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In Reply to: RE: too simplistic? posted by Aristarchus on December 10, 2019 at 22:04:37
You're looking for proof?
You said "fuses make a very significant difference, huge I would say."
Prove that!
You seem to have read to many opinions about audio and know very little about how audio electronics work.
I suggest you forget what you think you know and get a good technical book and try to learn something.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Follow Ups:
The proof is in the pudding. Just try different fuses and see if it makes a difference to you. It's a lot easier than changing resistors, coming up with inductance figures for specific resistors, etc. I'm wondering at what point the amount of inductance in a resistor creates an oscillation problem 20nH, 30nh, 25.5nH? Or likely not at all, like some people think? People who do know how electronics work. Like Ralph. I do know one thing, if you disconnect a grid resistor there will be no music. Then, as Nietzsche said, "Without music, life would be a mistake". The use of a carbon comp resistor that would effect the sound would also be a mistake, so why take the chance if it isn't necessary? As pertaining to this post Dr. Floyd Toole seems to have done some homework on the subject which, IMHO, seems to contradict the need to have a ridged 2hz point for the dc blocking cap so I thought it a reasonable question to ask where the proof that Dr. Floyd Toole was full of crap. Where is the homework that shows how much inductance in a grid resistor produces problems? A of S
"The party told you to reject the evidence of your eyes and ears. It was their final, most essential command." George Orwell-1984
"The proof is in the pudding. Just try different fuses and see if it makes a difference to you."
That is almost impossible to do for many reasons having do to many things including expectation bias. People always say "trust your ears" but that is a mistake. The human ear/brain mechanism is too easily fooled.
Don't burn your house down but try this. If you think the fuse is causing some kind of audible problem then get rid of it (as a test). Connect a short piece of 20ga wire across the fuse holder. Now there is no fuse to mess up the sound. Clearly it would not be safe to leave it that way but at lease now you know what the unit sounds like when there is no fuse to "mess things up" and now you have something to "shoot" for when picking which fuse to use.
"I'm wondering at what point the amount of inductance in a resistor creates an oscillation problem 20nH, 30nh, 25.5nH? Or likely not at all, like some people think? People who do know how electronics work. Like Ralph."
It will be a case by case thing. It will depend on how much stray inductance there is in the wiring before the tube's grid and how much Miller capacitance the tube being used has. There is no single answer to your question.
Ralph is wrong. A grid stop resistor does not stop the oscillations because of the low pass filter created between the total source impedance and the Miller capacitance. A grid stop resistor stops oscillations because it adds resistance to the LC tank circuit.
"The use of a carbon comp resistor that would effect the sound would also be a mistake, so why take the chance if it isn't necessary?"
There is no chance of a CC resistor "effecting the sound" when used in the grid stop position but many times grid stop resistors are not necessary.
What circuit are you using and why are you concerned about grid stop resistors? Why do you think your circuit needs grid stop resistors? Is your circuit misbehaving?
A 2hz f3 is only needed/useful if your system and speakers and room fully support 20Hz. In the low frequencies there is always a lot of phase shift do to speakers, room interaction (and with tube amplifiers) output transformers. Very few systems go down to 20Hz and none of them do so without phase shift.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
"There is no chance of a CC resistor "effecting the sound" when used in the grid stop position" Two people have brought up noise from CC as a potential negative on the sound. Others agree with you that there is so little, not zero, be so little voltage,current and heat that it won't cause distortion but their noise could still be a negative. Distortion and noise being two different categories. Let's see if Ralph weighs in? Maybe bring it up with him in tubes diy where they have me blocked for some reason? There are those, it would sure seem that Ralph is one of them that believe the math in relation to the inductance that would be in a metal film and it's leads does not support the creation of oscillation. There are those who say they hear a difference. To think one can take subjectivity out of this hobby would be a bit of a stretch. Anyone in this hobby, "should", IMHO, be able to hear the difference between a fuse and no fuse, and it at least some cases different types of fuses with the same or very similar operational specs.It is in no way shape or form almost impossible to do, I don't get why you would say such a thing. Just try a glass vs ceramic fuse and try something similar to your example, a thick short. Asking a baby not to cry might be impossible but changing a dam fuse,I don't think so.
"The party told you to reject the evidence of your eyes and ears. It was their final, most essential command." George Orwell-1984
I am saying that I could come to your house and change the fuses in your system (without telling you) and you would not be able to tell. I could tell you that I changed the fuses (even though I didn't) and then you would hear a difference because you expect to hear a difference.
I have to laugh at this one
"...in tubes diy where they have me blocked for some reason?"
You really can't figure out why they blocked you?
Have a nice day.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
I could come to your house and change those carbon comps with metal films and you couldn't tell the difference. Might you do or show me the math that might contradict my statement? Math showing how the amount of inductance in metal film as opposed to carbon comp will cause an oscillation or an oscillation at a frequency that would or would likely create a problem? Thanks, A of S
"The party told you to reject the evidence of your eyes and ears. It was their final, most essential command." George Orwell-1984
You never answered my question.
Why are you concerned about grid stop resistors?
Do you use the type of tubes that need them?
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
No I can't. Was it the big fish? There was no politics involved and I don't think there were any cus words or un-family friendly statement? 'splain it to me Lucy.
"The party told you to reject the evidence of your eyes and ears. It was their final, most essential command." George Orwell-1984
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