21-08-2013, 02:48 PM
I was not impressed at all! 
For a start, I found his style of delivery annoying and distracting. The section where he had 3 amplifiers in cascade and was talking about the 'gain' of each of those stages was very poor: he made no reference to whether the dBs he was referring to were voltage dBs or power dBs. He equated 'magnitudes' to a voltage or a current, but, by implication, not power. Technically then, he is incorrect: a 'magnitude' refers to a size of 'something': that 'something' could be a voltage, current, power, resistance - anything. When he was discussing frequency response of an amplifier, he kept referring to the frequency axis in units of dBs! He also made no reference to source and load resistances and that they often need to be taken into consideration when making dB calculations. There was also various other errors, but these come into the category of hair-splitting, so I have made no reference to them (not wishing to start an argument here!
)
But overall, his biggest mistake was his failure to point out, right at the beginning of his 'lecture', that dBs are fundamentally a measure of the ratio of two powers and that using dBs to compare two voltages (or currents) can indeed be done, and indeed is, but when that is done, great care is required.
To me, I feel that anyone who is confused about 'dBs' and then watches that is going to be even more confused by the time they've reached the end of it (and then taken a deep breath! ). Overall I feel that I could have done a much better job.
Al. / Aug. 20, 2013 //
For a start, I found his style of delivery annoying and distracting. The section where he had 3 amplifiers in cascade and was talking about the 'gain' of each of those stages was very poor: he made no reference to whether the dBs he was referring to were voltage dBs or power dBs. He equated 'magnitudes' to a voltage or a current, but, by implication, not power. Technically then, he is incorrect: a 'magnitude' refers to a size of 'something': that 'something' could be a voltage, current, power, resistance - anything. When he was discussing frequency response of an amplifier, he kept referring to the frequency axis in units of dBs! He also made no reference to source and load resistances and that they often need to be taken into consideration when making dB calculations. There was also various other errors, but these come into the category of hair-splitting, so I have made no reference to them (not wishing to start an argument here!
)But overall, his biggest mistake was his failure to point out, right at the beginning of his 'lecture', that dBs are fundamentally a measure of the ratio of two powers and that using dBs to compare two voltages (or currents) can indeed be done, and indeed is, but when that is done, great care is required.
To me, I feel that anyone who is confused about 'dBs' and then watches that is going to be even more confused by the time they've reached the end of it (and then taken a deep breath!
). Overall I feel that I could have done a much better job.Al. / Aug. 20, 2013 //
