Musings on tropo

This is a highly recommended source of information on technical issues which is invaluable for the long distance FM enthusiast:

The VK-VHF mailing list aims to serve the community of radio amateurs and others interested in the technologies and techniques of operating on the amateur bands from 50 MHz and up, with a particular focus on weak-signal or long-distance working and propagation.

Unfortunately, every time a group of enthusiasts get together on a forum or mailing list, politics ensues as every contributor has strongly-held, differing opinions. It’s been my experience that in any given specialty, including my own profession, a small minority of participants have failed to learn the requisite social skills involved in communicating properly in pursuit of purely selfish agendas. This list is no different in that regard. Having being a subscriber since 2009, I am pleased to announce that this list has been largely free of inflated egos for the last twelve months or so.

Let’s get some diverse views on tropo in Australasia…

The Tropo across the Australian bight is interesting. I often take note of that occurrence and then watch it settle across the pond afterwards. Not always, but a good indicator.

Steve ZL1TPH

Of course, to state the bleeding obvious, summer time is best. It is the weather conditions that really determine the propagation – a High nestled in the Bight is a great start but there’s more to it! Wally Howse VK6KZ wrote a great article on the subject:

WA weather chart

VHF, UHF & Microwave Propagation & the Great Australian Bight

Dave VK3HZ

I can remember talking with Kerry [Adams VK5SU from Ceduna] at the time about how he could regularly work the guys in Albany and Esperance like locals along the coastal duct, whereas the Adelaide stations would be hearing nothing.

Peter VK3QI

VK-VHF Digest, Vol 48, Issue 10 Feb 2012

It is usually assumed that being on mountain tops will get you further – that is not always the case. Those who have tried to operate along the Great Dividing Range from VK3/VK2/VK4 have often found shielding effects from population centres – it is REALLY difficult to find accessible spots in the Great Dividing range that provide good takeoff in more than one direction.

Quite often one can be too high and miss ducting. We had a documented example the last Summer FD between MtTassie VK3WRE/p and McLaughlin’s Lookout VK3ER/p a distance of 230 kms. Perfect signals (as one would expect) on 1.2, 2.4, 3.4 and 5.7 Ghz but absolutely nil on 10Ghz – (above the duct) – three hours later the duct had lifted and 10Ghz was as good as the lower bands – this is all on video see:

Is a 10 Ghz qso over 200 kms between two mountain tops easier than a 50 km qso between a mountain top and someone in an urban area shielded by buildings etc.? Does the same degree of difficulty apply to lower frequencies where urban obstructions are far less inhibiting?

One of the peculiarities of the Australian continent is the propensity for high pressures to develop and remain stationary over large areas of the continent. Not necessarily just the Great Australian Bight or the Tasman sea. An example of this occured last Summer when a large duct developed over western NSW and north eastern South Auatralia which enabled stations in northern NSW to work across to Adelaide on 1296 for a significant period of time when south of the Great Dividing Range there was limited propagation.

Peter VK3QI

VK-VHF Digest, Vol 40, Issue 15 Jun 2011

Toys part two

This article originally appeared on the now-defunct dbrmuz blog.

It was Sabrina that sung about ‘Toys, toys, toys’ in the eighties. OK, I lie. A reinvention of history. Perhaps if she had, the song might have been better. Sabrina’s back catalogue was more offensive than any content referred to in this blog. Funnier too!

The Kenwood KX-3080 cassette deck is on its way. At $87 (postage included), it is an absolute bargain from Ebay Australia.


It easily out-performs the Panasonic combination system which it will replace. That combo system has a frequency response of 40 Hz – 12,000 Hz (plus or minus 3 decibels, normal tape). The dual decks in the Panasonic have no Dolby, a signal to noise ratio of 52 decibels with wow & flutter at 0.1 % (WRMS).

The specifications of the Kenwood KX-3080 are identical to the Yamaha KX-380 single well cassette deck, described previously on this blog here and here.

This label is a slight concern, but ‘we shall see’ I suppose. For those who may not watch the news, the Chinese are those humorless ‘red raggers’ who were assisting in the construction of our National Broadband Network until ASIO stopped them. Perhaps this deck will only play communist propaganda spoken word recordings?

This is a single-well deck. Some enthusiasts vigorously argue that single-well decks are superior to dual-well decks due to mechanical issues. That statement seems like an oversimplification, or if you prefer, what Liberal National Party Senator ‘Barnacle’ Joyce describes as a ‘rational argument supported by facts’ in his inimitable coherent style of speech.

$87 for a 1997-vintage deck with a warranty? I think I robbed the guy. He included both Bob Katter & Anna Bligh as part of the sale, citing a bundled package deal of ‘obsolete technology’.

Supplies of metho & cotton buds are on hand if she is a dirty one. Here in the dbrmuz coffee room (below) we have plenty of metho available. Aged spirits are overrated, and frankly time consuming to distill. Metho is an affordable beverage that you can share amongst your family. Tip: simply infuse with a bottle of vanilla essence for the ultimate party drink.  

The above photographs are courtesy of these Hungarian sites (translated into English): 

Recording with consumer soundcards

When consumers record from analogue sources on their computer, the sound quality of the soundcard may be forgotten. Five years ago, a soundcard was purchased as a elementary step-up from Chinese soundcards integrated into a computer’s motherboard. Whilst it is rarely used, let’s crudely examine its relative quality.

My sound card

This old Yamaha DS-XG YMF724 ($60) soundcard uses the SigmaTel STAC9704 / STAC9707 integrated circuit which yields a Signal-to-Noise Ratio (SNR) of typically 87 decibels (A-weighted). The minimum figure is 75 decibels. Total Harmonic Distortion (THD) is 0.02 percent. These measurements are made when the soundcard is being used with an analogue line-level input using its Analogue to Digital (A/D) converter. The accuracy of the A/D conversion is paramount whether one uses a portable digital recorder or a soundcard.

This soundcard will be compared to a more expensive M-Audio Audiophile 2496 soundcard (pictured below), based on the AK4528 integrated circuit. The M-Audio card offers a 95 decibel SNR and THD of 0.001 percent. This card costs $108, as does the Zoom H1 portable recorder with uncompressed recording from line-in (or microphone) onto a microSD card! For that sort of dough, the logical choice seems clear.

Premium sound card

How important are these specifications? According to electrical engineer Richard Kuo:

A common way to measure the “cleanliness” of the output of a card is the SNR… SNR is measured in decibels (dB) and the higher the number, the cleaner or better the signal is. Above 90 dB is generally quite good and below 70 dB is getting down there. SNR measurements are usually only useful if you can make sure that all the measurements were done identically. Unfortunately, that’s rarely the case with sound cards. SNR figures from the manufacturer should probably be considered suspect. Your best bet is to figure out what the popular opinion about the soundcard you are considering is.

According to computer scientist Dr Qingkai Ma, inferior cards have a SNR of “30 to 50 decibels” whilst the “High-end range [is] 96 to 100 decibels”. He recommends Audio Win Bench to benchmark a soundcard.

Resampling chart

Unfortunately, the Yamaha soundcard resamples to 48 kHz. Digital artifacts (arguably as problematic as analogue distortion) can be a byproduct of poor resampling. On this card, analogue recordings must be resampled from the fixed 48 kHz to 44.1 kHz (used in the compact disc) for the recording. The Professional Music PC website explains this phenomenon in layman’s terms:

The audio codec or engine of the card is “rate locked” to 48khz. This means that the card resamples everything to 48khz for the dsp/codec chip on the soundcard. This is a big limitation in a card because it means if your recording in 44.1 the audio is at least resampled to 48khz once on the way and and another one the way out through the card to your ears. This also applies to the digital IO as well as the analog IO, in fact the digital output on any [Creative Labs’ Sound Blaster] or ac97 card will be rate locked to 48khz meaning its impossible to output a digital signal to a stand alone cd burner at 44.1 or [Digital Audio Tape] machine or many other products which may need 44.1khz spdif.

There’s many other downsides to this resampling besides just a downgrading of the audio’s quality. Some people complain of timing problems in some software ie overdubs drift out of time and sync errors are just a few. Cards which resample generally speaking have a much higher CPU load on the computer as bus mastering is not used with these cards.

Legacy sound card

iXBT Labs is a Russia-based website dedicated to reviewing all kinds of computer hardware. Tester Maksim Lyadov revealed good audio performance with a substantially-identical OEM variant of this card, the Aopen AW754. This suggests the Yamaha consumer soundcard may provide satisfactory performance.

Whilst no primary reference is provided, Wikipedia contributors also contend that the Yamaha DS-XG YMF724 soundcard was not of poor quality:

Relative performance was good despite the typical low cost. The cards were usually equipped with good quality 18-bit Digital-to-Analogue Converters, providing similar low noise and harmonic distortion levels to those found in semi-professional hardware.

From a casual comparison of the specifications alone, there seems little doubt that audible differences from the original source will creep into the recordings undertaken on any consumer grade soundcard.

FM enthusiasts will be acutely aware of the amount of junk any computer spills into the FM band! Potentially, this flood of noise has an effect on the soundcard too. According to Richard Kuo:

The fact is, your PC is an incredibly hostile environment for a soundcard to be in. All that electromagnetic noise is bad news for a soundcard just trying to get a clean signal in or out of your system. Basically, what this all means is that in order for a soundcard to be true to the original sound, it not only has to have good hardware, it also has to be properly shielded.


In closing, the solution seems simple. Avail yourself of the above medication and you will have full confidence in your recordings! Hmmm… If only life was that easy…

Simple comparison of lossy formats: tape vs MP3

It’s another horrible wet night, so let’s compare a tape recording to a MP3 rip just for some fun. The track chosen was the beautiful Natalie Imbrulia single ‘Wishing I Was There’ from the CD album ‘Left of the Middle’. The exact same song was treated in two different, yet profoundly simple ways.

The cassette recording was recorded from the CD album to a Japanese metal position tape and encoded with Dolby B noise reduction, invented in 1968. A well maintained & aligned portable Japanese portable boombox from the 1980s was used for the recording.

Once recorded onto the tape, the song was played back on the same machine into a Yamaha DS-XG sound card to convert from analogue to digital. On the computer, Total Recorder was used to create a digital uncompressed PCM recording.

In Audacity, digital noise reduction was used to remove any residual hiss present in the uncompressed recording. Hiss is rarely audible with metal tape recordings, but as it takes all of one minute to do, why not be thorough when forced to use Dolby B noise reduction?

Dolby C is roughly ten times more effective than Dolby B noise reduction at minimizing audible hiss & maintaining wide dynamic range. Decks with Dolby S noise reduction provides CD-grade signal-to-noise ratios of 90 decibels, which are indistinguishable from the original CD source.

Ghost in the Machine: Jim Morrison

Don’t worry, in the event this simple comparison of lossy formats gets too boring (too late?) just focus on the amazing cassette art from New Jersey artist Erika Iris Simmons, above and below!

On a computer, a MP3 file was extracted from the CD album using CDex software. The MP3 was encoded using LAME version 3.99 using the highly-rated 192 Kbps Variable Bit Rate (VBR) encoding (192 Kbps is the average rate of the musical recording). Use of VBR mode maintains a uniform signal-to-noise ratio. Again, Total Recorder was used to convert the MP3 recording to uncompressed format.

Ghost in the Machine: Nick Cave

Both uncompressed tracks were ‘normalized’ to a peak amplitude of 0 decibels. The stereo channels were converted to mono to aid visual comparisons. Head-to-head, the two candidates are pictured below.

Pictured below, the response of the spectrum audible to humans (20 Hz – 20 kHz) is wide and fairly uniform. As we compare the amplitude in decibels with the frequency response in Hertz. The boombox tape recording of the CD track shows a robust high frequency response. High frequencies begin to gently roll off above 15.5 kHz. Between 11-14 kHz there is not much content in this particular track. High frequencies begin to gently roll off above 15.5 kHz. The music range extends beyond 22 kHz.

On a good quality component cassette deck, with adjustable bias & Dolby HX Pro headroom extension, the high frequency response would likely show less deviation & start to gently roll off at around 20 kHz rather than the 15.5 kHz roll off visible below. On the audiophile-grade decks, such as the Nakamichi Dragon of the late 1980s vintage, the differences between the CD source material and the tape recording are reportedly indistinguishable, according to tests in Electronics Australia.

Let’s remember that a consumer-grade portable boombox was chosen for this test. This test is not about achieving transparency (that is, a virtually perfect duplication of the source). It’s far more interesting to illustrate the differences between simple lossy analogue & digital formats!

Turning our attention towards the MP3 copy of the CD track, below, the response of the audible spectrum is again wide, yet in some ranges slightly more uniform than the boombox tape recording. High frequencies start to sharply roll off above 16.5 kHz, slightly higher than the boombox tape recording. There is also less variation in the content from 6 kHz onwards. Consistent with the tape recording, there is emptiness between 11.5-14.5 kHz. There is no content after 18 kHz, a characteristic of digitally compressed audio. In his research for his masters degree, Chris Camilleri found that compressed audio changes the frequency response in the following manner:


192 Kbps MP3 was chosen because it is a popular bitrate for music downloads that provides good quality transparency. 192 Kbps preserves significantly more high frequency material than FM radio broadcasts do. On MP3 recorders such as the Samsung Yepp, 192 Kbps is the maximum allowable bitrate for encoding. For Audiophile-grade encoding, 320 Kbps MP3 is recommended.

Additional discussion

Home Recording. A comparison of tape vs MP3 by a New South Wales-based musician.

Melissa Clarke. A history of Vinyl vs Tape vs CD vs MP3. By a Queensland-bred music journalist.

Child of the Eighties. A history of Vinyl vs Tape vs CD vs MP3. By programmer Big Boo.po

The Guardian. How much difference is there between MP3, CD and 24-bit audio? By Samuel Gibbs et. al.

This entry was updated in August 2014.

3 machines in 1: Teac AD-800

The Teac AD-800 is an eye-catching hifi component which costs roughly $300 Australian dollars delivered when purchased from on-line sellers in the United States.

Overview of features

This device plays MP3 tracks from a USB device, MP3 & CD tracks from a CD-R or CD-RW & analogue tracks from compact cassette. What is instantly impressive with this highly-rated component is the full remote control for all functions of the USB, CD & cassette. Recording can be performed via remote control. The machine will record to USB from a CD, cassette or an external analogue source such as a turntable or FM tuner. In addition, Timer Recordings to cassette can be performed. The machine uses an adjustable recording level which are rarely found on portable MP3 recorders but can be important to maintain distortion-free digital recording.

The cassette section is full-logic with auto-reverse & pitch control which would be familiar to disc jockeys & announcers. Pitch control raises or lowers the playback speed by 10 percent. Pitch control can be valuable ‘if it does not sound right to you or does not match the playback speed of the original vinyl record it was taped from,’ according to an anonymous tester.

MP3 recording

On closer inspection, it seems that the machine is far from perfect. 128 Kbps MP3 recordings may not do the MP3 algorithm justice. Audiophile Zomax writes in his review:

I realized when playing back the MP3s on my computer through headphones: 128 [Kbps] does not cut it. Edith [Piaf records] actually sounded fairly good (probably given that the original recording already sounds like it’s am radio), but after I recorded some Nirvana, there was no ignoring the telltale wishy washy cymbals of low-rez digital. Unfortunately 128 [Kbps] is the only option — this will obviously be a deal-breaker for anyone looking to make serious digital recordings of their analogue sources.

192 Kbps MP3 recordings are subject to significant loss of high frequency sounds above 16 KHz, while 128 Kbps MP3 recordings hit the dust above 14 kHz.

Will Ryu of Ars Technica explains the inadequacy of 128 in the modern environment where a 2 GB Secure Digital storage card costs less than a pint of lager:

…At 128 [Kbps] I had no trouble discriminating the CD from the MP3s. At higher bit rates this became increasingly more difficult, but even at 256 [Kbps] I believe I could hear differences by concentrating on certain parts of the track which were more susceptible to encoding error.

..The listening conditions for MP3s have changed, but the standard bit rate of MP3 encoding hasn’t. If you can’t hear the difference between 128 [Kbps] & 192 [Kbps] then congratulations, the more hard disk space to you. But if you can, why settle for 128 [Kbps]?

Recently, three music writers for the Guardian tested the MP3 format:

In my view, there was a real discernible difference between the MP3 or CD and the studio master tracks…

What was very apparent is just how bad a poor-quality MP3 sounded, how good a 320kbps MP3 and CD sounded, and how cutting out the middle man in the audio production chain with a studio master could have unexpected results.

Cassette playback & recording

The Teac combo’s flat response between 50 Hz – 12 kHz with playback of metal cassette tape is barely satisfactory. Wow & Flutter (speed variation) is 0.25 percent using the standard Weighed Root Mean Square measurement, a specification not comparable to the better decks.

Cassette deck spectrum

By frequency response, this is what we are talking about. The spectrum from Programmer & Electronics Engineering Lecturer Albé Bredekamp, shows a white noise signal recorded onto Philips Chrome tape analyzed using Audacity software. The frequency response is measured using a signal at -20dB.

An analysis of 13 cassette decks by Industrial Engineer Alex Nikitin using Audio Tester software indicates that most will exhibit a flat response (that is, one with deviation above or below 3 decibels only below the graphical line) right up to 18 kHz – 20 kHz based on a -10dB recording level. Sony UX-Pro or TDK SA Chrome tapes were used by Alex.

On the Teac deck, the signal-to-noise ratio (even without noise reduction switched on) is excellent. Dolby B, the benchmark noise reduction for decoding pre-recorded cassettes, is included. Metal tapes can be played back but not recorded.

To sum up, the cassette mechanism has poor specifications relative to component hi-fi decks produced in the last twenty years. For example, the current Ion Tape 2 PC deck has far better specs for half the price. A better deck such as this could be plugged into the line-in inputs, but this seems like an unnecessary burden. Nonetheless, the response is superior to the average boombox. Audiophile Zomax (who evidently has great taste in music) maintains:

Tape playback was surprisingly good. Rush Chronicles and Nirvana’s Nevermind, both of which have been sitting around gathering dust for 15 years sounded crisp and surprisingly dynamic. It’s also great to be able to operate the tape playback using the remote.

A final word about recording

With respect to losing high frequency response when recording music using 128 kbps & 192 kbps MP3 bitrates or below-average grade cassette decks, Audiophile Goldear points out:

…Most material does not have such high-level [High Frequency] content. So, unless you are recording moog sythesizers which have a lot of HF energy, at high levels this really isn’t a problem (sic). Take a look at music on a spectrum analyser some time, and you will discover that the HF content above 10 kHz is usually 10 or 15 dB below the midrange in amplitude. So most of the time, you really don’t have that much of a problem.

Further information

Teac website. Full operating instructions can be downloaded.

American Ebay sellers. New stock is priced from $250 Australian dollars excluding air freight.

This entry was updated in August 2014. The article should not be construed as an endorsement of any particular device. Prospective buyers should carefully make their own enquiries. Now if we can persuade Teac for a test model? Pretty please…

Splitting WMA without inducing loss

WMA Snip is a lightning-fast programme written for the Windows XP operating system which will detect silence and reliably split large WMA files created by the Creative Zen V series recorders, pictured below. The cost of the software is roughly $19 AUD. A fully functional evaluation version which works for a fortnight can be downloaded so a prospective user can see if it is worth spending the dough. Users on have given the software a rating of ‘fair’, comprising 2.7 stars. According to the developer, Andy Bridle:

For large files containing multiple tracks, WMA Snip can automatically define segments using silence detection; WMA Snip also connects to the online music metadata service at Music, and can use its data to locate tracks within long recordings and define these as segments…

The editing is non-destructive, in that the only changes made to the original file are the addition of file markers defining sub-sections of the file’s audio content, known in WMA Snip as segments; the audio content itself is not affected.

WMA Snip does not re-encode the music in the WMA files it detects and splits when Direct Copy for Saving Segment Audio Data is chosen. ‘The most accurate results are obtained with this method, in effect creating a digital copy of the segment’s audio data. The compressed, unprocessed audio data is copied to the resulting WMA file,’ according to Bridle’s documentation. Splitting of MP3 and Wave files is also supported.

A free alternative is to just split using Audacity. Please ensure you download the FFmpeg Import/Export Library which will enable one to import WMA files into Audacity. Please note that the official download site for this FFmeg Library is slow. Downloading from 4shared instead is recommended.

Audio editors such as Audacity (pictured) transcode or re-encode compressed audio such as WMA files. Audio splitters such as WMA Snip do not. Transcoding may exaggerate noisy digital artifacts. Enthusiasts at the Hydrogen Audio forum have compiled a guide to transcoding. Programmer & hotel disc jockey Andrew Davidson outlines his excellent tips to minimize the drawbacks. Whilst transcoding or re-encoding is undesirable, he writes:

Very often transcoding sounds fine. There is a slight quality loss, but for most non-audiophile purposes (e.g. casual listening) it will work out fine. In my experience, a well-encoded 192 Kbps or higher bitrate MP3 at 44.1KHz frequency can be brought down to 128 Kbps for listening in a car or other noisy environment, or using poor headphones in a portable MP3 player.

In this blogger’s own limited experience, there was no significant impairment of quality when transcoding from 192 Kbps to 320 Kbps constant bitrate MP3. However, there was less audible noise (presumably, a byproduct of transcoding) when transcoding the same MP3 192 Kbps material to the highly-rated Ogg Vorbis aoTuV, using quality setting 10. The side effects will invariably depend on the quality of the original source material, including the type of music.

Analogue rules

This article originally appeared on the now-defunct dbrmuz blog.

The compact disc, introduced in 1983 is still the king of digital. But because of the need for internet distribution, sound quality has gone backwards.

Steve Jobs’ statue in Hungary Science Park, courtesy of Derzsi Elekes Andor.

Yeah, that’s the late Steve Jobs picking his nose. Seriously, though, Steve loved his music. According to the Australian:

[Neil] Young said the Apple co-founder [the late Steve Jobs] was such a fan of music that he didn’t use his iPod and its digitally compressed files at home. Instead, he used a physical format well-known to have better sound. “Steve Jobs was a pioneer of digital music. His legacy is tremendous,” Young said. “But when he went home, he listened to vinyl (albums).”

An Ipod Touch 4G, courtesy of Matthieu Riegler

Professional mastering engineer Ian Shepherd explains why he thinks MP3 sucks. His original article has been commented on for almost three years now!

How does [MP3] fail ? That depends a little on the encoder being used, but some of my own pet hates include:

    * MP3 sizzle – the artificial, unnatural swirling metallic noises that sound like someone’s added chime bars to everything, or there’s a mosquito buzzing in your ear. Some people actually say we prefer these noises in MP3s – I say bullshizzle!

    * Added distortion – Yet another side effect of the so-called Loudness Wars. MP3 encoders rarely include any headroom for the encoding process itself, so the added processing pushes the music even further over the limits, generating inter-sample peaks and adding even more distortion in the process.

    * Flat, two-dimensional sound – MP3 works by throwing away musical information that we supposedly can’t hear – up to 90% of the original information, at 128k. That means all the subtle, delicate stuff, like ambience, space and realism. So a lush, three-dimension original is reduced to a flat, cardboard replica of itself.

    * Mushiness – All but the very best MP3 encodes just sound fuzzy, muddled and – well, mushy.

These babies are the first to distort on MP3. Image courtesy of Joe Grimaldi.

Zero Paid journalist Drew Wilson explains in plain English:

A WAV file is essentially an uncompressed sound file. When someone encodes it to MP3, the “highs” and “lows” start being lost in an effort to make the file smaller. A good way to demonstrate to yourself what the sound differences are between a high quality and a low quality version of an MP3 is, listened to a song that’s at 320k, then compare that to the same song that’s in an MP3 format of 128k. If the differences are seemingly minimal, pay attention to the high hats or cymbals. You may notice that the hats get a little scratchy or distorted as quality is reduced. If you’re listening on, say, a subwoofer system, listen to how heavy the bass is as well. 

Nanook describes his impression of how MP3 ‘falls apart’:

With MP3 encoding quality at 320k is generally near CD quality but even at 320k high frequency details get lost. Symbols sound like paper scratches instead of metallic crashes. At lower bit rates the first thing I notice about MP3’s is that high frequency details tend to get mushy and bass tends to get muddy as well. At 160k, MP3 sounds roughly equivalent to FM broadcast. At around 128k, the highs take on a swishy quality and complex sounds become blurred. Individual instruments in a band tend to lose their distinction at 128k and below. At even lower rates the swishyness becomes very annoying and instruments begin to sound like they’re off-key and broken up like a cheap cassette recorder with bad wow and flutter and tape with drop-outs. 

Image courtesy of

Analogue can be a simpler and more resilient medium to work with than compressed audio (MP3, WMA, Minidisc ATRAC, DVD AC3, et. al.). The primary weakness of analogue has simple and effective remedies. Improvement of the signal-to-noise ratio on dirty vinyl, video or compact cassette can be performed digitally using software such as Audacity and Nero. Getting rid of digital artifacts however is next to impossible on MP3 clips, although downmixing to mono can help. If you record digitally on a PC, there are tricks to make the recordings sound more like analogue.

With the pre-recorded product, you get full album liner notes. I’m talking photographs, lyrics and history. Pulling out a CD, record or cassette is an experience. Ownership of an album gives the listener their slice of history. Significantly, you know the artist gets paid properly.

Analogue cameras. Pretentious enough for Scarlett… Image courtesy of Ruud

Hugh Robjohns from Sound on Sound magazine writes:

In many cases, the technical limitations and imperfections of analogue systems have become an integral part of the quality of the recorded sounds that we all grew up with — and the end result is perceived by many people as being more pleasing than we can easily achieve today with all-digital recording chains. Further than that, some of the sounds resulting from ‘abuse’ of analogue gear have become recognised effects in their own right (tube overdrive and tape saturation being obvious examples).

Interestingly, sound recording isn’t the only industry that has found this. Digital cameras and imaging software usually provide a range of ‘picture-style image processing’ options. My own camera offers Standard, Portrait, Landscape, Neutral, Faithful, Monochrome, and three user-defined modes, for example, each changing the tonal balance, colour saturation, sharpness, and contrast in different ways, to enhance the subject.

In short, enjoyment of an artistic product (be it a sound recording, a photograph, a film or whatever) isn’t necessarily about precision and accuracy: more often, it’s about mood, character and subtle enhancements that make the end result more vivid and interesting than real life.

Read more about why musicians might want to record using analogue equipment only. For everyone else, Nanook offers these precautions for those taking advantage of the convenience of digital recording:

In the old days of analog recording, most recording devices did not clip hard. Magnetic media in particular has a linear region which can reproduce the signal faithfully. After that analog region is exceeded there is a non-linear region where the signal is distorted, but it isn’t hard clipped. This made analog recording much more forgiving of recordings made at too high of a level. Because of the soft nature of clipping on these analog devices, the distortion that is produced by the occasional clipped peaks tended to be mainly even order harmonic distortion.

Digital recording is less than forgiving. A digital signal can’t be less than all zero’s or more than all one’s, so a digital recording is said to clip hard. Hard clipping produces mainly odd order harmonic distortion which humans tend to find aesthetically more objectionable than even order harmonic distortion produced by soft clipping.

A Melbourne photographer captured Metallica live in Munich in 2009.

This article is teetering on pretentiousness, so let’s return to the big picture. Whatever format you choose it is WHAT you are listening to that matters! I’ll end with an article from Sound on Sound by Richard Buskin about the analogue recording of what many consider to be the greatest Metallica record ever made:

In January 1988, Metallica regrouped following the release of three increasingly successful studio albums and the death, some 15 months earlier, of bass player Cliff Burton, who had been crushed beneath the band’s tour bus when it crashed in Sweden. Bassist Jason Newsted joined singer/rhythm guitarist James Hetfield, lead guitarist Kirk Hammett and drummer Lars Ulrich to begin work on …And Justice For All.

Recorded over the course of four and a half months in LA’s One On One Studios, this would turn out to be the breakthrough project for the Californian thrash-metal virtuosos, reaching number six on the Billboard 200 en route to eventually being certified eight times platinum by the RIAA. In what has since been named one of the 10 biggest upsets in Grammy history by Entertainment Weekly, the musically complex progressive metal album lost the ‘Best Hard Rock/Metal Performance’ award to Jethro Tull’s Crest Of A Knave.

Despite its popularity, the record also courted controversy among Metallica’s growing legion of fans. Many listeners were critical of what they perceived as the album’s overly dry and clinical sound; one which, for reasons that will be explained a little later, was largely devoid of Newsted’s bass. And for another, a lot of diehard fans weren’t happy that the band joined the commercial mainstream and courted the likes of MTV by shooting their first music video. Said video accompanied ‘One’, the fourth single off the album and Metallica’s first record to crack the Top 40 in the US, climbing to 35 on the Billboard Hot 100. With a running time of just under seven and a half minutes, its lyrics were inspired by Dalton Trumbo’s provocative anti-war novel Johnny Got His Gun, in which a WWI soldier lies helpless in a hospital bed, trapped inside what’s left of his body having lost his eyes, ears, nose, mouth, arms and legs in a mortar shell explosion. Despite struggling to get radio airplay, ‘One’ became Metallica’s first hit single, and remains a staple of their live performances.

Clip Cairns

On November 13th, 2011 tropo occurred to the following places.

Map of ducted stations

Here is tropospheric ducting from FM stereo broadcast 106.7 MHz ABC Local Radio Cairns. These ABC stations broadcast at 100 kilowatts and ducted across the Coral Sea at distance of 1,341 kilometres .

MSLP chart

Audio was encoded via Line In on the portable Degen DE1121 MP3 recorder at the maximum bitrate possible of 128 kbps. In the Americas, this receiver is known as the Kaito KA1121. Clips were split without re-encoding using the free software programme MP3Splt.

ABC Far North studio photo

I call bullshit: MP3 encoder preferences

This column originally appeared on the now-defunct dbrmuz blog. Warning: These articles are written to be deliberately controversial and may contain satire.

There is often much bullshit to be found in audiophile circles because audio quality is inherently subjective. And of course, where differences in sound quality can be perceived, a market can be found. That’s capitalism folks. My master’s previous post compared a recording made with a good deck using Dolby C encoding and metal cassette to the original CD, I wanted to do something similar. Today we are focusing on the possible differences between MP3 encoders.

For those living under a rock, this is what we mean by MP3. Andreas Westfeld and Rainer Bohme from the Technical University of Dresden in Germany explain:

The invention of the ISO/MPEG 1 Audio Layer-3 (MP3) audio compression algorithm is probably one of the most remarkable and far-reaching develop- ments in the area of digital media processing. The MP3 format enables compression rates of about 1/10 of the size of uncompressed digital audio while degrading the audible quality only marginally. Together with the moderate complexity of the compression algorithm—software implementations of MP3 coders/decoders (codecs) with acceptable performance even on low budget home computers soon became available—the format simplified the interchange of music and resulted in worldwide popularity for its users and sleepless nights for the music industry.

The maniac tested a freeware MP3 encoder that was created in 1998 called Plugger. Those that populate the Hydrogen Audio forums speak highly of it… Here are some examples of their praise:

Plugger is a very old mp3 encoder. AFAIK it is based on the ISO code and sacrifices speed for quality. It suxx big time (sic).

Their benchmark for “poor quality” was Plugger. Just to put things in perspective. I had to download a copy for myself, just to hear… yup, it’s bad. Real bad.

However after trying [Plugger] @320kbps I’d say it doesn’t sound shockingly bad (for the average person of course).. well, except with the fatboy sample.

These three singles were used for the test.

The above singles were ripped to uncompressed wave format from the original CD albums using Audio Grabber. Peak level normalization was performed on the tracks because the older CDs (for example, the unremastered 1987 Billy Joel CD) are notoriously of low volume. Normalization is considered undesirable because it may increase distortion, but in this instance it was unavoidable. The tracks were then converted using Plugger to 160 kbps MP3 format. I recorded all 6 tracks (3 x MP3, 3 x wave) onto a blank audio CD using Nero. After a few moments it was ready and I threw the audio CD into into my Sony CDP-397 CD player to have a listen with headphones.

I didn’t encounter one nasty artifact. And being an analogue addict, I can pick my artificial sounds (artifacts) with ease, just like Kevin Rudd can pick a comeback and Malcolm Turnbull can practice humility. Oh…  Anyway, what what was I saying again? Like all MP3 to CD comparisons, obviously the wave files sounded richer, particularly the guitar solos. The bass was tighter.

Perhaps the songs selected were inappropriate, perhaps with classical music the flaws of the encoder become far more evident? However, the conclusion is simple. Based on these tracks, Plugger produces entirely satisfactory MP3 recordings at 160 kbps and does not deserve the criticism levelled at it.

The aforementioned academic paper (statistical analysis of MP3 encoders) can be found here.

Regional DX

No último mês de Dezembro tive a oportunidade de viajar até Apiaí/SP para caçar as populares emissoras caribenhas na faixa de FM. Fiquei na casa do meu irmão, algo que trouxe comodidade, liberdade e obviamente tudo o que faz parte de uma visita familiar.

Começo destacando positivamente o uso do SDR. Por ser uma viagem primariamente familiar, sem ele a quantidade de escutas seria muitíssimo menor. Poder gravar 2 MHz do espectro é algo sensacional!

Foram quatro noites de muitas captações. Algumas aberturas chegaram a durar mais de seis horas, algo que eu jamais tinha presenciado. Durante o dia, nada de espetacular, infelizmente.

Trouxe cerca de 1 Terabyte em arquivos do SDR para posterior processamento. Aqui é importante refletir sobre um ponto que já vi discussões há algum tempo.  Dois meses depois da viagem consegui analisar apenas 4 MHz de um total de 20 em gravações. A produção foi elevada, mas ninguém…

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