There is a general misunderstanding of, and therefore misuse of, tv amplifiers.
An amplifier is not intelligent. It will amplify everything chucked at it which includes noise - the great enemy. Amplification can ruin a signal.
The most important aspect of any distribution system (or any aerial system come to that) is to collect the best possible signal. This is done by the aerial - there is no such thing as a 'digital' aerial. The next most important thing is not to degrade the signal so it is delivered to the outlet point as clean as possible.
Sometimes amplification is necessary. Surely in such cases it makes sense to amplify as close to the aerial as possible (1m min away to stop the aerial picking up any rf radiation) so that you are amplifying the minimum amount of cable noise, only the cleanest possible signals. This is best achieved with a masthead amplifier. It is very rare for me to use a setback amplifier at the back of a tv set and virtually unheard of for me to use these 6/8 way etc distribution amplifiers especially with the decline in wishing to distribute satellite and video signals (analogue signals can be very poor on some led and plasma tv's and there will be little need for tv's with an analogue tuner to be sold in the uk after switchover is complete).
Just because you are doing a distribution system does not mean it has to be amplified. Amplifying incorrectly can ruin a signal. I have distributed to 250 points using only two launch amplifiers, 25 houses over a distance of 500/600 meters using only one launch amp and 8 way domestic distribution systems using an internal aerial and no amplification etc etc.
I have read (perfectly correct) posts quoting the offcom guideline figure of 45-65db signal levels as being ideal. This is a bit misleading though as I could easily achieve 65db of signal to a point and still get no pictures if my signal was too noisy (or incorrectly amplified). Additionally this figure was 'set' in the early days of digital when tuners were not as efficient as they are now. I have had perfect results with signal levels as low as 35db but would not recommend this level, just using it to illustrate a point.
So, high signal levels do not necessarily achieve anything and low signal levels are not necessarily bad. We really only care about signal quality. Therefore do not assume you need to amplify just because you are installing multiple points. As with most things, simplicity and efficiency is the name of the game. Good cable (ct or wf 100 but since switchover I have been using rg6 on sub 15m runs increasingly as signal losses are not so important), good splitters (f type 2, 3, 4, 6, 8 way etc) and from a purist point of view try and avoid wall plates which are unecessary connections which are virtually impossible to use without creasing the cable which alters it's impedance charecteristics. If the results are not satisfactory then try a 1 way (pref variable gain) amplifier as soon as possible after cable entry into the property (or a masthead at the aerial if this is a long run from the aerial), but before the splitter. Unless you understand taps, do all your splitting in one central place. An 8 way splitter will attenuate the signal level by roughly 12db at each outlet whereas a two way splitter has a loss of 3.7db, split this again and your losses are already at 7.4db and again and you are at 11.1db for only four points! If still no good you will need a specialist aerial installer who will be able to deliver a useable signal to your distribution system.
One last point that is very easy to get wrong, when you connect the tv to the aerial point, do a factory reset / default values or a first time installation in the tuning menu if the former options are not available. You then know that the tv is looking only at what you are giving it and not some possibly eroneous information stored in it's memeory
An amplifier is not intelligent. It will amplify everything chucked at it which includes noise - the great enemy. Amplification can ruin a signal.
The most important aspect of any distribution system (or any aerial system come to that) is to collect the best possible signal. This is done by the aerial - there is no such thing as a 'digital' aerial. The next most important thing is not to degrade the signal so it is delivered to the outlet point as clean as possible.
Sometimes amplification is necessary. Surely in such cases it makes sense to amplify as close to the aerial as possible (1m min away to stop the aerial picking up any rf radiation) so that you are amplifying the minimum amount of cable noise, only the cleanest possible signals. This is best achieved with a masthead amplifier. It is very rare for me to use a setback amplifier at the back of a tv set and virtually unheard of for me to use these 6/8 way etc distribution amplifiers especially with the decline in wishing to distribute satellite and video signals (analogue signals can be very poor on some led and plasma tv's and there will be little need for tv's with an analogue tuner to be sold in the uk after switchover is complete).
Just because you are doing a distribution system does not mean it has to be amplified. Amplifying incorrectly can ruin a signal. I have distributed to 250 points using only two launch amplifiers, 25 houses over a distance of 500/600 meters using only one launch amp and 8 way domestic distribution systems using an internal aerial and no amplification etc etc.
I have read (perfectly correct) posts quoting the offcom guideline figure of 45-65db signal levels as being ideal. This is a bit misleading though as I could easily achieve 65db of signal to a point and still get no pictures if my signal was too noisy (or incorrectly amplified). Additionally this figure was 'set' in the early days of digital when tuners were not as efficient as they are now. I have had perfect results with signal levels as low as 35db but would not recommend this level, just using it to illustrate a point.
So, high signal levels do not necessarily achieve anything and low signal levels are not necessarily bad. We really only care about signal quality. Therefore do not assume you need to amplify just because you are installing multiple points. As with most things, simplicity and efficiency is the name of the game. Good cable (ct or wf 100 but since switchover I have been using rg6 on sub 15m runs increasingly as signal losses are not so important), good splitters (f type 2, 3, 4, 6, 8 way etc) and from a purist point of view try and avoid wall plates which are unecessary connections which are virtually impossible to use without creasing the cable which alters it's impedance charecteristics. If the results are not satisfactory then try a 1 way (pref variable gain) amplifier as soon as possible after cable entry into the property (or a masthead at the aerial if this is a long run from the aerial), but before the splitter. Unless you understand taps, do all your splitting in one central place. An 8 way splitter will attenuate the signal level by roughly 12db at each outlet whereas a two way splitter has a loss of 3.7db, split this again and your losses are already at 7.4db and again and you are at 11.1db for only four points! If still no good you will need a specialist aerial installer who will be able to deliver a useable signal to your distribution system.
One last point that is very easy to get wrong, when you connect the tv to the aerial point, do a factory reset / default values or a first time installation in the tuning menu if the former options are not available. You then know that the tv is looking only at what you are giving it and not some possibly eroneous information stored in it's memeory
