Bandwidth question?

Orpheus10,

We're all talking harmonics here. I mentioned summing of harmonics twice while Al mentioned it also few times. Highest fundamental is around 8kHz (church organs) but most often it is only up to about 2kHz as it is shown in this interactive chart:

http://www.independentrecording.net/irn/resources/freqchart/main_display.htm

I noticed that Harp has absolutely incredible range - never expected that.

Marakanetz, as I mentioned earlier, it does not seem to matter that the speakers lack the bandwidth of the amps. The phase shift that will occur in the amplifier due to bandwidth limitations is something that you hear well within the range of human hearing and nearly any speaker can reproduce it.

Don c55, nice link. I can't find the articles anymore, but it has been proven in the last twenty years or so that the human brain does definitely detect frequencies above what the ear can hear, scientists just don't understand exactly how yet.

Here is a YouTube video with a guy testing a couple of old tube amps. They're still going FWIW.[http://www.youtube.com/watch?v=jAjjc7ijGM4] [http://www.youtube.com/watch?v=Ayg6Y5CZgK0]

I watched the video and here is my interpretation of the performances. What he calls slant is actually called tilt or phase shift and it's measured in degrees. The Mac and the Dynaco look similar at maybe 20-25 degrees of tilt. This indicates that the low frequency response is rolled off. Possibly -3dB at 10-15 Hz. The Dynaco does a better job as the tilt is linear at low frequency. Therefore it's rolling off smoothly. The Mac on the other hand has tilt that is not linear at low frequency. At very low frequency the Mac frequency response might actually rise indicating some instability possibly caused by a coupling cap or power supply issue. High frequency response is similar on both amps with a bit of overshoot and only one or 2 cycles of well damped ringing. Some manufacturers do this so the amp sounds like it has greater high frequency response then it actually has. The Fisher looks like it has some major issues as it's high frequency response is not linear. It probably dips then rises and dips again. Either the amp has coupling cap issues, feedback cap issues, and/or the output coupling transformer is not properly compensated for. When the frequency response or any amp becomes non linear, i.e. rises and falls dramatically the test is pretty much over since that non linear response in not useable. I normally use sine waves to determine -3dB down points of an amp or preamp under test and confirm it with square waves.