Class A Power, Optical - HDMI Journey - www.AcousticFields.com

[@djhmax09]

Thanks for sharing! Digital has come a long way indeed

[@AcousticFields]

You bet!

[@Stelios.Posantzis]

1:41 I don't know whether it's Toslink that is being referred to here but, recently, in another youtube video I learnt that Toslink is nothing more than regular SPDIF with a coupled LED and photo-sensitive device pair at each end. In other words, electronically it's just another gimmick. Fibre-optically it's also kind of a gimmick as the the fibre is not a glass fibre, as most would have thought, but just something much closer to fishing line thread. Whether that leaves room for more or less electrical interference or pulse time-smear I do not know. RCA cables are cheap and do the job fine for SPDIF so not much point spending time to test this out.

[@zackw4941]

It's not a gimmick.. It is the same data format as SPDIF over any other medium. The advantage of optical is that it does not electrically couple the two components to each other. This reduces the possibility of interference and eliminates certain ground problems. The disadvantage of SPDIF vs USB and probably newer HDMI formats, is that SPDIF has the transmitting device set the clock. With USB, the receiving device sets the clock. Making it easier for the receiving device to keep the clock in sync reduces jitter. Some DACs will cache and reclock the signal internally. I had a Denafrips Venus which does this and I couldn't tell optical and USB apart. My Audio-gd R1 does not do this and I can tell that USB is slightly cleaner and higher resolution. Optical subjectively seems a little softer and warmer in my system. I prefer USB. That said, both Denafrips DACs I've used introduce enough lag time to be unacceptable to me for video playback or gaming. My R1 does not have this problem.

[@PanAmStyle]

Glass Toslink cables are available and make an appreciable difference. My system is currently limited to Toslink into the DAC. When I upgrade it will be all HDMI.

[@Stelios.Posantzis]

@@PanAmStyle I did not know about these - any examples of makes and models?

[@Stelios.Posantzis]

​@@zackw4941 I agree with the above explanations but it also depends on the definition of a gimmick. In particular, whether the conversion of the signal to a light signal affords it a better protection from interference by not introducing another worse problem at the same time. There are many accounts on-line of people experiencing a better reproduction via coaxial cable rather than via Toslink. I would venture claiming that the ground loop issue is usually more of a problem in studio environments as opposed to home use. Of course, if the DAC has caching ability, it doesn't matter which method of passing the signal is used since the DAC will re-create the digital signal avoiding any timing issues that are introduced by the signal transfer medium. So, I agree that in a studio environment, Toslink might not be a total gimmick but then I have two more questions: a) why is it even available on consumer devices b) I would not expect any sound engineer to use Toslink over an AES/EBU balanced digital connection which means that Toslink would probably be used only as an emergency/occasional solution e.g. in case of a quick demo from a home-recorded (or similar) medium. Like I already mentioned, the above are offered with the caveat that I have never compared reproduction using Toslink vs. coaxial - or if I have it was long ago and did not seem to me to favour one vs. the other. USB is a totally different animal/discussion.

[@zackw4941]

@@Stelios.Posantzis If anything, I would assume a studio environment to have higher quality equipment and things like ground loops to be sorted out. It's in the home where Joe Shmoe has any possible combination of consumer devices plugged in willy nilly and cables all over the place, that you start worrying about enexpected issues. People get really worked up about digital. At the end of the day, a messy 0 and a messy 1 tell the exact same story as a razor sharp 0 or 1. All that matters is that you avoid any catastrophic problems and have a stable clock. I have also tried coax vs optical at some point a long time ago and didn't tell any difference. But that doesn't mean optical isn't more fool proof in a wider variety of situations. The only gimmick if you want to call it that, if the cool factor that you're using light and one end of the cable shines red when the other end is plugged in. Who knows, that may have been a deciding factor when it was brought to market..

[@KB-os6lh]

Class A all the way!

[@mickburns4913]

Hi, just have a check, but I'm pretty sure that Plinius is from New Zealand

[@doozer-fv4hu]

Correct! As a kiwi I can confirm Plinius are in fact manufactured in Aotearoa, New Zealand :)

[@mickburns4913]

Maybe he doesn't think there is a difference, no disrespect. 😊

[@doozer-fv4hu]

@@mickburns4913 No offense taken! In fact I thought the same thing - or maybe it was purchased in Australia and he meant that...

[@mickburns4913]

Yeah that crossed my mind aswell

[@AcousticFields]

Lets focus more on the performance of class A than the originating country. How about a discussion on the damping and dynamic range as a start. How about the low distortion. Any feedback on those features.

[@brown-eyedman4040]

Absolutely agree about the advantage of class A amps. And yeah, the electric bill goes up! Back in the day, Crown amps were the thing in pro sound reinforcement. Driving big JBL cabinets. Unless you were the Grateful Dead and could afford the McIntosh powered wall of sound.

[@tz7813]

I have a 4k overhead projector that I want to connect to my AV receiver with a high quality HDMI cable for watching movies. The cable run would be around 30ft. Is it possible to achieve this with minimal signal loss? Any info appreciated.🙏

[@djpsychic]

The general optical toslink/spdif used has a limited bandwidth that limits the audio dynamics / frequencies when using multi channel. It was simply never designed for it. Aka it becomes lossy and audio quality will suffer for sure. For a 2 channel signal there is plenty of bandwidth and, medium limitations aside, a 2 channel digital 48kHz 24-bit signal is exactly the same using optical/spdif/hdmi etc. Even if some bits get corrupted somehow there is still error correction making the digital input equal to the digital output. So unless it's losing so much data that you can audible hear dropouts it's all the same. It doesn't simply go noisy.... that's the effect / feeling when using a medium for something it was never intended to. For multi-channel , yes hdmi is superior due to the much higher bandwidth which can result in far more lossless channels. But it also comes with limitations with ever increasing bandwidth/frequencies used. hdmi based on copper can only go a certain distance and the higher the bandwidth/frequency the shorter the distance. To overcome these limitations there are hdmi cables that convert to optical first and use optical fiber for the transport. They won't have any reduction in quality as it's a bit-to-bit conversion. These optical fibers are very different in thickness and material and are not to be compared with the cables used for toslink/spdif/optical.

[@flexeos]

yes beyond 2 channels the data is compressed in the original protocol. They could have done better though., In audio pro, with the same fiber/connector/transceiver 8 channels of uncompressed audio are transmitted ( ADAT)

[@djpsychic]

@@flexeos Uncompressed up to 8x 48k/24b or 4x 96k/24b or 2x 192khz/24b. There is simply no more bandwidth :) HDMI can (at minumum) do 8 ch up to 192khz/32bit uncompressed. It's the hdmi spec that differs , not the fact it's optical or electrical.

[@vinylrules4838]

What are the new speakers in the two channel room?

[@AcousticFields]

We use ELAC towers in our two channel room.

[@vinylrules4838]

@@AcousticFields Thanks!

[@benjoe999]

How is optical noisy? Optical is digital cabling,it can't pick up noise. It is the digital converter that is noisy maximum.

[@joneslarvell2075]

Search for ‘Jitter’… In shorts, the right ‘0s’ or ‘1s’ but at the wrong time. HDMI was heavily accused of that in the early days as well, but at the end of the day it also has to do with the quality of the timing clocks of devices that are used and the implementation of the circuitry / cabling. (ex.) An optical output on a 10k device might sound better than an hdmi on a $50 one. All things being equal however, I would choose hdmi as well, especially on a combo of devices where the player can output only audio info from a second hdmi and the pre-amp can ‘slave’ the clock of the player.

[@flexeos]

Modern implementations of optical audio signal transmission are of course not noisy. People tend to believe in things without understanding the technology behind because of urban legends. The optical connection (toslink) is nothing more than transmitting an S/PDIF signal over a fiber optics rather than on copper. That data transfer method was developed 40 years ago. At the time any hardware resource was very expensive ( eg the electronic density of an IC was 1 million time worse than today!). So the protocol was developed to limit the use of hardware. the 2 channels were sent over one wire and there was no separate transmission of the clock so the data signal was including the clock using something equivalent to a Manchester code. At the time a consumer implementation would recover the clock from the data and use it directly to control the DAC. As the transmission is always a little noisy and the signal is a little distorted, there could be some phase noise in the recovered clock( a little less with the optical transmission) which would add a little analog noise to the signal in the DAC, hence the original belief that S/PDIF or Toslink are "noisy". But we are not in 1983 anymore! Today any half decent engineer , working in "high end audio" would regenerate a long term stable local clock for the DAC and add a tiny buffer with few samples just before the DAC. The quality of the transmission would then have literally no impact on the quality of the analog signal. Now if people feel better listening music knowing that they have spent $100s to buy a digital cable, that's fine with me, there are all sort of belief systems that makes people feel better. A funny thing is that even if you look at a bad implementation of the protocol, as the noise origin is a phase noise, it impacts more the high frequencies than the low frequencies. More or less a signal with 4 times the frequency has about twice the noise, so worst case, you should feel that the high end is worse not the low end.