Are there any details for the on-board signal amp (booster) that can be switched on or off in the Tablo 4th gen? If it is documented somewhere I have not found it.
So if any of you know the specifics please let us know.
As far as I could tell in my testing, it’s about + 10db. However, it seems to be very prone to being over driven by the input signal level. So unless you are feeding it a very low signal, it is best to turn it off. There are many postings recommending this.
Note that even if the input signal is low enough to not overdrive the Tablo internal amp, boosting signal at the tail end of the signal chain is the least desirable option. Any and all noise introduced upstream of the Tablo will also be boosted, and s/n ratio will not be improved. The key to reliable decoding of the digital information is high enough s/n ratio, not so much signal strength.
It is much better to boost the signal as early in the signal chain as possible, and not use the internal Tablo amp. First and foremost, a proper antenna for your specific reception area/conditions pointed in the right direction is the best. Second, if needed, an amp located as close to the antenna as possible will boost signal before cabling/connections/splitters can introduce signal loss and noise. This combination will result in the cleanest signal (highest s/n ratio) introduced into the rest of your distribution system and ultimately into the Tablo.
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Got to click on product details. That’s all you get
Not sure what your point is. I went to the link you posted and found zero info regarding the amp specs. If it is somewhere buried on the website I could not find it and it is something that should be very obviously mentioned.
I’ll click on tech specs for you. It’s the only info I have found.
Tech Specs
What’s Included:
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Tablo device
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Power supply
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4′ Ethernet cable
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Quick start guide
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Tablo apps for every device
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Indoor TV antenna & 6′ high performance RG6 coaxial cable (when you choose the Tablo Total System “2-Tuner / with Antenna” and “4-Tuner / With Antenna”)
Concurrent Streams:
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2-Tuner / With Antenna: Watch and record up to two live channels simultaneously
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4-Tuner / With Antenna: Watch and record up to four live channels simultaneously
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2-Tuner / No Antenna: Watch and record up to two live channels simultaneously
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4-Tuner / No Antenna: Watch and record up to four live channels simultaneously
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Watch on up to six devices at once
Recording Capacity:
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50+ hours of onboard HD storage
Support for USB hard drives up to 8TB (~1000 hours of HD storage) -
Ethernet 10/100
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USB 2.0
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Coax
Processing:
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1 GB RAM
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128 GB Flash
Networking:
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100 Mbps Ethernet
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802.11ac dual band WiFi with MIMO
Dimensions and Weight:
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Height – 35 mm (1.37”)
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Width – 127 mm (5.00”)
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Depth – 127 mm (5.00”)
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Weight – 170 g (5.9 oz)​
Built-in Antenna Amplifier:
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11dB gain per tuner
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75 Ohm impedance (input and output)
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Can be turned off if using external amplifier
Video Format:
- MPEG2 (recordings saved to onboard storage will be transcoded to MPEG4 to maximize capacity)
Audio Format:
- Pass-through of 5.1 Surround Sound when available
Tablo Total System Included Antenna:
- Reception range – up to 35 miles
- Frequency range – 87.5-230MHz, 470-862MHz
- Receiving range – VHF/UHF
- Gain – 4-6dB
Impedance – 75Ω
Here’s another reference from the Tablo website:
Actually, the way this is written is a bit confusing. The Tablo must use an internal splitter to divide the incoming signal between either 2 or 4 tuners depending on the Tablo model. These splitters result in line losses of about 3.5db (2-way) and about 7db (4-way).
Assuming there is only 1 internal signal amp, then the 2-tuner model must have 11db + 3.5db = 14.5db gain in order to provide each tuner with a net 11db gain as noted. The 4 tuner model must have 11db + 7.0db = 18db gain in order to provide each tuner with a net 11db gain.
All just details. The bottom line IMHO is anything you can do to improve the signal at the antenna end of the system will improve signal strength (at better s/n ratio) to the Tablo tuners, which will improve performance and reliability much more than the internal Tablo amp. Just turn that thing off.
But my antenna is only 10-15 feet away from the tablo unit. What then.
Live with it if it works. Get something better up on the roof or whatever if it doesn’t. You can’t improve a “bad quality” RF signal with the Tablo internal amp. You can only “turn it up” sort of like a volume control. If it’s crap to begin with, you are just turning up the crap. Sucks, but it is reality.
I always thought the internal amp was to help compensate for the loss from the internal splitter.
I always thought it was to reduce the total cost of ownership for an OTA solution.
According to the specs, it adds 11db to each tuner. Unless there are multiple amps (1 for each tuner), it has to be before the splitter (which is the logical place for it, anyway). If so, and if I take the specs literally, it can’t add 11db to EACH tuner without first overcoming the splitter losses. So, it has to add more than just 11 db as I guessed in my previous post. Of course, it’s just a guess.
What I do know for sure from my detailed signal testing ahead of the Tablo, is that the internal amp is easily overdriven. The tuners themselves can handle a lot more than +11db signal when the amp is off. This makes sense to me as they must meet ATSC specs which require tuners to handle a very wide range of signal level. However, even signal levels well below the ATSC max cause the Tablo to “lose signal” when the amp is on. Thus my conclusion that the amp is easily overdriven.
This is corroborated by many others (including Tablo) that advise to not use the internal amp unless it improves performance in certain rare situations. Most think it’s the tuners that get overdriven, but it’s the amp. Again, I can demonstrate this easily in my setup by turning off the internal amp, and then increasing the input signal considerably (like 20 or more dB) with no ill effects on the Tablo performance. Conversely, if I turn the internal amp on I have to dial input signals way back to get the Tablo to work.
I agree that the internal amp can more than compensate for the internal splitter losses. However, I believe this is only useful in situations where the input signal is very low in the first place, and the internal splitter drops the levels below the decode threshold of the tuners. This is a very low level.
I think the issue most folks more likely face is there is not enough s/n ratio in the signal for the tuners to lock and decode in the base case, regardless of signal level. In this situation, no amount of signal boost from the internal amp will help. You have to go back to the front end (eg starting with the antenna) to make improvements.
In my case, s/n ratio from all physical transmitters is around 30db. Things start getting wonky around 25db (especially in adverse weather), and below 20db is just not reliable at all.