I continue testing with the oscilloscope, and when I put on the square wave, which is not very good because it comes from the cell phone's function generator, at maximum gain I hear a slight hiss coming from the amplifier, what is this due to? Is my amp oscillating?
Can you post the square wave output, even a photo with your phone?
This is a square wave at 1kHz? And at what amplitude?
Are you using an 8 ohm load? Never test tube amps without a load.
This is a square wave at 1kHz? And at what amplitude?
Are you using an 8 ohm load? Never test tube amps without a load.
It is a 1khz square wave, with an 8ohm load.
What you hear with all the gain is the square wave tone, but it doesn't come out of the cell phone, something oscillating?
What you hear with all the gain is the square wave tone, but it doesn't come out of the cell phone, something oscillating?
Looks about right, for a square wave with sharp filtering and low phase shift.
Use DC input coupling to avoid the tilt. Show only 1 or 2 cycles, with better focus.
The "ringing" is from the ABSENCE of higher harmonics.
Use DC input coupling to avoid the tilt. Show only 1 or 2 cycles, with better focus.
The "ringing" is from the ABSENCE of higher harmonics.
Attachments
Not good or bad, that's just the way it is. All systems are inherently low pass.
If you lower the input frequency, there will be less ringing, because there will be more harmonics,
since the bandwidth is constant.
Guess what a 20kHz square wave would look like if recorded on a standard red book CD.
Answer: a sine wave. No harmonics at all.
If you lower the input frequency, there will be less ringing, because there will be more harmonics,
since the bandwidth is constant.
Guess what a 20kHz square wave would look like if recorded on a standard red book CD.
Answer: a sine wave. No harmonics at all.
This same waveform just came up in another thread. Could be the bandwidth limit of your cell phone's output. A proper signal generator might tell a different story.
Digitally synthesized square waves will all have Gibb's "ringing"' .
How the Gibb's appears depends on the circuit bandwidth and any output filters.
See post #26.
How the Gibb's appears depends on the circuit bandwidth and any output filters.
See post #26.
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Yes, I put the oscilloscope directly to the output of the cell phone cable and the square wave looks the same, I guess I should look for a decent signal generator, and maybe I will find the square wave I am looking for
The other thread is "Riddle me this . . .
It is 53 Posts already, partly my fault.
Tubes/Valves area.
It mentions Gibbs.
Talks about "ringing" versus "ringing"
One is due to oscillations, another is due to digital filter delays and frequency response.
One is a Tiger, the other is a house cat (in that order).
You might find it interesting.
It is 53 Posts already, partly my fault.
Tubes/Valves area.
It mentions Gibbs.
Talks about "ringing" versus "ringing"
One is due to oscillations, another is due to digital filter delays and frequency response.
One is a Tiger, the other is a house cat (in that order).
You might find it interesting.