Faint shrill phase noise when chords ring out
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Faint shrill phase noise when chords ring out
Trying to pinpoint the source of where my amp is making a faint shrill kinda phasey overtone when chords ring out. Chopsticked. Changed tubes. Checked grounding. Used shielded wire to input. It’s a noise my other 18 watt TMB builds have not had. Happens when volume is dimed and master is above 3 on TMB channel.
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Re: Faint shrill phase noise when chords ring out
Sounds like it might be the dreaded fizz. Some amps seem to suffer from this. It is some time since that has been a subject of a thread. But you will find refs to it in historical threads. I had lesser fizz which I sorted with "the Paul Ruby Fix".
If you need to, come back and I will hunt up what that was.
Dd
If you need to, come back and I will hunt up what that was.
Dd
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Re: Faint shrill phase noise when chords ring out
Yes please do. What is the source of the weird fizz. The OT, PT. I used heyboer trannies and valve storm metro layout. It is honestly the best sounding amp out of 4 18 watts I’ve built except for the weird ghost overtone. Weird also it only makes the noise on certain chords like A. Different guitars same. I do see that jj’s el84’s do make it more pronounced.
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Re: Faint shrill phase noise when chords ring out
There is a sticky just above this topic dedicated to Fizz. That will tell you more than I can.
The fix I used was the Paul Ruby fix or mod which is very simple. You fit two diodes in parallel with each of the two grid leak resistors (470k) for the power valves. One standard 1N4007 and one zener, I used a 1N757A. My amp is a classic (original trem) version and the resistors are R15 and R16 on my schematic. Your layout diagram is too small for me to see what the equivalents are but you should be able to see two 470ks going to ground from the grid block resistors which are on pin 2 of the EL84s.
The orientation of the diodes matters. The banded ends of the diodes go head to head with the 1N4007 going to ground and the zener connected before the 470k. You may find a diagram somewhere but I did not see one looking quickly. It is a proven simple and cheap fix which will do no harm to try out for a solution to your issue.
If that does not solve it and you still think it is fizz you are dealing with, there are other options listed in the thread above which are more complicated and may affect other aspects of the signal. In any case come back and let us know your progress.
Dd
The fix I used was the Paul Ruby fix or mod which is very simple. You fit two diodes in parallel with each of the two grid leak resistors (470k) for the power valves. One standard 1N4007 and one zener, I used a 1N757A. My amp is a classic (original trem) version and the resistors are R15 and R16 on my schematic. Your layout diagram is too small for me to see what the equivalents are but you should be able to see two 470ks going to ground from the grid block resistors which are on pin 2 of the EL84s.
The orientation of the diodes matters. The banded ends of the diodes go head to head with the 1N4007 going to ground and the zener connected before the 470k. You may find a diagram somewhere but I did not see one looking quickly. It is a proven simple and cheap fix which will do no harm to try out for a solution to your issue.
If that does not solve it and you still think it is fizz you are dealing with, there are other options listed in the thread above which are more complicated and may affect other aspects of the signal. In any case come back and let us know your progress.
Dd
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Re: Faint shrill phase noise when chords ring out
Here's an alternate method that could be helpful: https://www.amplifiedparts.com/sites/de ... k-snub.pdf
GuitarPlayer.com took it off their website for some reason. Dummies.
Here's the thread Dd is referring to: viewtopic.php?f=4&t=22659
Avoid JJ EL84 tubes. They're trash. I've never had issues with any of their other tubes, but they can't make EL84 tubes right.
Thanks,
Josh
GuitarPlayer.com took it off their website for some reason. Dummies.
Here's the thread Dd is referring to: viewtopic.php?f=4&t=22659
Avoid JJ EL84 tubes. They're trash. I've never had issues with any of their other tubes, but they can't make EL84 tubes right.
Thanks,
Josh
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Re: Faint shrill phase noise when chords ring out
Thanks everyone !! I ordered the diodes to try. Would anyone have a pic of it on board. I’m pretty sure I have it down but doesn’t hurt to ask.
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Re: Faint shrill phase noise when chords ring out
That's it. That is the diagram I was looking for to post.
Dd
Dd
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Re: Faint shrill phase noise when chords ring out
That one is on this page: http://www.paulamps.com/18watterbuzz.ht ... Distortion
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Re: Faint shrill phase noise when chords ring out
The two diodes fix worked !!!! Gain and master can be dimed with no phase effect. Perfect !! Thanks for the help replies. On to the next one.
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