Splitting Coax properly for optimal speed

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Bnighgrow
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Splitting Coax properly for optimal speed

Post by Bnighgrow »

Hello All,

I am in the process of moving my modem from my office to my living room next to my Comcast box. I am try to research the best way to go about splitting my main connection coming into the house and which hardware is the best. I have 2 Comcast boxes and my modem that need a connection. Originally I had 3 way split at the beginning of the wire coming into the house, one going to 1 box, another going to another box, and the 3rd to my modem. Now I have to move my modem out of the office (it is becoming a nursery) and figured it would be convenient to have it next to one of my cable boxes since I have a permanent male connector coming from the wall. So two splits would be required, one feed going to supply the cable modem and cable box 1, then one feed to the additional cable box. Not sure what is the best setup.

To help show my example I drew a very artistic drawing, https://drive.google.com/file/d/0B817FilaBqvxNHRnSGRjLVFMTGc/view?usp=sharing

Any help would be much appreciated.

Thanks,

Brandon
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RaisinCain
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Post by RaisinCain »

Bnighgrow
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Post by Bnighgrow »

Yes I was looking at that first one, I should be good with splitting it twice with that one?


Thanks,
Brandon
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Philip
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Post by Philip »

Dual splitters generally lose 3.5db of signal per output port (you can also think of this as percentage, 100% signal in, 50% out on each leg). When you split it a second time, the signal at the end will have ~7db (25%) of the original signal. This is the same as using a 4-way splitter (each of the 4 output ports have 7db loss).

In other words, the fewer the output ports of a splitter, the better signal you retain. 2-way splitter will have stronger signal at each output than a 3-way splitter, so you definitely want to replace that. Most newer generation splitters would work (I'd get one that supports higher frequencies, i.e. up to 2GHz+, and good rated RFI shielding just for kicks).

However, there is another type of split that would work even better in your case, look for a "coaxial tap" (a.k.a. directional coupler) instead. A tap is a two-way split with different values at both ends, i.e. instead of losing 3.5db on both legs, you can have less than 1db loss on one leg, and 6-7db loss on the other.

If you get a tap, you can use it to bring the stronger signal to your cable modem/TV1, because you'll use a second 2-way splitter at that location.

If you're still not totally confused and want to do more... Look at your cable modem's signal levels (at http://192.168.100.1 for Motorola/Arris).. Check the downstream power level before and after an additional split, the ranges you want to retain are explained here: http://www.speedguide.net/articles/cabl ... evels-1197
Bnighgrow
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Post by Bnighgrow »

Very informative Thank you. Any suggestions on a specific tap?
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Philip
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Post by Philip »

Taps are less commonly available at local retailers, I'd just get one from Amazon/FleaBay, or any friendly cable tech will have them.
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RaisinCain
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Post by RaisinCain »

Make sure you get an amplifier with the split connections that you need. I have a similar setup at home and have never had a problem.
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Philip
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Post by Philip »

It is not always a good idea to use an amp, it depends on how strong your signal is... Cable amplifiers amplify both the signal and any noise on the line, they typically only amplify the downstream signal (yes, even bi-directional amps), and actually introduce some return loss. Cable modems are typically better off without/before them, as they need a good clean return signal.

You may want to check this FAQ for a bit more on this: http://www.speedguide.net/faq/should-i- ... lifier-455


The best thing you can do is use a tap to your cable modem instead of a splitter - you get 1db loss instead of 3.5 in BOTH downstream and upstream directions, and the return is often more important.
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