Thursday, June 10, 2010

Can Tweaking Your AC Cables Actually Make a Difference?

Electrical engineering-based logic dictates that doing such tweaks shouldn’t make a difference, but does tweaking your AC cables by using higher quality cables improve your hi-fi system’s sound?

By: Ringo Bones

As with the crappy quality freebie analog interconnect cables that most seasoned hi-fi buyers are already familiar with, an overwhelming majority - if not all – freebie IEC AC cords that come free with newly-purchased hi-fi equipment is stifling their ability to display their full sound quality potential. More apparently so when entry-level audiophile AC cords are substituted to the free AC cords that came with your CD player or other hi-fi audio equipment. Inexplicably, major electronics manufacturers seem to be unable to move away from supplying crappy analog interconnect cables and IEC AC power cords with their products.

From an electrical engineering perspective, one can logically deduce that tweaking the last ten feet of your AC mains cables by using higher-spec copper wiring configured in proprietary geometric configuration that results in RFI and EMI noise cancellation shouldn’t make a difference, doesn’t it? I mean the AC power that traveled from the generating plant all the way to your home is not exactly made with copper of 99.9999% - i.e. of six-nines purity. Neither are they ceramic-coated with superconducting “space age” materials nor have Teflon dielectric, and chances are doesn’t have conductors arranged around some mystical geometric pattern. Existing electrical codes around the world specify that 99.9% copper is good enough. Then why does using fully tricked-out AC cables – even those IEC AC equipment entry-level ones priced at around 20 to 25 US dollars – during the last 10 feet of mains to your CD / DVD player and power amp make such a noticeable improvement in sound quality?

I’ve heard the theories before – most are dismissed by “mainstream” / “tenured” electrical and electronic engineers as mere voodoo, but more importantly, I’ve heard the difference. As in greater dynamic range as if the music being played seems to immerse from a blacker background then shining brighter than it did after the generic AC cords had been substituted with better ones. My converted audio-buddies who were mere civilian bystanders – in audiophile terms - when I first asked them to be listening guinea pigs back in the late 1990s had since swore that AC cable tweaking makes a more-than-noticeable difference. Even with a beer-budget version of the test that I have conducted when I replaced the AC mains cabling of my out-of-warranty power amplifiers with well-reviewed entry-level speaker cables.

Yes, even speaker cables of suitable thickness to handle the power demands of the integrated amplifier or power amplifier you intend to use them with had shown a marked improvement in sound quality. After asking a qualified electrician in our neighborhood if what I’m doing violates any existing electrical codes. He says – it is still usually a he even till this day – given that those speaker cables are rated up to 600 Volts AC or DC, it is quite ok to use them as mains cable. He says they may even be safer than existing “zip-cords” oft used as AC mains cabling since these speaker wires contain more copper – i.e. thicker diameter. They are only a few percentage points purer than the copper used in freebie AC cords – 99.9% of ordinary zip-cords versus 99.999% of the hi-fi speaker wire. Can that much purer copper result in an inexplicable increase in sound quality?

If you’re lucky enough to have an integrated amplifier or a power amplifier that still works / you are still using that has already past its warranty and you are confident of your DIY soldering skills. You can try replacing the captive AC cords of your preamplifier, power amp or even the CD / DVD or other front-end with entry-level speaker wire like those from Bandridge, Gale, or Cable Talk that are priced between 1 to 5 US dollars per meter to improve its sound quality. This tweaks works very well with entry-level solid-state integrated amps with old-style captive AC cords, making them sound much closer to budget tube amps made during the Golden Age of Stereo or those 3,000 US dollar French-made solid-state integrated amplifiers.

Another source of cheap AC mains cords that are way better than the freebies that came with your CD / DVD player or integrated amp’s Styrofoam packaging are those IEC AC cords designed to protect against Van Eck radiation phreaking. Remember Wim van Eck, that Dutch computer researcher who in 1985 published the on how electronic emissions from a computer can be eavesdropped? Well, a friend of mine from the US State Department gave me – as in for free - 30 sets of IEC AC cords that formerly used in their computers that are capable of Van Eck Radiation filtering back in 1998 after their office computer workstations were issued “improved” models. Those 30 sets of 1992 Van Eck Radiation-compliant IEC AC cords also improves sound quality of my equipment that takes IEC AC cords. About as good sound quality wise as models priced between 500 to 1,500 US dollars from Electra Glide, Yamamura and even Cardas.

That Crappy Freebie Analog Interconnect Syndrome

To the casual and first-time buyer it usually came with the Styrofoam that comes free with your CD player, but are those crappy freebie interconnects unduly ruining real hi-fi’s reputation?

By: Ringo Bones

Its only saving grace is that the plastic RCA plugs – or phono plugs as they are referred to in merry old England - are already gaudily color coded to whether it goes to the left or right channel RCA jack. But are these cheap freebie interconnects that comes with your CD player’s / cassette tape deck’s / turntable’s / tuner’s packing Styrofoam really have bad sound quality?

Flatteringly, they can make your real hi-fi CD player – or any other hi-fi front-end previously mentioned – sound just like a run-off-the-mill mini system boombox. Or in short, these freebie cables’ inherent crappiness can ruin the inherently excellent sound quality – in comparison to a run-of-the-mill mini boombox - of your “proper hi-fi” or “real hi-fi” CD player or any other “proper hi-fi” or “real hi-fi” front end. This phenomenon is probably the reason why some anti-hi-fi and anti-tweaking fanatics swear by to that all equipment sounds the same mantra.

During the latter half of the 1990s, I was fortunate enough to have the opportunity to employ a few of our local music fans as hi-fi “guinea pigs. Given that their only experience to high quality sound is the weekend recital of a pop music academy in our local mall and most – if not all - of their CD listening is via run-of-the-mill boomboxes could make them about the most unbiased hi-fi auditioning test subjects that anyone could find.

Using Veruca Salt’s Eight Arms to Hold You CD – which was newly released at the time – as an ad hoc “audiophile demonstration disc” all of them commented: “Yeah, it truly sounds that there are two girls singing just like in the Volcano Girls music video”. And “Those cables make the interplay between the Gibson Les Paul and Marshall Amplifier stacks and the drums sound as if it is happening real life.” Maybe the young lady meant “live”, but the most surprising thing to me is that they thought that CD could never sound this good. Comparing “proper hi-fi” interconnect cables – even entry-level price range ones with those crappy freebie interconnects that come free with the packing Styrofoam can be a “Road to Damascus”-like experience.

Despite of their excellent sound quality in comparison to crappy freebie interconnects, entry-level hi-fi interconnects are not exactly cheap. Ranging in price from 25 US dollars to 100 US dollars – they are easily more expensive that those ultra cheap Chinese Mainland made DVD players. You know ones that had been raved for their surprisingly good sound quality as a “30-dollar Wadia CD transport” and a “30-dollar Krell CD transport” (more on this in the future). Fortunately, me and my seasoned audio-buddies had found away to make “interim” hi-fi interconnects that are still way better sounding than those crappy freebie interconnects.

If you are handy with a soldering iron, you can easily make your own ad hoc audiophile interconnects by using 1 or 2-meter sections of RG-58 or RG-59 cables and soldering them to reasonably-priced RCA plugs – or phono plugs for those living in the UK. If you know the right people, you can even get used RG-58 and RG-59 cables at 5-meter sections for free, while entry-level gold-plated RCA plugs – reliable ones - hover around 1.50 US dollars each. With a capacitance rating hovering around 28 to 32 picofarads (or pF) per foot, they can even be experimented as an ad hoc digital interconnects which I’ll discuss in a latter topic.

Sound quality wise, RG-58 and RG-59-based DIY analog interconnects have a more natural portrayal of the Gibson Les Paul and Marshall Amplifier sound as played in the opening of that Veruca Salt song titled Loneliness is Worse when compared to those crappy freebie analog interconnects. I have an audio-buddy who is “very careful with money” is still using the RG-58-based DIY analog interconnect cables I made for him back in 1998.

But why do reputable hi-fi CD / front-end equipment manufacturers still provide crappy freebie analog interconnects? God only knows, but this syndrome is not just confined to the entry-level price strata (the very competitive100 to 500 US dollar price range) of CD players. One of my audio-buddy fortunate enough to afford Sony’s 3,000 US dollar CDP-XA7ES CD player back in 1995 was somewhat astonished to find out that this 3,000 US dollar CD player too was afflicted with the crappy freebie analog interconnect syndrome.

Though his prized possession still runs till this day although he was a bit peeved when the rest of his audio-buddies has stumbled upon the phenomena of the 30-dollar Wadia CD transport / 30-dollar Krell CD transport last year – i.e. 2009. More so when it made our trusty-but-rusty 500-dollar Audio Alchemy DAC circa 1995 sound “superficially” way better than his 3,000-dollar Sony CD player bought in 1995.

Motional Feedback: The Future of Loudspeaker Design?

Best known as the working principle behind Velodyne’s patented High-Gain Servo System-equipped subwoofers, is motional feedback truly the future when it comes to hi-fi dynamic loudspeaker design?

By: Ringo Bones

Seasoned audiophiles, more often than not, had their first hand encounters with motional feedback technology via adverts – and hopefully purchases – of Velodyne’s world-famous servo-controlled subwoofers. These famed subwoofers are famed for their very low levels of harmonic distortion and coloration – when compared to their competitors’ offerings – that doesn’t use Velodyne-style High-Gain Servo System technology. But before we proceed any further, here’s a primer on what is motional feedback.

Motional feedback uses a second voice coil on the drive unit – typically a large woofer in stand-alone subwoofer systems – that provides a signal in which a tiny millionths of a second later is fed back into the amplifier, correcting distortion. The result – if correctly implemented – is amazingly powerful articulate bass / low frequencies devoid of coloration and distortion.

In those famous Velodyne subwoofer adverts of the 1990s, the company points to their use of a low mass – 2.5-gram accelerometer – that form the brains of their High-Gain Servo System. Velodyne mounts this amazing device directly on the voice coils of their subwoofer drivers, and measures the actual movement of the driver. The information is then sent back to a circuit, which makes corrections for any deviations from the pure output signal 3,500 times a second. Resulting in a virtually distortion-free bass even when the subwoofer is set at its highest frequency setting of 120-Hz.

My encounter with Velodyne’s FSR-18 subwoofer – one of the very best subs that we (me and my audio-buddies) can still afford when we still have Clinton administration era prosperity money during the 1990s. It can easily be described as a technological tour-de-force, imagine very loud and very clear bass subtle enough to portray the acoustic structure of the venue where the music being reproduced was originally recorded. Although early samples of the Velodyne FSR-18 subs were notorious for having loose wiring that came loose and slapped against the moving cone producing a tapping sound – evident when What’s Left by Lunachicks – from their Pretty Ugly album - was played during that particular listening session. Thus resulting in another flight to Hong Kong to our very friendly hi-fi dealer that gladly replaced our faulty subs.

In reality, motional feedback-type loudspeakers are a pain to design and make to work properly – tweaking one should only be a job for very gifted electrical / electronic / mechanical engineers – i.e. probably those skilled enough to make a humanoid robot that can run a hundred-meter dash in less than 10 seconds. It is not just Velodyne who had faced such problems developing and perfecting their very own motional feedback-equipped loudspeakers. Celestion and once-upon-a-time-loudspeaker-manufacturer Philips also experienced first-hand challenges one will likely encounter when flirting with motional feedback technology.

Graham Bank of Celestion once stated in a hi-fi magazine interview that a lack of positional reference in their prototype motional feedback loudspeaker design resulted in an enormous crack from the cone as it attempted to leave the chassis on musical peaks. Each time it did this, the connecting braids carrying the signal from frame to the voice coil broke, even though they were long enough to cope with the movement. Both Graham Bank at Celestion and Paul Mills at Tannoy have worked on motional feedback-type hi-fi loudspeakers during much of the 1970s and were somewhat convinced that that there were some deep seated difficulties in its application.

Even a notable demonstration of motional feedback technology by Philips – back when they were still making hi-fi loudspeakers – at their headquarters in Eindhoven, Holland, that motional feedback gave the sort of fast, tight and even bass most hi-fi enthusiasts dream about. Fantastic bass quality - provided that the user kept the volume down, otherwise, the driver instantly destroyed itself. The technicians at Philips also noted in their motional feedback loudspeaker experiments conducted during the 1970s is that much of the correction by the accelerometer and the servo system was being applied to signals above 100-Hz.

So is motional feedback the future of high-end hi-fi loudspeaker design? Well, remember how Velodyne’s FSR-18 subwoofer compares the deviation from the pure output signals and the one sensed by its low-mass accelerometer at 3,500 times per second? This is just with an audio bandwidth that rolls-off at 120-Hz – although it works beautifully, imagine this concept applied to the full Redbook spec CD audio bandwidth of 20,000-Hz. Corrections would be applied at 600,000 times a second – that’s just with a 20,000-Hz bandwidth. Imagine the difficulty with DVD-audio or Super Audio CD / SACD that reaches out to 100,000-Hz – a motional feedback hi-fi loudspeaker with a 100-KHz bandwidth would be doing servo corrections at 30-million times per second. Full audio bandwidth motional feedback hi-fi loudspeakers may be the future if its quirks are ironed out, but for now – and for simplicity’s sake – they’re only practical for subwoofers that only play notes as high as 120-Hz.