Re: Why Do TEF Systems read 3-5 dB high ?
Yes the numbers are not exact 4 or 8 or 16 ohms. Like the rest of us they are choosing a number that is close to the "standards".
That is why measurements need to be expressed in terms of VOLTAGE-no wattage and an impedance CURVE given-not just a single number.
When the standard TH115 went from 8 to 4 ohms, the actual impedance of the cabinet changed to 5 ohms. But it is called a 4 ohm box, because (believe it or not) if it was called a 5 ohm box, we would get lots of calls from people who could not find a spec on any amp to drive a 5 ohm box. YES- this actually happened on SH50 when we used to call it a 6 ohm box. I got tired of the calls and we now call it a 4 ohm box and nobody calls about that anymore.
So the sensitivity did not go up 3dB when going from the 8 to the "4" ohm driver. But it is close.
AGAIN, one of the reasons you have to look at bit closer at the specs-and the manufacturer has to provide enough of those real specs for a person to figure out if the product really does what it says or if it is right for an intended usage in a project.
You can't express complicated specs as simple numbers, so the closest simple number is usually choosen to keep it simple for the people who don't know enough to read the real specs.
Sad but true.
