LECTURAS de AUDIO OBLIGADAS

La Verdad sobre los cables:

Matrix-Hifi: Zona rona --> La "verdad" sobre cables de altavoz

Cómo resumen: no puede haber diferencias en la respuesta en frecuencia entre cables en tiradas domésticas (no muy grandes) manejando las cargas tipicas en las que se mueven las cajas acústicas si se tiene el grosor adecuado para la potencia necesaria; y si no hay diferencia en la respuesta no puede haber diferencia en el sonido (que no sea un cable defectoso o mal blindado que induzca ruido en el caso de los de interconexión).




"Las 10 grandes mentiras sobre el audio":


http://www.google.es/url?sa=t&rct=j&...48705608,d.ZWU



Un saludete

Cuelgo las 14 páginas del enlace sobre "la verdad de los cables" comentado, para el que le interese el tema:

































Supongo que Maty tendrá instrumentación y documentación más precisa y detallada para desmentirlo (que evidentemente no provenga de empresas que se nutren de vender cables o revistas del sector por propagandearlos) .


Un saludete

la importancia del porqué se han de comparar los aparatos en "blind test" (doble ciego) para eliminar el efecto placebo:

Porque debemos tomar con cautela Las evaluaciones hechas a la vista. | Arquitectura Aural


Un saludete

*** Dejamos este hilo EXCLUSIVAMENTE para textos relacionados con audio y similares.... ***

audiophilereview.com Supervinyl! by Roger Skoff

One alternative that’s not actually new, but does offer a real possibility of improvement is “half speed mastering.” In practice, this is really simple: To make the “master” recording, an original recording is played at half-speed (7 ½ ips [inches per second] if it was originally recorded on analog tape at 15 ips or 15 ips if it was recorded at 30) into a disc-cutting lathe which is also operating at half-speed (16 2/3 rpm instead of 33 1/3 rpm). Doing this reduces all of the frequencies to be recorded by half ― 20 kHz becomes 10 kHz, 1 kHz becomes 500 Hz, etc. ― and makes the job of the disc cutting head a whole lot easier. Because disc cutting heads, regardless of manufacturer, were limited in high frequency capability, and were typically rolled-off by 3dB or more at 15 kHz, half-speed mastering effectively doubles the high frequency response of the cutting head and allows for a new -3dB point well above 20 kHz, which is all there when the record is played-back at the normal speed of 33 1/3 rpm. Yummy!

Another option which increases available high frequency recording capability (at the cost of less recording time per disc) is cutting an LP at 45 rpm instead of the customary 33 1/3. Doing that increases the number of inches of groove that are cut every second by 35%, which doesn’t help the cutting head’s performance at all, but makes it easier for the playback cartridge to track the higher frequencies (and also explains the lowered maximum recording time). The one possible negative sonic side-effect may be somewhat higher “groove noise” as the stylus drags along 35% more groove for every second of playback. Dust in the groove may also be slightly more noticeable for the same reason, but if the discs are kept clean (and who doesn’t clean their vinyl before every play) it should be no problem…

Another vinyl alternative that may or may not be worthwhile to you is the 180 gram disc. Ordinary LPs are standardized at 130 grams of vinyl, so the 180 gram format is a bit more than 38% heavier (although still less than the 200 gram UHQR recordings offered at one time by Mobile Fidelity Sound Labs)…

Making discs heavier means, of course, making them thicker: When LPs are all 12 inches in diameter, if they’re all made out of the same stuff, about the only place the extra 50 grams of vinyl CAN go is into making them thicker. That can be an advantage because greater thickness makes them more resistant to both macro and micro warpage, which can affect the sound. It can also be a disadvantage because the extra thickness will change the effective vertical tracking angle (VTA) of your cartridge and even a small amount of VTA error can make your records sounds quite noticeably WORSE. If you are planning to use 180 gram discs, my best suggestions are to either use ONLY 180 gram discs and optimize your arm’s VTA setting just for them; OR buy a tonearm that features easy VTA adjustment and get really good at resetting it every time you change from standard to 180 gram records and back; OR, if you can afford it/them, get a turntable setup with two arms and two cartridges (and two phono cables) and a preamp with two phono inputs; set one arm up for 130 gram standard LPs and set-up the other for 180 gram discs and simply switch back and forth at your preamp. Mmmm, Good! Mmmm…

reddit.com Mastering engineer Bob Katz declares the loudness war as "won" (digido.com)

-> Digital Domain [Forum] THE LAST BATTLE OF THE LOUDNESS WAR HAS BEEN WON

“I have just completed loudness measurements of iTunes Radio using iTunes version 11.1.1. Tunes Radio’s audio levels are fully-regulated, using Apple’s Sound Check™ algorithm. This is a very important development,” Katz said.

During several hours’ testing, Katz measured the output level of several stations, and concluded that each song’s loudness averages -16.5 LUFS, within better than 2 dB, usually plus or minus 1.5 dB. The Apple release notes state that version 11.1.1 “improves stability”, which he interprets as having solved some loudness regulation issues which were present in the previous iTunes release.

It is clear that music producers want their music to sound as good as possible on the nascent but already popular iTunes Radio platform, given the many listeners instantly available. This immediately opens an opportunity to curtail the loudness race within the next few months. Added Katz, “The way to turn the loudness race around right now, is for every producer and mastering engineer to ask their clients if they have heard iTunes Radio. When they respond in the affirmative, the engineer/producer tells them they need to turn down the level of their song(s) to the standard level or iTunes Radio will do it for them—and not always in a pleasing way. iTunes radio will not just ‘turn down the volume,’ but may peak-limit the important transient peaks of the material and make the song sound ‘smaller’ and less clear than its competition.”

Katz suggests, “The engineer/producer should also tell their clients to turn on Sound Check in iTunes to hear their music exactly the way they will be broadcast on iTunes Radio. This makes all music played in iTunes, whether it be on IOS devices played while jogging, connected in the car, or on the desktop computer, perform consistently. It’s a revolution in the making, with instant positive results.“

Katz’s discoveries show that current squashed and smashed pop releases are being attenuated more than 7 dB in order to make their loudness equal to that of more-conservatively mastered releases. In other words, true peak levels of current pop songs are as low as -7.8 dB below full scale! “There is so much available peak headroom now in iTunes Radio that anyone who wants to master their songs with more conservative levels and prefers higher peak-to-loudness ratios will produce music with immediate loudness and sound quality advantages, compared to what’s being played out there now. The cream will soon rise to the top. The music will sound better, even a bit louder, and will attract more listeners. iTunes Radio is already so popular that it will end the loudness race by force majeure. This development is a great opportunity for producers to explain and demonstrate to their clients how to make their songs sound better on iTunes Radio and everywhere else.”…

About DSD.

audiocircle.com A visit to a Friend, Tape Project, DSD, Vision MC preamp, electrostats, & more by avahifi

…Finally DSD playback using the Schitt DAC. Well, this sounded very nice indeed, certainly something worth exploring further. My friend helped me set up J River playback software on myMac, loaded me up with a bunch of source material, and sent me home with his DSD DAC. I am not positive why DSD playback is so nice. I suspect that much of it is because the source material has had less mixing and cadiddling done to it. Simply better production values than with stuff normally stuffed on a CD. I do know that a lot of old great music will soon be available in DSD format at rational prices and terabyte hard drives are cheap now. I am enjoying playing DSD stuff here right now.

dB Cooper -> realhd-audio.com John Siau: Benchmark Audio Guru by Mark Waldrep

I actually had a SONY engineer say to me one time and this is quite few years ago…he said, ‘we realized after we got a ways down the road that DSD was kind of a mistake but we had too much invested in it’.

First comment is of John Siau:

Where does Benchmark stand on DSD vs. PCM, and why?

1. Benchmark recognizes that DSD (64x and higher) has significant advantages over 44.1/16 PCM.

2. Benchmark recognizes that high-resolution PCM (96/24 and higher) has significant advantages over 44.1/16 PCM.

3. Benchmark’s measurements and calculations show that the performance of 64x DSD is almost identical to the performance of 20-bit 96 kHz PCM (the in-band SNR of 64x DSD is about 120 dB). 64x DSD does not have any time-domain, frequency domain, or linearity advantage over 96 kHz PCM. DSD marketing materials have been very misleading.

4. 24-bit 96 kHz PCM has a 24 dB noise advantage over 64x DSD (144 dB vs. 120 dB), but this 24 dB noise difference is completely masked by the noise produced by other components in our recording and playback systems, and by the noise limitations of our recording and listening spaces.

5. Benchmark recognizes that 64x DSD and 96/24 PCM formats outperform most of the recording and playback chain. Bandwidth of either digital transmission system meets or exceeds the bandwidth of our microphones, amplifiers, and speakers. Likewise, the SNR of either digital transmission system meets or exceeds the noise performance of microphones, microphone preamplifiers, and power amplifiers. In addition, these digital transmission systems both exceed the performance of most A/D and D/A converters. 64x DSD and 96/24 PCM are not the factors limiting the performance of our audio systems. Focusing on DSD vs. PCM will distract us from much bigger issues in the recording and playback chain. Any sonic advantage of one digital system over the other will be very small when compared to improvements that can be made in other parts of the signal chain.

6. 64x DSD and 96/24 PCM both offer excellent sonic performance as distribution formats. PCM is more compact, but DSD provides better copy protection (a frustration to those of us who use music servers, but an important consideration for copyright holders).

7. Every A/D and D/A converter that Benchmark has produced uses Sigma-Delta conversion with equally-weighted 1-bit conversion elements. Benchmark never used multi-level conversion because of the THD issues caused by the linearity errors that are common to all multi-level systems. Benchmark has always placed high priorities on THD and linearity, at the expense of SNR. Sigma-delta 1-bit DACs tend to produce more noise than multi-level systems (such as ladder DACs), but the 1-bit systems achieve near-perfect linearity, which in our opinion is much more important than SNR. Benchmark has overcome the noise limitations of 1-bit conversion through the use of parallel 1-bit conversion systems. Our DAC2 sums the outputs of four balanced converters. Each of these four converters has sixteen equally-weighted balanced 1-bit converters (for a total of 64) that are summed together to improve the SNR of the system. These 64 1-bit converters can be driven from a 32-bit PCM signal, or from a 1-bit DSD signal. Either way, the performance is nearly identical, and none of the multi-bit THD issues exist. In this sigma-delta configuration there is almost no difference between the in-band performance of PCM vs. DSD. The only measurable difference at the output of the DAC2 is that 64x DSD signals produce about 8 dB more noise in-band than 96/24 PCM (due to the SNR limitations of DSD). Ultrasonic noise is not an issue at the output of the DAC2 because we are careful to remove the ultrasonic noise produced by DSD noise shaping. These same filters also remove the ultrasonic images that are always produced by D/A conversion (DSD or PCM).

8. The ultrasonic noise produced by DSD noise shaping must be removed after D/A conversion. It cannot be removed from the DSD signal before D/A conversion. This noise is due to the 6-dB SNR of the 1-bit DSD transmission system. Aggressive noise-shaping must be used in the DSD A/D, and at least once more in the mastering process. This noise-shaping is used to achieve an excellent SNR in the audible band by moving most of the 1-bit quantization noise to ultrasonic frequencies. Each time this process is applied, the quality of the DSD audio degrades (noise and distortion both increase). For this reason, the quality of DSD degrades very quickly in the mixing and mastering process. DSD has produced impressive results when the mixing and mastering processes have been omitted from the signal chain. To date, most of the DSD vs. PCM listening tests have omitted these processing steps. Unfortunately very few recordings can be produced without some mixing, editing, and mastering. Cascaded DSD noise-shaping processes should be avoided. For this reason, Benchmark does not recommend recording and mixing in DSD.

9. The 24-dB noise advantage that 24/96 PCM has over 64x DSD begins to become significant in the mixing and mastering processes. In terms of in-band noise, each DSD noise-shaping process is equivalent to at least 16 cascaded 24-bit dither processes. In terms of distortion, there is no comparison; the DSD noise-shaping process adds distortion while the PCM dithering process is distortion-free.

10. If the ultrasonic noise of DSD is not removed after D/A conversion, it will usually cause distortion in the playback system. The slew-rate limitations of most power amplifiers will fold the ultrasonic noise into the audible band causing distortion that is not harmonically related to the music. If the power amplifier has sufficient slew rates to pass the ultrasonic frequencies, similar problems will occur in the speakers. For these reasons, the ultrasonic noise must be removed from a DSD source after D/A conversion or before amplification.

11. Benchmark introduced 64X DSD on the new Benchmark DAC2 converter family. This gives our customers the ability to play DSD recordings in native format. Existing DSD recordings should not need to be converted to PCM to be enjoyed on a Benchmark converter.

12. Currently there is no practical way to play SACD disks through a high-quality outboard converter. SACD copy protection holds most existing DSD recordings captive to the limited quality of the low-cost conversion systems built into SACD players. It is our hope that many of the fine recordings that exist on SACD disks will be released for purchase as DSD downloads.

Aunque es obvio...:

Petrus:
We all know recording with 24 bits has tangible benefts. This test was about delivery; SACD could not be distinguished form 16/44. 16/44 has all the resolution we need for playback. Using 24/96 or whatever is perfectly legal and usefull (at least for recording), but claiming a big, audible difference in playback quality is simply not true.

Let's not mix up two different things, recording and delivery.
-----------------
Funny note: on a hifi bulletin board there has been two long winding threads about audible audio quality: one about different MP3 versions, one about this same CD versus ri-res formats. The funny part is that MP3 discussion is quite factual, people calmly admit they can not tell the least compressed MP3s apart, or distinguish them form CD quality. The CD/hi-res thread is much more emotional, there the whole question of even testing such a self evident fact [that hi-res is superior] is questioned, the validity of making test files is questioned and people refuse to take part in the test (or at least they decline to make any comments about their personal results).

I think this only can be caused by the monetary sacrafices these people have made. You can test different MP3 compressions without investing any money; any digital player can play anything MP3 and CD-WAV, so you are not going to loose face by admitting the best compressions sound the same. Not so with SACD/hi-res. Some people have invested thousands to play these formats, they will not admit they can not hear any improvement, they even refuse to listen to a simple test file to see it the difference can be heard.
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The difference between 16/44 and 24/96 can not be heard

From AES Journal 2007 September, Volume 55 Number 9:

"Audibility of a CD-Standard A/D/A Loop Inserted into High-Resolution Audio Playback

E. Brad Meyer and David R. Moran 775

Conventional wisdom asserts that the wider bandwidth and dynamic range of SACD and DVD-A make them of audibly higher quality than the CD format. A carefully controlled double-blind test with many experienced listeners showed no ability to hear any differences between formats. High-resolution audio discs were still judged to be of superior quality because sound engineers have more freedom to make them that way. There is no evidence that perceived quality has anything to do with additional resolution or bandwidth."

Test were done with a high grade stereo system and over one hundred test persons. Nobody could hear the difference between SACD and CD standard audio.

the difference between 16/44 and 24/96 can not be heard at DVinfo.net


Lo bueno de la AES es que poco a poco se van echando por tierra los mitos audiófilos; Resultados que coinciden 100% con los postulado en matrixhifi


Un saludete