Will an antenna's built in pre-amp make a difference to overall sensitivity?

As I understand it, Tablos come w/their own amplifier, which reduces sensitivity. However, if I attach an antenna that has its own pre-amp/booster/whatever, that will cause its own desens, but I don’t think that the desens will be compounded by the Tablo’s amplifier.
On the other hand, after reading Tablo How-To: Perfect Your Over-the-Air TV Setup with Antenna Accessories | Over The Air (OTA) DVR | Tablo I’m wondering if I don’t understand these amplifiers like I thought I did. I had the idea that you want an amplifier if you have a long transmission cable and/or you’ve split the cable to feed multiple tuners. However, the amplifier will be less sensitive than your TV’s tuner, which means if you have a short transmission line and that line goes straight into your TV (or whatever), then using an pre-amp will actually reduce reception. Looking at that blog article, it seems that there’s more to it than that. For instance, there’s that section about “In-line or Pre-Amplifers” which say what they do, but not what they are for.

Your antenna’s preamp can improve overall signal sensitivity if:

  1. you live in a fringe area and the signals are weak and/or
  2. you have long cable runs to the Tablo receiver, or
  3. you are splitting the signal for multiple devices (a 2-way splitter reduces the signal strength in half and a 4-way by a quarter)
    You likely do not need a preamp in an urban area with strong signals. In fact, too strong of a signal can cause issues, just a s a weal signal will cause breakup.

I would refer you to Getting Technical with Over-the-Air TV Reception (AKA: Why Can’t I Watch This Channel?) | Over The Air (OTA) DVR | Tablo for more in-depth info, as it is well written and accurate.

Here’s a post from a user explaining amp vs preamp without all the user friendly-ness comparisons, they kind of cut to the point.

can’t find what’s meant - “densens”?
As for tablo’s amplifier, here’s a reference to verify:

The main difference between the Tablo and a traditional TV is that the Tablo has multiple tuners - so that you can watch and record multiple shows at once.

The drawback here is a small loss in DB when the signal is split. We use amplified splitting technology to mitigate for this loss, so it’s nearly negligible. In some rare cases, you could have one channel on your TV that doesn’t appear on the Tablo.

My personal take, fancy “HD” antenna’s marketed with an amp/preamp is largely a marketing ploy. (much like naming an antenna specifically HD compatible). To start with, you only get the signal you got - period. Amplifying or booting a bad or weak signal doesn’t make it a good signal. That’s not to say there’s not a place for these.

To note, some users will paranoiaily tell you splitting your cable will cause your signal loss, yes. But if you have a good signal to start with, splitting it and cable runs won’t kill it! My antenna is 25’ up. I have an amp splitter (distribution amp). Then a 10’ run to 2 TVs and a tablo ( split - split, split) TVs work flawless, very rare occasional weak signal lost recording on tablo.
The second split from the amp runs 50’ to the end of the house and split TV and another tablo. No issues with either, rare occasional weak signal lost recording on tablo.

There are users who’ve discovered “over amping” their antenna caused signal issues as well. So you can have too much of a signal. I’ve seen this on a signal channel, it’s not easy to trouble shoot.

Desens == desensitivity. I was told that (pre-)amps reduce the sensitivity a bit, so if you have a weak signal, the amplifier will make it even harder to receive than if the receiver was the only thing to receive the feed (i.e. no splitter) and the feed was short (i.e. a very short transmission line). That’s why i don’t understand manicbiker’s #1.
I also thought I read somewhere that because of Tablo’s amplifier it might not receive as well as another receiver, but I can’t find it.
BTW, at my last house I had a roof antenna w/a pre-amp. It suited the long transmission length and the heavily split cable very well. (Although, I feel like if I put the TV on the roof and bypassed the pre-amp, I might have gotten some of the American stations better)

I have two 40 yr old Radio Shack antennas in the attic(the ones that are about 7’ long when folded out). First one has one 25’ drop and is split in the house to TV and Tablo #1. The second is split in the attic and goes to two TVs in two bedrooms. Then the one going to the master bedroom is split between Tablo #2 and TV. I get 90 OTA channels and the picture is great everywhere - no amp anywhere. I think the key here is I am only 9 miles from the transmission towers and get a very good signal.

Adding anything between your antenna and tuner can cause a very small reduction in signal strength. If you have adequate signal, it shouldn’t be noticeable but if you’re on the edge of good reception it could make it worse.

Plus, amplifiers boost the signal as well as the noise (bad signal) in the broadcast. If your signal is already weak and generating a lot of errors, an amplifier can indeed make it worse in that sense as well.

instead of referencing a loss of sensitivity, the researchable term to use is SnR (Signal to Noise Ratio).

Amplification will always make the SnR slightly worse because no amplifier is perfect. If your signal is already very noisy amplification is not helpful. The ultimate solution is using the right tool for the job- unfortunately determining “what is the right tool” is typically not a user friendly task without a goodly chunk of knowledge, awareness, experience, and hardware. (Thus forums like this and some time/ money to experiment are so useful)

I guess “desensitivity” is the ham term.
Ok, so as long as there isn’t a lot of noise, a decent amplifier is likely to be beneficial. Unfortunately, it’s very difficult for me to determine how much interference I’m looking at here.

unfortunately, proper signal analysis requires expensive, complex hardware, so detailed explanation in collections of knowledgeable folks of the specifics to a given users layout/ hardware is the best one can really do to figure out the optimal choices…

My antenna has built in pre-amp (I am 60 miles away from a TV Station) and it works fine. I think the signal is more degraded during the day than at night. Recording is best after 10:00 pm. I tried an antenna without pre-amp and got nothing; so, for me, the Pre-Amp does an amazing job getting the TV signal.

Ok, now that I understand what the issue w/amplifiers are, can I get confirmation on whether or not an amplifier will do any good when connecting only to a Tablo through a short transmission cable? How about a product comparison:

Amplified antenna

  • Boasts 120mi range (whatever)
  • 13ft transmission line

Then there’s one that isn’t amplified

  • ~40mi range (all the transmitters I expect to receive are 18mi away, however, they are 90° away from each other :frowning: )
  • 17ft transmission line

From what I’ve read, a 17ft transmission line is as good as lossless.
Assuming that the antenna won’t receive any interference, will the amplifier do any good connecting it to a Tablo which already has an amplifier?

Then there’s one more unamplified antenna that looks good, but with a 6ft transmission cable, I’d probably have to splice it :frowning:

I would recommend buying an antenna from a reputable manufacturer. I have this model here Channel Master Omni+ 50 It works well and lets me pick up channels from all directions. Being that your really close to the towers it should work well. I use an amp because i have like 30 feet or more of cable running to on the roof, but you likely wouldn’t need one. I would also run a search here at Rabbit Ears. Info to get info about signal strength for your location. It seems to be pretty accurate. Also make sure any none of the channels you need to get are on the VHF band or you will need an antenna like I use that has the longer eliminates that pull in the VHF signals better.

Great. So how about those other 2?
A UHF-only antenna would work fine for me. Right now there aren’t any stations I have any hope of receiving using real 13 or lower.

I haven’t used them I am too far away for reliable transmission for an indoor antenna. You could see some of videos from the Antenna Man on YouTube he reviews various types of Indoor/outdoor antennas. This might give you an idea how well they work. Antenna Man - YouTube

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