Is a amplifier and high quality splitters necessary??

[Rick67]

I'm setting up my network and I've been told to run my cable (AT&T Broadband) into a amplifier before going into a splitter? Here's what I've got. AT&T Broadband cable going into a two-way splitter. One output will be going to my cable modem and the other output goes to a four-way splitter which goes to all my TV's. My cable modem will be plugged into a Linksys router. I'll have lines (CAT5e cable) running from the router into a Leviton data module which is wired to CAT5e jacks in my townhouse.

Is the amp really necessary and does it get plugged in before the splitters? Also, I'm using 5/1000 MHz splitters and I was wondering if it would be worth it to change those out for the Acoustic Research gold plated 5 MHz-2 GHz digital splitters?

Any suggestions would be appreciated! Thanks,

 

[ScottMac]

The amp should go between the first split (cable modem / TV) and the four-way splitter (TV--> four TV feeds).

You will see ABSOLUTELY no benefit going to a 2G splitter, no matter who makes it (most, if not all, CATV systems only go into the 900MHz range ... analog or digital, data or video).

Every time you split the signal, the margin between signal and noise gets narrower. The more you split (four-way VS two way) the signal to noise margin get narrower. After your first split, the signal going to each barnch is ~3-3.5 db lower (-3db is losing half you signal). So, going into your four-way, you are already down a little less than half of the original signal, which is OK, most systems are a little hot (in anticipation of a consumer split).

The four-way is going to take that ~half signal, then divide it again by four (plus a little insertion loss on each branch) ...

If you put the amp beofre the first split, it'll have to be a bi-directional amp (because your cable modem must communicate "upstream." Bi-di amps (decent one anyway) are ~ US$100.00 or more.

SO ... there should be a good enough S/N margin after the first split to put a (relatively) inexpensive one-way (regular) amp, and still get decent video. The amp should be in the range of 3-9db (or tunable down to 3-6 db). Any more than that, and you're likely to overdrive the front end of the TV/VCR (which looks just as bad as not enough signal). Some of that value (gain) depends on the quality of the coax in your walls ... which, if I remember correctly, is fairly recent, and probably RG6 ... about 4.5 db loss per 100 ft (I think, trying to remember).

How'd the data cabling project turn out? Get everything hooked up OK?

Hope this helps....

Good Luck

Scott

 

[Rick67]

Scott,

Thanks for the info, you've been a lot of help!

I've got everything wired and tested and I'm just waiting for my router to arrive.

I picked up a Motorola Broadband Signal Booster at Best Buy today ($80). It has one input and one output and says it boosts the signal up to +15dB. If I understand you correctly, this amp won't work because I need to place it between the two splitters? So I would need an amp with two outputs correct?

BTW, all my cable is RG6.

Can I use this amp the way you described? Can you think of a better way of setting this up? Maybe where I only have one splitter?

Thanks again,

 

[ScottMac]

If the AMP is described as bi-directional or "cable modem compatible" ... something like that, then it can be placed before any splits.
... then do the two-way split, then do the four-way split. A +15 might be a little too hot (too much gain) for this kind of setup, you may be driving the cable modem too hard (+ 15 after a two way split is ~ +6.5 to +7 on each side of the split).

Your other option would be to do the first split (two-way), then the amp, then the four-way.

If you look at the installation sheet, many/most/all installers will do a signal check at the inside end of the cable and note it on the sheet for their records. Sometimes they put the number in a little hex (six-sided) box, either hand-drawn or printed on the sheet ... if that's already a positive number (like a +3), then do the two-way split, the amp, then the four-way. If the number is zero or negative, then put the amp in before the first splitter.

If the amp is not "cable modem compatible," then your only choice is to put it after the initial two-way split.

If the amp has a variable gain, then start with it at ~ halfway and adjust it as necessary. Amplifying the signal too much look as bad or worse then not having enough signal.

+15 is a little hard to work with ... give it a shot and post your results. Maybe try it both ways and pick the way that looks and works best from you. Some cable modems have a diagnostic page that shows what the signal levels are incoming and outgoing (like, aim your browser at 192.168.1.1 .....). Knowing what the signal level is would be very helpful.

Good Luck

Scott

 

[Rick67]

The amp is bi-directional and it didn't come with much of a manual. Actually it's just one sheet of paper showing how to hook it up.

I think I'll try placing the amp between the two splitters and run the amp to just the TV's (Four-way splitter) and the modem from the other half of the two-way splitter and see how that works. This should put my cable modem at 3dB and the TV's at 3.75dB if I understand this correctly.

 

[JackMDS]

It is relatively easy to judge the quality of the TV signal, good picture, and audio i.e. good signal.

It is a little more difficult to evaluate the quality of the Internet broadband signal.

I would start with connecting the incoming line to the Cable modem only. Surf a little, ping your provider and download a big file, see what you get.

Next stage add the splitter, and the TV lines once at the time, each time check again the Internet connection as above.

It is possible that you will find that you do well without the Amp. or that you need it further down the line. I saw situations in which these Amps. Make the Internet connection worth rather then better.


BTW, high quality splitter is good idea. By high quality I don?t mean the frequency, but the coating of the metal, low quality coating tend to corrode in time and reduce the quality of the connection.

 

[Rick67]

Well, I've been testing the heck out of all the different configurations and I can't tell the difference with our without the amp (this is both TV and Internet).

 

[JackMDS]

.

I can't tell the difference with our without the amp

I am not surprised!

Return the Amp. 😀
If it goes bad in the future you can always buy one.

 

[LiLRiceBoi]

When I got my cable.... RR gave me an amp cuz my signal was weak comming up to my room (from a 5 way split)