World mail May 2013 issue

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Your experts are -
NK Noel Keywood, publisher; PR Paul Rigby, reviewer; TB Tony Bolton, reviewer; RT Rafael Todes, reviewer (Allegri String Quartet);  DC Dave Cawley, Sound Hi-Fi, World Design, etc.

An independent record shop in Oxford, Truck Store, stage promotional

gigs and will order new releases on LP, says Graham Gough.

HMV

My local branch of HMV – Oxford – does not appear on the list of HMV closures, but something pretty radical will have to happen before I’m able to part with much cash there. Like you, I have no interest in the merchandise, games and gadgets, only music. 

But for me, the trouble with HMV is that it’s piled disproportionately high with reissues and back catalogue (oh dear...does that also describe Hi-Fi World’s vinyl reviews...?)

I’m no youngster, but I am looking for new releases of new music. It is rare that I can find what I want in HMV, on either CD or vinyl. There is a half-hearted acknowledgement of renewed interest in the latter, served by a couple of dozen LPs at best, many of them...you guessed...reissues. 

I can’t help but wonder how many times HMV expects the record-buying public that remains wants to buy the same things again and again. 

I am lucky that Oxford has a great independent record shop too. Unlike HMV, it’s a walk and bus ride to get to, not in the city centre, but well worth the effort. Truck Store (http://truckmusicstore.co.uk/) will pre-order new releases, and the staff try very hard to stock and recommend titles they feel their customers will like. There are free promotional gigs from live bands on a tiny, cramped stage (I saw Ides of Gemini from Los Angeles there one evening last summer) and coffee. 

Sadly, HMV has had little to offer for a very long time. Those of us still lucky enough to have an independent record shop need to use it like never before.

Keep up the good work.

Graham Gough

Thanks for you views Graham, which reflect those of others I’ve seen. HMV became large, diffuse and unfocussed it would appear, as customers see it. By contrast your local record store appears to have focus – and commitment. 

   For my part I would stroll away from HMV Oxford Street casually wondering whether they should fill their front-of-house displays with colourful LPs, a few ‘record players’ and band posters to play up the glamour of the format and the glamour of its heyday. Then I’d think “no, that’s your interest, not that of others” and scold myself for it. 

Now I see in Oxford Street’s biggest new store, of cruise liner style and proportions, a large new concession called Urban Outfitters (I am meant to know about them, but I don’t!) has a mock LP store in its entrance, no less. The LP has now become a fashion statement and cool, it seems. 

    It’s the music on it that matters and gives it value, but the two are inextricably linked, as countless TV programmes on The Beatles, The Kinks, Queen, Mark Knopfler et al remind us, almost nightly. What a shame that HMV never really understood this or exploited it. 

    Promoting new bands and featuring their albums, as well as making good re-issues available (yes, I buy them!) is a far more creative approach. I just hope it is profitable for them too, because returns for LP were high when we sold them at Hi-Fi World and processing the returns disproportionately high against the profit on them. NK

RECORDING WITH AUDACITY

I read with interest your article about using PC hardware to record and manipulate audio. Thanks for taking a step to acknowledge the power and flexibility that contemporary computer hardware brings to audio management and manipulation.

However, I must raise a grumble about your comments on input and output hardware. Since 2004 there has been a standard for multichannel audio in PCs. Intel created the Azalia project to improve on the AC97 standard and to permit routing and mixing of more than one pair of audio channels in hardware on a PC. 

Intel HD Audio[1] is the standard that came out of that project, and its fruit of manipulating two channels at 32-bit/192kHz resolution or 8 channels at 32-bit/96kHz has really widened out the capabilities of PC Hardware. It has become a standard part of home desktop and laptop computers, and every Mac on Intel CPUs is capable of handling high-definition audio.

The crunch comes when your article suggests buying the best that your readers can afford. There’s no reference to the need to buy a card with good noise floor isolation – so that signals from other parts of the computer don’t cause interference to the audio signal via the ground lines – or that current chips can provide extremely high levels of SNR (signal-to-noise ratio). 

Due to the race to include features and improve computer chip performance, the capabilities of even low-end chips have good noise floor isolation and high signal-to-noise sensitivity. An example is the ASUS Xonar DGX card which is only 23[2] and has a sibling for older computers available for 22[3]. Reviews take the stated specification for the chips, and test it, showing exceptional noise floor and THD[4]. (Clock jitter is pretty-much forgotten when the audio processing chip is operating at a few hundred megahertz and managing sample rates at best a few hundred kilohertz – three orders of magnitude lower).

I understand that you publish a hi-fi magazine and home computing is not obviously a part of that, so I repeat my thanks that you stepped into a new arena. My home setup is the product of being a CD kid, that almost all the music I own came on 44.1kHz/16-bit digital stereo discs, and so they have migrated to backups in my home computer network, emerging from DAC-Amp-Speaker setups around my home on demand. This calls for some home networking, but the boon of small, silent computers which have high sample rate and high bit rate compatibility on a very low noise floor has liberated my enjoyment of the music I own.

Wishing you all a Happy New Year, 

Ken Harpur-Lewis

Asus Sonar DGX card offers 'good noise floor isolation and high

signal-to-noise sensitivity' and great specs (below) says Ken Harpur-Lewis.

notes: [1]: http://en.wikipedia.org/wiki/Intel_HD_Audio

[2]: http://www.overclockers.co.uk/showproduct.php?prodid=SC-015-AS&groupid=701&catid=11&subcat=

[3]: http://www.overclockers.co.uk/showproduct.php?prodid=SC-011-AS&groupid=701&catid=11&subcat=

[4]: http://techreport.com/review/23358/asus-budget-xonar-dgx-and-dsx-sound-cards-reviewed

A Meridian 818 preamplifier produces almost negligible levels of distortion

with 24bit resolution audio files – just 0.02%. Budget audio players typically

offer a performance seven times worse. 

Thanks for your views Ken. But there are issues here! 

You state modern computer cards have an exceptionally low noise floor and low distortion (THD), in spite of working in an electrically noisy environment, but I view this with some scepticism. Firstly, budget digital signal processing chips used in low cost computer peripherals, such as USB receivers, DACs, sample rate convertors etc commonly use cheap’n’dirty methods to do their work. Our measurements show, for example, high noise and raised distortion where sample rate is not a multiple of clock rate (e.g. a 96kHz sample rate signal being processed by a system using a 44.1kHz CD clock), and noise from the digital domain that falls through into the analogue domain (dither illustrates this phenomenon). And then there is the issue of 24bit files being truncated to 16bit for the sake of compatibility: they play, but with 16bit quality. This may be acceptable as consumer audio goes, meaning tablets, iPods, PCs etc, but it has never been fully accepted as high fidelity to audiophiles. 

    Cheap chips found in cost-cut PC peripherals do not deliver top audio quality. At best it is satisfactory for the purpose intended. Our measurements reveal these issues, but you need a Rohde & Schwarz UPV to run such tests and few possess this instrument. 

If you don't have one of these, then you are probably measuring the wrong thing, says Noel. It is a Rohde & Schwarz UPV audio analyser with 24/192 digital generator and an analyser able to measure true noise levels.

    Noise measurement? The easy way is to run a silent file, invoking digital muting. Noise drops to nothing (-120dB or so). But this does not represent real life situation; we don't listen to silent files! In our tests we run a 24bit, 1kHz, -60dB test tone and notch it out to measure noise, lifting muting. This will typically yield a -92dB – 110dB noise floor. So measuring noise in a digital system isn't straightforward, A no-noise result is ncommon, because it is what a simple test comes up with. 

So I somehow doubt the veracity of reviews on computer cards showing they offer a flawless performance. Here’s an example: our 24bit, -60dB test files produce 0.15% distortion on budget product, but through a Meridian or Naim product 0.02% distortion – seven times less distortion. That’s the difference between budget and audiophile.

Go to Letters, June 2012 on our website, and page 6 (Digital Cables) to read more about sending music via ethernet. Cables add jitter, termination reflections and RF noise. Not a good idea. At home I use a LaCie Whizkey and sneakernet, because it offers a smoother, richer sound. But then I am surrounded by my neighbour’s wi-fi transmitters and mobile phones, to which my ethernet cable acts as a great aerial.

    That jitter reduces to inconsequentiality through downsampling depends upon its percentage in the first place. Jitter, radio-frequency pickup and noise are pervasive influences not so easily eradicated in any electrical engineering idiom, in spite of overly optimistic claims made by engineers over the ages. Today they still plague us; I was told recently these factors are a big issue in modern jets, where data and communications networks are critical items potentially compromised by such degradation. Don’t be too quick to assume the CD you hear over ethernet is perfect, and jitter non-existent! 

    Try to audition a modern high resolution player running a 24bit file if you can, to hear how the world is moving ahead from CD and its rather mechanical presentation, unloved by so many – especially those brought up on analogue. 

    Even the music industry is declaring they have seen the light: there is a headlong rush back to old analogue sources, and a greater awareness of the need to record new material through the latest high resolution analogue-to-digital convertors. The limitations of 16bit and CD are clearly audible against 24bit.

Today’s digital standards are a lot higher than those of even a few years ago. That’s why recent, high quality post-CD digital recordings or old pre-CD analogue recordings generally rest easier on the ear than anything made during the dark age of audio that the computer business still clings to. 

    This situation will change soon when Apple release a high resolution iPod that plays 24/96 Mastering Quality recordings made available through iTunes. Then the PC business will enter the arena of high fidelity in a headlong rush. Well, it will try! NK

The player of tomorrow, an Astell&Kern AK100 plays 24/192 digital files

through headphones or the hi-fi. Sound quality is audibly superior to that

of current portables