So first off you need to learn the relationship between input sensitivity and voltage gain.
Input sensitivity is the amount of signal required to put the amplifier at full power. Voltage gain is the steps of gain it takes to reach full power.
They are conversely interlinked.. i.e. the higher the input sensitivity, the lower the voltage gain. The higher voltage gain, the lower the input sensitivity.
Now the Thoman manual is actually a little miss-leading in that the voltage gain displayed is when the amplifier is on a 4 ohm load with an input sensitivity of 0.775V.
0.775V = to 0dBU (signal at which amplifier will be at full and producing 550W
Change the input sensitivity to 1.4V and the voltage gain drops to around 30.5dB
1.4V = +5dBU (ish).. So your amplifier requires an extra 5dB worth of signal to reach its full power and its dropped by 5dB on the voltage gain.. therefore this effects your limiter point, by 5dB
In this particular case, the amp doesn't produce double its 8 ohm power on a 4 ohm load, otherwise you would expect the voltage gains to be relatively the same on either load... in this case on a 8 ohm load with an input sensitivity selected at 0.775V the voltage gain is actually around 36.6dB
Because logarithmically input sensitivities and voltage gains are interlinked, we use the voltage gain vs the RMS power of our drivers to determine a limiter point. The limiter calculator you use is fine, though if you certain of the voltage gain;
http://www.funktion-one.com/settings/ - this is a little quicker.
A lot of amplifiers have either selectable voltage gains or input sensitivities. The difference is as follow;
Say you had a 350 - 400W RMS speaker, with an amplifier that had a selected gain of 32dB, it would be roughly 1.4V input signal for an amplifier to achieve 350 - 400W... which is roughly 5dBU, so your limiter point would be roughly 5dBU or -17dBFS on the ultra drive. ** Rounding up decimal places here **. So actually it doesn't matter what size amplifier you put on this 350W/400W speaker (providing it matches or exceeds 350/400W) your limiter point will not change as long as the voltage gain is the 32dB
For example, say my amplifier was 2000W @ 8 ohms, with a selected gain of 32dB, it requires around 3.1V (+12dBU) to reach its full 2000W... however to reach 350 / 400W, it still requires 1.4V (+5dBU)... double that, stick a 4000W @ 8 ohm amplifier on your tiny driver... at a voltage gain of 32dB, it needs around 15.5dBU to reach the full 4000W... it still only needs 1.4V (+5dBU) to hit 350 / 400W.
This is not true with selectable input sensitivities;
Take our 2000W @ 8ohm amplifier... Lets pretend you have selected 0.775V as an input sensitivity. It requires 0dBU to reach its full 2000W, so our limiter point is around -7dBU, which will limit the amplifier around 350/400W... Now lets take out 4000W @ 8ohm amplifier. You select 0.775V as an input sensitivity and your limiter point becomes around -10dBU! This is because both amplifiers require the same amount of signal to full output, however achieve different outputs with alternating voltage gains! Where our 2000W amplifier would have a voltage gain of around 44dB, the 4000W amplifier would have a voltage gain of 47dB.
If your amplifier doesn't have selectable voltage gains or input sensitivities, you can alter this by using your the output gains on your LMS. Consqeuntly, every time you change your output gains on your LMS, you need to alter your limiter point!
SO lets say are running your TA amp on a 8 ohm load on 1.4V (31.5dB voltage gain), the limiter point for your Brooke mid top is +2.7dBU or -19.3 dBFS. This is at 0dB on your LMS output gain. If you move this to -1dB, this correction technically means you are running at 30.5dB voltage gain, therefore your new limiter point will be +3.7dBU or -18.3 dBFS. Its the same in reverse order... notch your LMS output gain to +1, this correction means you are running at 32.5dB voltage gain, therefore your new limiter point would be +1.7dBU or -20.3dBFS
Can you see how this starts to relate to calculating limiter points?
My advice would be;
. Choose at what input signal you like to run your system . Work out the limiter points . Balance your system how you see fit and remember all alterations with gain need to be accounted for
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