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December 2010 issue - Page 2

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December 2010 issue
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LAND LINES

The assertion made by Mr. Hogkinson (Letters, October) that listeners who celebrate the analogue quality of FM stereo radio are in fact demonstrating that they are happy with digital, is an interesting one and is worthy of further examination.


Even a live acoustic performance, starting life as an analogue signal in the studio, will be digitally encoded for distribution to the various radio transmitters in the network. On arriving at a transmitter, the digital signal is decoded and is transmitted in the form of an analogue FM radio wave. The celebrated analogue quality of FM stereo therefore relies on a lot of digital processing!


So why introduce the digital processing in the first place? The reason is that the old land lines, which distributed analogue signals adequately in the early days of radio, produced unacceptable levels of corruption when asked to carry more complex analogue signals. The replacement of these land lines by more robust digital links guaranteed the integrity of signal transfer for the era of FM broadcasting.


The BBC was one of the first broadcasting organisations to employ digital encoding of the analogue signals originating from its studios. The first 13bit, 32 kHz digital links were installed between its FM transmitters in the late 1960s.


The signal bandwidth in FM stereo broadcasting, due to the multiplexing of the two channels, is restricted to around 15kHz. This explains the BBC’s adoption of a 32kHz sampling rate, since the rate must be at least twice that of the signal’s highest frequency. Compare this with the 44.1 kHz sampling rate of Compact Disc which allows a bandwidth of up to 22.05 kHz.


The basic assertion at the beginning of my letter could be extended to readers who celebrate the analogue quality of LP records. Since it was as early as 1973 that the first 13bit digital recordings were released on LP, you may not always be listening to pure analogue quality from LPs pressed after that time.


This, of course, explains why the procedure of transferring the original master tape recordings direct to vinyl is so popular with audiophiles!

Alan RJ Scott

 

chord-blu-dac64

 

Chord Electronics DAC64 reached 16kHz but sounded wonderful.

 

Sometimes I think it is best not to get too involved with the numbers and stand back a little. The fact that the BBC uses digital land lines is one of those hoary old “proof that digital is okay” examples. Well, quite obviously it is okay, but no better – and is that good enough? Hook up a good tuner and listen in and you hear back to source well enough. When this is a live talk from a studio what we hear is almost virgin, unprocessed basic audio and, having done a few radio talks in my time, I know fairly well that what we hear is close enough to the damped sound of a studio, as well as the slightly embarrassing oral behaviour of the various souls at the microphones.


Similarly, live broadcasts can be astonishing.  The digital landline may well be degrading this slightly, but the source material is so arresting it hardly matters. And that’s why VHF/FM radio can sound so good.


Back to figures. CD can be band limited to 16kHz (Wadia, Chord Electronics DAC64, Denon Lambda processing and Pioneer Legato Link players) and VHF/FM tuners can have a frequency response that extends past 20kHz. That CD makes 21kHz as a statement means little; everyone liked the Chord Electronics DAC64 that reached 16kHz.


The world has moved on, thankfully, and now we can start to hear the improvement brought about by 24bit, and it is quite obvious and significant. I am less certain that higher bit rates are so obvious, but then this may come down to filter limitations in the recording chain. If possible, try to listen to some 24/96 Blu-ray discs through a high quality system and see what you think of, for example, John Mayer’s ‘Where the light is”.  Another powerful example are the differences between Carlos Santana’s DVD-A (24/96) of Supernatural, and the CD. I have both and find the CD almost unbearable against the DVD-A.


So early digital might well adequately convey studio quality down a landline, and CDs can sound pretty good too, but a lot better is possible quite frankly. You will surely be fascinated by the following letter. NK

 

LIVE IN VIENNA

I write this letter, because singer Rickie Lee Jones was here in Vienna last week and gave a wonderful concert. I recorded her onto DSD on a mobile handheld MR-1 from Korg with very good results. But listening to RLJ on the analog track of the Laserdisc sounds quite close to a real live event itself. Laserdisc was able to carry an analog movie signal, but also an analog audio signal (besides digital audio tracks). I was always wondering what could have become of Laserdisc if Pioneer had developed pure music discs without digital tracks and without video signal. I guess they could have been the size of CD, carrying two analog audio tracks, difficult to copy and therefore automatically copy protected and with awesome analogue sound...


I own nearly 100 music Laserdiscs. A lot of them are astonishing:  you should hear the difference between Bob Dylan MTV on the analog tracks of the Laserdisc compared to the same content on Vinyl or DVD!


I also own an awful lot of prerecorded reel-to-reels for my two Revox G36 recorders. More tape hiss than Laserdisc, but sound wise similar exceptional quality.

Since I play all formats on all kinds of equipment I dare to give a rating for listenable audio – how my ears and soul feel about it. I ranked from 1 to 200. Top 1 is live concert. Last place 200 is MP3 at 320 kbps. LT III means Leak Troughline III VHF/FM tuner. I am really happy with recording live operas or live rock concerts through my wonderful Leak Troughline III onto DSD-files. I left ranking-places empty to represent the differences in sound quality between the formats more pregnantly:

 

1 Live without amplifying

8 Live with amplifying

22 Live through LT III

24 Prerec. Reel 15 ips 2 Track

28 Prerec. analog  NTSC Laserdisc

29 Rec. Live LT III 7.5 ips 4 Track

33 Prerec. Reel 7.5 ips 2 Track

36 Prerec. Reel 7.5 ips 4 Track

38 Prerec. Reel 3.75 ips 2 Track

40 Prerec. LP on TD124, mono Ortofon SPU on Ortofon arm

42 Prerec. LP on TD124 Decca Gold London, Hadcock Unipivot

44 Prerec. 78s on TD124 with Shure mounted on a funny Panasonic

45 Live direct to DSD 2.8MHz

52 Rec. Live LT III on DSD 5.6 MHz

60 Prerec. LP on Oracle Delphi IV

Lyra Clavis  on Graham 2.0

65 Rec. Live LT III on DSD 2.8 MHz

68 Blu-ray 5.1 HD

70 Rec. Live LT III on VHS-Super

80 Rec. Live LT III on 24/192

85 Rec. Live LT III on 24/96

90 Prerec. MusicCassette

100 Rec. Live LT III on 24/48

110 Prerec. SACD

135 Prerec. DVD-A 24/96

160 Prerec. CD-source

165 Rec. Live LT III on 16/44.1

200 Prerec. mp3

 

korg-mr-1

 

Record your own DSD, as Erwin does, using the amazing Korg MR-1.


You might wonder why I placed DSD quite high ranked, but SACD far behind. Simply, I never got a commercial SACD (and I own a lot) that sounds like DSD as recorded via my KORGs.


The same is true for DVD-A: my own recorded 24/192 burnt onto DVD-A sounds much more promising than the commercial ones.


Looking at today’s available digital and analog formats it is remarkable that the best sound I can get nowadays from classical music is from good old FM-radio!! Live listening in front of my Leak Troughline III beats everything that is on the market. I recorded operas and bought them half a year later on Blu-ray (Netrebkos Figaro). And the FM recording beats the commercial Blu-ray content. Happily, Austrian Broadcasting is still delivering the analogue signal via FM and transmit it digital only for satellite surround-sound 5.1 (sadly, simultaneous transmitted television pictures and the analog FM sound do not match, because for television also the digital audio signal is transmitted, and therefore the television picture always lags behind the analog FM sound). For live events I record the analogue FM sound on DSD-files and the television on HD-movie files...).


So here I am, the great audiophile, waiting for the moment when the radio ‘speaker stops, to press the record button as I have done in my childhood (I’m 44 now).


Thanks for all the help over the years. Your magazine transformed my system from a clinical Oracle Delphi and Krell system into a wonderful sounding tubed, vintage audio system with some modern sources. It is 5.1 surround with all channels direct into tubed power amps with source Oppo 83 SE from Nuforce. My Thorens TD 124 has three tonearms: for stereo played through Tannoy 700D speakers and mono and 78s played through a Tannoy center speaker combination. Back speakers are all Tannoys.


Keep up the great work. I love your non-professional professional style!

regards,

Erwin Pani,

Vienna.



 

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