Tuesday, September 22, 2009

A (Not So) Brief History of Electric Guitar Pickups

Without pickups, electric guitars won’t make a sound, but do most of us guitar enthusiasts know the origins of this iconic invention?

By: Ringo Bones

The electric guitar pickup has been around for quite some time now that – believe it or not – it even was invented before the electric guitar! And unlike that fraudulent Wikipedia entry – reminiscent of that David Beckham being an 18th Century Chinese goalkeeper – single coil electric guitar pickups were not invented by Slash of Guns N’ Roses. The patent application for a single coil electric guitar pickup appeared as early as 1926. Although no particular person was credited in the single coil pickup’s invention; it was probably John Dopyera – a Slovak émigré to America and inventor of the dobro – probably invented the single coil electric guitar pickup. After a growing demand by Jazz guitarist at that time to find a six-string that can be played as loud as a grand piano, or loud enough not to be drowned out by a typical Big Band’s brass horn section. Which is kind of strange given that Richard Wagner would have been the most likely one to demand such an instrument to be played in his gigs at Bayreuth – or is it Gustav Mahler?

It wasn’t until the 1930s when single coil pickups began to be used in the musical instrument we now know today as the electric guitar. Rickenbacker International Corporation of Santa Ana, California – founded by Adolph Rickenbacher and George Beauchamp – were credited to be the first ones to make a production run of the electric guitar in 1932 utilizing those single coil pickups that were first patented in 1926. Although Les Paul was more famously known as the electric guitar’s inventor because he holds the most number of patents that enable us to play and appreciate more of the electric guitar. Like the multi track recording technique.

Single coil electric guitar pickups are renowned for their tonal sparkle and clarity, but are notorious for picking up noise signals - Particularly those from power transformers or motors operating from the 60-Hz alternating current. Worse still, single coil pickups propensity for stray EMF noise pickup gets worse when comes near to electrical devices reliant on “mangling” the 60-Hz sinusoidal waveform in order to supply them with a high-voltage DC - Like those Budweiser neon signs populating most club stage venues being lit up by solid-state multiplier circuits. Not to mention the 15.75-KHz horizontal sweep frequency generated by the fly-back transformer of CRT-based computer monitors - which makes single coil pickups buzz like a 10,000-strong hive of angry yellowjackets. More bad news to those recording their guitar tracks with a desktop PC-based hard disk recording system. All spell bad news to those who fell in love to the ping and shimmer of a vintage Fender Stratocaster.

Back in 1954, Seth E. Lover – a design engineer for both Fender and Gibson – designed what is now commonly known as the humbucking pick up. Humbucking pickups are composed of two single coil pickups connected in series and out-of-phase with each other. Or the end of winding terminal of one single coil pickup is connected to the end of winding terminal of another single coil pickup (or the start of winding terminal – whichever produces the loudest sound, better tonality, hum cancellation etc.). This pickup is simply a double-coil pickup interconnected so that the signals introduced by extraneous noise such as hum are cancelled out while retaining the signals introduced by vibrating strings. Although not perfect in canceling hum – though it is perfect for canceling that pesky 15.75-KHz horizontal sweep fly-back transformer noise of TV monitors – the performance in terms of signal-to-noise ratio improved significantly.

As a rule, single coil pickups are much louder than their humbucker counterparts. And although most – if not all – Fender Strats made from the late 1950s onwards has a dual-pickup setting where the reverse-wound / reverse-polarity middle pickup becomes a de facto humbucker pickup – with the requisite hum cancellation – by setting the switch to positions 2 and 4. It still can’t match the open tonality of the accompanying single coil pickups. Humbucking pickups produce a sound which most veteran guitarists describe as “phasoid” and has a midrange hump that can manifest itself as a honk when used with the requisite vintage tube-based amplification – not that there’s anything wrong with it though. Just ask those legions of Gibson Les Paul and Marshall Amplifier owners.

Fortunately, there had been advances in single coil pickup design since Seth E. Lover invented the humbucking pickup in 1954. Although most of it is primarily “tone-driven” not noise cancellation. Like those Lace Sensor pickups by Actodyne General Incorporated - which the company also holds patents for the US Patent # 4,809,578 with their Lace Micro-Matrix Comb technology. Made famous by the guitar legend Jeff Beck in his custom Fender Strat, Lace Sensors are revered by guitarists around the world as the Holy Grail of electric guitar single coil pickup technology - Although there are others who swear by Full-Frequency single coil pickups by Evans – which were made famous by Queensrÿche during the late 1980s and early 1990s. But for those who prefer “scientifically verifiable improvements”, they gravitate towards EMG pickups with their active electronics that prevents all of the harmful effects of external noise signals -although they are seen as anathema by those who grew up on vintage pickups sporting post-WW2 era Alnico magnets.

At present, electric guitar pickup designs that capitalize on hum and noise cancellation while retaining the vintage sound of Rock N’ Roll are touted as the most advanced pickups in the market today. Like the latest models of DiMarzio’s Virtual Vintage passive replacement pickups that uses transformer winding technology – probably from Nikola Tesla’s old notes – that damps noise signals while retaining that traditional Fender Stratocaster-style spank. But others still clung on to their real vintage pickups like those original Alnico magnet equipped Fender-style single coil pickups and P-90 pickups. Although none of today’s major electric guitar pickup manufacturers had offered solutions to minimize and eliminate noise coming from cellular phone / mobile phones and their transmitting towers (and Internet Modem noise?).

Monday, September 7, 2009

Should We Be Using Op-Amps for Our Guitar Effects Fuzz Boxes

Although 99.9% of guitar effects / fuzz stomp boxes now use op-amp chips, if great tone is the goal, is it a question of should we be using op-amps instead of can?

By: Ringo Bones

If you are old – or rich - enough to experience the hi-fi wonders of the 1990s when 500 US dollar CD players began to sound as good as entry-level vinyl LP replay. Then it is more than likely that you heard the hype of the “tone enhancing” effects of premium-grade op-amp chips. After choosing to emulate my past experiments of using op-amp integrated circuit chips with audiophile credentials in guitar stomp boxes for ultimate tone. You could probably end up asking yourself should we – rather than can – be using op-amp based guitar stomp boxes? Before proceeding to the long-winded narration of my experiences with “boutique” op-amps, here’s a primer on what happens when an electric guitar is played.

Whenever you pluck the strings of your electric guitar or strum a chord, the guitar’s signal varies from a few millivolts to as high as 1 volt peak-to-peak depending upon how hard the strings are plucked or strummed or the kind of pick-up used. The electric guitar’s output signal when viewed on an oscilloscope is characterized by a sharp rise to a maximum value and then diminishes rapidly. This makes a tube-based electric guitar amplifier with a good vacuum tube pre-amp section or a fuzz box – i.e. distortion effects stomp box – a necessity if you want a pleasingly sustained tone from your electric guitar.

During the 1960s – when Jimi Hendrix and countless other guitarists – began experimenting with electric guitar effects boxes, most of these fuzz boxes were made with discrete small-signal transistors and germanium signal diodes. This provided those effect’s signature smooth tone and a long sustain compared to more recent op-amp chip based fuzz boxes. When the venerable 741 op-amp (LM741 op-amp and related variants) became available in 1966 after being made by most IC manufacturers, it was tried as an active amplifying device in guitar fuzz boxes to see how it compares to discrete small-signal transistors.

Sadly, many found out that the rate of decay is much faster than a conventional guitar fuzz box that uses discrete transistors. Op-amp based guitar fuzz boxes only became popular in the 1980s during the rise of high-decibel Heavy Metal music when the harsh sound of the op-amp based electric guitar effect fuzz box became de rigueur. Not to mention the silicon signal diodes that replaced the almost extinct germanium signal diodes only made the op-amp based fuzz boxes sound even harsher and Death Metal ready. Thus making the tonal versatility of a Marshall amp bristling with EL34 tubes really worth the very steep price premium.

By this time you could be asking yourself, if the “hi-fi world” can get away with using those gorgeously toned Electro-Harmonix reissued tubes, why can the “guitar world” benefit from using op-amps with audiophile credentials to improve the tone of their fuzz boxes? The short answer is music performance recordings, either from vinyl or CD (the two leading “state of the art” domestic mediums) has a vastly more complicated signal waveform in comparison to what a typical electric guitar produces no matter how beautifully played. Audiophile-grade JFET input op-amps like the AD845, LF356, or high slew rate types like the LM318 might be the cheapest way to make Iron Maiden or Veruca Salt sound as if they were playing right in your bedroom. But these premium grade op-amps don’t do squat – tone wise - when used in guitar fuzz boxes.

Audiophile-grade op-amps only shine when supplied with a well-regulated plus / minus 15 volts split power supply. You can’t tell the difference if you use them in place of your bog-standard LM741 found in your Hyper-Metal fuzz box being supplied by a 9-volt PP3 battery. And if you ever try to shoehorn a switching-mode power supply to power these audiophile-grade op-amps from a 9-volt PP3 in the hopes of a 12AX7 based preamplifier on the cheap. I tried it and it doesn’t work. Or it does play, but tone-wise you’re better off taking the all-tube route. An overwhelming number of fuzz boxes today are even using op-amps with much lower specs than the venerable LM741 op-amp. Good luck trying to find guitar stomp / fuzz boxes using high slew rate types like the LM318.

As it was in the 1960s as it is today, tube amps are still the best way to get the ultimate fuzz tone effects. If the contrary is true, how come I still see thirty-something housewives wearing a Lunachicks T-shirt hunched over their 1965 Fender Twin with soldering iron in one hand and a 6L6 tube in another? In truth, fuzz circuits do mirror the “quality hierarchy” found in the hi-fi world namely tubes are the best, followed by discrete transistors, and op-amps being the budget sector. Even though a skillful designer can still create great sounding gear using the right op-amp in the proper application.