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Upgrade Clock on Cisco Ethernet Switch

omicron1: A low-jitter, low phase noise clock generator for upgrading digital audio devices

Upgrade Clock on Cisco Ethernet Switch

Postby DIYingInCt » January 1st, 2020, 4:48 pm

I would like to upgrade the clock on my Ethernet switch. I am enclosing photos of the board. It seems to have a single clock @ 25kh. in front of the clock there are three small surface mount components. C31, R44, C30. This does not seem to resemble the disable original clock diagram on the AMB overview page. Any thoughts of converting this board would be greatly appreciated. Thank you in advance.
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Re: Upgrade Clock on Cisco Ethernet Switch

Postby amb » January 1st, 2020, 7:54 pm

What's the point of doing this? I don't see any benefit in this.
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Re: Upgrade Clock on Cisco Ethernet Switch

Postby DIYingInCt » January 2nd, 2020, 8:59 am

My understanding is that the quality of the clock on the switch that is between the computer that is serving the music and the computer that is streaming the music has significant effect on sound quality. There are several places where people are offering highly expensive upgraded switches. I am trying to make one myself.
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Re: Upgrade Clock on Cisco Ethernet Switch

Postby amb » January 2nd, 2020, 11:54 am

No, that is not fact. The oscillator inside a ethernet switch has no bearing on sound quality or the integrity of the digital audio being sent through the network. The point about upgrading the master clock inside a DAC is to ensure correct timing (i.e., reduce jitter). But the network is different. The timing of packets being transported through the network is inherently random and uncontrolled. That's just the nature of the network itself, and there is nothing you can do to make it better in an ethernet switch. The receiving host on the network, the one doing the audio playback, will have a large software buffer to pre-fetch enough audio data, so that it can be clocked out accurately by a good DAC during playback.

There is an awful lot of junk information and snake oil fixes out there, and this is one of them. For those who claims to "hear" an improvement in sound from changing the oscillator in a network switch, all I can say is that psychology played on them.
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Re: Upgrade Clock on Cisco Ethernet Switch

Postby linux-works » January 2nd, 2020, 2:06 pm

as a network engineer of many years (I worked at cisco, juniper, etc) - you are 100% wasting your time and effort.

packet switching is a store and forward process. the clock frequency 'jitter' will have less than no effect on the data transmission jitter.

for future looking things, do a search on sync-e (synchronous ethernet); its a fun standard that truly does shift the baseband freq of the ethernet clock and keeps it accurate enough so you can calibrate your BITS building clock from it. this is not for audio, though, lol.

for audio, search on TSN (time sensitive networking). its the new hotness and it will ensure that data is delivered jitter-free, but requires a HUGE set of standards to be implemented at both hardware and firmware levels.

fwiw, its being used in cars, now, for self-driving; you need very accurate timing in electric l2-l4 cars and TSN is being considered by many to be the new standard for time critical networking.

but again, this is future stuff. will be a long time before tsn (used to be called AVB, audio video bridging) comes to home pc's and home audio.
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Re: Upgrade Clock on Cisco Ethernet Switch

Postby DIYingInCt » January 2nd, 2020, 7:11 pm

Thank you both for your feedback. I will put my efforts elsewhere. Would I be correct to consider the beginning of my signal path as starting at the usb output of my streaming computer? I am using Roon on a server connected by Ethernet to a switch to a nuc roon endpoint.
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Upgrade Clock on Cisco Ethernet Switch

Postby amb » January 2nd, 2020, 7:27 pm

If you’re using a USB DAC, then yes, choose one that supports asynchronous transfer mode and has a good low jitter DAC implementation for best performance.

In the AMB lineup, the γ1.5 and γ3 DACs both use the ζ1 USB-I²S module which has async transfer mode. The γ3 has unmeasurable jitter.
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Re: Upgrade Clock on Cisco Ethernet Switch

Postby linux-works » January 3rd, 2020, 9:48 am

we use NUCs at work and I hate them.

they have many problems. their video system is strange (linux and even windows has occasional driver issues). ethernet is not reliable in all cases (we've lost some ethernet ports, maybe due to static). their usb system is underpowered and does not have enough output jacks.

I prefer mini-itx systems that use well reviewed motherboards.

the NUC is nice and small, but it has 'issues'. intel is not at their best game with this series of systems.

its 'ok' for audio, but I just don't recommend NUCs for so many reasons.

fwiw
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Re: Upgrade Clock on Cisco Ethernet Switch

Postby linux-works » January 3rd, 2020, 10:35 pm

in case anyone wants to see what the future of networking is (for audio, and other realtime things):

https://www.youtube.com/watch?v=oxURD2rr4Y4

its pretty technical but worth a watch.

with this level of network precision, yes, the 'network clock' in the switch starts to matter, but then, its now software controlled ('steered' or 'disciplined') and it listens to a higher precision clock, the PTP grandmaster clock.

lots of neat new terms and ideas with this new networking stuff ;)
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