Leslie Organ Speaker: The Ultimate Electric Guitar Speaker?

Even though the product is primarily intended to be used in early electric church organs, is the Leslie Organ Speaker the ultimate electric guitar speaker?

By: Ringo Bones 

Maybe it is its built-in paper coned woofer that is the primary reason for its sweet as honey sounds, or the rotating horn being rotated by a surprisingly silent motor system, or maybe the built-in vacuum tube based amplifier – which resembles like either a Leak TL12 Point One or a Quad II – that makes it the ultimate electric guitar speaker and amplifier. Either way, why can’t today’s electric guitar amplifier / speaker manufacturers offer something similar or even something better than the original Leslie Organ Speaker?

The often used model of the Leslie Organ Speaker by electric guitar players is the Leslie Model 145 Organ Speaker. It was used as a recording session electric guitar amplifier when the late guitar legend Jimi Hendrix recorded the studio version of Little Wing during the late 1960s. And despite his preference of using Fender guitars an Marshall amplifiers during his live performances, Jimi Hendrix prefer to use low-powered 1950s era Fender tweed amplifiers connected to dual cone / whizzer cone equipped 15-inch musical instrument speakers and Mosrite electric guitars with Bigsby tremolo bars. 

All guitarists have the US Navy researcher Donald Leslie (any relation to John Leslie?) to be eternally grateful to because it was he who designed the first generation of Leslie Organ Speakers equipped with a silent motor system to rotate the middle frequency-high frequency horn speaker to make its sound to fill a rather large church space despite its built in vacuum tube based amplifier is only capable of producing 12 watts or so. The good thing about the Leslie Model 145 Organ Speaker is that its built in vacuum tube amplifier can easily be modified – with just as easily as equipping it with a ¼-inch electric guitar input jack – to be able to accept and play an electric guitar. And by the way, other famous legendary guitarists who use the Leslie Organ Speakers when playing and recording electric guitar were Stevie Ray Vaughan and Pink Floyd’s David Gilmour.  

Even though there are digital guitar effects processors today that allow you to be able to replicate the sound of a classic Leslie Organ Speaker, they usually fall short in replicating the sweetness and the sound-staging capabilities of the real thing – like the iconic Leslie Model 145 Organ Speaker if one wants to mimic Hendrix’s Little Wing riff as he originally recorded it. Sadly, most Leslie Organ Speakers – especially the Leslie Model 145 Organ Speaker – is too low powered sound wise to be used in live stadium rock settings.

As a “solution” to the Leslie Organ Speaker’s inability to play loud enough in stadium rock concert settings, Pink Floyd guitarist David Gilmour tried using Maestro Rover units. Even though they are clearly much louder than the Leslies in studio recording session settings, the Maestro Rover revolving / rotating full range electric guitar speakers were still deemed not loud enough for stadium rock concert application settings. Then Phil Taylor and Paul Leader designed something that provided Gilmour with that distinctive “Leslie” effect that was adequately loud enough for stadium rock concert use – thus the Doppolas were born.  The Doppolas are rotating speakers - la Leslie Model 145 Organ Speaker - except that the Doppolas are equipped with two six inch 100-watt drivers making them loud enough for live stadium rock concert use. Looks like today’s digital audio processing modeling technology for electric guitar effects processing use is still not advanced enough to replicate that rotating and whooshing Leslie Organ Speaker tone. 

Can Nuvistors Be Used As An Electric Guitar Preamplifier?

Even though they are for all intents and purposes just ultra small vacuum tubes that were discontinued back in the late 1971, why do electric guitar preamplifier manufacturers never made one using nuvistors? 

By: Ringo Bones 

Even though nuvistors were briefly reintroduced back into the consumer electronic marketplace when Musical Fidelity CEO and Classically trained clarinetists Antony Michaelson released the Nu-Vista Pre-Amplifier back in August 1998 and the Nu-Vista 300 hybrid power amplifier before Michaelson got too busy playing with the Michelangelo Chamber Orchestra while being recorded by Tony Faulkner, these ultra-miniature vacuum tubes were sadly largely discontinued when the 1970s rolled around. It was largely Michaelson’s fortunate bulk-purchase of a stash of unused Mullard 6CW4 high-mu triode nuvistors that somewhat saved the largely forgotten electronic devices from total obscurity. 

Nuvistors are a type of miniature vacuum tube introduced by RCA into the world’s consumer electronic markets back in 1959 though Mullard also produced it under license from RCA during the 1960s. The technology behind nuvisors became possible after the 8-year long research of Dr. Harvey C. Rentschler allowed him to conclude that atoms of gas – like oxygen, hydrogen or nitrogen – actually dissolve in the crystalline structure of some metals just as salt dissolves in water. These gas particles “loosen” the electrons in this structure, causing them to be emitted from the metal more readily as heat is applied. Dr. Rentschler’s findings were later published in the July 1943 issue of the Scientific American magazine. And such phenomena lead to the development of smaller and more efficient vacuum tubes that eventually lead to the development of the nuvistor. 

Nuvistors are thimble shaped but are actually 5 to 10 times smaller than an actual thimble and much smaller than conventional preamplifier vacuum tubes that were manufactured after World War II. Nuvistor triodes and a few tetrode types were made. The newfangled ultra-miniature vacuum tubes were made entirely of metal and ceramic. 

During its heyday, manufacturing nuvistors require special equipment since there is no intubation system to pump gases out of its ultra miniature metal envelope. Instead, the entire structure is assembled, inserted into its metal envelope, sealed and processed in a large vacuum chamber with simple robotic devices. Even though the “vacuum” inside a typical thermionic vacuum tube is 50,000 times less rarefied than the Horsehead Nebula, the vacuum chamber used to mass produce nuvistors must have been a technological manufacturing tour-de-force of its day to be able to maintain a “vacuum” of about 0.000001 Torr or millimeters of mercury – a level required for a high quality consumer electronics grade vacuum tube. By way of comparison, normal atmospheric pressure at sea level is 760 Torr or 760 millimeters of mercury. 

One of the most popular types of nuvistor during the electronic device’s heyday was the RCA 6DS4 Nuvistor triode vacuum tube. It measures 20-mm high and 11-mm in diameter. During much of the 1960s, nuvistors were among the highest performing small-signal receiving tube. They feature excellent VHF and UHF performance plus lower noise figures than early point-contact germanium transistors. Nuvistors are widely used throughout the 1960s in television sets beginning with RCA’s “New Vista” line of color TV sets in 1961 with the CTC-11 chassis and top-of-the-line radio and high fidelity equipment’s RF sections. Nuvistors competed with the solid-state revolution of the 1960s along with General Electric’s Compactron and probably held it at bay for a few years. RCA discontinued the use of nuvistors in their television tuners by late 1971. 

One famed application of nuvistors during the electronic device’s heyday was in the Ampex MR-70 open reel tape recorder for studio use – it was a costly studio tape recorder whose entire electronics section was based on nuvistors. Another application of the very small nuvistor vacuum tube was in the studio-grade microphone of the 1960s – the famed AKG / Norelco C12a, which employed the 7586 medium-mu triode nuvistor – the first nuvistor released on the market. It was later found out that with minor circuit modifications, nuvistors could sufficiently serve as an “ad-hoc” replacement of the then obsolete and no longer produced in the 1960s Telefunken VF14 tube used in the famed Neumann U47 studio microphone.

Given that the “roadie / guitar tech” who first made those fuzz-boxes / stomp boxes for the famed 1960s guitar-god Jimi Hendrix used to be Jimi’s regular TV repairman, it is quite a mystery why no examples of do-it-yourself nuvistor based electric guitar preamplifiers or effects / fuzz boxes are in existence. The famed Dallas Arbiter Fuzz Pedal used 1960s era germanium small signal transistors – imagine if some enterprising TV repairman familiar with the working of nuvistors experimented replacing the early germanium trannies with one. 

Technically, nuvistors can operate up to 110 volts DC and as low as 30 volts DC so powering one with a 9-volt PP-3 could be an engineering challenge back in the 1960s, though today’s high-voltage lithium polymer batteries used in Airsoft gaming applications could easily supply the 30-volt DC anode voltage required for nuvistor fuzz pedal operation. A typical nuvistor has an amplification factor or mu of 64 – comparable to the 12AX7 preamp tube’s 100, but  nuvistors have a much stronger transconductance or gm compared to the 12AX7 preamp tube. So if today’s top Russian vacuum tube manufacturers like Svetlana or Sovtek / Electro Harmonix  or those in Mainland China decides to remanufacture nuvistors, it would probably end up as electric guitar preamplifiers and fuzz / distortion effects pedals and boxes. 

Dr. Harvey C. Rentschler: Unsung Hero Of The Post world War II Electric Guitar Revolution?

Even though his work is largely devoted to energy efficient UV lamps for zapping dangerous microbes, does Dr. Harvey c. Rentschler’s other discoveries pave way for the post World War II electric guitar playing revolution and Rock N’ Roll?

By: Ringo Bones 

Unlike Albert Einstein, Dr. Harvey C. Rentschler never became a household name for much of the 20^th Century, and yet without his important discoveries, contemporary popular music and electric guitar playing after World War II would have been very different. And music recording via mixing desk like those in the iconic Sun and Abbey Road studios would never had existed without his discoveries and the world would also had never heard of Elvis Presley or The Beatles without his discoveries that led to the more efficient, smaller and cheaper thermionic vacuum tubes. 

When he told his findings to a meeting of the American Physical Society which was then published in the July 1943 issue of the Scientific American magazine, Dr. Harvey C. Rentschler told the attendees about what he had found out in experiments which he conducted eight years before. It led him to conclude that atoms of gas – oxygen, hydrogen or nitrogen – actually dissolve in the crystalline structure of some metals just as salt dissolves in water. These gas particles then “loosen” the electrons in this structure, causing them to be emitted from the metal more readily when heat is applied. This explanation, according to Dr. Rentschler, should result in longer-lasting thermionic vacuum tubes and accomplish important savings to the size and number of batteries, generators and other apparatus needed to supply the filament power. 

Without discovering the then unknown principles that led to the advanced thermionic vacuum tube design principles that led to smaller, more energy efficient thermionic vacuum tubes by Dr. Rentschler, Rock N’ Roll would never had existed and electric guitar playing would be a rather expensive hobby dominated by large inefficient vacuum tubes and ultra-expensive gear the average kid from the 1950s could never afford. Dr. Jim Marshall would probably use something else entirely when he developed his now iconic Marshall Amplifier back in 1962. Thanks to Dr. Harvey C. Rentschler, we have 12AX7 preamplifier tubes that can operate with anode voltages as low as 45 volts DC – making the now 48 Volt DC phantom power de rigueur in the modern post World War II recording studio when Les Paul invented it. 

Paper Coned Loudspeakers: Electric Guitar Speakers?

Despite advances in hi-fi loudspeaker cone materials in the 1990s, does paper coned loudspeaker still mean electric guitar speakers like Heinz means catsup? 

By: Ringo Bones 

Since the heyday of Les Paul to recent concerts of Yngwie Malmsteen or Joe Satriani that still attract hoards of electric guitar music fans, it seems like the paper coned loudspeaker – especially ones with a whizzer cone and seems to have dated back to the early 1920s – had been exerting a stranglehold on the electrical musical instrument industry as the only musical instrument loudspeaker suitable for electric guitar playing use. But how did such a self-made paper coned loudspeaker empire came to reign over the electric guitar playing world? 

Guitar virtuoso Yngwie Malmsteen may have recently endorsed paper coned loudspeakers as the only ones suitable for serious electric guitar use. A recent “tone testament” by Malmsteen on the paper coned Celestion G12T-75 speaker shows his praise for its fluidity and praises its violin-like tone sustain and feel that compliments his style of guitar playing only reinforces the facts – and preconceived notions -  surrounding paper coned loudspeakers use in the electric guitar playing world. Boutique Marshall electric guitar amplifiers that use their exclusive paper coned Sheffield speakers still further reinforces the perception even more. 

Enthusiasts in the audiophile world who are heavily into rock music are not helping much either. Retro-looking hi-fi loudspeaker systems made in the 1990s like that by Lowther that looks like it dates from the early 1920s with its horn-loaded paper coned alnico-magnet equipped loudspeaker with a whizzer cone are often praised for its realistic rendition of late 1980s electric guitar heavy hair metal era heavy metal music. Given that electric guitar and hi-fi speaker system for playback both use paper coned loudspeakers - it is safe to assume, and in actuality, that both seem to compliment each other seamlessly. 

Hi-fi reviewers can never be accused of being miserly in their praise for paper coned loudspeakers and their righteous reproduction of electric guitar based heavy metal music. Hi-Fi World magazine reviewer Douglas Floyd-Douglass stated in the October 1995 issue of the magazine on his review of the Wharfedale Valdus 500 that: “Lead and rhythm guitars sound excellent, which I’d attribute to the paper cones – a favorite choice used in hundreds of famous electric guitar amplifiers. Their partiality to rock was further emphasized by Richie Blackmore’s scorching lead and powerful backing on ‘Rainbow’s Power’ and Miss Mistreated’.” And high-end hi-fi manufacturer Yamamura Churchill further reinforces the mystique surrounding paper coned hi-fi loudspeakers with the use of rare paper from Japan made from select bamboo pulp as its “magic ingredient”. Given the dominance of paper coned loudspeakers in the electric guitar and hi-fi world, how does the alternative cone materials fare? 

Around the late 1980s, an electric bass guitar amplification manufacturing firm named Hartke Systems had used metal coned – as in aluminum coned - loudspeakers to go with their electric bass guitar amplifiers. Around that time, Hartke Systems electric bass guitar amplification systems were used by Aerosmith bassist Tom Hamilton among others and many of its users say that Hartke’s aluminum coned speakers provide a big, clear dynamic sound on top with maximum punch on the bottom, though nobody tested it for heavily distorted loud electric guitar use for obvious reasons. 

Part of what makes paper coned electric guitar loudspeaker and vacuum tube amp system like Marshall’s have a “musically desirable” tone is due to the fact that paper coned loudspeakers act – according to the laws of acoustics – like a bandpass filter that works between the audio frequency of 75-Hz to around 6,000-Hz. Especially with a distorted electric guitar tone, high frequencies produced by an overdriven tube amp that sounds bad to our ears – and can destroy tweeters - are brought down to desirably pleasing levels via the paper coned loudspeakers inherent inability to produce very high audio frequencies. While the paper coned loudspeaker’s inability to produce lower bass frequencies below 75-Hz – as it is most often mounted in an open baffle configuration in electric guitar applications – filter the “reactance thumps” between the electric guitar strings and the pickups that can easily overload dynamic microphones in live stage miking situations. 

I’ve also experienced using first hand a mineral-filled polypropylene coned loudspeaker into electric guitar use back in the late 1980s and all I can say is – it was the quackiest mess I’ve ever heard. Unless you are doing a rock concert scene for a sequel of Howard The Duck or a quacky, parody version of Mötley Crüe’s Kickstart My Heart, mineral-filled polypropylene coned loudspeakers are only suitable for domestic hi-fi use, as they have been since the mid 1970s, when they are not played too loud. It seems like paper coned loudspeakers are the only ones that distorts in a musically consonant manner when played at excruciatingly loud levels. 

Germanium Transistors: The Best For Electric Guitar Distortion Pedals?

Even though 9-volt battery powered electric guitar distortion pedals that use germanium transistors are the best ones around, how come these types are still a rarity?

By: Ringo Bones 

Every self-respecting electric guitar wielding musician with experience knows that germanium transistor based 9-volt battery powered electric guitar distortion pedals are the best there is – as in those 21^st Century era reissues of Dallas Arbiter Fuzz Face pedals now starting to appear again in musical instrument stores. Even though such pedals are not that expensive in terms of quality guitar accessories – at around 150 to 300 US dollars each – why then are germanium transistor based electric guitar distortion pedals rarer than their silicon transistor based or even integrated circuit / IC operational amplifier based counterparts? 

The reality is, germanium transistors – which are the first of its type mass produced for commercial applications during the 1950s onto the early 1960s are not very stable and somewhat difficult to manufacture compared to more modern silicon transistors and semiconductor devices. Even during the start of the 1960s where the relatively affordable prices of transistorized radios started to capture the market previously dominated by vacuum tube based radios, germanium transistors are very hard to mass produce with consistent parameter quality. Electronic enthusiasts “toying” with germanium transistors during the early 1960s have noticed first hand that they have very variable gain, leakage, noise and overall tone – even germanium transistors manufactured from the same batch. 

The inherent parameter variability of germanium transistors means resistor values selected for proper AC and DC biasing, feedback, gain and stability that worked fine on one functioning circuit – like an electric guitar distortion pedal – will have to be “tweaked” (use a slightly higher or lower resistor value) to make one sound as close as possible to the previously finished circuit – even from germanium transistors of the same batch. Thus making the manufacture of germanium transistor based electric guitar distortion pedals a somewhat very labor intensive endeavor. 

Although, one can make silicon transistor or even I.C. op-amp based electric guitar distortion pedals approach the sound of germanium transistor types by using germanium signal clipping diodes in the feedback loop, purists still prefer the tone of the authentic germanium transistor based electric guitar distortion pedal, especially if your hi-fi system is righteous enough to realistically reproduce the guitar intro of Iron Maiden’s Two Minutes To Midnight – as in the original vinyl or the mid 1990s era Sony Super Bit Mapped CD reissue. The Sony Super Bit Mapped mastering even brought out the “germanium signature noise” on the very start of this iconic Iron Maiden track.