diz's forum posts

#1 Posted by diz (929 posts) -

@cloudforest: I never claimed greater "fidelity" for vinyl across the frequency range - I pointed out that vinyl had a greater frequency range than CD, which is true. You seemed to introduce various reasonings about high frequencies included (or not) in vinyl recordings that can either be mitigated against or don't really exist anyway. Spectral analysis between vinyl and CD output shows the greater frequency range that records can bring to a reproduction. Vinyl frequency reproduction is also reasonably flat to 30KHz anyway and experimental pressings have been made up to 120KHz.

Your point about mass consumption is lost on me since we are talking about a niche market for audio here and the possibilities (as Peter Walker from Quad opined) for the "closest approach to the original sound". Design philosophies that can easily and faithfully reproduce all original frequencies interest me more than design philosophies that would sharply filter out frequencies above the old "red book" standard because the designs themselves would introduce their own additional harmonic distortion. "Mass consumption" means "mp3", which is objectively lower quality than CD! Your point about the "majority" of playback systems only underlines my earlier points about the exacting nature of vinyl (or any faithful sonic) reproduction.

Recent developments in audio with SACD and higher bit-rates and sampling frequencies becoming standard for audio recording and mastering indicate that the old "red book" standard is not sufficient and that better quality (with high end systems) can be attained with improved technologies. These improvements would not have become the new standard for digital if 16 bit 41KHz was considered sufficient for "perfect" audio.

DAC designs have improved, but oversampling techniques have also been used in the early CD players to maximise the sample rate so that frequencies approaching the Nyquist limit have sufficient resolution and have reduced artifacts for brick wall filtering. The additional headroom of higher sample rates makes it easier for filters to work above the audio range and reduce phase and aliasing errors. Although perfect on a mathematical level, the actual waveform produced near the nyquist limit has always needed additional processing for the human ear.

#2 Posted by diz (929 posts) -

@oldguy: That would be all well and good, except that the majority of records ever produced were recorded by analogue means. At the advent of CDs, there wasn't the convenient means to record digitally and the early CDs were "AAD" (Analogue recording, Analogue mixing, Digital Transfer). CD players have been available since the early 1980s, whereas computing power and/or commercially priced hardware that enables digital multi-track recording came much later than that.

Also, don't forget about your analogue amplifiers there! As for the most nusto thing in hi-fi I've ever seen; I was around when Peter Belt (PWB products) came to notoriety. Look him up if you don't know about his contribution to audio engineering with his statically charged paint brushes, safety pins and stickers.

#3 Edited by diz (929 posts) -

@cloudforest said:

Everything else @diz said I agree with completely but there's a couple of real-world issues with the statement about the frequency response of vinyl compared to CD (which is "red-book" audio not "white book" BTW).

The first is that, putting aside the frequency range for a moment, the frequency response of vinyl within that range isn't flat which compromises the fidelity with which a vinyl record can reproduce the original source. The mastering engineer can try to compensate for that but it's usually very imperfect and therefore a vinyl record won't be able to match the flatness of frequency response of a CD.

The second is that during the cutting process high-frequencies are rolled-off above a certain point due to the fact that sustained levels of those high frequencies would burn out the tiny motors used to guide the cutting head. So in reality this theoretical maximum isn't really achieved.

The third issue is that the act of playing a vinyl record gradually destroys the higher frequencies in the vinyl. The worst offender in this respect is the use of conical needles in the cartridge. Elliptical needles are better in this respect but the damage done by playing a record with a conical head is irreversible, so whether that vinyl record you picked up second-hand will have retained the higher end of the frequency range depends on what equipment it's been used with before it got to you and will continue to degrade on every playback.

The last issue is that power amplifiers often suffer from non-linear distortion when they're fed signals that contain frequencies above 20kHz, so it's not even clear that it would be beneficial to the overall reproduction of the original if the recording medium could reproduce signals containing those frequencies. It's one of the reasons why there's some debate over the merits of 24/96 as an end-user format (although it's pretty much as standard at the recording/mixing/mastering stages).

Most people are lucky if their able to hear stuff above 16-17kHz, let alone above 20kHz, and that only gets worse as people get older, so it's a moot point whether anything above the current limit for CD audio is actual required at all.

Firstly, apologies - I did mean "Red book", although "White book" does have the same audio specifications.

Secondly, the vinyl itself is encoded with a waveform and it is the encoding and transcription equipment that would reproduce it accurately (or not). The accuracy of reproduction is more challenging with vinyl, since there are many more areas of issue (both mechanical and electrical) than for digital reproduction.

The frequency response of cutting lathes is far higher than the frequency response of CD audio. High frequency content in audio is typically not sustained. Although sometimes high frequencies are rolled off on vinyl (as they are naturally on the tape masters), this is often done far above the 20KHz maximum for CD audio. Look at these traces for analogue vs digital from here:

"Supertramp"- "Dreamer" Vinyl LP

"Supertramp" - "Dreamer" CD

The third issue you describe about deterioration in records is true across all frequencies and is partly down to the quality of bearings in the tonearm, the suspension and tracking weight of the cartridge, although it is inevitable with physical contact and heat generated while the needle is in the groove.

Your final issue is easily resolved with proper amplifier design. I know that my record deck cartridge will start to roll off above 50KHz and my speakers will reproduce sounds in the 30KHz range (I have super-tweeters in my transmission line speakers). My preamplifier and amplifier will be capable of also amplifying that range of sound far above most human hearing.

Perhaps an issue with modern amplification is that it uses "class D" (switched mode) power supplies and amplification, which although more efficient, add a high frequency component that compromises audio quality above certain frequencies. More expensive amplifiers can use large power supplies and esoteric amplifiers running in "class A" mode (my preferred type of amplifier) won't have the switching or high frequency distortion that lesser "AB" or "D" mode amplifiers suffer.

The issue with CDs is that the maximum sampling frequency is dictated by the Nyquist theorem, so a brick wall filter must be applied over this frequency (since the samples taken will not correspond to their sampled waveforms). But leading up to the maximum sample frequency, the samples taken will less accurately describe their sampled waveform, since there will be fewer data points per high frequency wave. It led to notion that CD sounded harsh and brittle at higher frequencies. Vinyl does not have this issue and high frequencies can sound smoother and cleaner because at those high frequencies leading up to the maximum sample rate, the analogue waveforms are more accurate.

Your final thought is an interesting one and this is where objectivity departs and subjective ideas begin. We all have different hearing abilities and these abilities change (degrade) in our lives. Although I do remember an interview with an amplifier designer years ago, who stated that although we might not all hear things at ranges above 20KHz, we may feel them (as presence or ambiance) in the same way that we can feel ultra low frequencies that we can't hear either. The fact remains that if instruments can produce harmonics beyond the standard range of hearing, why shouldn't audio equipment be able to reproduce them? The CD limit was imposed at the time due to technical constraints that closely bordered the audibility of most people, so should not be used as an absolute reference in my opinion, especially since the digital waveform degrades as it reaches the maximum sample rate.

#4 Edited by diz (929 posts) -

(I wrote this a while ago and posted it in these forums but I thought I'd rehash it here again.)

I am a vinyl lover, user, audio nut and a realist. I have a large collection of records and a very good quality record deck, arm, cartridge and amplification. But there are distinct technical disadvantages to reproduction in vinyl. A myth is being built up about the use of records, which can be easily demystified with some clear evidence:

  • The "loudness wars" (i.e. compression used) in some music can also exist on vinyl. Typically, vinyl mastering is an added extra stage after the digital master has been created, so inherits all the compression used in the recording and mastering of the original sound. Compression used in recording and mixing can not be removed by "clever" mastering to vinyl. Vinyl often sounds more compressed (i.e. less dynamic) than a digital counterpart.
  • The dynamic range (difference between loudest and quietest bits) available for vinyl is far more limited than it is for digital media. Music with really quiet, then really loud portions tends to suffer by comparison. These dynamic range issues also affect vinyl's transient response in comparison to digital media. Digital music also offers better channel separation to vinyl.
  • Vinyl records have issues in reproducing bass frequencies. That's why all records have RIAA (cut bass and boosted treble) equalisation performed on them prior to pressing and then are further equalised to restore the RIAA frequency response (boost bass and reduce treble) in the phono stage of your pre-amplification circuitry.
  • To improve bass response and reduce the movement load on the cantilever of your stylus, records have their lower frequencies summed to both channels (i.e. mono in the lowest frequencies). This is a common additional mastering technique with vinyl that is not necessary (although still often used) with digital media.
  • There are issues in mastering vinyl in fitting the material in each side of an LP disk. If the grooves are spaced close together, than dynamic range and channel separation are further reduced with the additional penalty of sound over-spill between grooves. Once again, these additional steps in mastering for vinyl simply don't exist for digital media.
  • The output from a moving magnet record cartridge is far lower than the output of any other "line level" source, so has to be boosted with extra amplification to reach line level (in the amplifier phono input stage). Some of the more exotic moving coil type cartridges have an even lower output, so need greater amplification. This extra amplification stage can induce signal-to-noise and dynamic range issues with end equipment, even with high quality MM/MC input stages.
  • With the vast majority of record decks (I.e. all with a pivoting tonearm and excepting linear tracking turntables, which have their own set of issues), the needle in the cartridge tracks the record across an arc (the exception being in the linear tracking tonearms). This means that the tracking angle of the stylus is only optimal in 2 narrow areas in a well adjusted set-up and off-set across most of the disk. This is due to the stylus moving across the record in an arc rather than a straight line used in the cutting lathes that all have linear movement in their cutting heads. The off-set tracking angel affects distortion, and channel separation.
  • Materials and temperatures used in pressing vinyl can have a huge effect on the resulting quality of recording.

If you have a cheap record player, I would doubt that any vinyl you buy for it would sound better than for a digital equivalent (or even as good). You need some rather special equipment to get a decent quality reproduction from vinyl. I would personally advise against decks like the Technics SL1200 - which are great for DJs because they have light, direct drive platters and no suspension aside from their feet. They can therefore be used for cueing and scratching records, rather than for listening to them at the highest quality. Decent turntables tend to have weightier platters for speed stability, be belt driven (so motor noise isn't transmitted directly through the platter), have suspension and often a facility for using tonearms from different manufacturers. Such a deck would be rather crap to DJ on though, since they'd wobble about too much and take far longer to spin up.

To mitigate some of the above, the advantages of vinyl are:

  • Vinyl has a far higher frequency range than standard CDs ("white book" specification). Records can go up into the 50KHz range whereas CDs stop dead at less than 20KHz because of their brick wall filtering due to their sampling frequency. These issues are solved with things like SACD and other HQ digital formats with greater bit depths and higher sampling frequencies (i.e. 96KHz at 24 bit is a standard for recording, then the end result is dithered to white book 44.1KHz at 16 bits for CD and worse for mp3).
  • In comparison to MP3, vinyl can often sound superior - even compared to 320Kbps MP3 quality. People don't seem particularly interested in quality any more if the rise of the MP3 is anything to go by.
  • The LP sleeve notes and album design are far more pleasing, larger, often better printed and sometimes more inventive.
  • There is a nostalgia to listening to vinyl, especially in expecting certain cracks and pops in often played tracks.
  • Some stuff is only available on vinyl, else it has been digitally recorded from a vinyl source. For those recordings where the master has been lost, the vinyl option could potentially sound better than a digital reproduction, given suitable equipment.
  • 12" 45 RPM "singles" can sound fantastic. This is partially due to the considerations relating to wider groove spacing in the vinyl master (one or two tracks per side rather than the usual 4 to 7 for an LP) and partially due to the increased speed with which they pass under the stylus.
  • New vinyl pressings off a production run also sound better than the later pressings from the same master plates, which degrade with each pressing made.
  • The first tracks from a record often sound better than the ones at the end, since the grooves are moving faster under the stylus.
#5 Edited by diz (929 posts) -

@rethla: @burgavo: I agree with burgavo. If you have a look at that Rossi video again, you'll see that the gravel really slows him down and stops him hitting the wall after he slid on the tarmac. As a biker, I can say that leather protects you for several seconds of sliding on tarmac. After that, it wears through to your skin. It's the same thing with helmets; they don't offer complete protection - only a compromise between safety, risk and comfort.

I think burgavo's point about bike vs car safety is well made and they have different track considerations, aside from my initial general criticism that tarmac run-offs are turning racing into punishment by decree (or not - from race officials) rather than mistakes made directly affecting a car or bike's ability to continue to race.

#6 Posted by diz (929 posts) -

@rethla said:

I dont know the exact rule paragraphs but the conditions that was in japan gp i dont think they would have started the race and when it starts to rain during a race they are always much quicker to red flag. Changing tyres doent work like in f1 obviously and as shindig said the drivers are much more exposed so its very reasonable for motogp to have stricter rules. On astroturf, gravel traps etc. Its really easy to loose balance on a bike but unless you crash in the wall cars can ride it out and be back on the track again, Unless they manage to dig in ofc..

In parabolica they didnt put tarmac everywhere just along the track limits. That is to prevent what happend to Rossi, further out its still an speed absorbing graveltrap. If you come charging straight into the graveltrap at 130mph like Bianchi ofc. it wont stop you but im sure it slowed him down, it might even have saved his life. Aquaplaning on a tarmac run off area surely wouldnt have helped him.

They change bikes rather than tyres in MotoGP for wet weather racing. But they do race in the rain in MotoGP though and that's what made that race so exciting. They don't always have dangerous bike races (like the IOM TT) in the rain though, but UK safety laws would not allow a race like the TT outside of the Isle of Man - which has it's own laws on safety.

Have a look at these pictures of how much tarmac there is now at Parabolica that reduces the gravel traps. They do this to give control to the the driver of a wayward car. The unfortunate side effect is that it makes going off the track trivial, where it used to be race limiting (i.e. in losing many places or not being able to continue). Rossi's accident would have happened similarly if it took place at the Parabolica, since there is also that green astroturf there. And as I said and showed with the video link I posted earlier, he flipped the bike when he lost control on the astroturf at the edge of the track boundary. The purpose of the astroturf is to make the rider/driver stick only to the track and is designed to resist adhesion with a tyre.

Also; aquaplaning only occurs when there is significant water on a part of a track. They could resolve such issues with cutting grooves into the tarmac run-off areas, like they do a Spa though. I don't think any material could have altered the severity of Bianchi's impact, outside of kitting the removal vehicles out with "Tekpro" barrier skirts, or similar. But you can't mitigate for every risk and a big appeal of motor racing is it's inherent danger.

#7 Posted by diz (929 posts) -

@shindig: There was a gravel trap at both the Schumi and Bianchi crashes.

@rethla said:

Ofc. you dont wanna get stuck in it and it destroys the car ;)

Its there for safty reasons alone.

Motorbikes have generally much stricter safty regulations regarding wet races. Also running out in a graveltrap most likely makes you totaly loose control even if you just glance the edge of it with a motorbike. Rossi can attest to that ;)

Gravel traps have also made cars flip and roll if they dig in ;)

Rossi was forced on to wet astroturf at the Aragon corner - that caused him to lose control flip his bike before the gravel trap ;) What are the stricter safety regulations for wet weather racing in MotoGP then :?

#8 Posted by diz (929 posts) -

@rethla said:

@diz: well with a brake failure i dont think tarmac would have helped Shumie ;)

You are right however that in a fully functional car with a consious driver tarmac is better. A car that has lost all control and especially under wet circumstances gravel is preffered. For bikes its entirely different as they never race in these conditions.

The ability to steer might have helped him ;) Who is gravel preferred by? I thought race drivers don't want to get stuck in it and, as I said, it doesn't always slow the car down,

Did you not see the last MotoGP at Aragon? Rossi, Marquez and Pedarosa (and others) all crashed out in the wet race ;)

#9 Posted by diz (929 posts) -

@rethla said:

The tarmac around Parabolica is becouse of the suberbikes? For cars gravel traps is better as they slow down the speed even in wet conditions right?

Don't think so. Gravel traps won't always slow a car down, especially if it's going quickly (like Schumacher's Stowe corner crash and many others besides). When on the gravel, the driver has no control over their car at all, but in a tarmac run-off area, the driver can regain control and break before the barrier.

#10 Posted by diz (929 posts) -

@gaggle64 said:

Suzuka is a great track but it needs modernizing. A properly-sized gravel trap designed for modern F1 machines would have reduced Bianchi's speed exponentially before getting near the tractor, at the very least. Ideally no car should be able to even get near the tyre wall on a modern circuit.

Gravel traps don't always work since the cars tend to skate over them sometimes. They are getting replaced these days with tarmac run off areas (like the Parabolica at Monza). The problem I see is that with the "old" tracks there were consequences for going off and added impetus to drive within limits. I do wish Bianchi all the best in his recovery, but think he had green coloured "intermediate" tyres in wet conditions and should have respected the previous aquaplaning accident in his own driving.

I dislike the "modern" approach of (seemingly arbitrary) committee based punishments for exceeding track limits (on the newer tracks) and think excessive safety is ruining F1.