Schematics
I see my attachments were lost in my previous post. Let me try again... Stephano's first as I can't see how to attach two files.
Ian.
I see my attachments were lost in my previous post. Let me try again... Stephano's first as I can't see how to attach two files.
Ian.
Schematics part 2
Here is my variation. Perhaps someone could explain to me how I can attach two files in future? I suppose I could include then both in one zip file.
Ian.
Here is my variation. Perhaps someone could explain to me how I can attach two files in future? I suppose I could include then both in one zip file.
Ian.
Ian Macmillan
Actually, I was able to find it in an earlier response of this thread but I downloaded the one just posted to compare. The idea of X-SOZ monoblocks that can operate at 8 watts with 21dB peak headroom in a 10" cube is the ultimate dream amp for me. I have never built an amp so forgive my naivete but would I be able to fit the electronics for 21dB (128W) of headroom in a 10" cube without inviting noise and other undesirable effects? I'm picturing a massive toroid with 0.25 Farad of capacitance driving that single stage, is it even possible? Is this a question for (zen Master Builder) HPotter?
Actually, I was able to find it in an earlier response of this thread but I downloaded the one just posted to compare. The idea of X-SOZ monoblocks that can operate at 8 watts with 21dB peak headroom in a 10" cube is the ultimate dream amp for me. I have never built an amp so forgive my naivete but would I be able to fit the electronics for 21dB (128W) of headroom in a 10" cube without inviting noise and other undesirable effects? I'm picturing a massive toroid with 0.25 Farad of capacitance driving that single stage, is it even possible? Is this a question for (zen Master Builder) HPotter?
Great thread this one, thanks to Stefan and Ian, an not to forget "The One and Only".
I am going to rebuild my last SOZ, an because of that I am interested i this XSOZ. I would like to keep the original soz without currentsources, and only experiment withe adding some feesback resistors (like in the attached scematic) and some inputcaps.
Therefore i have some questions:
1)
Will i obtain all ore some of the benefits from this x-Construction in the attached scematic, or do i need the currentsources like Ian suggests in Ian-X-SOZ.
2)
Since SOZ only consist of one diffrential stage there is no X to see as i the AlephX. So my questin is: Does the feedback in the XSOZ goes from out- to in+ and from out+ to in- through the cources of the mosfets, by conditions stated by the tail? And if not how?
May be i am totally wrong in my conception of the X-thing, so if anyone could explain, i would be a happy littel boy on 53.
I am going to rebuild my last SOZ, an because of that I am interested i this XSOZ. I would like to keep the original soz without currentsources, and only experiment withe adding some feesback resistors (like in the attached scematic) and some inputcaps.
Therefore i have some questions:
1)
Will i obtain all ore some of the benefits from this x-Construction in the attached scematic, or do i need the currentsources like Ian suggests in Ian-X-SOZ.
2)
Since SOZ only consist of one diffrential stage there is no X to see as i the AlephX. So my questin is: Does the feedback in the XSOZ goes from out- to in+ and from out+ to in- through the cources of the mosfets, by conditions stated by the tail? And if not how?
May be i am totally wrong in my conception of the X-thing, so if anyone could explain, i would be a happy littel boy on 53.
Attachments
Current sources v resistors
Henrik, no problem with using resistors rather than current sources for the Drain loads. The only disadvantage is lower efficiency (more power disipated in the resistors due to the need for increased voltage to compensate for the voltage drop across said resistors). One can also use either current source or resistor for the diff pair 'tail'. Here the current source will give better performance with a SE input.
I wouldn't try looking too hard for the magical X, it is more a concept than a particular topology. The essence is arrange the feedback such that signal is fed back negatively and distortion positively (to the other half). The latter cross feedback is indeed via the MOSTFET Sources.
Ian.
Henrik, no problem with using resistors rather than current sources for the Drain loads. The only disadvantage is lower efficiency (more power disipated in the resistors due to the need for increased voltage to compensate for the voltage drop across said resistors). One can also use either current source or resistor for the diff pair 'tail'. Here the current source will give better performance with a SE input.
I wouldn't try looking too hard for the magical X, it is more a concept than a particular topology. The essence is arrange the feedback such that signal is fed back negatively and distortion positively (to the other half). The latter cross feedback is indeed via the MOSTFET Sources.
Ian.
Both Stephano-X-SOZ and Ian-X-SOZ are properly
X circuits. They both provide cross-coupled error
correction through the Sources of the input differential
pair, and reduce differential error through symmetric
feedback. The output of each side taken alone looks
like the open loop performance (except for gain), but
the differential waveform is greatly improved due to
error cancellation.
Henrik, it is not essential to have a constant current source
bias for the diff pair to get X benefit, but it does help. If you
are driving the circuit balanced, it is less necessary, but if
you drive it single-ended, you really want the current source.
X circuits. They both provide cross-coupled error
correction through the Sources of the input differential
pair, and reduce differential error through symmetric
feedback. The output of each side taken alone looks
like the open loop performance (except for gain), but
the differential waveform is greatly improved due to
error cancellation.
Henrik, it is not essential to have a constant current source
bias for the diff pair to get X benefit, but it does help. If you
are driving the circuit balanced, it is less necessary, but if
you drive it single-ended, you really want the current source.
To resist or not resist
Hmmmm thats a tough one. It seems that the resistor approach would be more in keeping with the SOZ concept: less efficient and less active devices, so that seems right. AND most people use a Balanced line source as a pre amp so Nelson says not such a big deal. SO this would differenciate it from the X Aleph.
BUT, with current source, it is beginning to sound like
" The Greatest Amp ever Made" and I'd hate to miss out on that!
I guess we need to compare both someday...like when they exist!
Hmmmm thats a tough one. It seems that the resistor approach would be more in keeping with the SOZ concept: less efficient and less active devices, so that seems right. AND most people use a Balanced line source as a pre amp so Nelson says not such a big deal. SO this would differenciate it from the X Aleph.
BUT, with current source, it is beginning to sound like
" The Greatest Amp ever Made" and I'd hate to miss out on that!
I guess we need to compare both someday...like when they exist!
HPotter
Is the email listed for you on this forum active? I've written you several times without a reply so I'm prompted to ask. Very innovative of you making narrow towers. I bought a pair of Vandersteen 3's just for nostalgia of the Trade Center Twin Towers. Several visitors have also remarked on the association without any promting so I guess there is real pathos here.
Do you have a parts list and layout schematic for your SOZ monoblocks. I am curious why you think you needed to force air. The eighteen inch height would seem to be able to generate enough thermo differential to accelerate at least 5 ft3/min. Could you reconfigure the layout so an air channel can be guided directly over the mosfet?
Is the email listed for you on this forum active? I've written you several times without a reply so I'm prompted to ask. Very innovative of you making narrow towers. I bought a pair of Vandersteen 3's just for nostalgia of the Trade Center Twin Towers. Several visitors have also remarked on the association without any promting so I guess there is real pathos here.
Do you have a parts list and layout schematic for your SOZ monoblocks. I am curious why you think you needed to force air. The eighteen inch height would seem to be able to generate enough thermo differential to accelerate at least 5 ft3/min. Could you reconfigure the layout so an air channel can be guided directly over the mosfet?
Now we have at least one happy little boy i Demark!
Ian and Nelson, thanks a lot for your concerning answers to my questions.
Ian:
I have alredy build the SOZ, in the original design, and it playes butiful thou.
I just want to reorganise some of it, i underestimated the heatdissipation from the dioderectifiers. Besides from that, i am in the mood for som heat, it's ok.
So your good news to me is, that the use of resistors instead of currentsources wil leave me at least some benefits from the "crosscoupled error-corrections" (wow! I would love to have som of that) delivered by the "X"-circiut.
I am driving my SOZ with the Balanced Zen Linestage, so i get pretty good performance without a currentsource at the tail.
I am happy that you can confirm, that the X-thing works throu the mosfet Sources.
Once again Ian, thanks for your answer, but i can´t promise you not to dig a little more into the "magical X".
Nelson "The One and Only":
I just reread all the posts in this thread, and found, that you already had given some of the answers, but sometimes your writing is very compressed, so as a reader you have to stay close to every word of yours, and if you get it, it is very clearley spelled out. Besides from that i just read your wellwritten article on Su-Sy, wich gave me the kick to look deeper ito your patent, most intresting.
In your reply, you indicated, that in nonbal. mode i woudn´t achive much from the X-coupled circiut, but since i am drving the SOZ in bal. mode i schould get some or the most of the error-correction.
Never the less, i will try it out.
Accordingly to my simulation of the circiut with and without x-feedback, it seems as i will loose some gain. My Org. SOZ will go to full swing (13v) at 0,9v input and with the x-feedback it needs 1.8v, so i need to adjust my linestage to deliver this increesed gain. Then the question is, will the increesed gain in my linestage generate more noise and distortion than cancelled in the X-feedback?
Many people have told you, how kind you are revealing your knowlege in this forum, so that i will do once more. A big thank you.
When i have made the first test with this magical-X, i will come back, it will not be tomorrow, it takes time when you have to do things like staying alive without starving.
On mondy i will more tha stay alive, i am going on vacation to Nordkap in Norway for at least 4 weeks, putting ny head and lounges into this cleen air and intensley look at teese huge mystical mountins in front of the wild North Sea.
so long.
Ian and Nelson, thanks a lot for your concerning answers to my questions.
Ian:
I have alredy build the SOZ, in the original design, and it playes butiful thou.
I just want to reorganise some of it, i underestimated the heatdissipation from the dioderectifiers. Besides from that, i am in the mood for som heat, it's ok.
So your good news to me is, that the use of resistors instead of currentsources wil leave me at least some benefits from the "crosscoupled error-corrections" (wow! I would love to have som of that) delivered by the "X"-circiut.
I am driving my SOZ with the Balanced Zen Linestage, so i get pretty good performance without a currentsource at the tail.
I am happy that you can confirm, that the X-thing works throu the mosfet Sources.
Once again Ian, thanks for your answer, but i can´t promise you not to dig a little more into the "magical X".
Nelson "The One and Only":
I just reread all the posts in this thread, and found, that you already had given some of the answers, but sometimes your writing is very compressed, so as a reader you have to stay close to every word of yours, and if you get it, it is very clearley spelled out. Besides from that i just read your wellwritten article on Su-Sy, wich gave me the kick to look deeper ito your patent, most intresting.
In your reply, you indicated, that in nonbal. mode i woudn´t achive much from the X-coupled circiut, but since i am drving the SOZ in bal. mode i schould get some or the most of the error-correction.
Never the less, i will try it out.
Accordingly to my simulation of the circiut with and without x-feedback, it seems as i will loose some gain. My Org. SOZ will go to full swing (13v) at 0,9v input and with the x-feedback it needs 1.8v, so i need to adjust my linestage to deliver this increesed gain. Then the question is, will the increesed gain in my linestage generate more noise and distortion than cancelled in the X-feedback?
Many people have told you, how kind you are revealing your knowlege in this forum, so that i will do once more. A big thank you.
When i have made the first test with this magical-X, i will come back, it will not be tomorrow, it takes time when you have to do things like staying alive without starving.
On mondy i will more tha stay alive, i am going on vacation to Nordkap in Norway for at least 4 weeks, putting ny head and lounges into this cleen air and intensley look at teese huge mystical mountins in front of the wild North Sea.
so long.
magical-X
Ian, i just unrestood your warning against looking too hard for the magical-X, of cource you are wright, the X just by accident became an ikon for the cross-feedback, the essence is to get the cross-feedback no matter how it looks.
So my reply to yo will be: I can´t promise you not to look deeper into te essence of cross-feedback. But since you didn´t warn me against this, there is no meaning in this answer. Sorry for my misunderstandig.
Any way thanks again.
Ian, i just unrestood your warning against looking too hard for the magical-X, of cource you are wright, the X just by accident became an ikon for the cross-feedback, the essence is to get the cross-feedback no matter how it looks.
So my reply to yo will be: I can´t promise you not to look deeper into te essence of cross-feedback. But since you didn´t warn me against this, there is no meaning in this answer. Sorry for my misunderstandig.
Any way thanks again.
You can get quite good performance from the X circuit
and a single-ended input, but the diff pair is constant
current sourced when you do.
With the feedback on SOZ, the gain will go down, but you
can short the Sources together to get the gain back up.
and a single-ended input, but the diff pair is constant
current sourced when you do.
With the feedback on SOZ, the gain will go down, but you
can short the Sources together to get the gain back up.
Shorting Sources
Henrik, glad to be of help. You may have noticed that in my earlier posting, I also shorted the Sources together for greater gain. This does of course result in an increase in common mode output noise but this is of little consequence in this application.
Nelson, I see you have hinted several times about the folded cascode X front end from the patent being a potentially interesting X-SOZ. I also see that nobdy has yet taken the bait, although presumably Stephano's circuit comes close. Does the master fancy dispensing a little more of his free advice to give us an inkling of why this approach might be better than the obvious one I already posted? Or is this perhaps the subject of a forthcoming article? I cannot fathom the advantage of the folded cascode in this application - it just seems to have additional overhead in terms of more current sources. Maybe it has something to do with the flexibility of DC biasing of the output?
Ian.
Henrik, glad to be of help. You may have noticed that in my earlier posting, I also shorted the Sources together for greater gain. This does of course result in an increase in common mode output noise but this is of little consequence in this application.
Nelson, I see you have hinted several times about the folded cascode X front end from the patent being a potentially interesting X-SOZ. I also see that nobdy has yet taken the bait, although presumably Stephano's circuit comes close. Does the master fancy dispensing a little more of his free advice to give us an inkling of why this approach might be better than the obvious one I already posted? Or is this perhaps the subject of a forthcoming article? I cannot fathom the advantage of the folded cascode in this application - it just seems to have additional overhead in terms of more current sources. Maybe it has something to do with the flexibility of DC biasing of the output?
Ian.
Well it does offer DC coupled rail-to-rail swing, and
the diff pair sees constant voltage, so you can get
less distortion, more bandwidth.
With the folded cascode there are some additional
efficiency losses, but Xing a diff pair is not particularly
efficient either.
I wouldn't want to spoil your fun with too much
advice 😉
the diff pair sees constant voltage, so you can get
less distortion, more bandwidth.
With the folded cascode there are some additional
efficiency losses, but Xing a diff pair is not particularly
efficient either.
I wouldn't want to spoil your fun with too much
advice 😉
WOW ! I will start following the SOZ concept that is for me the absence of active current sources.
I would like to build a front end like on patent . But ,
Not taking POWER output directly from the cascode device ( stephano-x-soz) will leave me the choice of :
Design the front end for lower power levels , that is to say 100 mA or so , and go on with a Power
Source follower/ common drain arrangement.
The Pass class A amp article give me inspiration.
Will this be two stage too?
Suggestions are welcome🙂
I would like to build a front end like on patent . But ,
Not taking POWER output directly from the cascode device ( stephano-x-soz) will leave me the choice of :
Design the front end for lower power levels , that is to say 100 mA or so , and go on with a Power
Source follower/ common drain arrangement.
The Pass class A amp article give me inspiration.
Will this be two stage too?
Suggestions are welcome🙂
Way to go!
Ste fa no!
So you agree that a true Zen doesn't have active current sources.
Despite Nelson steering us toward the active design, I am also really curious about the passive (?) approach. If you are changing your existing design, just change one channel so you can compare!! Or are you going to whip up a schematic first?
Are you and Henrik both doing this approach (with different designs?) or is there a difference?
Ste fa no!
So you agree that a true Zen doesn't have active current sources.
Despite Nelson steering us toward the active design, I am also really curious about the passive (?) approach. If you are changing your existing design, just change one channel so you can compare!! Or are you going to whip up a schematic first?
Are you and Henrik both doing this approach (with different designs?) or is there a difference?
Modfying SOZ to X-SOZ
I shouldn´t sit here doing this, but i am too exited to wait.
Nelson
Thanks for the tip on shorten the sources together. I can see in my simulatator, that it will give me allmost all gain back to normal, and with less noise than if i increesed the gain in my Balanced Zen Linestage by decreesing the resistor tying the sources together. And i promise you, never never in my hole life, to drive this thing from an unbalanced linelevel source!
Ian
I noticed that you had shortend the sources together in one of your previus posts, but i wasn´t shure if it had something to do with your draincurrentsources or not. Now when Nelson mentioned it, i gave it some thoughts and sims, an now i se things more clearly, i hope. Isn´t that great!
Variac
As i see Stefanos project, he will add 2 more mosfets than in the org. SOZ, i am only trying out a modification of a SOZ, that i allready have build, into a X-SOZ.
In the attached file you will se what i intend to doo, an if sombody should have any comments or suggestions, they are more than welcome.
I didn´t expect to get so close to the idear of an X-SOZ that quick, what i need now is to know if it performs better than te original SOZ.
I shouldn´t sit here doing this, but i am too exited to wait.
Nelson
Thanks for the tip on shorten the sources together. I can see in my simulatator, that it will give me allmost all gain back to normal, and with less noise than if i increesed the gain in my Balanced Zen Linestage by decreesing the resistor tying the sources together. And i promise you, never never in my hole life, to drive this thing from an unbalanced linelevel source!
Ian
I noticed that you had shortend the sources together in one of your previus posts, but i wasn´t shure if it had something to do with your draincurrentsources or not. Now when Nelson mentioned it, i gave it some thoughts and sims, an now i se things more clearly, i hope. Isn´t that great!
Variac
As i see Stefanos project, he will add 2 more mosfets than in the org. SOZ, i am only trying out a modification of a SOZ, that i allready have build, into a X-SOZ.
In the attached file you will se what i intend to doo, an if sombody should have any comments or suggestions, they are more than welcome.
I didn´t expect to get so close to the idear of an X-SOZ that quick, what i need now is to know if it performs better than te original SOZ.
