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Old 3rd June 2005, 06:10 PM   #1
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Default Carlosfm...Snubber Guide Lines?

Carlosfm: seems you have a lot of successful experience with snubbers. Can you tell me how you go about decideing what values to use in your snubbers? I assume that once you have a basic value that you play with it up and down by ear to fine tune?
The standard filter equation: F = 1 / (2 pi R C). So what criteria do you use to pick you chosen frequency? As the value of R comes down what kind of impact is there (aside from heat) on the circuit? Thanks for any help from those who know.
I put a snubber on the secondary of an Acoustat 0ne plus 0ne high voltage step up transformer and was very pleased with the results. I have not played with the values, I used 10 ohms in series with 0.01 uf. Best regards Moray James.
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Old 3rd June 2005, 07:19 PM   #2
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I think the formula used is to be found in this paraphrase of a quote from the Bogart movie "Treasure of the Sierra Madre":

"Formulas, we don't need no stinkin' formulas".
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Old 3rd June 2005, 08:27 PM   #3
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Default Ok if formulas don't count?

There has to be some criteria with which to judge at the very least a starting point. I have no problems with listening to choose a best value however you need to have a value to start with! Regards Moray James.
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Old 3rd June 2005, 09:20 PM   #4
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Quote:
Originally posted by jackinnj
I think the formula used is to be found in this paraphrase of a quote from the Bogart movie "Treasure of the Sierra Madre":
"Formulas, we don't need no stinkin' formulas".
That also sounds like Jocko.
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Old 3rd June 2005, 09:30 PM   #5
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Hi Moray,

I can calculate the values for the snubber but to be spot-on (or almost) I would ideally need an impedance graph of the PSU.
Easy when we're talking about linear regulators, because they are well documented.
Measurements would also do, of course, if you have a way to make them.
Without that, I can make a calculation based on guessings, that you may need to fine-tune.

The formula is secret...

I can give you a first hint, though: you don't want a 10R resistor for the snubber on a PSU. You need a much lower value.
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Old 3rd June 2005, 09:45 PM   #6
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Default Re: Ok if formulas don't count?

Quote:
Originally posted by moray james
There has to be some criteria with which to judge at the very least a starting point. I have no problems with listening to choose a best value however you need to have a value to start with! Regards Moray James.
Thorsten simulated the whole circuit and it was pretty accurate, as much as can be expected.

One for sure (right Carlos) is to loose the unsnubbed capacitor.
have you seen my "Enhanced Carlos Snubberized Power Supply"
Carlos' snubberized Gainclone Power supply, Part II

The first thread became pretty enlighting and my first question in my frist post was answered by measurements that Carlos' basic idea had no or little effect, seen in measurements but "my" idea had.
Carlos' snubberized Gainclone Power supply

No offence Carlos but you won't kill the peak resonance only with adding a C + R. You must loose the lonely C also... 100 uF // 100n+1R (or so) will do the trick.... to remove the "big" peak of 4-6 dB at 2-4 MHz... altough this is still a bit of a sugarpill but at least it can be measured.
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Old 3rd June 2005, 10:01 PM   #7
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Default Re: Re: Ok if formulas don't count?

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Originally posted by peranders
No offence Carlos but you won't kill the peak resonance only with adding a C + R. You must loose the lonely C also... 100 uF // 100n+1R (or so) will do the trick.... to remove the "big" peak of 4-6 dB at 2-4 MHz... altough this is still a bit of a sugarpill but at least it can be measured.
100uf electrolythic?
Nah...

No offense, but I don't like to see you calling your speculations the "Enhanced Carlos Snubberized Power Supply".
Specially coming for you, who doesn't have the honesty to give an oppinion if the snubber is an improvement or not.
Objectively or subjectively speaking, you simply don't say what you think.
You are just dicking around.
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Old 3rd June 2005, 10:33 PM   #8
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I was just having fun at Carlos' expense. There is a notable lack of maths from some quarters
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Old 4th June 2005, 06:16 AM   #9
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Carlos, I have noticed that you haven't commented neither Thorsten's simulations nor Joseph_K's real world measurements saying that you still have a peak which you claim will be removed be your solution. You haven't commented my solution either so I'll guess you circuit will or remove something we don't know about.

This is what I think, now and before: It's not particular important and it makes not a huge difference.

Notice also that I don't say: It's totally unimportant and it makes absolutely no difference.
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Old 4th June 2005, 09:57 AM   #10
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Originally posted by peranders
Carlos, I have noticed that you haven't commented neither Thorsten's simulations nor Joseph_K's real world measurements saying that you still have a peak which you claim will be removed be your solution. You haven't commented my solution either so I'll guess you circuit will or remove something we don't know about.
That peak is not important, you're pickink on something that is ridiculous.
The snubber attenuates the peak.
Very important for an audio amp IS a low impedance PSU.
Any cap of a smaller value that is placed after the big PSU caps will create a peak.
That means if you use 10,000uf caps on the PSU, you would have to use this value everywhere, including as a "bypass" cap on the chip.
Your suggestion of 100uf to bypass the big caps will bring the peak to a much lower frequency, not good.
You are walking in circles here.

You caught me in the mood, because I don't have to comment anything you say.

And you still didn't say if the snubber improves you amp, while those who have tried it on YOUR amp will never go back.
What makes you think that a bridge and a cap makes a good PSU?
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