it seems that problem is ( and that's why this thread is already at 60-th post without any firm conclusions) that you're scanning people's replies just partially.
in different case , you'll be already asking some simple and practical questions about building amps which already are drawn and tried .
there is at least another one thread , started by me , which covers all your needs; either you're going with mosfets , LU cascoded with mosfet , mosfet cascoded with mosfet , Semisouth Jfet , Papafet - all that with input buffered, or not.
sort of one size fits all amp
so - to cut a story short :
- you don't know how to bias Jfet
- you don't know how to determine OLG of the stage
- you don't know how to make a stage capable to be fed with +26dbU without being overdriven
- you don't know why is LU cascoded
-you don't know why LU always must be cascoded
-you don't know what's reason for modulating that cascode
-you don't know why that cascode modulating is redundant in SUSY stage
but :
-you know that you need SUSY stage
-you know to differentiate CCS role as pure CCS and as magic voltage source
-you know how to starve CCS so either it will not work because of lack of voltage , or parts on top of him will be waiting eternity for proper biasing
- you know difference between voltage gain stage and xconductance one
-you know when to stop reading threads and replies , because you know
-you know that I'm tired now of writing down all things you obviously don't know and pretty well know
so - because it is so obviously easy to help you in altering your level of knowledge I should stop now messing in your thread , just hoping that someone who is going to read this in the future will not take for granted enormous number of irrelevant issues brought along .
so , back to Papa's Pub , there is some chat about old school bikes
Hey, Z.M., for someone who complains as much as you do, I can't believe that you just wrote a whopping 350 words without a single piece of constructive information.
So far in this thread, you've said:
I need input caps (that are not in your donut)
Your Donut amps thread are not fully tested
Donuts amps are SUSY, "not splitting the hair or arguing , that's just fact"
you "have no intention to give ... certificate on inspection"
that I have an attitude
that I'm "obviously even greener" than you
the "least important thing in Donut amps" is SUSY
"who cares about SUSY"
that Aleph X amps "hardly" work
and the clincher is:
you "first need to see that [I am] certified for asking questions"
Do you realize how incredibly annoying it is for you to make negative criticisms without positive suggestions? Admittedly, you've given me a couple of tidbits of useful information, but you rarely respond to my direct questions. Instead, you've answered far more questions from other people in this thread that have nothing to do with my topic. Whenever the conversation drifts back to my topic, you're back to elusive name-calling and bragging about your Donut.
Seriously, if there is a non-transformer output version of the Donut amp, then you wouldn't need to write 350 words when a single link to the specific posting number of another thread would be much nicer way to communicate. For that matter, why isn't there a schematic on some web site?
Please be aware that I spent a long time reading the articles. I published the "Concise Guide to the Published Amplifier Circuits of Nelson Pass" included in the sticky thread here and on official web sites. I read page after page on this diyAudio site where one bloke after another has attempted to build something on top of Nelson's circuits. I downloaded many of the amateur schematics and layouts for "X" amps. I can't promise that I read every word on the site, but I read more than I could stomach. I took several weeks off the site between my studies and starting this topic, so I'm sure people have said a lot in the interim that I missed. At this point, I think it's disingenuous of you to suggest that I "search" the other threads for answers. If I haven't found what I'm looking for by now, then there's no way I will find it without a few hints from those who seem to know it all.
If you have the time to point out very specific flaws in my draft circuit, then please be kind enough to answer my direct questions, or at least point out specific postings that have already answered my questions. Don't point me to the start of a 100,000 word thread. That's insulting.
What really bothers me is that you say your design is SUSY, but you won't discuss it. You claim that as a fact, without citing any evidence. Then you say I have an attitude. How can it be that I have an attitude when I come here humbly asking for advice? How can I learn anything when you just claim to know everything without discussing any details? Then, after making a big deal about how it's a fact that your amp is SUSY, you then make an about-face and say that SUSY was the least important consideration, and further that nobody cares about SUSY. How is any of this supposed to help anyone?
I asked specifically if cascode modulation is not needed because of the distortion canceling features of SUSY. I could have just been lazy and asked you to explain your original comment, but I decided to at least do a little work and try to figure out why you said what you said. Instead, you don't even respond, but later use my questions as a way to criticize this entire thread.
I'm not opposed to building the Donut instead of my completely untested Frankenstein, I'd just like to see helpful replies instead of empty braggadocio.
So far in this thread, you've said:
I need input caps (that are not in your donut)
Your Donut amps thread are not fully tested
Donuts amps are SUSY, "not splitting the hair or arguing , that's just fact"
you "have no intention to give ... certificate on inspection"
that I have an attitude
that I'm "obviously even greener" than you
the "least important thing in Donut amps" is SUSY
"who cares about SUSY"
that Aleph X amps "hardly" work
and the clincher is:
you "first need to see that [I am] certified for asking questions"
Do you realize how incredibly annoying it is for you to make negative criticisms without positive suggestions? Admittedly, you've given me a couple of tidbits of useful information, but you rarely respond to my direct questions. Instead, you've answered far more questions from other people in this thread that have nothing to do with my topic. Whenever the conversation drifts back to my topic, you're back to elusive name-calling and bragging about your Donut.
Seriously, if there is a non-transformer output version of the Donut amp, then you wouldn't need to write 350 words when a single link to the specific posting number of another thread would be much nicer way to communicate. For that matter, why isn't there a schematic on some web site?
Please be aware that I spent a long time reading the articles. I published the "Concise Guide to the Published Amplifier Circuits of Nelson Pass" included in the sticky thread here and on official web sites. I read page after page on this diyAudio site where one bloke after another has attempted to build something on top of Nelson's circuits. I downloaded many of the amateur schematics and layouts for "X" amps. I can't promise that I read every word on the site, but I read more than I could stomach. I took several weeks off the site between my studies and starting this topic, so I'm sure people have said a lot in the interim that I missed. At this point, I think it's disingenuous of you to suggest that I "search" the other threads for answers. If I haven't found what I'm looking for by now, then there's no way I will find it without a few hints from those who seem to know it all.
If you have the time to point out very specific flaws in my draft circuit, then please be kind enough to answer my direct questions, or at least point out specific postings that have already answered my questions. Don't point me to the start of a 100,000 word thread. That's insulting.
What really bothers me is that you say your design is SUSY, but you won't discuss it. You claim that as a fact, without citing any evidence. Then you say I have an attitude. How can it be that I have an attitude when I come here humbly asking for advice? How can I learn anything when you just claim to know everything without discussing any details? Then, after making a big deal about how it's a fact that your amp is SUSY, you then make an about-face and say that SUSY was the least important consideration, and further that nobody cares about SUSY. How is any of this supposed to help anyone?
I asked specifically if cascode modulation is not needed because of the distortion canceling features of SUSY. I could have just been lazy and asked you to explain your original comment, but I decided to at least do a little work and try to figure out why you said what you said. Instead, you don't even respond, but later use my questions as a way to criticize this entire thread.
Hey, the entire Donut thread is not a "reply" to my question. All I said is that I did not read that entire Donut thread a second time. I have been reading your replies here completely, not partially. The real problem is that your replies are intentionally vague, apparently only intended to show off your prowess as the Choky Donut creator.
I'm not opposed to building the Donut instead of my completely untested Frankenstein, I'd just like to see helpful replies instead of empty braggadocio.
I sincerely hope that you haven't been eliminated from the game. So far, I've received very useful suggestions and discussion from your postings here, so please do not bow out.
However, reading assignments are always a good thing, so long as they do not completely prevent you from continuing the conversation.
Yes, I did. Thanks. The author is CheffDeGaar, and the exact title is "UGS Power : it's U.P."
Pretty pictures! It's certainly a beautiful construction. Now I want to make my amps as cubes! (well, maybe not really).
I went to the linked web site, too. However, those are all complementary push-pull output stage designs, with the negative speaker terminal grounded, and I'm not interested in building something like that at all. Perhaps I should add another requirement to my list:
5) Balanced Single-ended Output stage
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you're wasting your time and our time with carpet of words all the time
first - you missed (even making that famous Papa's articles list ) grasping what's written about SUSY in ZV6 and ZV7 articles
otherwise , you'll not need Divine Hand to show and confirm what's SUSY and what's not .
in post #6 of this very thread I gave you link to one donut thread
you missed posts #117 and #118 in that thread
you missed at least one post there from another member who previously made similar amp
you missed searching and finding http://www.diyaudio.com/forums/pass-labs/169323-semisouth-donuts.html
everyone who invest even little time searching through Pass Labs forum here , not looking just for technical fact , but taking care about people , will find that I'm not here in ego trip but because of other ppl and all good things I can have with them .
so - ZM isn't important , Donuts are not important .
what's important is that you can learn from already chewed , but you don't want to do that , asking further questions without thinking about already given answers .
donuts are boiled water , derivation of Papa's work - so there can't be any reason for me to be overly proud and to preach my Donuts as best thing after bread .
take it or leave it , your choice .
first - you missed (even making that famous Papa's articles list ) grasping what's written about SUSY in ZV6 and ZV7 articles
otherwise , you'll not need Divine Hand to show and confirm what's SUSY and what's not .
in post #6 of this very thread I gave you link to one donut thread
you missed posts #117 and #118 in that thread
you missed at least one post there from another member who previously made similar amp
you missed searching and finding http://www.diyaudio.com/forums/pass-labs/169323-semisouth-donuts.html
everyone who invest even little time searching through Pass Labs forum here , not looking just for technical fact , but taking care about people , will find that I'm not here in ego trip but because of other ppl and all good things I can have with them .
so - ZM isn't important , Donuts are not important .
what's important is that you can learn from already chewed , but you don't want to do that , asking further questions without thinking about already given answers .
donuts are boiled water , derivation of Papa's work - so there can't be any reason for me to be overly proud and to preach my Donuts as best thing after bread .
take it or leave it , your choice .
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First time for everything. Just tell him to go sit on concrete pole. I think there might even be a picture somewhere to help with point
ZM has given you bread crumbs without the whole piece of bread. Donut migjt not be what you want, but with simple changes to certain things, you have what you seem to be describing. As far as the UP thread is concerned, i pointed tou there for the concepts talked about not the amp itself. You rejected opa1632 because it would not include output stage in corrective stage, but is that even necessary? UP thread showed both ways and gave subjective results. You say you wanted alanced SE output. How about opa 1632 with (2 reduced in size) BA1 output stage. Plenty of gain, SE, can include output in feedback loop if you choose. You could even make output stage from Lu fets if you want. Lots of options out there.
Yes, I noticed that someone else suggested input caps in that thread.
If you think so, then would you care to mention a post number?
That looks quite interesting. I'm going to spend some time studying those circuits.
Now, please tell me how I would have known to search for SemiSouth Donuts?
Trust me, I spent months searching this web site, paying attention to specific posters' names and especially grabbing clues from sticky threads that supposedly list favorite topics. Also trust me that if I ask a question, then telling me to search is not productive. Been there, done that. I learned a lot on this site, but I have not read everything, and it can be rather difficult to find useful postings without the help of others who know where the gems are. I've certainly found many useful schematics and stored them on my computer, but so far I haven't seen the same focus that I'm interested in building.
The inductors are the load, not the output.
A simple toroidal transformer can do, with no problems added.
Magura
1) No, no, you got it wrong, he is bragging about MY Donut
2) There is AFAIK no transformer output version of the Donut, as I find that straying just a bit too close to something Choky would like (hollow state).
3) The schematic is not published the usual places, as I for one am done supporting rip-off artists. The same goes for the fluffy Serb. If we feel somebody is genuine, and so forth, we hand out schematics, usually followed up with help and advice.
4) ......and yes, the Donut is made by me, with (great) support of Choky, a bunch of other less fluffy Serbs (you know who you are), a nationality confused Frenchman, a Dutchman, a German, and a couple of Americans, so actually there are a whole bunch of Donut creators.
Sadly, there is only one Donut owner/builder (till the fluffy Serb gets going).
Magura
What am I missing out on when I hope to make the speaker the only load?
I should add another item to my NICE-TO-HAVE FEATURES:
C) Current Output Stage (hopefully as an option, since I don't know yet whether my speakers will like this)
Seems to me that a current output amplifier would do best when the speaker is the only load, but this area of amplifier operations is the newest concept for me.
I totally understand this. One of the things I learned after reading hundreds of postings on this forum is that there are too many rip-off products. If it's too easy to just download the finished plans, then the IP violations are increased. Nelson tends to keep each idea in a separate article, sometimes combining a couple of ideas together, but he never really puts all of his techniques into one public schematic. The Pass Laboratories products are where all his tricks go into one bag. Not to mention the fact that he's always trying new things, and thus new tricks appear all the time. I noticed that his lawyers had him remove some of the First Watt schematics from the web site manuals section because they were a bit too much of a giveaway. All of this makes perfect sense.
Hand in hand with "not feeding the IP rip-off artists," I also see a theme here on diyAudio that veterans don't do a lot of hand-holding with newbies. The ethos is that DIY folks should learn by doing, and not have every answer provided without requiring at least a little thought.
I actually had a mind to build my amplifier without ever sharing. You'll note that I did not include resistor values on my schematic (partly because they haven't been dialed in yet). My primary reason for putting my schematic here is that I plan on making some boards, and given the minimums required, I might as well share them with other interested folks. Thus, it seems prudent to share my design before I make the boards so that folks have a chance to make suggestions for a reasonable amount of flexibility.
One thing I decided to do after reading Choky's comments is to put degeneration source resistors on the input JFETs, and capacitors on the inputs, even if I have to solder wire jumpers in the event that I decide I don't want them. I'd rather solder jumpers than cut traces and have a mess.
P.S. I read every page of Bob Cordell's book, enjoyed it immensely, but was not interested in building anything but Class D. Funny that my two DIY interests turned out to be Class A balanced SE SUSY and Class D, spanning the spectrum from fairly inefficient to highly efficient. The Class D amp would go in my electric car for longest battery life, and the Class A would go in my main, stationary listening position.
Maybe in my next update I'll restate my goals, requirements, and other features I'm interested in, just to be clear. I've mentioned almost everything I'm looking for so far, but my comments are rather spread out in this thread.
Ah, well, I am willing to rip out the crossovers. In fact, these speakers are designed for normal wiring, bi-wiring, and bi-amping. Conversion involves changing or removing the crossover. Apart from a lack of schematics for the crossovers, there's nothing stopping me from doing a little homework to see what changes would be needed for driving them via current output.
I hope I am not being too naive when I believe Nelson when he says that speakers react most directly to current, not voltage. Thus, with proper connection, any speaker should work, provided you're willing to alter or remove the crossover. I should read those articles again, though...
My plan is to bi-amp these speakers eventually, since I have at least 8 DAC outputs available. The DAC has non-volatile memory for various DSP effects, so I could program in the appropriate active crossover frequencies and have them available immediately upon power-up.
If I can successfully build one amplifier, I should be able to build four or five.
The inductors in the Donut are simply replacing a CCS, giving much higher efficiency. We are approaching 20% efficiency in real class A by using an inductor load.
So what is the point of using an inductor as load VS. a CCS you might ask?
It is so that if you want real class A, as opposed to pseudo class A, you will end up with a huge power demand, offering a relatively limited power output.
Now if you go with a CCS, the effort needed for heatsinking and PSU, is going to be massive. Using an inductor, makes those demands much lower, as in less than half, for the same output.
The other solutions like active current source, are still in the pseudo class A category (let the flaming begin), and in comparison quite dull IMHO.
I have built quite a number of amps over the last 15 years, starting out with class AB PP, over single ended class A, and balanced single ended class A.
Of those, most of them have been built in many iterations, testing among other things current output, transformers, SUSY, you name it.
The only way to find out what really pleases you, and fits your speakers, is to experiment.
Mostly current output only works well with full range drivers, but can also be of benefit with band tweeters.
The Donut can easily be configured to run as current output amp, so makes no big difference to the amp choice.
In your shoes, I'd build a simple Zen V1 , a Aleph, an AX, a Zen 9, and a Zen 7. Play around with them, and find out what pleases you, and find out how to reach that goal.
The Donut is made to please me. It fits my speakers well (full range horns), and that's pretty much it.
It was never the intention to make an amp that anybody else likes.
Magura
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