Hi 2 picoDumbs,
As you saw already, I am not getting that <10mV. Now it is 16mV with FET filter and 47000 UF cap. In my test setup the ripple from the SMPS is 70mV and after DC DC converter it is doubled like 140mV. After the FET filter it is around 20mV, with 47000UF added I see 16mV.
I kept the test setup on all day long and I now hear the noise from the SMPS itself. 🙁 But I am building this amp and will try this supply first, I hope in the mean time someone find and share proven linear supply solution.
The wire wound resistors are 10ohm 100W+ 4ohm 50W + 4ohm 50W, total 18 ohm at 60VDC which makes 3.3A. At first I saw the smoke from the resistors after buring up some of the coating materialfor about 5 minutes (?) they are now OK. This is from my Son of Zen experience. 😀 It does not look safe but this WW resistors are OK to abuse as a dummy.
We talked about battey for this amp.. Well I have this 30V 15A Li-ion(8 of 4.2V 15A cells in series). This is a surplus from a canceled electric car project. But I cannot get them anymore. 4 of these can make two channel supply and give you about 4 hour listening? But managing these batteris with balanced charging, etc.. could be bigger project than normal linear supply with big caps........
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Thanks all for the reference material. I've read it, but it doesn't quite answer my question.
How are we defining "Schade" feedback?
Are we calling any sort of feedback from Drain (Plate) to Gate (Grid) "Schade" feedback?
Maybe we should call all negative feedback "Black" feedback.
Incidentally, FWIW, other forms of voltage feedback also have a pentode-to-triode effect. 🙂
How are we defining "Schade" feedback?
Are we calling any sort of feedback from Drain (Plate) to Gate (Grid) "Schade" feedback?
Maybe we should call all negative feedback "Black" feedback.
Incidentally, FWIW, other forms of voltage feedback also have a pentode-to-triode effect. 🙂
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Ideally feedback should turn pentode into a perfectly straight IV relationship (like a linear resistor).
My observation of the Schade is it produces far more pure 2nd Harmonic with very little 3rd and higher order harmonics, eg a 20dB or greater differential between 2nd and 3rd Harmonic. I haven't seen this property in the more regular type of loop feedback. My experience is very limited though
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as many other things , Schade feedback was particular thing in particular time ; some of these things were revolutionary/first of kind , some were exploits of free place to push in variation of something else
one of these days I'm going to patent Chokysymmetry ....... even if that damn thing is , coincidentally, even named by Baaaad Papa!
though , I believe that Otto H. Schade is recognized as true pioneer in field
https://en.wikipedia.org/wiki/Otto_H._Schade
O. H. Schade - Engineering and Technology History Wiki
one of these days I'm going to patent Chokysymmetry ....... even if that damn thing is , coincidentally, even named by Baaaad Papa!
though , I believe that Otto H. Schade is recognized as true pioneer in field
https://en.wikipedia.org/wiki/Otto_H._Schade
O. H. Schade - Engineering and Technology History Wiki
@ZM
Well now, I wouldn't want anyone to think I'm down on Mr. Schade. 🙂
We've given a name to a particular kind of feedback mechanism, and I'm simply asking what those particulars (or generalities) are.
@2 picoDumbs
I don't think I would attribute any particular 2nd-to-3rd relationship specifically to "Schade" (whatever it may be 🙂) That's going to be gain device and load line specific.
I'm not being contrary here guys, I'm just trying to sweep away the pixie dust. 🙂
Well now, I wouldn't want anyone to think I'm down on Mr. Schade. 🙂
We've given a name to a particular kind of feedback mechanism, and I'm simply asking what those particulars (or generalities) are.
@2 picoDumbs
I don't think I would attribute any particular 2nd-to-3rd relationship specifically to "Schade" (whatever it may be 🙂) That's going to be gain device and load line specific.
I'm not being contrary here guys, I'm just trying to sweep away the pixie dust. 🙂
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The point is it seems to be far easily achieved without any effort of chasing load lines. That is it nearly works for any load line or it is far less sensitive to load lines.
My understanding of load lines is cancellation of 2nd harmonic not cancelation of 3rd harmonic , which in my observations is what schade seems to do (ie far less 3rd and virtually nothing higher)
I had , somewhere in the past , pleasure to acquaint Mr. Ivan Bukumira , in that time engineer in RC EI Nis (now defunct tube factory) ; His father was long time Tech. Manager (or something like that ) , Head of Team responsible for KT90
Besides being generous in sharing his knowledge about all things Tube , he shared many details and stories about craft and ppl (all kind of ) involved
Anyway - I still have papers - data sheet for KT90 ; I'm still stunned by sheer Demonstration of Force - ruler flat , 45deg oriented , equidistant curves for Ultralinear mode of KT90 operation ......
many ways to skin the Cat , or whatever Day's flavor is
it's probably time to read Sweet Spot article between the lines , few times more
btw. Graal polishing must be/is specific case sensitive , altering both inherent device characteristics (induce whatever you want and observe it further as black box ) and parts environmental to gain/black box device
to repeat - one of few things Pa told me about .8 series is - every different amp/model demands specific mix of actual tricks
Besides being generous in sharing his knowledge about all things Tube , he shared many details and stories about craft and ppl (all kind of ) involved
Anyway - I still have papers - data sheet for KT90 ; I'm still stunned by sheer Demonstration of Force - ruler flat , 45deg oriented , equidistant curves for Ultralinear mode of KT90 operation ......
many ways to skin the Cat , or whatever Day's flavor is
it's probably time to read Sweet Spot article between the lines , few times more
btw. Graal polishing must be/is specific case sensitive , altering both inherent device characteristics (induce whatever you want and observe it further as black box ) and parts environmental to gain/black box device
to repeat - one of few things Pa told me about .8 series is - every different amp/model demands specific mix of actual tricks
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I'm sorry, I'm not following your point. That's not specific to "Schade". Thanks just the same. 🙂
In every other amp I have built using regular feedback I usually get the following results. Just an example.
2nd -70dB
3rd -77dB
4th -84dB
5th -91dB
In every schade feedback amp I get results like this
2nd -70dB
3rd -95db
4th not measureable
5th not measurable
These have been my observations so far but I haven't tried to implement schade on push pull so I can't make any conclusive remarks other than to say these are the observations I consistently make.
Reductio ad Hitlerum. 🙂
No, I'm sure he'll offer insight when I consult the plastic educator.
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Thank you, I understand you are convinced, and I hope you'll forgive me for not being convinced at this time.
Shall we give our typing fingers a rest for now? 🙂
I understand the point you are making though and I tend to agree that feedback is designed to work this way regardless.
Based on my personal observations there does seem to be some substance to Schade Feedback and I have almost blind faith in Papa.
My understanding of semiconductive properties of materials on a deep level is pretty terrible. I have massive holes in my knowledge of electronics, I've never read a book on the subject except every word that came forth from Papa. I learn mostly through personal experimentation and observation. I don't know what the hell I'm doing most of the time.
Hahahahahah
I have utter faith in Papa as well. I'm not challenging his ideas, I'm trying to actually understand them.
No worries, we're here for the same reason 🙂
Also, I've been preparing a general tutorial on feedback mechanisms for this winter and I'd like to add "Schade" to the mix, but naturally I wan't to understand it in a more comprehensive way first. So, I have an ulterior motive. 🙂
No worries, we're here for the same reason 🙂
Also, I've been preparing a general tutorial on feedback mechanisms for this winter and I'd like to add "Schade" to the mix, but naturally I wan't to understand it in a more comprehensive way first. So, I have an ulterior motive. 🙂
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The only other point which might be worth pondering on eg feedback through the source eg F5 (and many other amps) is not an effective form of correction compared with correction (feedback) of the pure signal at the gate (Schade).
That idea could be a bunch of poppycock but it was a thought that crossed my mind a few times
That idea could be a bunch of poppycock but it was a thought that crossed my mind a few times
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what's driving a JFet is voltage between G and S
it really doesn't matter which one you gonna shake with NFB
2picopicoDodo
it really doesn't matter which one you gonna shake with NFB
2picopicoDodo
Yes but what I am thinking is once the signal passes the gate the device has already introduced some distortion to the signal, so the feedback is correcting a signal which is already distorted so the correction is not as effective as correcting the unadulterated signal before it hits the input device.
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