An amplifier is an amplifier is an amplifier. What I mean is that there’s nothing actually different about the amplification process between a preamp and a distribution amp. In a pinch you could use either for either task. But there are some differences in the way they’re designed to function.
The main job of a preamp is to overcome a single long distance run from antenna to TV. Preamps can also be used to amplify weak signals so they travel more effectively down the cable and into the house. Preamps are usually weatherproof and only have one output. They’re also usually more powerful, such as this 30dB amp, which increases the signal strength 1,000 times before it heads down the wire. That means that weak signals won’t be swallowed up by noise as they travel toward the house.
Preamps are usually powered through the coax cable so they need solid copper core cables.
A distribution amplifier is there to help you overcome the losses created by splitting the signal. Since they’re often used with splitters, distribution amps often come with multiple outputs. They’re usually not weatherproof since they’re designed to be used inside, and they usually have a lower power level. This distribution amp, for example, has 20dB of gain, about the highest number that you’ll find in a distribution amp. An 8-way splitter introduces 14dB of loss into the line – that’s just simple math since 14dB loss is just another way of saying 1/8 of the power. So this amp compensates for that and also has a little power left over so the signal leaving the amplifier is stronger than the signal that came in, even though you’ve split it 8 times.
Distribution amps are usually powered by plugging them into the wall.
And the bottom line…
As I said you could use a distribution amplifier for a preamp if it didn’t have a built-in splitter and you were using it in an attic. You could use a preamp as a distribution amp if you added a splitter to it. It’s just better to use them the way they were intended, right?