Power Options for Switches

[Haninger]

I use a Cisco SG-200-08 switch for my audio system, television, and AppleTV. The switch is connected (via Cat6 in the wall) to a Verizon router which is in a closet on a different electrical circuit.

 

Currently, I'm using PoE from that closet to power my Cisco switch, but I've been told to avoid PoE because it can negatively effect SQ. Not sure if that is true, but would appreciate thoughts.

 

As the Cisco switch is on the same electrical circuit as my audio system, I could power with a LPS and I might have an extra output already. Does anyone know the input DC voltage and amps required for the Cisco SG-200-08? For some reason, I can't find this information online.

 

Thanks!

[Superdad]

That switch model takes 12V. The stock wall wart that came with it likely has a 1.5 amp rating, but the SG200-08 consumes far less than that.

 

Hope that helps.

Best,

--Alex C.

 

 

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[Solstice380]

Or, just take a look at the original wall wart - it should be labeled with the V and A rating.

 

 

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[Haninger]

Thanks, both. Much appreciated.

I had misplaced the original wall wart after setting this up as PoE a couple years ago.

 

 

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[plissken]

I have your same switch. I just spun up my Catalyst 3750 POE 48 port switch. Can't tell any difference in audio vs the wall wart.

[cjf]

One thing to consider is that the higher end Cisco switches don't appear to use an SMPS power supply. They use a standard 3-Prong AC cable stright to the wall verses an external brick. I can't say for sure if the internal power supply is an SMPS or not but based on my own caveman testing with an AM radio it's far less noisy then the other switches I've tested from the likes of Belkin, Linksys and ASUS ...etc which all use an external SMPS brick.

 

I use a Cisco Catalyst 2960G which uses the standard 3prong cable as described. Whether or not any of this matters in terms of SQ is another story but I sleep better thinking it might only because all my computer audio related gear shares its ports so maybe there is less chance of all those physical connections polluting each other from an electrical standpoint. In terms of delivery of the 1/0's I have no belief it matters at all.

[Superdad]

One thing to consider is that the higher end Cisco switches don't appear to use an SMPS power supply. They use a standard 3-Prong AC cable stright to the wall verses an external brick. I can't say for sure if the internal power supply is an SMPS or not but based on my own caveman testing with an AM radio it's far less noisy then the other switches I've tested from the likes of Belkin, Linksys and ASUS ...etc which all use an external SMPS brick.

 

I use a Cisco Catalyst 2960G which uses the standard 3prong cable as described. Whether or not any of this matters in terms of SQ is another story but I sleep better thinking it might only because all my computer audio related gear shares its ports so maybe there is less chance of all those physical connections polluting each other from an electrical standpoint. In terms of delivery of the 1/0's I have no belief it matters at all.

 

I can guarantee that even the higher end Cisco routers--with built in power supplies--are using an SMPS. Notice how their IEC inputs don't have a switch to go from 120>240V operation? They are labeled 100V-240V input. Only SMPS units do that. A linear would have a dual primary and a switch to series or parallel them.

 

 

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[cjf]

I can guarantee that even the higher end Cisco routers--with built in power supplies--are using an SMPS. Notice how their IEC inputs don't have a switch to go from 120>240V operation? They are labeled 100V-240V input. Only SMPS units do that. A linear would have a dual primary and a switch to series or parallel them.

 

 

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You may very well be right..

 

But I do know that whatever PS they are using inside the Catalyst Cisco switch is significantly "quieter" then the other flavors I mentioned previously.

 

I should note that I'm not against SMPS's by any means (heck, every audio component I own uses one) but those cheap little "bricks" given away for a few pennies with most gear are almost always VERY nasty in terms of their radiated pollution and backwash.

[mikicasellas]

On 12/1/2017 at 2:33 AM, Superdad said:

 

I can guarantee that even the higher end Cisco routers--with built in power supplies--are using an SMPS. Notice how their IEC inputs don't have a switch to go from 120>240V operation? They are labeled 100V-240V input. Only SMPS units do that. A linear would have a dual primary and a switch to series or parallel them.

 

 

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Hi Superdad,

 

Can i power the Cisco SG-200-08 and the AQVOX switch with the LPS-1?

 

Regards

 

 

[nkbg]

Thought I should chime in. I have the Cisco 2960 as well. 

 

I removed the internal SMPS (12V) and installed a 2.1mm DC input. I am currently, using a JS-2 to power the switch. Having tried two other much cheaper LPSs, I can say the LPS quality does make a difference. 

 

Compared to a Netgear Nighthawk switch, powered using the same setup, the Cisco clearly sounds better.

 

Also, I don’t recall the difference between internal SMPS vs. external LPS. I did this a long long time ago. 

[Ultrarunner]

I use a JS-2 to power my Cisco switch also. I don’t know if the sound improvement is due to supplying the switch with cleaner power, that reduces noise on the output, or if the JS-2 puts less noise back onto the AC line than the SMPS. Either way, it’s just better!  I’ll buy the EtherRegen when it’s available and hope for more improvement. 

[Superdad]

My recollection, from the one time I opened my Cisco 2960, is that the 12V SMPS supply in it is rated at just 0.6A—well within the capabilities of an UltraCap LPS-1.2.

I have not bothered to mod mine for an external supply because, well obviously we have our own switch coming soon. 

[Miska]

On 1/8/2017 at 4:25 PM, Haninger said:

Currently, I'm using PoE from that closet to power my Cisco switch, but I've been told to avoid PoE because it can negatively effect SQ. Not sure if that is true, but would appreciate thoughts.

 

Don't worry, PoE to power the switch works just fine as long as you don't use wrong type (shielded) of cables to connect your audio devices. Network signals between switch and devices are transformer isolated. Shielded cables would connect grounds together and create possibility for all kinds of dirty leakage currents. One of the points of using ethernet for audio is that it allows isolation for example USB doesn't. So only use standard UTP cables!

 

I also power some of my switches and all wireless access points over PoE.

 

 

All built in PSUs of switches are SMPS for efficiency, size and heat reasons.