Wednesday, December 26, 2012

Does Your Car’s High Fidelity System Have an Alternator Load Dump Filter?

Common sense dictates that your car’s electrical system never rises above 13.8 volts DC, but is it equipped with an alternator load dump filter nonetheless?

By: Ringo Bones 

It seems like 1992 was only yesterday when “mainstream” electrical and electronic engineers where dumbfounded on why their car audio / car high fidelity system gave up the ghost after only eight months or so. Well, these tenured “mainstream” engineers seems to have failed to research one of the nasties that’s been lurking inside every automotive electrical system called alternator load dump and how it could shorten the lives of solid-state integrated circuit based electronics of a typical car stereo / car hi-fi system. 

An alternator load dump occurs when the load to which a generator is delivering current to is abruptly disconnected, causing a brief but relatively high spike in output voltage from the generator. In a typical car’s alternator-car battery system, this applies to disconnecting the car battery while it is being charged by the alternator. Ever since automotive technicians equipped themselves with electrical measuring equipment, it has been found out that during alternator load dump situations, voltage measurements can be as high as 87 to 120 volts and may take up to 400 milliseconds to go back to 13.8 volts. 

Given that spec sheets of automotive solid-state integrated circuit based power amplifiers - like the AN214 - that operate in the 12-volt DC environment of the car can only handle a power supply voltage spike of only 48 volts for up to 500 milliseconds or so, even a “brief” alternator load dump that more often than not exceeds this voltage is enough to shorten the lives of solid-state integrated circuit based car hi-fi. Is there a solution to protect one’s car hi-fi from the inherently hostile automotive electrical system? 

There are commercially made / ready made alternator load dump filter boxes available out there and due to the prevailing ignorance of a majority of do-it-yourself electronic enthusiasts of what constitutes such filters, they are priced as if they are made of gold by unscrupulous manufacturers. But a reliable alternator load dump filter can easily be made by using unused parts lying around in a typical DIY electronic enthusiast’s electronics workbench. 

A typical alternator load dump filter consists of an inductor-capacitor or L-C filter. Usually a 100 to 300 milliHenry inductor and a 1,000 microfarad 16 volt electrolytic capacitor whose negative terminal is connected to the car’s negative ground. To further save costs, one can even wind his or her own 300 milliHenry inductor using a 30-foot piece of number 20 AWG magnet wire into a ½ - inch plastic bobbin with a ½ - inch E-I silicon steel core to increase its inductance. One can even over-engineer the alternator load dump filter by using a 10,000 microfarad 35 volt capacitor for the L-C filter. This type of filter can also has the benefit of further minimize the hum to inaudibility of an AN214 IC based amplifier connected to a 12-volt full wave center tap power supply plugged into a typical home’s 220-volt 60-Hz ac current. 

Tuesday, December 18, 2012

High Fidelity Versus Public Address Systems: Insurmountable Kultur Kampf?

Even though both can play back recorded music when fed with an audio signal, is there a preexisting insurmountable Kultur Kampf between home high fidelity systems and PA systems?

By: Ringo Bones

It may be down to one’s ears’ aesthetics but almost all audiophiles – even new recruits – have readily perceived the preexisting and insurmountable Kultur Kampf between domestic high fidelity systems and Public Address systems used in high capacity stadium rock concerts. Even though pro audio public address speaker systems manufacturers have yet to manufacture a stadium rock PA system speaker whose sound quality is as beguiling that of a 200 US dollar entry level hi-fi loudspeaker for domestic use, are the two worlds forever destined in a “never the twain shall meet” stand-offish behavior?

My very own “epiphany” on questioning why PA systems never sound as good as well-shorted entry-level budget domestic high fidelity systems may seem oxymoronic to anyone uninitiated to the hi-fi world, but to hi-fi enthusiasts, the truth can be self-evident to one’s own ears. As an amateur heavy metal musician who judge “naturalness” of a heavy metal rock recording via live-in-the-studio standards, I kept on wondering till this day on why live concert PA systems and / or pro audio gear manufacturers had kept on ignoring the sound quality aspect of their PA loudspeaker rigs.

Assuming one judge the “naturalness” of the sound of a live heavy metal rock concert using the preexisting sound quality of the Public Address system loudspeakers being used, does this mean that an overdriven 200 US dollar bookshelf hi-fi loudspeakers destined for domestic use is the “natural sound” of a live heavy metal rock concert? You got to be shitting me!

Remember Stereophile magazine editor John Atkinson’s review of the Wilson X-1 Grand SLAMM hi-fi loudspeakers back in the December 1995 issue of Stereophile? Well. One of his statements on that specific review probably brought a sense of relief in me back then that I’m probably not the only one “astonished” by the sound-quality Diaspora between domestic hi-fi and pro-audio live concert PA Systems; According to Atkinson: “The bass guitar…thundered fourth from the (Wilson) speakers’ big Focal woofers in a way I had previously experienced only from live rock.” Not surprisingly, this was inevitably followed by scores of Stereophile subscribers writing in “angry letters” pointing out to John Atkinson the inherently low-fi sound quality of live concert PA systems.

Inevitably, John Atkinson issued a response on subsequent next issues of Stereophile magazine on the matter of the sound quality Kultur Kampf between domestic hi-fi rigs and PA systems that goes: “When you use a PA system to play back recordings, you are involved in a creative act, which is not what the concept of high fidelity is about. However, when recorded faithfully, the big, underdamped roar of a live bass guitar through a PA rig is just as much an authentic acoustic source as any other. It is also one that almost all hi-fi speakers, other than the big Wilsons get wrong in trying to recreate.”

Given that PA systems tend to be 5 to 10 times cheaper than their “proper” domestic high fidelity audio systems when compared in a power output per dollar basis, many had perceived Stereophile magazine editor John Atkinson’s statements about the difference between hi-fi and PA systems as nothing more than being self-serving to the whole hi-fi industry back then. But is it? Well, given that almost all hi-fi enthusiasts -including me – already possess ears that already know that there is indeed really a difference on how domestic hi-fi and the pro-audio PA system world play back music, is just makes me sad on why the two tribes can never see eye to eye when it comes to sound quality. After all, hi-fi enthusiasts go to live rock concerts too, while live concert FOH engineers also buy proper domestic hi-fi rigs.

Thursday, December 13, 2012

Open Baffle Loudspeakers: Best High Fidelity Loudspeakers?

Even though do-it-yourself hi-fi for the home started with open baffle speakers, why is it that mainstream hi-fi loudspeaker designers frown upon the very concept of it?

By: Ringo Bones

D.I.Y. high fidelity loudspeaker design books whose “self-worth” is invested upon the mathematics behind the Thiel-Small Parameters often view open-baffle hi-fi loudspeakers as “a fish out of water” due to their low bass output being 100 times less in comparison to closed-baffle box hi-fi loudspeakers optimized via Thiel-Small Parameter based mathematics. But is this really so?

Believe it or not, home D.I.Y. or do-it-yourself hi-fi as a hobby started a few years or more before the “Golden Age of Stereo” got underway in the mid 1950s. Back then, the home constructors set-up consisted of a 15-inch Tannoy Dual Concentric loudspeaker mounted in an open baffle in the corner of the listening room – or some young hobbyist’s bedroom – driven by a home built zero negative feedback single-ended triode amplifier putting out 3-watts or so. Such open-baffle hi-fi loudspeaker set-up was known for their open and natural midrange qualities that made recorded singers sounds as if they are really singing in front of you. But the higher bass output – probably the inherent “boominess” of closed-boxed loudspeakers commercially designed and manufactured around the Golden Age of Stereo and the advent of Rock n’ Roll Music probably won out in the end, relegating the open-baffle hi-fi loudspeakers by the wayside.

Surprisingly almost out of nowhere, the 1990s came and the “Western World’s” single-ended triode amplifier revival, which again resurrected the charmed qualities of the open-baffle speakers. Given the “irresistible” mid-band qualities of open baffle speakers, why do mainstream hi-fi loudspeaker manufacturers view open-baffle hi-fi loudspeakers – bass volume aside - with such a “low opinion”?

Sadly, despite rigorous scrutiny of every annual convention of the Audio Engineering Society, adherents of the closed box design parameters based on the white papers of A.N. Thiel and Richard Small are not quite entirely truthful in telling the D.I.Y. hi-fi hobbyists about the shortcomings of closed-box hi-fi loudspeakers – ported or not. The cabinet that is placed around the rear of a “conventional” closed-box hi-fi loudspeaker drive unit to contain back radiation – and to boost low frequency bass response below 100-Hz or so – imposes a low-frequency limit upon bass reproduction. More often than not, closed-box hi-fi loudspeakers’ low frequency limits just roll-off too high or too early to allow low notes of properly recorded bass-based musical instruments like acoustic upright double bass and full-sized pipe organs to be played properly with convincing fidelity in a typical listening room.

Closed-box loudspeakers also compromises perceived bass quality by making it sound lumpy, boomy, uneven or just dry and anemic in comparison to the recorded acoustical music event. The panel resonance enclosing the rear of a typical closed-box hi-fi loudspeaker also adds mid-band coloration that makes singers’ voices sound “electronic”, whilst box echoes add whoomph, chestiness and a megaphone effect. Add in the cost of the woodwork, its weight and volume and you have a severely bad idea staring you in the face.

And believe it or not, it gets worse. In my years of actual usage of conventional closed-box hi-fi loudspeakers, the least understood but perhaps the most significant drawback of the closed-box hi-fi loudspeaker: it is a monopole (while open-baffle hi-fi loudspeakers are dipoles in its sound radiation) that cannot be properly matched into an enclosed space – i.e. your listening room / bedroom / hobby-room in other words. All that pulling and pushing of closed box hi-fi loudspeakers in the left and right corner of your listening room to get good – or just maybe “bearable” – bass performance from them is down to this property.

Believe it or not – according to first-hand acclaim to seasoned hi-fi hobbyists – the best hi-fi loudspeaker of all time to them is the Quad ESL-63 Electrostatic, which not surprisingly, is an open-baffle design. So does the naturalness and vocal qualities of the Quad ESL-63 be transferred to the “inherently uncouth” dynamic magnetic coil loudspeakers? In a word, yes, if you mount one in an open baffle and use zero negative feedback single-ended triode amplifier designs to drive them.       

Friday, December 7, 2012

Was Stereophonic Recording Invented During World War II?

Given the widely published assumption of the subject at hand, does anyone ever wonder how many audiophiles know that stereo recording was actually introduced during the height of World War II?

By: Ringo Bones

Contrary to popular belief, stereophonic or stereo recording wasn’t introduced or even invented during the mid 1950s during the beginnings of the “Golden Age of Stereo”, but in actuality, during the “dark days of World War II – in Nazi era Germany of all places! Given that – from a historical perspective – war intends to initiate the strongest impetus of progress in scientific and technological developments, the how’s and why’s of the development of stereophonic recording / stereophonic sound in Nazi era Germany seems to elude the interests of tenured historians until a few years after the fall of the Berlin Wall.

The Haus des Rundfunks (Broadcast House) in Berlin, which later became known as Das Berlin Funkhaus, the radio station building of the Reichs-Rundfunk Gessellschaft or RRG when Adolf Hitler got elected as Chancellor of Germany - that was inaugurated back in 1931 was the first ever building in Europe specifically designed for recording and broadcasting. Part of the structure was then devoted to the Grosser Senesaal – a large hall from which symphony orchestra concerts frequently were transmitted live. By 1942, after some years of development by the Reichs-Rundfunk-Gessellschaft (RRG) technicians, the AEG/Magnetophon R22 magnetic tape recorder for recording and broadcasting was pressed into service.

Sound quality wise, the AEG/Magnetophon R22 magnetic tape recorder for recording and broadcasting was an audio engineering tour-de-force during its day because during the height of World War II, the Allies thought the Nazis had successfully developed a very high speed aircraft because live broadcasts of Adolf Hitler speaking in Berlin were followed a short time later by similar broadcasts from Hamburg and Munich. Given the excellent sound fidelity – at the time – of the magnetic tape recorder used by Nazi era broadcasters at the time, the Allies were not aware – until after World War II – that they were hearing magnetic tape recordings of Adolf Hitler’s speeches – one’s at the time totally indistinguishable from live radio broadcasts.

By 1943, one of the Reichs-Rundfunk-Gessellschaft (RRG) technicians by the name of Helmut Krüger, regularly made magnetic tape recordings of symphony orchestra concerts from the Great Hall in the Berlin Broadcast House a then newly upgraded AEG magnetic tape recorder that ran at (77-cm/sec.)  in which high frequency premagnetization or a.c. bias, then recently patented by its inventor – Walter Weber, was used – affording far better performance compared to contemporary recording machines. Imagine – back in 1943 – a magnetic tape recorder with a frequency response of 50-Hz to 10,000-Hz with a dynamic range of 60-dB and a harmonic distortion of 1.5%. An audio engineering feat that American broadcasting and recording engineering firms were only able to replicate – let alone exceed – at the start of the 1950s.
The two-channel recording head upgrade to one of the AEG/Magnetophon R22 magnetic tape recorder for recording and broadcasting for the RRG was the very impetus that made Helmut Krüger “experiment” and test out his own ideas on stereophonic sound. Although, the two-channel recording heads were originally intended to reduce harmonic distortion in monophonic taping sessions by recording two channels in push-pull.

Ironically, Krüger’s “unauthorized” experimental pioneering stereophonic audio recordings were – for all intents and purposes – actually bootleg recordings! This became so because during regular monophonic with the orchestras, Krüger ran separate signal cables from his microphones and directed them to a small input console with four potentiometers and thence to his “modified” AEG stereo recorder set up in an isolated room in the Broadcast House.

Believe it or not, Krüger was using a spaced-array mike pickup – where one mike is placed to the left of the conductor, another to the right, and a third in the center – which Krüger fed to the left and right channels of the recorder. The mikes were 2 meters in front of the orchestra and 1 meter above the conductor’s head. This set-up, with slight variations, was used by Bob Fine in his Mercury recordings, by Bert Whyte in his Everest recordings during the Golden Age of Stereo of the 1950s – and even Jack Renner frequently used it until today in his Telarc recordings.

According to surviving records, by the end of World War II, Krüger had made between 200 and 300 stereophonic tape recordings – which were stored in a bunker in the Broadcast House and in several other locations. Sadly, when the Stalin-era Soviet troops occupied Berlin took shelter in the Broadcast House, almost all of the tapes there where either lost or destroyed. Of all the stereo tapes recorded by Krüger, only five of which are known to have survived and it wasn’t until 1993 during the 94th AES convention which was held in the first time in post-Cold War era Berlin were mere “civilian” audiophiles had the chance to hear the pioneering tapes first hand with their own two ears. Some had even to wait a few months later when Krüger’s pioneering stereo tape recordings were transferred to CD.

After hearing CD transfers - mastered via an early 1990s version of Sony’s Super Bit Mapping technique - of Krüger’s pioneering stereo tape recordings back in 1995. The residual tape hiss is only slightly louder than those of 1950s era stereo analog tape recordings of orchestral concerts form the mid 1950s. But what fascinated me most was their warmth and pristine tone that 1980s era fully digital recordings of Classical Music orchestras still fails to capture – even during the mid 1990s! The very first Classical Music orchestral recordings may have been made in various places during the mid 1950s at the start of the Golden Age of Stereo – but Helmut Krüger truly deserve the credit for pioneering stereophonic tape recording during the dark days of World War II. 

Tuesday, November 27, 2012

Nine Easy Steps To Fit A Turntable Cartridge

Fitting a cartridge to one’s turntable may seem to be a dying art in the hi-fi world, but does the nine easy steps shown proof that it doesn’t have to be?

By: Ringo Bones

Given that leading legal commercial digital music download sites have yet to make their music wares sound as good as the Redbook spec 16-Bit 44.1 KHz sampled CDs offered by Mobile Fidelity Sound Labs and other music outlets catering to audiophiles, it was the supposedly dead music format – in the form of the vinyl LP – that made the biggest revival in the second decade of the 21st Century. Most entry-level turntables are supplied with a cartridge already properly fitted in by the manufacturer as a complete package. But even if you happen to buy an upmarket turntable without a cartridge from a specialist hi-fi dealer, it’s very unlikely to leave the shop without one being properly fitted – especially if you’re a first time buyer or just a vinyl LP novice.

Fitting a cartridge these day and age can be considered a dying art, but careful installation is vital to ensure a good sound. Simply attaching one at random to the front of the tonearm is likely to do more harm than good, severely damaging your records; So one should follow the proper simple guide for perfect results every time. For the benefit of those who were not yet born – or were too young to remember - during the vinyl LPs heyday during the 1960s and 1970s, here’s nine easy steps to fit a vinyl LP cartridge to your newly acquired turntable.

1  )      Loosely fit the cartridge to the slotted grooves in the headshell of the tonearm. Tighten the mounting nuts and bolts, but leave enough slack to reposition the cartridge by hand.

2  )      Using a pair of tweezers - fit the four color-coded wires from the tonearm onto the appropriate color-coded pins at the rear of the cartridge.

3  )        Place the turntable on a level platform. Remove the stylus guard from the cartridge. By moving the rotating counterweight to be found at the rear of the arm, attempt to balance the cartridge, so that the arm floats freely along the horizontal plane. Set the free-spinning dial on the counterweight to zero and dial in the tracking force of the cartridge by moving the entire counterweight assembly. The tracking force is usually given in the cartridge manufacturer’s specifications and is typically between 1.5 grams and 2 grams.

4  )      Place an old record on the platter but do not set the platter spinning. Place the arm on the record. By sight, try to make the cartridge parallel to the record. Replace the arm on the rest and adjust the Vertical Tracking Angle of the cartridge by raising or lowering the pillar at the rear of the tonearm.

5  )      Adjust the overhang and tracking of the cartridge using an alignment protractor like the Polestar. Take great care to get the alignment correct, as care and attention at this point reaps great sonic rewards. Once this alignment is correct, tighten the cartridge bolts so that there is no more play and the cantilever is the only part of the cartridge that can still move. Re-check the alignment, in case it has been moved accidentally when tightening the mounting bolts.

6   )      Repeat steps 3 and 4 with greater care and attention.

7   )      Position the anti-skating dial (or adjust the hanging weight) to match the downforce of the cartridge being used.

8   )      Clear away all the tools, sit back, relax and play a record. The cartridge will normally take many hours to run in – if you are impatient, leave the cartridge tracking through a locked groove (like The Beatles’ Sergeant Pepper) for a weekend. This will help to bed the cartridge properly.

9  )      Remember that most moving magnet cartridge have a removable styli that should be replaced every two to three years, depending on use. Unfortunately, moving coil cartridges do not have removable styli and need replacing – or retipping – every two to three years or so.

Tuesday, November 20, 2012

The Microphone: High Fidelity Audio’s Final Frontier?

Though a topic more likely to be discussed and reviewed in a professional-audio magazine than in a hi-fi magazine does the microphone truly represent the final frontier in our pursuit of high fidelity sound?

By: Ringo Bones

During the Golden Age of Stereo, all audio recording equipment – even one’s destined for domestic use – were all equipped with microphone inputs to facilitate do-it-yourself recording for the audio enthusiast. And as time went on – as in around the 1980s, every audio recording gear destined for consumer/ domestic use – like hi-fi cassette tape decks and later recordable CD decks, mini disc, DCC and even DATs – seem to forego the inclusion of a microphone input as a feature. Given that virtually all music and audio recording that we will eventually be listening to our home audio gear was first captured by microphones, does the microphone truly represent the final frontier in our quest for high fidelity sound that’s indistinguishable from the one that occurs naturally? Or does existing microphone technology actually “hear” music the way our ears do?  

As stated by Stereophile magazine editor John Atkinson during the recording of their Encore CD in the January 1998 issue of their magazine, there is absolutely nothing natural about recording an acoustic event – let alone making it sound as natural as possible. As a testament as being the engineer of the scores of recordings commissioned and sold in Stereophile, Atkinson – and probably every other experienced recording engineer like him – is ready to admit that microphones don’t “hear” music in the same way that our ears do. And far from being natural, are actually chosen for their sound during sound recording / music recording.

As an example in the live Classical Music recording session world – if one is recording violins, the polar distribution of the radiated power along the axis of the violins’ top plates is such that it will overwhelm any other sounds the microphones are intended to record – so one is forced to record from any position but one along that axis. Most recording engineers choose to raise their microphones well above it since that solves other problems relating to the way microphones perceive – or “hear” - the musical instruments on a performing stage.

To cite Atkinson’s another example: Simply by using spaced omni-directional microphones, a recording engineer can create an illusion of spaciousness that may not truly exist in the recording venue. The distance between the microphones affects lateral time cues on the recording; the perception of spaciousness can be profoundly influenced simply by varying that spacing.

The rather novel microphone setup known for its unrivaled naturalness in capturing the sound of the recording venue used by John Atkinson on all of the Stereophile live music recordings made in the 1990s are compared to “multi-way speakers” by other recording engineers since the microphone setup is optimized to pickup either the lower or the upper part of the audible spectrum. They consist of two outrigger B&K omnis that were hung by their leads from the ceiling 8-feet from the stage and 13-feet from the floor. A central pair of B&K cardioid microphones was mounted on a stereo bar, and hung by their leads from the center of the ceiling 11-feet above the level of the stage and the same 8-feet back the omnis. The two cardioids were used in what is called an ORTF configuration: the mikes angled at 115-degrees, their tips spaced about 7-feet apart. The ORTF microphone technique was developed in France and gives a nicely defined soundstage, but the tonal balance lacks low-frequency bloom. The spaced omnis, on the other hand, give a wonderful sense of bloom and very accurate tonal color, but have mediocre stereo imaging. Such rather elaborate setup results in a Classical Music recording that has the sound-staging of a minimally-miked recording with a tonal naturalness of a multi-miked recording.

Unfortunately, such recording set-up that works very well in the Classical Music recording world doesn’t work very well in the heavy metal / rock world – which requires quite a different microphone, recording  and mixing set-up altogether. One of the problems is purely technical: To create a clean heavy metal / rock recording with excruciatingly loud electric guitars is extremely difficult when the guitar amps, the drum kit, and the vocalist via a loud PA system used as a monitor are all going at the same time in the same room / acoustically unisolated recording venue.

 Because the sound of the instruments leaks into the microphones used to record the sounds of the other instruments, a muddy sound is the result. Given that most bootleg heavy metal / rock concert recordings made from the 1970s and the 1980s have their sound captured by a microphone set up that resembles the one intended for minimally miked Classical Music recording, most bootleg heavy metal / rock recordings tend to be unbearably muddy sounding in comparison to their studio recorded counterparts – or a live concert recording “overseen” by a skillful FOH mixing engineer. In conclusion, we still need skillful live music recording engineers / FOH mixing engineers to make existing microphone technology sound as natural as the way our own two ears hear music – whether Classical or heavy metal rock.

Wednesday, October 3, 2012

Paraphrase Circuit: Brilliant Audio Engineering Solution?

As a product post World War II era English frugality and common sense, did the paraphrase circuit withstood the test of time as a brilliant audio engineering solution?

By: Ringo Bones

Maybe I’m just paraphrasing from Ken Kessler’s book Quad: The Closest Approach whenever I hear a fully restored Quad II amplifier and praising its sound quality made possible by an unseemly circuit design of the famed amplifier’s input section called the paraphrase circuit, or am I just looking this venerable vacuum tube based design that’s now over 70 years old with rose-tinted glasses. Anyway, what is it about Peter J. Walker’s famed paraphrase circuit that had pundits calling it a brilliant audio engineering solution cobbled up in the austere fiscal climes of post-World War II Britain that later become an iconic fixture in the Golden Age of Stereo?

A typical Peter J. Walker designed Quad II amplifier, whether original, a 1996 era Diamond Jubilee Edition or a 2004 era Classic, is a class-A push-pull monophonic amp with only two active stages. The input stage contains two EF86 miniature low noise pentode tubes, each of which is capacitor-coupled to its own output tetrode tube, but only one which – designated as tube No.1 – gets the original input signal. From there, in addition to driving its corresponding output tube, input tube No.1 drives input tube No.2 with a portion of its reverse-phase output, attenuated by some 6dB. Thus the output of the second EF86 is equal to but out of phase with the output of the first EF86 tube, and this balance is maintained through the output transformer’s primary winding, where the full music wave is put back together. This is the working description of a paraphrase circuit, used to be quite popular, arguable because it accomplished phase inversion and voltage gain in one stroke – and so allowed the designer to keep both distortion and parts cost to a minimum. By the way, the KT66 output tubes of the Quad II amplifier was later used by the late, great Dr. Jim Marshall in designing his first Marshall electric guitar amplifier – the JTM 45 Blues Breaker.

But to “audio purists” - what they see as the greatest weakness of the paraphrase circuit is that the signals at the grids of the two output tubes – and thus the two halves of the music waveform at the output transformer – are not perfectly in time and in phase with one another, given that the signal on the grid of input tube No. 2 has already been amplified, whereas the signal on the grid of input tube No.1 has not. Of course, one has to remain open to the possibility that this very technical anomaly of the paraphrase circuit resulted in some form of another a “musically consonant form of distortion” that most converts to Peter J. Walker’s Quad II amplifier just happens to find pleasing. When paired with another of Peter J. Walker’s famed designs – the Quad ESL-63 electrostatic loudspeaker – almost all hi-fi enthusiasts on the planet claim it to be the most perfect hi-fi rig money can buy.

Believe it or not, the only other power amplifier utilizing the benefits of the paraphrase circuit was designed by Kevin Hayes in his VAC PA160 mono amp which was marketed around the mid 1990s – a time when vacuum tube circuit revival in the hi-fi world was steadily gathering steam. For all intents and purposes, the VAC PA160 can be seen as a more powerful version of the 12-watt Quad II amp that uses KT88 tubes that can provide 160 watts in pentode mode, 152 watts in Ultra-Linear mode. Though quite different from the paraphrase circuit used in the Quad II, Kevin Hayes’ version uses a 6SN7 octal-based dual triode configured in a floating paraphrase phase inverter. In this arrangement, the input signal is applied to the grid of a triode acting as a common cathode amplifier, which provides one phase of the stage’s output signal. This output is resistively coupled to a common point – which for convenience, I shall call “point x”. The other triode’s plate, also resistively coupled to point x, provides the other phase of the stage’s output. A coupling capacitor from point x drives the grid of the second triode. In actuality, this amounts to a stage that provides one output phase directly and couples that output to another stage, which has 100% inverting feedback, to provide the other output phase. From a circuit purist’s standpoint – i.e. fans of single-ended triode amps – this scheme has the glaring disadvantage that the second generated phase goes through one more tube than the first generated phase. Further, the output impedance of the two phases is likely to be quite different. But given they resulted in a good sounding design, does this mean that the paraphrase circuit – born out of postwar English frugality and common sense truly had survived the test of time?   

Monday, September 10, 2012

Nude Vinyl LP Replay Cartridge: Sexy Sounds?

As the 21st Century vinyl LP revival / “craze” seems to continue for as long as it did, does it  still really matter what vinyl LP replay cartridge / needle to use? 

By: Ringo Bones 

It seems like major record labels don’t give a damn about the sound quality of their offerings anymore. I mean the last time I ever saw those “audiophile apps” that supposedly makes your digitally downloaded (legally I hope) compressed music files sound like good old vinyl LP being exhibited to an unsuspecting public was back in 2006. If a typical 21st Century audiophile wants better quality sound from the one offered by the Redbook 16-bit 44.1-KHz sampled CDs, he or she won’t likely to find it on the DVD Audio and SACD discs being stocked on mainstream record stores at the mall because these too are getting scarcer and scarcer since 2009. For a better sounding than CD prerecorded music format – vinyl LPs are still the answer, as used record stores and those weekend vinyl LP and antique stereo swap meets that typically opens after weekend scheduled Airsoft games are getting more popular here in South-East Asia since 2006. Assuming you’re lucky enough to find a treasured vinyl LP or 7-inch single you’ve been seeking since 1987, does it still matter what vinyl replay cartridge to use? 

According to seasoned “vinylophiles”, nude vinyl LP replay cartridges offer the sexiest sounds for the money – and not all of them are stratospherically expensive, though the very expensive ones are oft reviewed in leading hi-fi magazines. To the vinyl LP replay novice, a typical nude cartridge’s most striking feature is probably its lack of bodywork. Like no non-resonant aircraft-grade aluminum alloy, titanium, carbon fiber, exotic woods like Mpingo or whatever – just the magnet structure left open to the elements, albeit with a backing of a substantial flat mounting plate that’s either made from transparent acrylic or Lucite – or non-resonant aluminum alloy, titanium, carbon fiber, Mpingo or similar tonewoods or anything that doesn’t resonate or whose resonance is consonant to the music being played. 

Probably the most famed nude moving coil cartridge in existence is the van den Hul Grasshopper. At around 5,000 US dollars or so (the last time I checked in Hong Kong back in 2010) the Grasshopper is about the same price as a well-reviewed entry-level 4-door sedan made by a famed South Korean automaker making it out of the price range of most vinyl LP enthusiasts. But to every vinyl enthusiast fortunate enough to see it with their very own eyes, the most amazing part about the van den Hul Grasshopper cartridge is its lead-out wires from the coils, which are exposed to the elements and are so thin that they are very difficult to see with the naked eye to anyone on the wrong side of 40. A jeweler’s loupe didn’t offer much improvement either. How van den Hul managed to solder those wires, I don’t know, it’s simply amazing – with an amazing sound, holographic walk around imaging and soundstaging, to match the looks and the price. 

Some very seasoned vinyl enthusiasts argue that the nude construction of the van den Hul Grasshopper is not the very reason or the main factor why it sounds so good. They cite that it was something that Dutchman A.J. van den Hul invented in the late 1970s that makes the Grasshopper cartridge sound as good as it should – i.e. the Type 1S Diamond Stylus. The famed vinyl LP replay stylus is also used in another famed moving coil cartridge by van den Hul that’s only half the price of the Grasshopper – namely the van den Hul Frog. Though the Frog sports a “British racing green” colored non-resonant aluminum bodywork. And there are even some skilled vinyl enthusiasts out there who ditched the Frog’s aluminum bodywork and tweaked it into an ad hoc nude moving coil vinyl replay cartridge that sounds as good as the twice as expensive Grasshopper. I wonder if those very skilled vinyl enthusiasts have dubbed it as the “van den Hul Nude Froghopper”.  

Another famed nude moving coil vinyl replay cartridge that can be bought around the same price as the van den Hul Frog is the one by the famed Japanese cartridge maker Dynavector called the Te-Kaitora - named after the Maori phrase for “The Discoverer” because it was designed by Dynavector’s New Zealand branch. As with all nude moving coil cartridges, the magnetic structure of the Dynavector Te-Kaitora is left open to the elements, albeit with a backing of a substantial sized flat non-resonant titanium plate. And as a warning to overly enthusiastic potential customers, the nudity of the Dynavector Te-Kaitora exposes several millimeters of its very fragile – very expensive and almost invisible – boron-rod cantilever with the famed Ogura Pathfinder stylus. The wiring is made of silver and the cartridge features Dynavector’s proprietary magnetic tweaks – i.e. a flux dumper coil on the front and magnetic softening via ferrous metal strips. 

And probably the cheapest nude moving coil vinyl replay cartridge out there is probably the Sumiko Blue Point Special at one-twentieth the price of the van den Hul Grasshopper. It is top of the range in Sumiko’s Oyster Series and its “skeletal” construction makes it the most vulnerable of its sibling cartridges. Though the overall structure is sound – complete with a non-resonant aluminum cantilever – and electrical engineering is impressive throughout. And even though it is only one-twentieth the price of the van den Hul Grasshopper, the Sumiko Blue Point Special seems to offer 90% of the Grasshopper’s sound. Though some seasoned vinyl enthusiasts claim that the Sumiko Blue Point is not a true nude moving coil cartridge because of its extra large mounting plate. 

Sound quality-wise, nude moving coil vinyl LP replay cartridges are notable for their holographic walk-around soundstage and very dynamic pace, rhythm and timing that’s much closer to what live music actually sounds – rather than a mere electronic reproduction of a recording as portrayed by lesser vinyl replay cartridges. The nude construction undoubtedly contributes to the beguiling transparency and purity of tone right across the broad midband, which can be a delight with well-recorded acoustic instruments. 

Friday, August 31, 2012

Remembering Open Reel Tapes

Given that at this very moment, the music industry is currently retooling their product outlet into the online digital music download and streaming service realm, will the open reel tape go down in history as the best domestic music recording and playback format ever? 

By: Ringo Bones 

With the music industry now too busy to profit from the recent success of post Napster legalized online digital music download and music streaming sites like Pandora, Spotify and We7 over physical media, many true-blue hi-fi enthusiasts and serious audiophiles now wonder if one asks which domestic music format has a better sound quality than the good old vinyl LP – more often than not – they will be answered with the open reel tape. But is this symptomatic of the apparent lack of innovation in the music industry? 

Here in South East Asia, SACD and 24-bit 192-KHz sampled DVD Audio became as ubiquitous as hen’s teeth since 2005. I mean have you ever seen a Judas Priest or Ozzy Osbourne greatest hits compilation on SACD discs released by Sony Records on your local record store, never mind the Tower records and HMV here in Singapore and Hong Kong? And those “software doodads” supposedly to make your digital music downloads sound better than vinyl LPs - like the Burwen Bobcat – quite pricey at the time when I last saw it being demonstrated around Hong Kong and Singapore back in 2007 seemed to vanish without a trace back in 2011 with no cost-competitive alternative being offered. When it comes to “better-than-CD-music”, your only choice here in SE Asia are those weekend audiophile swap-meets where used vinyl and – if luck allows – used mint condition prerecorded open reel tapes are traded in a flea-market style setting.  

Commercially-produced prerecorded open reel stereo tapes for domestic use adopted the quarter-track – i.e. playable in both directions – format and companies like Barclay-Crocker gladdened the hearts of audiophiles by issuing many fine tapes right up to the demise of the format in 1986. Sadly, I only have 4 Barclay-Crocker style prerecorded open reel tapes – Lionel Richie’s Can’t Slow Down, Bon Jovi’s Slippery When Wet, An RCA Classical Music recording/compilation titled Music For Frustrated Conductors that came with a conductor’s baton in its packaging (I wonder how will RCA package this album for cassette or CD format?) and an Ampex open reel alignment / test-tape that came with the Teac X-3 Open-Reel Tape Deck I bought in a swap meet back in 1998. Sound wise, prerecorded open reel tapes have much more air and space in their recorded acoustic when compared to their vinyl equivalents. Though the open reel version of Bon Jovi’s Slippery When Wet have a definite DAT (as in 16-Bit 48-KHz sampled Digital Audio Tape mastered) timbre. 

Back in the mid 1990s, even a dog-eared condition but functionally perfect two speed - as in playable at 3 3/4 i.p.s. and 7 1/2 i.p.s. quarter track open reel tape decks started to fetch second-hand prices way above their Blue-Book resale values. “Notorious” examples are the Revox B77 and A77 open reel tape decks, models from Sony and Akai that dates from the early 1980s – and the Philips Black Tulip Open Reel Tape Deck, a superbly built 3-head machine (like the Teac X-3) that never really took off in its day started selling at over 200 US dollars. Vacuum-tube based tweaks could easily drive the second-hand sale price into the 1,000 US dollar price range.  

If you think listening to prerecorded Barclay-Crocker Open Reel Tape albums on your two-speed quarter-track stereo open reel tape deck is an adventure in itself this day and age, just wait when you try to record live music being performed by your local wunderkind in one. Believe it or not, an intrepidly diligent open reel tape enthusiasts can still find an unopened Scotch 111 blank open reel tape in most weekend audiophile swap meets here in SE Asia. The Scotch 111 open reel tape was often described by seasoned live recording enthusiasts as a “hoary old product” - even in the 1960s part of the Golden Age of Stereo because it had the history that descended linearly from the infancy of tape recording in the United States. Probably as far back as the post-World War II half of 1945 when Jack Mullin of 3M bought one of those “captured” Nazi-era German-made open reel tape recorders back to America to be demonstrated in front of the general public and prospective audiophiles in San Francisco. 

During the Golden Age of Stereo, not even the creator and manufacturer of the Scotch 111 open reel tape, the 3M Company, would argue that it was an “outstandingly good tape”. There were certainly other products available that offered much greater potential performance when it was finally discontinued around the latter half of the 1970s. But for a long time, the Scotch 111 reigned as the standard tape – because according to first-hand users – it was fairly consistent and widely available and it was the direct evolutionary heir to the first American ventures into magnetic recording. Open reel tape deck recorders worldwide were adjusted to suit the Scotch 111’s characteristics and when you were in doubt as to what open reel tape to use for a particular recording application, you could almost always fall back on the old Scotch 111 with a reasonable expectation of getting the magnetic recording job done adequately.