the 42 62 instrument is very useful for measuring the frequency response of any audio devices this is because the instrument has an internal function generator which can sweep sine waves from DC up to 20 kilohertz and hence very easily measure the frequency response of any audio device so here we can see the signal has been applied to an amplifier and here we are monitoring the output of the amplifier all the controls of the amplifier at the moment have been set to flat so here's the generator so we can look at the generator so here we've got the sweet mode so if I just disable that for a moment so here's the start frequency so we're just generating now a 10 Hertz signal now I can activate also the sweep so we're going to sweep up and down I'm going to sweep up to a frequency of 20 kilohertz so now we can see the output of the amplifier being monitored and it's sweeping up and down the frequency range I can now adjust the treble control to Max lift on the amplifier and we can see that the high frequency response of the output R now has been boosted we can make a more accurate measurement of this using the spectrum mode which will give us a amplitude against frequency plot so here we can now see the sweeping frequency and we can almost just visually see now that the amplitude is increasing as it goes up in frequency but further we can actually change the settings to actually hold the Max value and apply that so now we get a very clear visual indication of the frequency response of the device under test further options here we can change the number of spectrum bin so this is the number of points across the screen and here we can change the window function and these have different features for different application this particular one the flattop is the best choice as it gives the most accurate response the vertical display has been set to log so this is DB's and now we can measure directly the gain with cursors so now I can bring on a pair of cursor so I can measure the max lift and the response at DC so now here we can see Delta curses the max lift is in fact 10 debase