Originally Posted by tripelo
Originally Posted by JHBrandt
Also, is that the new CM-7777 ... It also has a much higher noise figure so it may not help as much.
Curious, since I have seen no advertised NF specs. for the new version, or measurements comparing the two preamps;
Wonder how much higher noise figure (new vs old CM7777)?
The old version bragged a NF of 2.8 dB on VHF and 2.0 dB on UHF. The UHF figure was the lowest I've seen for a consumer-grade preamp. It was likely the best you could get even if the advertised NF was low-balled a bit.
All CM will say about the new version's NF is that it's "less than 5 dB," which reminds me of the old joke: If a product is advertised as "less than $50," you can bet it's not $19.95. (Actually, they probably just eliminated quality control, so if you're lucky, your preamp might have a NF that rivals the old version; but if you're not, too bad.)
And to add insult to injury, they eliminated the separate UHF/VHF inputs (although that may not matter to some), raised the price, and then had the gall to advertise it as "improved." To be fair, they did boost the gain some, but Antennacraft and Winegard sell high-gain preamps with noise figures they aren't afraid to advertise; yet they're generally much less expensive than the new CM-7777.
If you're splitting your signal 8 ways, you'll lose 10-12 dB, which is probably pretty close to your antenna's gain. So without a preamp I'd expect each of the 8 TVs to get only as much signal as a rabbit ears+loop antenna would provide. If you're in Collin county that's probably not enough, so intuitively a preamp does sound like a good idea.
But you might be in a high-elevation area where there's just enough signal. I'd check every TV; if they all receive all the channels you want, and all the TV signal meters show some safety margin, then you can get by without a preamp.
If you do need a preamp and the CM won't do the job, you can get a medium-gain, low-noise Antennacraft or Winegard preamp for around $30 plus shipping. (There are probably other brands that would be fine too. Those are the most popular brands besides CM though.) That should fill in your missing channels without causing overload. (Unfortunately I couldn't find any preamps locally at Radio Shack or Fry's, so the Internet is probably your best bet.)