On the origin of the Aleph-X: It's somewhere in Petter's X-100 thread. Whatever that date is, that's when I realized that the two would fit together; that the X topology was primarily a front end concept and the Aleph topology was mainly an output topology. This was well before the introduction of the XA-200, so it's not as though I could have seen a crude, hand-drawn reverse-engineered schematic of the circuit. At the time, I didn't even realize that Nelson had any plans along those lines, I was just thinking out loud. After my post, and some derogatory posts that followed, Nelson posted something to the effect that an amp of that sort would be coming, which sorta changed things.
What...you think Nelson, for devious reasons of his own, called me up and said,"Grey, I've got this really oddball thing that I want you to do. I want to slide you this circuit under the table and have you advance it as your own." Get real, Fred. Nelson's got plenty of avenues he can use to put circuits out in the public domain. He doesn't need me. And why me, of all people? I'm just a guy playing with parts out in the wilderness. Even if he didn't want it associated with his name, for who-knows-what reason, it'd be easier to push it across the desk to Cyclotronguy (or any number of other people) and have him do the deed.
For what it's worth, there were only two real changes between my original conceptual (i.e. pre-prototype) schematic that I sent to Nelson and the one I eventually posted in the Aleph-X thread. 1) Variable drive on the current source for the front end. 2) Resistors from the outputs to ground. When Nelson warned me that I'd have absolute DC offset at the output, I went in prepared with a few ideas once I got a chance to build a prototype. I'd run it as a thought problem on the drive to and from work and scribble ideas at stop lights. I started in with fifteen or twenty ideas, maybe more, I don't remember. One of them was the resistors to ground at the outputs, but the lowest value I was comfortable trying was 1k--which didn't work--and I discarded the idea. Nelson suggested that I try 30 ohms sometime later that spring (which really shook me up--I'd figured that I was getting pretty low with 1k). That was the only formal "help" I received from Nelson, and I believe that I mentioned it in the Aleph-X thread. If I neglected to do so then, I will say it now:
Thanks, Nelson.
The variable current source I did on my own. I'd tried varying the front end load resistances. It works, but why do two adjustments when you can accomplish the same thing with one?
Ian MacMillan (I think I got the last name right; I believe it's Mac instead of Mc--if not, please accept my apologies, Ian) got the resistors-to-the-current-source trick. I had that idea on my original list of things to try, but managed to convince myself that it wouldn't work before I even tried it, so Ian gets the credit. That one embarrasses me--I should have followed through.
Thanks, Ian.
Your contribution? Running in circles crying to the heavens that anyone who hooked up such a P.O.S. circuit was wasting their time, money, and quite probably endangering their speakers.
Thanks, Fred.
And, actually, you can do quite a lot with parts and a bench. It most assuredly doesn't take an EE degree. I take as my inspiration the ham radio guys. (To those looking for textbooks, you could do worse than to buy a copy of the ARRL Handbook.)Their that-looks-good-enough approach gets the job done. Rules of thumb, while anathema to uptight snobs, do actually work in the real world. My hat's off to the ham folks. They're the ones who cobble together a working radio from baling wire and chewing gum and summon help after earthquakes and hurricanes. Meanwhile, obsessive EE-types are still bemoaning the fact that their expensive CAD programs won't run because their computer's down. The joke being, of course, that the CAD program (once the EE steals juice from the ham radio guy) tells the EE that the ham fellow's circuit won't work. That's about the time that the rescue choppers are coming over the hill, naturally.
Just a Sallen-Key filter? Yep. And I'll say it again: It's just a Sallen-Key filter. Put the numbers in, turn the crank, and out pops the answer. The formulas are quite simple; just basic algebra. Anyone who tries to mystify the process has an agenda. Mind you, the end user still has to choose the frequency and Q intelligently, but that's another story, entirely. F=1/(2*PI*R*C) is well within the capabilities of the members of this site. I use a spreadsheet and sometimes an old non-programmable hand calculator. In a pinch, it can be done with a pencil and paper. If you try hard enough, you can get an approximate answer by doing the math in your head.
All it takes is an opamp, either chip or discrete, a cap or two, and a few resistors. Tube folks can even do it with a follower (as can solid state people, of course). Easy.
Hats off to Sallen and Key.
As to posting about the crossover in the DIY progress thread--as I recall someone asked. Everything else I think I've addressed in the Xenover thread.
In short...yes, given the tone of your post, I'd say it's clearly emotional. Thanks for offering, but I don't need your support or approval. The Aleph-X works, the Mini-A works, the Xenover works. If I haven't actually built a circuit, I say so. In most cases, I build it before posting unless it's trivial. I don't bother simulating, it's a waste of time. Proof? Note how many people said the Aleph-X wouldn't work, based on simulations. I'll take a working circuit over a simulation any day.
Or, as Professor Ludwig admitted near the end of the semester, back when I was in school,"All this calculation and stuff is fine, but sometimes you've just gotta build it and see."
And the funny thing is...he was right.
Grey
What...you think Nelson, for devious reasons of his own, called me up and said,"Grey, I've got this really oddball thing that I want you to do. I want to slide you this circuit under the table and have you advance it as your own." Get real, Fred. Nelson's got plenty of avenues he can use to put circuits out in the public domain. He doesn't need me. And why me, of all people? I'm just a guy playing with parts out in the wilderness. Even if he didn't want it associated with his name, for who-knows-what reason, it'd be easier to push it across the desk to Cyclotronguy (or any number of other people) and have him do the deed.
For what it's worth, there were only two real changes between my original conceptual (i.e. pre-prototype) schematic that I sent to Nelson and the one I eventually posted in the Aleph-X thread. 1) Variable drive on the current source for the front end. 2) Resistors from the outputs to ground. When Nelson warned me that I'd have absolute DC offset at the output, I went in prepared with a few ideas once I got a chance to build a prototype. I'd run it as a thought problem on the drive to and from work and scribble ideas at stop lights. I started in with fifteen or twenty ideas, maybe more, I don't remember. One of them was the resistors to ground at the outputs, but the lowest value I was comfortable trying was 1k--which didn't work--and I discarded the idea. Nelson suggested that I try 30 ohms sometime later that spring (which really shook me up--I'd figured that I was getting pretty low with 1k). That was the only formal "help" I received from Nelson, and I believe that I mentioned it in the Aleph-X thread. If I neglected to do so then, I will say it now:
Thanks, Nelson.
The variable current source I did on my own. I'd tried varying the front end load resistances. It works, but why do two adjustments when you can accomplish the same thing with one?
Ian MacMillan (I think I got the last name right; I believe it's Mac instead of Mc--if not, please accept my apologies, Ian) got the resistors-to-the-current-source trick. I had that idea on my original list of things to try, but managed to convince myself that it wouldn't work before I even tried it, so Ian gets the credit. That one embarrasses me--I should have followed through.
Thanks, Ian.
Your contribution? Running in circles crying to the heavens that anyone who hooked up such a P.O.S. circuit was wasting their time, money, and quite probably endangering their speakers.
Thanks, Fred.
And, actually, you can do quite a lot with parts and a bench. It most assuredly doesn't take an EE degree. I take as my inspiration the ham radio guys. (To those looking for textbooks, you could do worse than to buy a copy of the ARRL Handbook.)Their that-looks-good-enough approach gets the job done. Rules of thumb, while anathema to uptight snobs, do actually work in the real world. My hat's off to the ham folks. They're the ones who cobble together a working radio from baling wire and chewing gum and summon help after earthquakes and hurricanes. Meanwhile, obsessive EE-types are still bemoaning the fact that their expensive CAD programs won't run because their computer's down. The joke being, of course, that the CAD program (once the EE steals juice from the ham radio guy) tells the EE that the ham fellow's circuit won't work. That's about the time that the rescue choppers are coming over the hill, naturally.
Just a Sallen-Key filter? Yep. And I'll say it again: It's just a Sallen-Key filter. Put the numbers in, turn the crank, and out pops the answer. The formulas are quite simple; just basic algebra. Anyone who tries to mystify the process has an agenda. Mind you, the end user still has to choose the frequency and Q intelligently, but that's another story, entirely. F=1/(2*PI*R*C) is well within the capabilities of the members of this site. I use a spreadsheet and sometimes an old non-programmable hand calculator. In a pinch, it can be done with a pencil and paper. If you try hard enough, you can get an approximate answer by doing the math in your head.
All it takes is an opamp, either chip or discrete, a cap or two, and a few resistors. Tube folks can even do it with a follower (as can solid state people, of course). Easy.
Hats off to Sallen and Key.
As to posting about the crossover in the DIY progress thread--as I recall someone asked. Everything else I think I've addressed in the Xenover thread.
In short...yes, given the tone of your post, I'd say it's clearly emotional. Thanks for offering, but I don't need your support or approval. The Aleph-X works, the Mini-A works, the Xenover works. If I haven't actually built a circuit, I say so. In most cases, I build it before posting unless it's trivial. I don't bother simulating, it's a waste of time. Proof? Note how many people said the Aleph-X wouldn't work, based on simulations. I'll take a working circuit over a simulation any day.
Or, as Professor Ludwig admitted near the end of the semester, back when I was in school,"All this calculation and stuff is fine, but sometimes you've just gotta build it and see."
And the funny thing is...he was right.
Grey
level Red DIY forum terrorist alert
"Running in circles crying to the heavens that anyone who hooked up such a P.O.S. circuit was wasting their time, money, and quite probably endangering their speakers.'
This is the most disingenuous that you have ever said. I was so amazed that it several minutes to even figure out what P.O.S. meant. Are you implying that is my opinion of Mr. Pass's work or yours? Do you consider your schematic of the Aleph X to be based more on your ideas or his? For someone accusing me of emotionalism, subterfuge, and hidden motivations it is a remarkable statement. I guess your motivation is clear at least. For the record, I expressed concerns that people pay attention to making sure the amp is stable and would offer that advice on building any amp. As for wasting time and money....... I have no idea what you are talking about. Do you?
"Just a Sallen-Key filter? Yep. And I'll say it again: It's just a Sallen-Key filter. Put the numbers in, turn the crank, and out pops the answer."
Do you really think active filter design is that trivial? I don't. Doing a little reading is pretty beneficial as to understanding what difference between the something like a Bessel and Butterworth filter and the Qs for to achieve them. I believe Some of these standard filter alignments have been used for decades and there is a reason. I believe Mr. Pass even used standard filter alignments in his crossover. If I was as evil as you say, I would ask if you even knew what a Sallen-Key was before it was discussed in the thread. But, I'm not and I' won't
I don't know why you want to trivialize the act of designing. There seems to a resentment for anyone who actually might want to know how circuits work beyond just throwing parts together and playing around on the bench. I know people have limited time but a little time reading will save you a lot of time and frustration. Learning some circuit theory will not keep you from building audio equipment and will help you understand others circuits (even Mr. Pass's) and build better circuits of your own. Wake up and smell the coffee. most of the post on the forum are by someone asking a question about how something works. I would guess that most of them are looking for something other than anthropomorphic storys about the emotional lives of circuits that do very little explain how they work.
"Note how many people said the Aleph-X wouldn't work, based on simulations." I don't remember even one.......... does anyone else?
I don't want to scare anybody off from building equipment. Having some knowledge of how it works is very helpful. As I remember, Mr. Pass even puts some theory in his construction articles! Grey, I remember you bemoaning the state of education once and agree with you on declining education standards. I find ironic that with that viewpoint that you try so hard to keep anyone from learning anything about audio design. Education never hurt anybody but a lack of it puts some real limitations on how far one can go in most endeavors.......... even audio. How's the work on the X-Type preamps that said you were working on month going?
Fred
PS I read your latest story in analog. I always did think your real talent was in writing fiction, unfortunately it seems to be creeping into your post here as well and at a growing rate ........... If you will excuse me, I have to hike out to the hills to look for iron.
"Running in circles crying to the heavens that anyone who hooked up such a P.O.S. circuit was wasting their time, money, and quite probably endangering their speakers.'
This is the most disingenuous that you have ever said. I was so amazed that it several minutes to even figure out what P.O.S. meant. Are you implying that is my opinion of Mr. Pass's work or yours? Do you consider your schematic of the Aleph X to be based more on your ideas or his? For someone accusing me of emotionalism, subterfuge, and hidden motivations it is a remarkable statement. I guess your motivation is clear at least. For the record, I expressed concerns that people pay attention to making sure the amp is stable and would offer that advice on building any amp. As for wasting time and money....... I have no idea what you are talking about. Do you?
"Just a Sallen-Key filter? Yep. And I'll say it again: It's just a Sallen-Key filter. Put the numbers in, turn the crank, and out pops the answer."
Do you really think active filter design is that trivial? I don't. Doing a little reading is pretty beneficial as to understanding what difference between the something like a Bessel and Butterworth filter and the Qs for to achieve them. I believe Some of these standard filter alignments have been used for decades and there is a reason. I believe Mr. Pass even used standard filter alignments in his crossover. If I was as evil as you say, I would ask if you even knew what a Sallen-Key was before it was discussed in the thread. But, I'm not and I' won't
I don't know why you want to trivialize the act of designing. There seems to a resentment for anyone who actually might want to know how circuits work beyond just throwing parts together and playing around on the bench. I know people have limited time but a little time reading will save you a lot of time and frustration. Learning some circuit theory will not keep you from building audio equipment and will help you understand others circuits (even Mr. Pass's) and build better circuits of your own. Wake up and smell the coffee. most of the post on the forum are by someone asking a question about how something works. I would guess that most of them are looking for something other than anthropomorphic storys about the emotional lives of circuits that do very little explain how they work.
"Note how many people said the Aleph-X wouldn't work, based on simulations." I don't remember even one.......... does anyone else?
I don't want to scare anybody off from building equipment. Having some knowledge of how it works is very helpful. As I remember, Mr. Pass even puts some theory in his construction articles! Grey, I remember you bemoaning the state of education once and agree with you on declining education standards. I find ironic that with that viewpoint that you try so hard to keep anyone from learning anything about audio design. Education never hurt anybody but a lack of it puts some real limitations on how far one can go in most endeavors.......... even audio. How's the work on the X-Type preamps that said you were working on month going?
Fred
PS I read your latest story in analog. I always did think your real talent was in writing fiction, unfortunately it seems to be creeping into your post here as well and at a growing rate ........... If you will excuse me, I have to hike out to the hills to look for iron.
Boys, Please take this outside. It reminds me of the Dan Akroyd/Jane Curtin spoof of Point/Counterpoint. "Jane, you ignorant...." Amusing at first, but now wearing thin.
You both have a lot to offer this community. How about agreeing to disagree on philosphy? Maybe a "responding to each other's posts" moratorium would be a good thing.
Thanks to both of you for your positve contributions.
You both have a lot to offer this community. How about agreeing to disagree on philosphy? Maybe a "responding to each other's posts" moratorium would be a good thing.
Thanks to both of you for your positve contributions.
Hey Nelson!!!!
I'm on board!!!! I had put off answering because I was going to look into ordering tickets to make sure I could get in!! Now you've solved that probleem!!!Evil work has kept me hopping. I've got great zydeco cred, having lived in Houston, I've seen Clifton Chenier, Buckwheat, others. Love that music....
I will respond via e-mail
Thank You,
Mark
I'm on board!!!! I had put off answering because I was going to look into ordering tickets to make sure I could get in!! Now you've solved that probleem!!!Evil work has kept me hopping. I've got great zydeco cred, having lived in Houston, I've seen Clifton Chenier, Buckwheat, others. Love that music....
I will respond via e-mail
Thank You,
Mark
