Gnobuddy,
1. If I remember correctly, a Champ guitar amp uses a 6V6 Beam Power output tube, and no negative feedback. It is not wired as a triode, and it is not wired in ultra linear. That gives the amp a very low damping factor.
Put a guitar loudspeaker on that, and the speaker load presents a rising impedance as the frequency increases, due to the inductance of the voice coil. The effect is a rising voltage output from the amp as frequency increases. The amplifier’s internal low pass filters do not totally overcome that.
Also, a non-negative-feedback Beam Power tube creates Harmonic Distortion (Plus, Intermod Distortion if two or more strings are strummed at the same time). The amplifier's internal low pass filtering does not, and can not, get rid of those distortions, they are created at the output, not the earlier stage. Drive it to low power, get low distortion. Drive it to moderate power, get moderate distortion. Drive it to high power, get high distortion. How would you like it to sound?
The guitar speaker frequency response curve you attached earlier was probably created by driving that speaker from a low impedance (high damping factor amp). Therefore, there is no rising amp output voltage as the frequency rises. You get the frequency response curve of a constant voltage drive.
Take that same speaker, and apply a current source amplifier (6V6 in Beam Power mode). The response curve will not fall off nearly as rapidly. Yes?
Now, take that same Champ amp, and load it with a Power Resistor Load. The constant current 6V6 output voltage will not rise as the frequency increases. Constant current into constant resistance.
2. I am really lost, I was not aware of the Cello like sound out of a specialized guitar amp(s) and speaker that gave such an overall system sound.
Can you tell me, what Cello sound? I generally think of a Cello as either: Smooth, dreamy, beautiful. Biting, expressive, emotional . . full of harmonics, like the rosin is going to stick so bad as if either the bowstring or Cello string is going to snap. Of course the Cello can be played anywhere between those two limits.
3. Yes, the cell phone mic and amp are not designed to distort. But the early Codec was designed to use early artificial intelligence to make average American English be “squashed” into the least possible bit rate. That is the first order effect of the design by the engineer I worked with. Other voices in the room, other noises, etc. will all make such an early artificial intelligence Codec fail to give good results (not to mention a foreign language). But back then, we did not have high data rates. A large portion of that data was just system housekeeping, sync requirements, etc.
4. Perhaps sometime, I can spend some more time listing some of the things I learned over the early years with an analog scope, and later with the real time analyzer that I used to have access to.
Now I only have access to an inexpensive digital scope that also has an FFT. You would be surprised what you can do with some simple test equipment. You learn to improvise when you do not have the proper test equipment and proper repair parts, especially when you are in the middle of the Pacific Ocean on a US Naval Destroyer, and the Captain wants that piece of electronic gear fixed ! ! !
And in another subject area, the amplifier, transformer, and loudspeaker studies that I did when I had access to a very highly capable Vector Network Analyzer that could start at 10 Hz (and it had very high dynamic range from that low frequency, to way beyond audio frequencies).
Later.
1. If I remember correctly, a Champ guitar amp uses a 6V6 Beam Power output tube, and no negative feedback. It is not wired as a triode, and it is not wired in ultra linear. That gives the amp a very low damping factor.
Put a guitar loudspeaker on that, and the speaker load presents a rising impedance as the frequency increases, due to the inductance of the voice coil. The effect is a rising voltage output from the amp as frequency increases. The amplifier’s internal low pass filters do not totally overcome that.
Also, a non-negative-feedback Beam Power tube creates Harmonic Distortion (Plus, Intermod Distortion if two or more strings are strummed at the same time). The amplifier's internal low pass filtering does not, and can not, get rid of those distortions, they are created at the output, not the earlier stage. Drive it to low power, get low distortion. Drive it to moderate power, get moderate distortion. Drive it to high power, get high distortion. How would you like it to sound?
The guitar speaker frequency response curve you attached earlier was probably created by driving that speaker from a low impedance (high damping factor amp). Therefore, there is no rising amp output voltage as the frequency rises. You get the frequency response curve of a constant voltage drive.
Take that same speaker, and apply a current source amplifier (6V6 in Beam Power mode). The response curve will not fall off nearly as rapidly. Yes?
Now, take that same Champ amp, and load it with a Power Resistor Load. The constant current 6V6 output voltage will not rise as the frequency increases. Constant current into constant resistance.
2. I am really lost, I was not aware of the Cello like sound out of a specialized guitar amp(s) and speaker that gave such an overall system sound.
Can you tell me, what Cello sound? I generally think of a Cello as either: Smooth, dreamy, beautiful. Biting, expressive, emotional . . full of harmonics, like the rosin is going to stick so bad as if either the bowstring or Cello string is going to snap. Of course the Cello can be played anywhere between those two limits.
3. Yes, the cell phone mic and amp are not designed to distort. But the early Codec was designed to use early artificial intelligence to make average American English be “squashed” into the least possible bit rate. That is the first order effect of the design by the engineer I worked with. Other voices in the room, other noises, etc. will all make such an early artificial intelligence Codec fail to give good results (not to mention a foreign language). But back then, we did not have high data rates. A large portion of that data was just system housekeeping, sync requirements, etc.
4. Perhaps sometime, I can spend some more time listing some of the things I learned over the early years with an analog scope, and later with the real time analyzer that I used to have access to.
Now I only have access to an inexpensive digital scope that also has an FFT. You would be surprised what you can do with some simple test equipment. You learn to improvise when you do not have the proper test equipment and proper repair parts, especially when you are in the middle of the Pacific Ocean on a US Naval Destroyer, and the Captain wants that piece of electronic gear fixed ! ! !
And in another subject area, the amplifier, transformer, and loudspeaker studies that I did when I had access to a very highly capable Vector Network Analyzer that could start at 10 Hz (and it had very high dynamic range from that low frequency, to way beyond audio frequencies).
Later.