No global feedback and class A ... voodoo of many people... how easy... Your statement is overly exoteric, John.... I never heard your " babys ", but babys of other apostles of " nonglobality " ( NP and ChH ) yes....Yes, is truth, that at first listening you are surprised by pleasantness of reproduction, but by focused listening you can find also inperfections of reproduction, caused by high distortion at peaks.... Absence of feedback is only one side of coin and it help not in every cases....
Blowtorch Principle
Hello Uli,Mr.Curl and others
Thank you for the fast respons. I didn't get an email from the forum so i'm a little bit late with my reaction.
Sorry if i offend you
Of course i realise that a compl.diff.folded cascode is a well known principle. Probably the inventor of such a circuit is from the tube age and buried a long time ago but this thread is a little bit of Mr.Curl so ...
A few week ago i tried the x-configuration in my experimental compl.diff.folded cascode but the frequenty response was very bad. Where did you made the cross?
The last time i'm thinking of a setup with a "motherboard" with the powersupply,connexxions etc. and a "bunch" of pre-amp modules which are easy to swap. That's the only way to listen to different variations under the same circumstances.
Mybe wishful thinking ...to much work and to less time.
Regards,
Johan.
uli said:Johan,
Its not a variation of the "Blowtorch Principle" (when I did this
circuit, I didnt even know Mr. Curl
There are lots of variations of the idea to use both legs of a diff
amp: Pass, Curl, Borbely, Hansen et al.
Uli
Hello Uli,Mr.Curl and others
Thank you for the fast respons. I didn't get an email from the forum so i'm a little bit late with my reaction.
Sorry if i offend you
Of course i realise that a compl.diff.folded cascode is a well known principle. Probably the inventor of such a circuit is from the tube age and buried a long time ago but this thread is a little bit of Mr.Curl so ...
A few week ago i tried the x-configuration in my experimental compl.diff.folded cascode but the frequenty response was very bad. Where did you made the cross?
The last time i'm thinking of a setup with a "motherboard" with the powersupply,connexxions etc. and a "bunch" of pre-amp modules which are easy to swap. That's the only way to listen to different variations under the same circumstances.
Mybe wishful thinking ...to much work and to less time.
Regards,
Johan.
If I am correct, one cannot 'X' a bridged amp circuit with no global feedback. The circuits from Mr. Curl & Mr. Hansen are balanced circuits with diff pair input. Once after the first stage, there is no mixing between the left & right arms, as there is in the Pass topology.
I also hope that at least most of us are here to learn circuitry design, and not try to fish the Blowtorch circuit, which Mr. Curl has repeatedly stated that he is not going to publish. I, for one, respect that fully.
Patrick
I also hope that at least most of us are here to learn circuitry design, and not try to fish the Blowtorch circuit, which Mr. Curl has repeatedly stated that he is not going to publish. I, for one, respect that fully.
Patrick
John,
Okay, I'll bite...can you suggest a decent readily available current-manufacture part for the second stage? I've got a marvelous first stage, but run into problems in the second (output) stage, due to the limitations of any currently available part I can lay hands on.
I get excellent results if I limit the rail voltage and use something like the ZTX450/550, but they won't take much voltage/current. Scale up to the ZTX453/553 and the performance drops a bit, but not too badly, however the device is still severely limited current-wise and thermally. A TO-220 device would be ideal, but the IRF MOSFETs limit performance so severely that it makes me want to cry. Add to that the glitch in the IRF P-ch transfer curve and it's pretty much a non-starter for a low or no feedback design. Vishay/Siliconix...zilch. Zetex...zilch. I had some Motorola MJE15030/15031s on hand. Tried them. Given that they're an "audio" part I expected reasonable behavior. Woefully short of the mark.
As I've noted prevously, I've gotten as low as roughly 7dB NFB for decent performance (circa 300kHz bandwidth, .07% distortion [quoting from memory--I'd have to look up the actual numbers]--and pretty decent sound), but this time I'd like to get closer to 0dB if possible. Any idiot can make a mediocre circuit then 'cure' it with enough feedback. No feedback would be a nice goal, but I'd settle for, say, 3dB or so, that being about half what I used last time.
Dammit, I'm willing to accept my own limitations--I can learn my way out of those. Parts limitations, however, are driving me to distraction.
Grey
P.S.: I've been severely time-constrained recently and have no earthly idea what's happened in this thread since the last time I posted. When I have a moment, I'll try to catch up. Please accept apologies if this has been covered in the interrim. Thanks.
Okay, I'll bite...can you suggest a decent readily available current-manufacture part for the second stage? I've got a marvelous first stage, but run into problems in the second (output) stage, due to the limitations of any currently available part I can lay hands on.
I get excellent results if I limit the rail voltage and use something like the ZTX450/550, but they won't take much voltage/current. Scale up to the ZTX453/553 and the performance drops a bit, but not too badly, however the device is still severely limited current-wise and thermally. A TO-220 device would be ideal, but the IRF MOSFETs limit performance so severely that it makes me want to cry. Add to that the glitch in the IRF P-ch transfer curve and it's pretty much a non-starter for a low or no feedback design. Vishay/Siliconix...zilch. Zetex...zilch. I had some Motorola MJE15030/15031s on hand. Tried them. Given that they're an "audio" part I expected reasonable behavior. Woefully short of the mark.
As I've noted prevously, I've gotten as low as roughly 7dB NFB for decent performance (circa 300kHz bandwidth, .07% distortion [quoting from memory--I'd have to look up the actual numbers]--and pretty decent sound), but this time I'd like to get closer to 0dB if possible. Any idiot can make a mediocre circuit then 'cure' it with enough feedback. No feedback would be a nice goal, but I'd settle for, say, 3dB or so, that being about half what I used last time.
Dammit, I'm willing to accept my own limitations--I can learn my way out of those. Parts limitations, however, are driving me to distraction.
Grey
P.S.: I've been severely time-constrained recently and have no earthly idea what's happened in this thread since the last time I posted. When I have a moment, I'll try to catch up. Please accept apologies if this has been covered in the interrim. Thanks.
Perhaps the lateral toshibe mosfets. 2SJK1013 and 2SJ313 could be woth a try. Anyway I rate the laterals much higher than the verticals. I dont think they will improve your high frequency performance as they have slightly higher input capacitance than the IRF. but i do think they'll improve your sonics. If you want to use less feed back you can think about useing a cascode to shield the input capacitance.
John, I and I think others would love to, but when questions regarding open loop line-stages and closely related DC-servo or power supply circuits are presented with schematics you most of the time answer with a simple (enigmatic) remark leaving us in the woods. My last postings with relevant questions have been brushed aside with the remark that certain topics have been discussed already. True, but to what extend?
So I'm a bit disappointed and even more in doubt as to who's/what purpose is served by this thread.
disappointed !!??!!
This thread has lots of interesting comments, thoughts etc. Power supply, parts, hints on design, its not a how to but certainly IMHO one of the most interesting and inciteful threads. This is a very educational thread, maybe not a 'here is my design' now go and copy it but lots of interesting stuff. Maybe it could be condensed, but if it had been probably many of the more interesting comments would have never been made. Thanks to all who have had input and may it continue...
Bill
This thread has lots of interesting comments, thoughts etc. Power supply, parts, hints on design, its not a how to but certainly IMHO one of the most interesting and inciteful threads. This is a very educational thread, maybe not a 'here is my design' now go and copy it but lots of interesting stuff. Maybe it could be condensed, but if it had been probably many of the more interesting comments would have never been made. Thanks to all who have had input and may it continue...
Bill
Why do you all persist in trying to milk this guy's bread and butter out of his pocket?
It has become very childish, "trying to guess what John has done".
John doesn't take his money from the DYI crowd.
Why is it so hard to understand?
About 2,000,000 posts back I made rather rude comments regarding the wiring practice. I have no questions, but John answers all of you... as best as he can.
I won't get on either side of the fence, but there are many people here saying bad things about feedback, those same people, could not even post the fundamental feedback equation.
I won't argue with John's position either... feedback causes many types of distortion.
You are all acting like babies. If you want to steal his design... BUY A BLOWTORCH.
Babies, big stupid babies...
It has become very childish, "trying to guess what John has done".
John doesn't take his money from the DYI crowd.
Why is it so hard to understand?
About 2,000,000 posts back I made rather rude comments regarding the wiring practice. I have no questions, but John answers all of you... as best as he can.
I won't get on either side of the fence, but there are many people here saying bad things about feedback, those same people, could not even post the fundamental feedback equation.
I won't argue with John's position either... feedback causes many types of distortion.
You are all acting like babies. If you want to steal his design... BUY A BLOWTORCH.
Babies, big stupid babies...
Had a hard day, Poobah ?
Completely disagree with you... Just have a second look on the name of the Forum...
I am quite sure that most of us are just expeimenting now with some disregarded concepts John introduced to us... I am here on the no feedback loop shunt regulation John talk about...
Did I copy anything from John here ? NO ! simply have the idea in mind, and so is the challenge : to have a working one by th breakfast time (perhaps the diner...).
Not seen a Blowtorch here in Europe, and I suspect that I will never see one... But a as the Blowtorch was an experiment (as per John's own words), I (we ?) go experiments too... With lot of dicussions around the subject, either on the Forum, or directly between us...
Funny project to "double guess" what is inside the Blowtorch... to take some info from the 2 very bad pics we have for now... and next to challenge to undertand HOW it works, WHY John did anything that way, WHERE to pick up parts, and so on...
My own guess is that John tried to show anybody that a superlative work would born from ordinary or industrial grade parts, but with a (very) competent and innovative design... Now I bear that in mind : no good audio stuff without a good design first... Parts are far second...
And certainly we report on the Forum also results from experiments we made, lectures we had... I suspect that John is also interested in those, or wouldn't certainly not be on the Forum and share the blanket with us !
Just my 2 cents...
Jbaudiophile
Completely disagree with you... Just have a second look on the name of the Forum...
I am quite sure that most of us are just expeimenting now with some disregarded concepts John introduced to us... I am here on the no feedback loop shunt regulation John talk about...
Did I copy anything from John here ? NO ! simply have the idea in mind, and so is the challenge : to have a working one by th breakfast time (perhaps the diner...).
Not seen a Blowtorch here in Europe, and I suspect that I will never see one... But a as the Blowtorch was an experiment (as per John's own words), I (we ?) go experiments too... With lot of dicussions around the subject, either on the Forum, or directly between us...
Funny project to "double guess" what is inside the Blowtorch... to take some info from the 2 very bad pics we have for now... and next to challenge to undertand HOW it works, WHY John did anything that way, WHERE to pick up parts, and so on...
My own guess is that John tried to show anybody that a superlative work would born from ordinary or industrial grade parts, but with a (very) competent and innovative design... Now I bear that in mind : no good audio stuff without a good design first... Parts are far second...
And certainly we report on the Forum also results from experiments we made, lectures we had... I suspect that John is also interested in those, or wouldn't certainly not be on the Forum and share the blanket with us !
Just my 2 cents...
Jbaudiophile
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