This is the one I picked up:
Mikrotik S-85DLC05D is a 1.25G SFP transceiver with a 850nm Dual LC Connector, for up to 550 Meter Multi Mode Fiber https://a.co/d/6SukrPu
Which MikroTik switch are you using for your optical connections? Iām using this one and in general really like it:
MikroTik 5-Port Desktop Switch, 1 Gigabit Ethernet Port, 4 SFP+ 10Gbps Ports (CRS305-1G-4S+IN) https://a.co/d/03xv1P5
MikroTik hEX S Gigabit Ethernet Router with SFP Port (RB760iGS)
Itās a non wireless router but I have it set up for switch duty only.
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Thatāll work! 
Thatās what I really like about MikroTik, itās very flexible. Maybe a little over complicated for a home setup, but I like the extra features and flexibility. Everything but my wireless access points in my house are now MikroTik. Fan boy 
Doing a little more research on this and was looking at some of the after dark hardware and even though they sell their Project Clay X solution with a single mode cable, when I look up their part number for the transceiver is says LC Duplex Pluggable, SFP+. It does feel like the wild west out there so Iām leaving well enough alone for now as I believe there are lower hanging fruit for me.
Iāve heard from a couple of you guys via PM that you did pick up the cable I recommended and it seems to have made a positive difference. Itās bizarre and as I said, Iām not going to dig too deep into an explanation cause in the end it was a $35 dollar cable. lol
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So from my research, this is what I found.
- LC duplex - that just means the connector type and two of them
- Multimode vs single mode have different sized fiber connections and shouldnāt really be used together. Single mode has a 9um vs 50/65um core.
- UPC vs APC - most of the modules I researched are only UPC. If you get an APC cable with a UPC module, the connectors will not contact correctly. You can technically damage the connections if you mix them.
- All the recommended modules from afterdark are single mode
Iāve now seen multiple people, including myself who have used single mode cables with multimode modules still getting sound and even liking it. Why does it work? I donāt know. Maybe we all like errors more than we like to admit.
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Sometimes you can get a link with an MM SFP using SMF, but typically only with specific switches (Cisco is notoriously picky about this), and with shorter distances. Itās not ideal, but in the right conditions it can work fine. When you combine SMF and MMF cable wise, you encounter something called Differential Mode Delay, and that will cause the bandwidth, reliability, and span of the connection to decrease, but it still can work. DMD basically just means the beam splits into different unintended paths and get different delays and interfere with eachother, this also can create jitter as well. This doesnāt always come up, and from what I know itās most prominent when patching 2 physical cables of opposite type together with a mode conditioning patch, I donāt know if this also applies to using MM SFP to SMF.
Aside from the cable differences, the difference between a MM and SM SFP is that the MM uses a typically wider wavelength vcesl (or sometimes LED actually) that tends to be of lesser quality/precision than the lasers in SM SFC (which is why SM tends to be more expensive, more demanding on quality for both the sfp and the fiber itself). While MM SFC using SMF can sometimes work, Iāve never actually gotten SM SFC with MMF working myself so that seems more like a no go entirely. So I wonder if you just donāt run into any issues because of the short distance, and I donāt think the bandwidth drop would be a problem, but that still leaves the question about jitter that might occur. Might not be an issue since DMD is most prominent when patching physical cables together using differing transceivers, and considering single mode fiber is well single mode, perhaps DMD doesnāt really manifest when using MM SFC + SMF, and you more just run into the quality of the laser/light not being ideal for the glass but it still is just one beam
It is interesting to see the general preference toward single mode fiber when it comes to audiophile use, something Iāve seen suggested by various mfg and many on forums also report improvements over MM, but I do tend to see some using MM SFC with SM fiber and it working just fine. I personally use single mode fiber and single mode sfp, since from my experience that showed a bit of improvement over a MM setup, but Iāve not tried mixing and matching the two
Also different light wavelengths (typically SM is 1310/1550nm and MM is 850/1300nm), and different methods of creating that light as mentioned above
Correct, thereās many fiber connectors but Iād say these days LC is most common (though some audio products might actually use ST fiber as well for not just ethernet but also toslink)
Edit: some more info on how a MCP cable works, basically just offsetting the single core fiber to the side of a multimode fiber core to make it better fill the cable and not get some of that unwanted dispersion
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As I understand it, Single mode cables are designed for REALLY long runs over 500M (1600ft) I believe, in a house you should be using multi mode cables.
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Yes, MM canāt reach the level of SM for sure. That being said, if you can afford SM fiber, I donāt think thereās really any downside to using it (aside from cost), itās going to be a better connection with higher bandwidth and distance, and will offer more flexibility as well since you can use coarse or dense wavelength division multiplexing if you really need it which you canāt do with MM. From what I know, the cost difference between the two really isnāt that extreme anymore networks running under 10 gig, but cost might be a greater factor if youāre above that. In the past you might have had the problem with SM needing extra attenuation between links but I donāt really think thatās a problem with most average modern setups
Actually makes me think lol, wonder if anyone has tried using some optical attenuators between their fiber links to see if thereās any sound change lol
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Yes I guess ther is no minimum distance in the spec, and the cables are actually cheaper, so as long as your electronics support it, there isnāt any harm.
But most of us can get away with an OM1 cable since thatās 10Gig to 200+M.
Iād love to hear the reasoning for any change in an optical ethernet device, from just the cable, itās packetized, not timing critical, and there is no path for ground noise, so the only real effect that I could imagine are lost packets (which I doubt) or possibly noise introduced by the electronics.
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All of this above discussion makes perfect sense.
With respect to the LC/APC cable @dB_Cooper got a few of us to try, itās clearly a single-mode specified cable, but I canāt get it to work with Finisar single-mode SFP modules (between switches or streaming endpoints).
But it works great with multi-mode SFP modules. Maybe the finisar SM SFP modules I have arenāt designed to properly support APC? Itās interesting to me that the multi-mode works at all with this cable given how picky/specific optical networking tends to be. Maybe given that multi-mode can be implemented with something as simple as a blinky led, are the tolerances for multi mode wide enough to be functional over short 2m cable even if the cable is out of spec?
And itās wild that it clearly sounds different (better), to me thereās no way that mismatched cable / SFP should even work let alone sound good.
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My head, it hurts.
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Yeah itās very strange to me. Iāve been talking to a guy who is using the finisar 8571 which is multi but is able to use single cables with it.
With regards to finisar single not working with the APC cable, i think itās definitely the UPC/APC issue. I wonder if due to the larger connection size of the MM, the APC cable works but when youāre using a SM with an APC cable, itās not gonna work without the right connection. AFAIK, the audiophile approved finisar modules are UPC only based on the datasheets.
Picked up a Sonore opticalModule as an experiment to see if it would sound better than going from the SFP out of a Mikrotik switch. What convinced me to try this was the fact that itās supposed to have great Ethernet clocking to match the opticalRendu and thinking that whatever the Mikrotik is doing for clocking it not going to be doing the same thing.
@M0N I think you have one of these connected to your signatureRendu, are you using a good quality PS for the opticalModule?
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Using an illuminati v3, I like the pairing, it also powers my etherregen. That being said if it wasnāt a dual output I donāt think Iād spend that much on it for the opticalmodule
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Yeah, important lesson learned in the hobby, multi output multi voltage power supplies are the way to go for saving money in the long run.
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Itās definitely way more convenient lol. I was tempted to keep the hypsos around just for the fact itās adjustable to like anything but found myself using other psu instead when Iād get something dedicated. I think in some cases itās better to just get a really balls to the wall single rail psu specifically matched for a component, but otherwise having something even slightly adjustable or multi rail is nice for the smaller or lesser important things
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If anyone is interested in using the 1475 meme from afterdark, I bought these recently and offered $42 per unit (bought 2). The cheapest Iāve seen for this model so far. Iāve been enjoying it so far.
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Are you using them with an OpticalRendu? Or some other piece of your network?
Iām using them with my fiber PCIE card and the afterdark diretta network bridge.
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