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Post by MartinT on Nov 30, 2022 9:26:19 GMT
This is such an important factor in achieving a highly resolving natural sounding digital system that it's fundamental for success. The reason that so many digital systems sound harsh, lack resolution or sound two-dimensional is noise (including vibrations). Contrary to some mistaken beliefs, digital replay is anything but "just ones and zeros" and requires as much, if not more, attention to noise control as with an analogue system. However, noise in digital systems rarely manifests as noise in the music (as it does with analogue systems); rather, it damages the sensitive digital to analogue conversion stage by polluting the input to the DAC (remembering that it's really an analogue waveform) and corrupting the timing (jitter) and frequency (phase noise) of the output. Some of these factors are: - Mains power and power supplies - Network-borne noise - EMI/RFI shielding - Ground plane noise - Vibration control - Self-generated noise, including poor clocks This is an exaggerated example of what can happen to the signal before it enters the DAC.   Some ways of addressing noise in the digital playback chain are: - Mains filters and regenerators - Low noise power supplies - Electrical isolation - Shielded or EMI/RFI rejecting cables (but beware that shielding can make things worse) - Grounding boxes - Vibration control footers, platforms and weights - External clocks This post is just a starter for further discussion. happy to justify and explain any of the above, for starters. I'm sure I've missed out even more. |
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Post by MikeMusic on Nov 30, 2022 9:51:00 GMT
Great post Martin
Very interested to hear everything there is to hear on this
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Post by HD Music & Test on Nov 30, 2022 10:18:30 GMT
Not forgetting shot noise, its quite interesting also ISI a lot of so called quality audio manufcturer do not feel this is important which I find quite amusing given the cost of some of their equipment, espeiclaly those with a lot of dsp & short narrow tracks on the board. Remember total transmission line is EVERYTHING in that signal pathway from the start of the Tx to the end of Rx inclucing the cables. Oh and analogue jitter to, yes really  |
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Post by MartinT on Nov 30, 2022 10:22:04 GMT
Isolation is a good place to start with. Whether your data is sourced from files (e.g. a network connected NAS drive) or streaming (e.g. Spotify), you need to ensure that line/network based noise is minimised. Even in a home network not connected to the internet (who has one of those?), the cables will pick up all sorts of RFI/EMI from the likes of switched mode power supplies, big motors like heating pumps and washing machines, electronics like satellite boxes and computers. The internet connection itself can add considerably to this, especially if telephone line or copper based. The techniques used in isolation are mainly air-gapping, where there is an electrical break in the connection which will carry the signal across, but not the noise. Typical different kinds of air-gapping for isolation: - Mobile 4G/5G data - Wi-Fi network (but watch out for jitter) - Optical link - isolation transformers - Moats Some example products for isolation: - 4G/5G router with mobile (cellular) data service - Wi-Fi router - Ethernet optical link involving SFPs and optical fibre cable - LAN isolator such as the Acoustic Revive LAN-1 or DXE-ISO-PLUS - Uptone EtherREGEN or Gustard U18 with moats  Typical results from one or more stages of isolation are an ease in musical flow, an expansion of the soundstage in both width and depth, greater note decay and filigree detail, and a lowering of harshness/sibilance/glare. |
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Post by MartinT on Nov 30, 2022 10:26:23 GMT
Not forgetting shot noise, its quite interesting also ISI a lot of so called quality audio manufcturer do not feel this is important which I find quite amusing given the cost of some of their equipment, espeiclaly those with a lot of dsp & short narrow tracks on the board. Remember total transmission line is EVERYTHING in that signal pathway from the start of the Tx to the end of Rx inclucing the cables. Thanks, Tony. Am I right in including shot noise under the category: self-generated noise? |
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Post by mattspl on Nov 30, 2022 10:36:00 GMT
This is interesting and another upgrade rabbit hole I can see myself going down.
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Post by HD Music & Test on Nov 30, 2022 12:26:29 GMT
Not forgetting shot noise, its quite interesting also ISI a lot of so called quality audio manufcturer do not feel this is important which I find quite amusing given the cost of some of their equipment, espeiclaly those with a lot of dsp & short narrow tracks on the board. Remember total transmission line is EVERYTHING in that signal pathway from the start of the Tx to the end of Rx inclucing the cables. Thanks, Tony. Am I right in including shot noise under the category: self-generated noise? Shot noise is random electron movement which is really a force of nature, when we are performing really tight measurment investigation into high speed serial data transfers and looking at transmission lines and eye patterns, you do and will get odd reading sometimes, which is why you need to obtain mutlipule measurments to average out any possible 'random elecments' you have not taken into account.
Also on die noise generated by the chips themselves (yes we measure this as well) along with veers and point deliver points on the circuit board, placement is critical along with impedence checked pathways etc.
the bigest causes of electrical noise are, mains noise from many perspectives, common mode, harmonic content, dc offset, IP over power etc. especially solare power with its crappy inverter noise. Earth noise and / or return pathway. DC rail noise, switching noise from FET's/clocks/regulators/transistors etc. Leaking caps (not neccessarily physically leaking but electrically) fractured traces inbetween board layers. RF three types, radiated, conduced and immunity, vibrational noise but internal and external, remeber your audio system is self deafeating it generators air pressure by moving the drivers which in turn distrub the sir which not only delivers sound to your lug holes it also acts upton yoour audio system. The list goes on.So if you want a top quality audio system, Seal your system hemetically apart from the speakers its all good fun!
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Post by MartinT on Nov 30, 2022 12:40:11 GMT
Ground plane noise. We're talking about noise that gets onto the ground plane (theoretical 0V return in component circuits) that affects sensitive circuits which need to accurately reference 0V. Put noise on the ground plane and your 0V reference becomes corrupted with all that that entails. This has nothing to do with safety earth! Putting steps into place as above to isolate noise from getting through the replay chain is good, but what about other noise affecting the ground plane of components such as NAS, PCs, routers, reclockers, streamers, DDCs and DACs? That's where grounding boxes come in. A grounding box acts as a "mini mother Earth" to suck noise from the 0V by connecting it to the ground plane of the component (not the chassis). That is why they are often provided with a connector such as phono or USB, or an alligator clip to clip to an exposed socket ground or a grounding terminal. It is often filled with crystals and magical dust (!) to emulate a piece of the Earth at a micro scale, which should absorb ultra-high frequency noise. Grounding boxes are contentious because people think that a single cable is not completing a circuit, but we are talking about sucking ultra high frequency noise away. Think of it like tying a weight to the end of a lasso. Now you can't make the tip move as much as before.  One other way of applying grounding boxes is to ground the mains power earth. What this does is to 'quieten' the noise appearing on the household earth, which does affect grounding planes albeit indirectly. You can get cables for grounding the mains earth, which connect only to the ground pin inside the plug. |
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Post by John on Nov 30, 2022 13:31:48 GMT
I find with my DAC the more cables I connect to my RTZ 2 the better. So, I use the following cables from my R26
RCA x 2
Coaxial x 1
AES x 1
I2s x 1
I still find I need to ground my Router even though I am using a Ethernet optical converter plus cable. I wish the grounding to the router did not make a difference
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Post by MartinT on Nov 30, 2022 13:40:45 GMT
I still find I need to ground my Router even though I am using a Ethernet optical converter plus cable. I wish the grounding to the router did not make a difference I find that grounding to every component from the router up to the DAC is critical to best sound quality. For single terminal grounding boxes, it is important that they are not shared as you would be connecting the ground planes of the items together. Multi-connector boxes, like the RTZ, are fine as each connection is isolated from others. For me, one box per component works very well. |
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Post by HD Music & Test on Nov 30, 2022 14:25:43 GMT
Noise on the return rail in dc systems can be caused by many issues not just in audio, although due to audio being sonically listened to many people can identify a difference when RF noise is removed from the system, although we cannot physically hear these frequencies, those that are generated can affect other components inside that particular device OR the devices which are attched to that box via conducted and radiated methods (usually the casework stops a lot of this) however it does have an effect and for best possible method of removal of the RF conducted emissions a single collection point is best. Have set up many in field demonstrations to show this. As the ideal method for best performance will bring ALL of the connected '0' volt connected rails back to one common single point of reference.
What a lot of people don't understand is that we are not completing a circuit in the literal sense, IE a battery to a light bulb and back so current flows around the circuit back to the battery to complete the circuit. RF energy doesn't require a wire. Think of using your mobile phone, you make a call the signal finds the local base station then bounced to the satelite and back to the local mobile tower near the person you are calling all without wire. It uses air as its dielectric to travel. Although the transmit signal is small in the milliwatt range it still travels these distances. RF energy travels down the pathway provided for it. WE have measured over 3Ghz of BW and the most amount of RF current I have measured was 54uA, which isn’t a great deal at all that’s millionths of an amp, however its the components inside the equipment its affects and that in turn causes the issues you can hear or can't if you have these devices in place! Just goes to show how sensitive new dsp and FPGA are sensitive to external signals.
Interesting point we found the other day, one gent had been experimenting with grounding from various manufacturers to greater or lesser results, but had hit a brick wall, this chap was using solar power direct to his system (quite a nice install up to) he also had a dedicated 7 foot 75mm copper rod buried in the garden (no mean feat!) tied with what looked like suspiciously looking lightening rod connector cabling strips (lol) to cover the earthing. Yes, we did make some quality gains, but not in the way we were expecting.
This chap was 200% adamant that SP was the cleanest simplest method to good sound, with these cases you have demonstrate for the person for the penny to drop. Even for ourselves we were taken about at the amount of noise reduction in that particular systems when the earth noise was treated, and bear in mind the specialist earth measures this gent had gone to.
Just goes to show how specific types of electrical noise can ruin your day
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Post by John on Nov 30, 2022 14:41:11 GMT
I still find I need to ground my Router even though I am using a Ethernet optical converter plus cable. I wish the grounding to the router did not make a difference I find that grounding to every component from the router up to the DAC is critical to best sound quality. For single terminal grounding boxes, it is important that they are not shared as you would be connecting the ground planes of the items together. Multi-connector boxes, like the RTZ, are fine as each connection is isolated from others. For me, one box per component works very well. I think we both have travelled this road a lot in the last couple of years and I believe we both trust in what we hear and experience in our journeys. For me the difference is often obvious in my system, and I know you experience the same. |
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Post by mansie on Nov 30, 2022 14:44:46 GMT
This is interesting and helpful. I have some experience with PC -> hardware communication, with COM, CAN and increasingly TCP. How is an audio stream represented in TCP packets? I assume one packet contains information on time in the song and intensity and the responsibility of the streamer is to
1) Buffer the the TCP packets (+ error correction)
2) Put them in the right order from time information
3) Fill up a send buffer to output to the DAC
The oscilloscope could be a good help in diagnosing where the problems are and even entry level digital storage oscilloscopes can analyze the modern communication protocol packages. This is where you can see if any packages are corrupted (like in the first image). I don't know how you would go about analyzing the digital jitter. One component in the chain can do its best for another one to mess up.
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Post by MartinT on Nov 30, 2022 14:49:56 GMT
Indeed, John, I still remember having inadvertently knocked an alligator clip off a grounding box to my DAC and spending half the evening trying to discover why the sound quality had taken a dive.
Grounding boxes most definitely work.
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Post by mattspl on Nov 30, 2022 14:50:30 GMT
Has anybody here that is using grounding boxes tried contact enhancer on the grounding cables?
I’d imagine this and tightness of connections would have an impact on sound if different types of grounding cables do.
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Post by MartinT on Nov 30, 2022 14:54:03 GMT
How is an audio stream represented in TCP packets? I'm pretty sure that most streams are sent as UDP packet streams, a direct representation of the file contents, to be decoded from FLAC, Ogg or mp3 encoding ready for the DAC, plus sync flags and stuff. |
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Post by MartinT on Nov 30, 2022 14:58:17 GMT
Has anybody here that is using grounding boxes tried contact enhancer on the grounding cables? Yes, I have done that. The cables themselves make a difference, too. Plus occasionally shaking the ones filled with crystals and magic dust. Plus using Black Ravioli footers under and weights on top to provide vibration control. Believe it or not, they all make a difference. |
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Post by John on Nov 30, 2022 15:10:49 GMT
The weights are one tweak I cannot hear. So use them to help reduce crosstalk from my cables
Raising cables off the floor has helped but not by a large margin.
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Post by HD Music & Test on Nov 30, 2022 16:36:58 GMT
This is interesting and helpful. I have some experience with PC -> hardware communication, with COM, CAN and increasingly TCP. How is an audio stream represented in TCP packets? I assume one packet contains information on time in the song and intensity and the responsibility of the streamer is to 1) Buffer the the TCP packets (+ error correction) 2) Put them in the right order from time information 3) Fill up a send buffer to output to the DAC The oscilloscope could be a good help in diagnosing where the problems are and even entry level digital storage oscilloscopes can analyze the modern communication protocol packages. This is where you can see if any packages are corrupted (like in the first image). I don't know how you would go about analyzing the digital jitter. One component in the chain can do its best for another one to mess up. We can observe ALL formats of ethernet protocol including auto ether net here with the correct fixtures we have, I would suggest that the tx & rx issuesd have been sorted, its not like the dacs are dropping packets by the 30e-10 lol
The issues that can cause these SQ problems are more locally based and to do with connectivity and IP service quality plus the electrical noise that audio system generate right across the frequency spectrums.
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Post by palace on Nov 30, 2022 19:30:33 GMT
I live atop a hill in NW London surrounded by 2 airports a plethora of large phone masts/communication towers and Ealing Broadway with communication transmitters on top of buildings. The RFI/EMI is so bad that if an insulated wire with an inline capacitor is used to ground/earth any of my metal cases the capacitor will charge. including my Caiman SEG(50) & Dorado 3 or Sony Blu-ray or CDPs/transport & Virgin Ultra TV box. I now have 100 clip on Ferrite's on all digital leads, all power leads and HDMI leads & leads to the low voltage LPSU's. I can with no signal turn the vale pre-amp to max gain on the volume control into 100 WPC valve amp feeding a pair of OTA Quad 57's silence even with the Croft phono stage valve switched in a slight hiss. None of the phono leads are fitted with ferrite's.
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