC-mandated 100% modulation limit.
The 8000A gained an average of 3dB greater total modulation for an FM station by using a phase-compensated 19kHz filter, and integrating the stereo generator with the limiter, to allow direct connection to the transmitter - bypassing unneeded line-level transformers and the typical non-phase-compenated, ‘ringing’ exciter 19K filter. It rapidly becomes a major-market standard.
Orban’s 1980 design of the Optimod 8100A used a patented distortion-cancelled clipper, which added another 2dB of loudness. The total of 5dB greater volume above the noise spelled the end of interest in Dolby FM, which was expensive, somewhat sonically incompatible, troublesome for the home listener to calibrate, and not widely available, if at all, in mobile radios, where it would have particularly been a benefit.
Automatic blend-to-mono circuitry, which is reliant on integrated circuits, would be two decades in the future. One notable attempt at improving fringe area reception, after Dolby FM had failed, occured in 1987, where the CBS CX noise reduction system of the early 80s (used on a few LPs and many Laserdiscs) was repurposed to become ‘FMX’, which purported to improve the fringe reception in the same way that dbx MTS stereo did for television in 1982. Unfortunately it dramatically increased multipath interference, as discovered in testing, and was quickly shelved.
A classical FM station just north of our facilities in Boston was instrumental in conducting FCC trials for the current FM stereo system, in combination with equipment manufacturer H. H. Scott. The station was entrusted via estate to remain playing classical music in perpetuity after the founders death, but once his trusted assistant also passed away, the station was then sold to a for-profit company. WGBH-FM in Boston shelved their long-standing classical-music format in 2009, moving to NPR talk-radio, and subsequently transferred their classical music over to this FM station which they purchased and again turned non-commercial. We will note that the station’s audio quality improved dramatically as soon as WGBH engineers took ahold of the plant. However, its output power, coverage and reach is dramatically smaller than WGBH’s main signal.
1961 - Acoustic Research (‘AR’) releases their first turntable, a manual unit with unusually high performance for the price. Its belt-drive, suspended-subchassis design will go on to inspire countless similar units including Linn. The turntable will remain available for many years.
1962 – GE revises their 3-transistor phono preamp design with NPN Silicon transistors. Now using a 2N2049 or 2N1983 input, 2N635A second stage, and a 2N1304 emitter follower output, this design produced 55dB S/N (GE 1962 Transistor manual, p. 139) using an +18V supply.
With all of these designs, the necessary input capacitor contributes to VLF phase shift. While these designs are direct coupled from Q1 to Q2, there is an electrolytic bypassing Q2’s emitter at audio frequencies, in order to develop DC feedback to the first stage.
In broadcasting, it is well known that in order to peak uncertainty, or “bounce”, to less than a few tenths of a dB, extended low frequency response is needed, down to 0.15Hz (or 100X lower than the lowest used frequency). Otherwise low frequency phase shift will distort the waveform and cause loss of modulation when peaks are set to 100%.
This may be one additional reason why tubes were often preferred for an input stage – their inherently high input impedance enabled them to be directly coupled to the input cartridge, with no time constant from the presence of an input capacitor. FETs can, in some cases, be used similarly, but these were rare in commercial practice.
Darlington Labs J-FET phono inputs are directly coupled, with no LF time constant present.
1962 - Harmon Kardon introduces their Citation A, a Germanium-transistor-based high-end full-function preamplifier. Stewart Hegeman, Murray Barlowe and the Citation Engineering Group are credited with the design. It is based on a master chassis and plug-in circuit cards, based on glass-epoxy boards with computer-type connectors. A 1963 Journal of the Audio Engineering Society details the design, which includes 34dB of DC and AC feedback in each gain block. A special loop on each card deals with thermal tracking and leakage problems in the Ge transistors. Notably, it also features passive RIAA EQ and regulated power supplies with a +20V, +10V and -10V rail, with individual isolation between circuit cards.
1962 – October – J. Gordon Holt founds Stereophile Magazine. The background of this story is found in the front editorial of Stereophile Dec. 1993 (Vol. 16 No. 12, featuring ‘The Mighty CAT’ (SL-1 preamplifier) on the front cover.
1963 - Marantz C22 preamp is introduced, an update to the earlier C20. Some commentators report this as similar to the Marantz 7. While true in general, it differs in some important but subtle ways. Overall, there was substantial similarity between manufacturers of 2 and 3-tube 12AX7 style phono preamps from Marantz, McIntosh, Dynaco, Heathkit, Sherwood, Fisher, Scott, and others. Manufacturers tended to have their own twists and unique details, however. Minor but potentially important revisions were made between models and are far too numerous to detail here. The C-22 was sold from July 1963 to 1972 and moved over 6,000 units.
1963 - Germanium Transistor power amplifiers with RCA 2N2147 stacked and driver transformers are widely used by Fisher, Heathkit and others.
1964 - Harman Kardon introduces the Citation B, a 40W per channel all-silicon power amplifier, with all-NPN outputs, rated for 150V. Military and space-grade parts abound, although the power supply is completely unregulated, unlike the companion Citation A preamp. Possibly the only commercially-available solid-state power amplifier with a user-adjustable front-panel biasing setup (via preset screwdriver adjustments and calibrated by a large front-panel VU meter). It reminds one of the mid-1970s industrial look of top-of-the-line Audio Research power amplifiers. The Citation B did not appear to sell well, and is believed to be one of the rarest ‘serious’ models offered by a US manufacturer.
1964 – Semiconductor Process Engineer Dave Talbert and Robert Wildlar develop the uA702 op amp at Fairchild Semiconductor, was the first monolithic IC to be a widely-used commercial product. The first known published IC phono preamp circuit that we have found based on this IC is in 1969. The 1967 Fairchild Linear IC Applications Handbook provides an excellent overview.
1964 – GE publishes an all-NPN Silicon transistor-based RIAA phono preamplifier. It features a 2N2925 input, 2N2924 2nd stage 2N3397 or 2N2924 or 2N2925. 22V at 3.5mA. Reprinted in Radio Electronics magazine (with modern transistor types but otherwise unchanged) in an early 1990s Ray Marston article.
Specs: 6mV in for 1V out, 0.15% THD at 1V (2dBu) which is 15dB below clipping (at +17dBu). +/-1dB from 40K to 12K with Shure M77 Dynetic cartridge. 72dB S/N A-wtd. Separately, a tape playback amp with 2N3391A is shown which is specified at 57dB S/N unweighted, 66dB weighted. Darlington Labs auditioned this design in 1996, finding that it substantially outperformed a professional broadcast preamplifier. See GE Transistor Manual, Seventh Edition, 1964, p. 257.
1964 - McIntosh C24 Transistor Preamp is introduced. This will be sold simultaneously with the existing tube C22 through 1968.
1964 - Cycles per Second (CPS) is gradually replaced by Hz (for Hertz, an electrical pioneer and inventor).
1964 – Bob Wildar develops the uA709 op amp at Danelectro which is subsequently bought by Fairchild Semiconductor. PS Audio’s first product in 1974 will be 2 x 709C per channel phono preamp with passive RIAA. Selling commenced with an ad in the April 1975 AUDIO magazine. PS Audio will move to discrete transistors by 1979 with the PS-II phono preamp. 1967’s Fairchild Linear IC Applications Handbook has an excellent writeup on the uA709 and the uA702.
1965 - Leak’s Stereo 30 Integrated Amp (Germanium version) is introduced. It will be updated shortly to the Leak Stereo 30 Plus (Silicon); Leak Stereo 70; Leak Delta 30; and Leak Delta 70. The Delta 70 will continue through 1978. In 2020, Leak introduced a new Stereo 130 integrated amplifier which contains styling cues from these original models.
1965 - Sherwood goes “all-Silcon” with their S-9900 and S-9500 Silicon Transistor integrated amplifiers. Styled similarly to the S-5000 tube line, the Phono preamps feature NPN Silicon transistors and capacitive coupling between the stages. and high impedance direct biasing. Transistors are individually selected and binned for Hfe (current gain).
Three stages of revisions appear in the service manuals, but they prove quite reliable (we restored a 1967 sample in 2017 which needed only a complete electrolytic recapping — all original semiconductors being intact, functional and quiet, even though traces were pulling off of the early etched PCBs). The power amplifier is essentially a H.C. Lin design with an apparent anti-latching circuit for the bottom side of the output totem pole, which also may improve the crossover characteristic. The Baxandall Diode or other crossover mitigation would be three to four years in the future.
1965 - Silicon transistor technology continued to replace germanium transistor technology for most commercial, industrial and military uses – based on the excellent performance characteristics (relative to prior Germanium transistors), device consistency and manufacturability of silicon epitaxial planar process.
1966 - Neumann uses the new uA709 op-amp in their SG-66 disc cutting control amplifier of their their new VMS-66 lathe, potentially the first widely-known audio use of the chip. We note that a number of high-end separate mastering studios considered the Neumann drive electronics package to be less-excellent that the Neumann cutter heads themselves, and many would custom-modify and “home-brew’ or ‘hotrod’ their own signal path.
1966 - Dynaco Stereo 120 Power Amp (with PAS-3X with lower output impedance) is introduced.
1966 - Marantz 7T, a transistorized version of the Marantz 7, is introduced and the tube unit is discontinued. The Marantz is extremely well reviewed. Owners are reported to be less enthusiastic, with some returning their 7T models and wanting the old tubed 7 units back. Sid Smith, designer, is reported to say that he thought the 7T was the more successful design.
This will potentially foreshadow 1976’s introduction of Audio Research’s first solid-state SP-4 preamp. Salesmen at dealers anectdotally reported many newly-sold SP-4s coming back in the first week for return, many having been compared with the aural memory of the earlier AR SP-3 tubed unit which was sold from 1973. Reviewers (mostly of the Subjective-type) weren’t as enthusiastic for the SP-4, by comparison, as the earlier (mostly Objectivist-type reviewers) were for the Marantz 7T.
In retrospect, this was the era when the J-FET was becoming practical and Motorola, one of the J-FET manufacturers, had themselves in March 1966 published a passive J-FET phono preamp based on the RCA 1954 design. We surmise that the reason a J-FET was not used in the phono input stage of the 7T was due to the design efforts having begun years earlier, concerns over component availability, variability, price, or parameter change over time. The 7T topology is clever and well-executed, but in our opinion, is let down by the conventional bipolar junction transistor input, running on a very small current. In fact, germanium PNP transistors like the 2N508 produced lower noise than silicon NPN but would have been seen as old-fashioned and unreliable (probably especially by Marantz) in 1966. See the famous mid-1970s ad about a Marantz receiver than survived a house fire and was featured in an ad.
Fisher follows suit, updating its tube line to the 500-T and 400-T, most using the RCA interstage transformer Germanium circuit.
Reliability of the Germanium transistor models was reported to be mediocre to downright catastrophic, by sources that were involved in the industry. This led to an opening for the burgeoning Japanese manufacturers, who had been perfecting solid-state technology for a number of years, to move solid state away from small-signal radios and tape recorders into the integrated amplifier and receiver market, particularly coinciding with introduction of reliable silicon NPN power transistors around 1965. The Japanese components could be sold through American dealers for a much greater mark-up, and the Japanese were also reportedly willing to “push money under the table” for salesman cash incentives, as well as significant magazine advertising as well as potentially cash payments to magazine reviewers.
1966 - The KLH Model 9, designed by Arthur Janzten and released in 1960, is reviewed in Stereophile’s June issue. It will become JGH’s reference. He summarized the KLH Nine in October 1968’s Stereophile (Vol.2 No.10) in the following way: This is probably the most nearly perfect loudspeaker we have tested until this time.”
1966 - Arthur Bailey publishes an excellent 3 silicon transistor preamp in Wireless World as a companion to the “High Performance Transistor Amplifier”, (December 1966). It contains a unique, high performance DC level-shift between the first and second stages, with an emitter follower output and optional sharp cutoff LF rumble filter.
1967 - Popular Electronics December 1967 issue features the ‘Lil Tiger’ fully complementary HC-Lin-style amplifier with the newly introduced Motorola MJ470 and MJ480 complementary silicon planar output transistors in TO-126 style case. 22 Watts of Music Power is advertised, and the domestic cat sitting atop the enclosure looks both A) slightly menacing and B) quite pleased.
1967 - The Dynaco PAT-4 preamp is introduced. The phono stage runs on 20V, features 2 silicon NPN transistors and is a feedback design patterned after the PAS-3X.
1967 - Robert Widlar moves to Danelectro, which is quickly bought by National Semiconductor (from Fairchild Semiconductor) and, now working again for his old boss whom he left in a dispute over compensation, but both at a different company, creates the LM101, LM201 and LM301 series op amp. It is a two-stage design, with active loading on the first stage. This enables high gain with only two basic stages (plus a unity gain output). It requires an external compensation capacitor (usually 30pF) and this is because the National Semi process cannot accommodate an on-chip capacitor. A competitor, Fairchild, will later do so the next year as the uA741.
1967 – In June, The Beatles' Sgt. Pepper's Lonely Hearts Club Band is one of the first significant non-classical LPs to be released in stereo, helping trigger the second boom in hi-fi component sales, in which the major Japanese brands dominate the mass market.
1967 – Doug Sax, Sherwood Sax, and Lincoln Mayorga open The Mastering Lab in California. With Doug at the controls, and the all-tube signal chain designed by Sherwood, the new mastering lab will master The Doors debut album in December 1967. The operation goes on to become one of the major players in the industry, mastering 20% of the Billboard 100 by 1972. They were also famous for Sheffield Lab audiophile recordings, producing many quality Direct to Disc LPs in the 1970s and early 1980s. Sheffield Lab started with Scully lathes and Neumann cutterheads, driven by a customized EICO HF-89 power amplifier. It ran until Doug’s death from cancer in April of 2015. Much of the gear was purchased and moved to the US midwest for Chad Kassem’s operation.
1968 - Arnie Nudell, Cary Christie and John Ulrick found the speaker company Infinity, whose first location will be Arnie Nudell’s garage. The Servo-Statik-1 will be one of the first products to launch, to be reviewed in Stereophile in December 1970.
1968 – Dave Fullagar at Fairchild Semiconductor designs and releases the uA741 op amp, which is very closely related to the Fairchild LM101 series, but including the 30pF compensation cap on the chip, because the Fairchild process is able to accommodate the cap. The widely-sourced 741 became the first widely-used op amp.
However, with its internal compensation (which allowed unity gain connection without oscillation) meant that it had a unity gain frequency of only 0.5MHz. The resultant 741 slew rate limiting caused the inability to cleanly pass a 20kHz sine wave at full output. However, because of the spectral distribution of audio (the total spectral power tends to roll off above approximately 2K) entire mixers were built with 741s in the early 1970s, and most user complaints centered on a relatively high noise level, rather than audibly-distorted high frequencies.
1968 - Radford introduces one of the first commercially-well-known Fully-Complementary-Symmetry amplifier using the NPN/PNP pair of Motorola MJ470 and MJ480 outputs. They pair it with a fully Regulated power supply using an rare thyristor (SCR)-controlled-regulator topology. In 1970, the Audio Amateur republishes a Wireless World article with a unit featuring a lightly simplified circuitry as well as a more straightforward power supply. Note our later entry under 1995 for the Woodside SC-26 preamp, as Woodside was a follow-on company from Radford, created by ex-Radford staff. To our knowledge, the reformed Woodside concentrated on vacuum-tube electronics and did not resurrect their early solid-state entries, which in our opinion, may have still had technical merit, if not a certain level of “cache”, in the 1990’s marketplace.
1968 - In October, Lee Hulko and Joe Paschek found the mastering studio Sterling Sound in NYC. It had a late-model Neumann VMS-66 (1966 being the year of it’s introduction, a tradition continued by Neumann for their future VMS-70, VMS-80 and DMM-capable VMS-82) lathe with the newest heilium-cooled Neumann SX-68 cutter head, driven by new Neumann high-power solid state amplifiers. A Neumann mastering console with equalization and dynamics control was combined with a recent Telefunken M10A tape deck which itself had a ‘preview head’. This head was physically before the main tape playback head, and fed the lathe's analog computer, which controlled groove pitch and depth based on loudness, frequency, and phase information from the musical signal. Preview heads and variable groove spacing was introduced by Neumann with an all-tube unit in 1956.
Variable spacing can be easily seen by the eye looking at the groove spacing on a wide-dynamic-range LP. It was particularly beneficial for use with the first stereo LPs in 1958. Bob Ludwig, the famed mastering engineer, left the mastering division of A&R Records and joined Sterling after he was loaned an SX-68 for demo by the Neumann distributor, but A&R wouldn’t buy one for him to keep. Bob realized that no matter how good his work, it would no longer be as competitive as other studios if those studios had the “secret weapon” SX-68. The famous LZ II pressing would be cut by Bob at Stirling the next year, and copies with the “RL” in the leadout groove fetch four figures on auctions sites currently, in good condition.
1968 – Stereophile physically downsizes to a smaller digest-format style as of 1968: Vol.2 No.8, Issue No.20, "Spring (1)," This smaller format will continue for the next 25 years through December 1993 when it moves back to full-size.
1969 – Popular Electronics magazine author Daniel Meyer publishes a discrete J-FET phono preamp article in May using Texas Instruments TIS-58 J-FETs on a 35V power supply rail, with 100K Drain and 22K Source resistor (in parallel with a large cap) together with an unbypassed resistor to set AC gain.
1969 - In August, the Woodstock Music and Arts Festival in upstate New York will feature a custom PA designed by Bill Hanley of Hanley Sound, a Boston firm. It will be powered by McIntosh tube and solid state power amplifiers, including the recently-introduced 350W tube monoblock (MI-350). Selected bass cabinets and other accessories eventually made their way to South Africa, continuing to be used commercially into the mid 1980s.
In the August 1989 BAS Speaker (the newsletter for the Boston Audio Society, available free online) there is a fascinating first-hand account from Bill who was a guest at the audio society. The 2020 book about Hanley Sound goes into substantially more detail about Hanley’s long career and exploits both before and after his most-famous gig.