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Post by MartinT on Jun 14, 2024 9:15:35 GMT
I was perusing the latest updates on the EtherREGEN Gen 2 development programme when I caught this comment by Alex of Uptone: He advocates using Direct Attach Copper (confusingly known as DACs) for short runs, obviating the need for an optical SFP such as the Cisco that some of us favour. So let's remind ourselves of the potential pros and cons of using an optical cable versus a DAC: | Pros | Cons | | Fibre gives galvanic isolation | Fibre requires electrical<>laser conversion at both ends | | Fibre does not suffer from EM pickup | Fibre can generate some ground plane noise |
| Fibre conversion adds jitter |
A DAC is just a copper twinax run, connecting the SFPs together with no electronics. It should allow the ER's excellent fast flip-flop generated signal to arrive at the other end relatively well preserved. What I cannot predict is whether the direct lower-noise but more prone to EM pickup DAC will outperform the galvanic isolation and lack of EM interference provided by fibre. Only one way to find out, so I have a couple of different 4m DAC cables arriving on Monday for a fun experiment. Stay tuned!  |
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Post by mattspl on Jun 14, 2024 11:14:35 GMT
I’ll be interested to hear how you get on with these. I’m currently using an Ethernet cable with the shielding removed from both ends and RFI absorber placed inside the rj45 connector.
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Post by MartinT on Jun 14, 2024 18:57:37 GMT
Just a quick note: I tried finding a uGreen DAC cable but they don't do one.
One cable arriving is a gnodal and the other a Cisco compatible, both SFP+ DACs.
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Post by Clive on Jun 15, 2024 8:10:54 GMT
I’m super interested to know how the DAC cable works out…easily available and low prices, my sort of thing!
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Post by Clive on Jun 15, 2024 9:19:37 GMT
Just a quick note: I tried finding a uGreen DAC cable but they don't do one. One cable arriving is a gnodal and the other a Cisco compatible, both SFP+ DACs. Is this the Cisco compatible one? www.amazon.co.uk/dp/B0BY8GGHMJ?ref=emc_s_m_5_i_atc&th=1It’s interesting that some others from the same company are a third to a half the price….they vary quite a bit but aren’t expensive. |
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Post by MartinT on Jun 15, 2024 9:34:48 GMT
No, that's another one.
I'll wait until Monday and evaluate them. If there is a clear winner, I'll post a link to it.
If they don't compare well with the Cisco AOC, no matter, it's always worth the experiment.
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Post by Clive on Jun 15, 2024 10:15:38 GMT
I see the gnodal…4 available, 1 sold 😀
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Post by MartinT on Jun 16, 2024 20:46:32 GMT
One more thing: my EtherREGEN now runs cool, as opposed to when it ran at around 40C with the AOC fibre cable.
I dare say this has reduced power supply load at both ends, benefitting both the ER and Rendu.
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Post by John on Jun 17, 2024 5:06:24 GMT
Do you have a link to where you purchased the above cable
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Post by MartinT on Jun 17, 2024 5:29:59 GMT
Do you have a link to where you purchased the above cable John, as I said above, I will complete my evaluations and will test both cables before making a recommendation. I need to know that burn-in isn't going to go backwards, as it did with that Finisar fibre cable. |
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Post by John on Jun 17, 2024 5:32:45 GMT
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Post by MikeMusic on Jun 17, 2024 5:48:44 GMT
Cool is cool
The ER running cooler has to be good
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Post by Clive on Jun 17, 2024 17:47:34 GMT
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Post by nicholas on Jun 17, 2024 19:13:01 GMT
My early experience with the Ipolex 10G Twinax cable seemed to be a step backwards from the Cisco SFP-10G-AOC optical cable. While there was an improvement in clarity and detail, the image and soundstage contracted somewhat. A couple of nights on the Tara Labs break in appears to have returned depth and width to everything I have heard so far.
The half meter length of the new cable coupled with a dramatic reduction of heat being generated by the EtherRegen bode well for the Ipolex remaining in the system going forward.
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Post by orange55 on Jun 18, 2024 18:41:26 GMT
Another 24 hours and the 4m £39.99 gnodal DAC cable has settled into a superb level of performance. This is definitely an advance over the Cisco fibre cable, without doubt. The best 40 quid I've spent in a long time. Was there a specific recommendation for the brand of cable or was that just what was available? |
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Post by mattspl on Jun 18, 2024 19:53:59 GMT
Another 24 hours and the 4m £39.99 gnodal DAC cable has settled into a superb level of performance. This is definitely an advance over the Cisco fibre cable, without doubt. The best 40 quid I've spent in a long time. Was there a specific recommendation for the brand of cable or was that just what was available? Also, do you need to order a specific type of DAC depending on the make of your switch/device that the cable will be used with? |
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Post by MartinT on Jun 18, 2024 20:12:51 GMT
Research, as usual. No recommendations for hifi use, just general quality measures.
It's a passive DAC cable, they should all be good for SFP+ use in short runs.
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Post by orange55 on Jun 18, 2024 21:15:25 GMT
Thanks. I found a genuine Cisco one, so will give that a go.
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Post by mattspl on Jun 18, 2024 21:32:51 GMT
Thanks. I found a genuine Cisco one, so will give that a go. I just ordered a Ubiquiti one. |
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Post by John on Jun 19, 2024 4:35:01 GMT
Sorry
I figured out how it connects
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