Cable TV "coax" splitters?

[valnar]

I'm moving into a new house and want to plan out my cable TV cabling. SageTV is an important part of the overall picture, so forgive me for posting a generic cableTV type question but it's the input of the Sage aficionados that I seek.

I will need a total of 6 coax connections. I know enough to buy RG6-Quad shielded cable but I'm having problems deciding the best way to split the single cable coming in from my cable company.

The end points will be:
2 PVR-250 boards for Sage
1 VCR
3 TV's

If you include my cable modem too, that'll be seven. In my current house, I have a good 2Ghz 4-way splitter, a 2 way splitter and an amplifier.

Cablecompany--> 2-way--> cable modem
................................|
................................|
................................|--> amplifier --> 4-way splitter--> two TV's, PVR-250, VCR


When I move, I'm adding a TV and an additional PVR-250 to my HTPC.

Does anyone buy 8-way splitters? Is it a good idea? Or should I stick with a combination of 2 and 4-way splitters? All this is on analog CableTV, except for the cable modem. In my current house illustrated above, I have the cable modem split on a 2-way before the amp because my cable company requested I do it that way. I have no idea if I should keep it that way in the new house, or if it's even required to maintain a good data signal. 'Just following orders.

I'm looking for recommendations of the best way to do it in the new house when I add the two more tuner endpoints.

-Robert

[stanger89]

I think the ideal split is 1, 2-way for Cable modem and TVs. Cable modems are (or at least were) much more sensitive to signal level than analog TVs. Then split the TV feed as evenly as possible, or alternatively run your most important signals through as few splitters as possible. Remember there's loss at each splitter, roughly:
3dB for a 2-way
6dB for a 4-way
9dB for a 8-way.

Now realistically there's a bit more, like 3.7 or so for 2-way and 7.5 for a 4-way. Also, consider that there's more loss going through more splitters than necessary. The ideal setup would probably be 1, 2-way (modem/TVs) then an 8-way off the TV side. If you can't find an 8-way, use a 2-way feeding 2x 4-way splitters.

Also, rather than an amp+splitter config, you might want to consider a distribution amplifier:
http://www.markertek.com/SearchProdu...f=85&sort=prod

[valnar]

Thanks. The distribution amplifier link didn't come up right. What's the part# ?

Robert

[stanger89]

I don't know why it didn't for you, but it's an A550.

[waynedunham]

Originally Posted by valnar

Thanks. The distribution amplifier link didn't come up right. What's the part# ?

Robert

I had the same problem. Clicking on the link (via Firefox) gave me an error page on the site. However when I right-clicked and did a "Copy Link Location" and then pasted that into my browser it worked. <shrug>

[Menehune]

Channel plus da550?

[stanger89]

Your caption is right (Channel Plus DA550) but the link doesn't go to the right place.

[waynedunham]

Ok, I'll give it a shot......

Channel Plus DA550

Does that work?

Here's the one I'm using.....

8 way RF amplified splitter

edit: Ok, those links both worked for me.

[valnar]

The DA550 link never comes up for me. Weird.

So I went to the MFG page here and see there is a DA-550BID and DA-550HHR. Which one is preferred for straight analog cable TV? The first one? Or is the 550HHR a superset of the 550BID, so in all ways better???

-Robert

[stanger89]

It must be tied to your/my browser because my link works for me, and yours sends me to the same thing Menehune does.

Anyway, Channel Plus DA550 is what I was thinking. And FWIW, I don't know of anything specific about that particular distribution amp, just that I know the "store" and it was an example.

[waynedunham]

Originally Posted by valnar

The DA550 link never comes up for me. Weird.

So I went to the MFG page here and see there is a DA-550BID and DA-550HHR. Which one is preferred for straight analog cable TV? The first one? Or is the 550HHR a superset of the 550BID, so in all ways better???

Here's the pertinent part of the description from the original posters web link.

-----
# The DA-550 is the heart of a multiroom distribution system with outputs to eight televisions, coax runs up to 150 feet, and three inputs (one from a CATV or antenna and two from modulators
# CP-DA550BID is for bidirectional interactive cable systems
# CP-DA550HHR is used with off-air antennas or satellite systems.

------

So for future compatability with things like Pay Per View and anything else where there has to be communication back through the cable/Stb I think the BID is the one you want.

[stanger89]

I'd vote BID, since for Cable modems, STBs, etc you need the 2-way communication.

And (one more time) I don't mean to recommend these, as I've never used them, I posted the link mainly as an illustration of concept

[waynedunham]

Oh, forgot to mention the one I have from SmartHome that I posted ( 8 way amplified RF splitter ) is also Bi-Directional.

[Menehune]

That's weird, the link worked at work, but not a home. I must've been logged in to the markertek site...
I get .asp errors when I search at markertek, so maybe the site crashed...

[src666]

Buy for the future - buy a bi-directional (BID) unit.

Also, just in case, a couple of rules of thumb.

1. When amplifying a signal, put the amplifier as close to the cable entry as possible.
2. When splitting a signal, put the splitter as close to the "consumer device" as possible.
3. When using an amplified splitter, rule 1 applies.
4. Never "chain" a large number of the cheap, small splitters you can buy for $5. Read "large number" as any number over 1.
5. If you have to use one of the cheap small splitters with more than 2 outputs (3, 4 or 5 way), you need to remember that each output has a different level of signal loss. One of them is about 3.7 dB of loss. The next one is 7, etc., with the last pair of outputs having the same signal loss. Try to find out which is which. Run your longest cable off of the output with the least loss.
5a. Throw that cheap thing away and buy a distribtion amp/splitter that balances the loss and (hopefully) corrects for tilt.\
6. It is possible to overamplify. Know how much amplification you need. Most people don't need any, because the signal from the cable company assumes the need for several splitters, and usually is targeted at entering the house at +6dB. With a good quality splitter that is designed to maintain signal levels (active splitter, has a small amp built in), that's plenty. Most people have no need for these +15 dB amplifiers they sell at Radio Shack, Home Depot, etc.

[kelemvor]

I just re-wired my house last weekend and we did it like this...

Line in from outside --> Amp
Amp --> 2-way splitter
---Line A goes to Sage PC
---Line B goes to 2-way Joiner
S-Video Out from SagePC --> RF Digital Modulator --> Coax Jack --> Joiner (reverse splitter)
Signal from Sage and Signal from Cable from 2-way Splitter join back up in the joiner
Joiner --> 8 way splitter
8-way splitter goes to cable modem and 7 TV outlets

This way I can watch my SageTV stuff on any TV in the house by tuning them to the channel I set in the Modulator. I could put the amp after the joiner but am not sure if it will make a difference. Still have to do some testing on that part.

[src666]

You probably want to add a notch filter to the unmodulated leg of the original split, to ensure that there are no signals (real or noise) in the band where you are inserting channels. Otherwise the re-combined signal _will_ have issues.

Also, if the signal from the cable company is good, you might be better off amplifying either after the combiner, or just the unmodulated leg of the split. Keep in mind that most modulators put out a pretty high signal, so you are going to end up with an imbalance in signal strengths unless you can measure it at each step, and make the proper adjustments.

Another potential problem is that most consumer grade modulators need at least one empty channel above and below the "target" channel. 2 is better, if you can swing it.

Right now the best thing is to find the amplification and attenuation specs on each item, and try to arrange it so that the signals are balanced at the combiner, possibly by attenuating the modulated output.

From there, you can decide where you need amplification. Use as little amplification as you can, or you get into issues with "tilt" (amplifiers amplify low frequency signals better than high frequency signals, so the end result isn't a straight line +X dB across the spectrum.)

[kelemvor]

I'm still waiting for my video out card and modulator to arrive in the mail so I haven't tested it yet. But the cabling is all laid out so ll I have to do is hook it up and see what happens.

My brother works for TIme Warner so he has access to all the good stuff in case something has to be changed.