I was doing some measuring and while the F2 was out I thought I’d revisit. The following scope pics show the signal generator at 10k disconnected, connected to the F2 input but switched off, and connected to the F2 input with the amp switched on.
I’m pretty sure it didn’t look like this back in 2006. Can anybody suggest what might be happening here before I strip it down?
I’m pretty sure it didn’t look like this back in 2006. Can anybody suggest what might be happening here before I strip it down?
It's a treble cut.
The manual shows a perfect 10kHz sine wave at the output of the amplifier.
I would try a different signal generator. Impedance mismatch?
The manual shows a perfect 10kHz sine wave at the output of the amplifier.
I would try a different signal generator. Impedance mismatch?
all graphs are of the input signal. Good call Netlist, maybe my sig gen has got a problem. I'm pretty sure I tested the amp when I built it and it behaved as expected(I should have some original jpegs somewhere). Is it possible the sig gen is now struggling to drive the insignificant input load?
I've found the service manual for the sig gen so maybe best to start there.
I've found the service manual for the sig gen so maybe best to start there.
Many thanks for looking chaps.
I’ve tried the F2 with 3 sets of leads now, at x1 and x10. Always the same result.
Here is the mofo with exactly the same measuring setup this morning. I did a full set of mofo measurements a week ago and they were good.
I think this conclusively points the finger at the F2. It produces the same artifacts on both channels so I’m definitely scratching my head now.
@Hugo, your cameo prompted me to look out the Jane Birkin album. Don’t think I’ve listened to it since your signature picture first reminded me, all those years ago…it’s still a good listen tho’.
I’ve tried the F2 with 3 sets of leads now, at x1 and x10. Always the same result.
Here is the mofo with exactly the same measuring setup this morning. I did a full set of mofo measurements a week ago and they were good.
I think this conclusively points the finger at the F2. It produces the same artifacts on both channels so I’m definitely scratching my head now.
@Hugo, your cameo prompted me to look out the Jane Birkin album. Don’t think I’ve listened to it since your signature picture first reminded me, all those years ago…it’s still a good listen tho’.
Are we still looking at the input of the F2? I guess the upper trace is output generator not connected to amp and lower trace connected but amp turned off?
Did you calibrate the probes? Do you know how to do this?
If not, read the manual, it will be on the very first pages, as this is one of the very first things to do when using a scope.
I don't know what mofo and cameo are, but it isn't very important to understand your message. 🙂
Did you calibrate the probes? Do you know how to do this?
If not, read the manual, it will be on the very first pages, as this is one of the very first things to do when using a scope.
I don't know what mofo and cameo are, but it isn't very important to understand your message. 🙂
cameo is the picture on your signature entry.
mofo is the amp championed by Mike Rothatcher and written about copiously elsewhere.
Yes, the probes are calibrated.
The last image posted(post #6) is the scope showing the mofo, top trace is the input, bottom trace is the output. As my last post states in paragraph 2 sentence 2.
The generator/scope setup used in the last photo for the mofo is exactly the same setup as shown in the fist photos, except the first photos don't show the output.
mofo is the amp championed by Mike Rothatcher and written about copiously elsewhere.
Yes, the probes are calibrated.
The last image posted(post #6) is the scope showing the mofo, top trace is the input, bottom trace is the output. As my last post states in paragraph 2 sentence 2.
The generator/scope setup used in the last photo for the mofo is exactly the same setup as shown in the fist photos, except the first photos don't show the output.
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Ok, now I understand. 🙂
What does the output of F2 looks like? With and without load?
If it shows the same waveform as the input, something must wrong at the input of the F2.
What does the output of F2 looks like? With and without load?
If it shows the same waveform as the input, something must wrong at the input of the F2.
The output of the F2 showed the same as the input with gain. I didn't include the output in the original photos because I thought it unnecessary as the input was already deformed with the amp switched on or off.
yes, something is wrong at the input to F2.
yes, something is wrong at the input to F2.
Check your grounding scheme.
If I add 20k - 22k in the ground line I get this, but only at the output.
Square wave is 10k.
Hope this helps or gives a clue.