Thanks Nico. I agree completely that the amp as simple as it is performs quite well, especially in speed and stability domain. For the DIY-ers the most important thing is to get a stable amp in any conditions and if there is a nice sound too, even better.
Also we could easily radically improve the schematic to more complex one but the question is where to stop. If there is possibility to make some little improvements to sch, it is reasonable to do so, otherwise it is better to leave it like it is.
Maybe the use of IRF610/9610 as drivers to power BJT outputs would give much better results (higher transconductance), since this would not complicate the sch to much?
Also we could easily radically improve the schematic to more complex one but the question is where to stop. If there is possibility to make some little improvements to sch, it is reasonable to do so, otherwise it is better to leave it like it is.
Maybe the use of IRF610/9610 as drivers to power BJT outputs would give much better results (higher transconductance), since this would not complicate the sch to much?
Good, will check the sound with new feedback loop resistors values.
Yes good observation Nico, actually they are 1uF ML bypass caps, as I do it automatically every time. PCB should have them cause they take little space (5mm pins distance).
Thanks again Nico, I said to myself why not to share it, so lets just fine tune the circuit-values for DIY-ers.
Can you make sim as proposed, turning the output mosfets to IGBT's?
Yes I can. Which ones did you have in mind?
I found it a little bit strange.... my simulation show it becomes very unstable
if you try to overdrive...needs huge current in stand by mode to operate fine...... distortion was big in my simulations 0.026% THD....maybe i have made something wrong.
Interesting circuit....maybe some tweaks...i will wait you tweak it for tuning.
regards,
Carlos
if you try to overdrive...needs huge current in stand by mode to operate fine...... distortion was big in my simulations 0.026% THD....maybe i have made something wrong.
Interesting circuit....maybe some tweaks...i will wait you tweak it for tuning.
regards,
Carlos
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Something like that for the outputs, as these were inside my test configuration
Would it give any better THD results?
Before that change, please check the results if adding one BC550c to 1k bias trimmer forming thermally adjusted zener to give proper stabilisation to the quiescent current of the input pair. Should do some improvement with only one BJT added, so not a big change.
Would it give any better THD results?
Before that change, please check the results if adding one BC550c to 1k bias trimmer forming thermally adjusted zener to give proper stabilisation to the quiescent current of the input pair. Should do some improvement with only one BJT added, so not a big change.
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No, no, don't worry it will stay simple as possible. We just have to investigate the idea which will give better results, than we will return to a basic sch and give just a little push in that direction. It must stay simple as it was intended to be. BTW thanks for your interest Carlos.
Something is wrong with your sim model or so, because in practice tests I couldn't make it oscilate in any load circumstances. Very stable design, only we have to lower THD a little bit.
Using two series connected diodes instead offers best results. I used 1N4004. Lazy Cat, you want to actually make an IGBT? In my humble opinion, I don't think that making it that complex is worth the effort. You have a good amp here it will satisfy most.
Calos, I think there may be a problem in your diagram. I have not checked the re-captured diagram but I work from Lazy Cat's pencil drawing, re-capturing schematics easily produce errors. This amp overdrives cleanly and symmetrically, I cannot find any fault with Lazy Cats design besides it not using 100 transistors and does not have fractions of a percent distortion.
One must keep in mind, harmonic distortion is not the be-all and end-all of amplifiers. The fact that there is almost zero phase shift over the entire audio band, in fact way up to 100 kHz will make this amp sound pretty realistic regardless of the relatively high odd order artifacts which only alters the character to the extent of maybe sounding a little clinical.
Unless you are a person with perfect pitch (only a small fraction of the world population has) you will find little to complain about. I have not built it yet (and intend to in the next few days) but I can read the merits of well engineered stable amplifier regardless of simplicity.
I think this is a relatively inexpensive amp that will satisfy the tastes of many listeners, a perfect group-build project and I am not shy to say I support this design wholeheartedly. For many it may just be "The Best Amplifier They Ever Heard" regardles of a few very minor short comings.
Nico
Calos, I think there may be a problem in your diagram. I have not checked the re-captured diagram but I work from Lazy Cat's pencil drawing, re-capturing schematics easily produce errors. This amp overdrives cleanly and symmetrically, I cannot find any fault with Lazy Cats design besides it not using 100 transistors and does not have fractions of a percent distortion.
One must keep in mind, harmonic distortion is not the be-all and end-all of amplifiers. The fact that there is almost zero phase shift over the entire audio band, in fact way up to 100 kHz will make this amp sound pretty realistic regardless of the relatively high odd order artifacts which only alters the character to the extent of maybe sounding a little clinical.
Unless you are a person with perfect pitch (only a small fraction of the world population has) you will find little to complain about. I have not built it yet (and intend to in the next few days) but I can read the merits of well engineered stable amplifier regardless of simplicity.
I think this is a relatively inexpensive amp that will satisfy the tastes of many listeners, a perfect group-build project and I am not shy to say I support this design wholeheartedly. For many it may just be "The Best Amplifier They Ever Heard" regardles of a few very minor short comings.
Nico
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IGBT's from Toshiba GT20D101/201 are non complex change if they would make a justified improvement.
Yes... distortion is not that important...but for me it became important
because i love people to build my amplifiers... so, i use ideas from others too as i have not born knowing audio electronics..i have learned from others...i do think everybody is this way.
I do have noticed that people trust in THD...when levels are high they do not have interest to build our stuff.... so...i am always searching for circuits and interesting ideas but they must present nice numbers...as i will use this as a lever to produce advertisement and some guys will build my stuff.
My personnal beliefs that distortion does not matter is something people does not accept, or distrust, or prefere to build something that is published with a lot of zeroes in the left...these 0.0009 % THD or even less...they think this is good....so.... they trust...and this is what i need..their confidence to try my amplifiers.
They are other guy's ideas tuned (my amplifiers)....as i have not invented Class A , Class AB, or invented amplifiers nor transistors.... all i know was Klipsch, Self, Slone, Sinclair, Brice, Duncan ,Singmin, Davis, Patronis, Watkinson, Hugh Dean, Karris, Cordell, Pass and many others that helped me a lot and are sources of important information.
So...if distortion is higher than 0.009 % THD... then do not interest me anymore...as i will not succeed to tune it to my own ideas about sonics and to offer it built, tested and tuned..dedicated to DIY community, for them to build... i do think they will not be interested.
I will look forward to see this amplifier progress....maybe i will build to listen it in the future... if not too much complicated.
Carlos
because i love people to build my amplifiers... so, i use ideas from others too as i have not born knowing audio electronics..i have learned from others...i do think everybody is this way.
I do have noticed that people trust in THD...when levels are high they do not have interest to build our stuff.... so...i am always searching for circuits and interesting ideas but they must present nice numbers...as i will use this as a lever to produce advertisement and some guys will build my stuff.
My personnal beliefs that distortion does not matter is something people does not accept, or distrust, or prefere to build something that is published with a lot of zeroes in the left...these 0.0009 % THD or even less...they think this is good....so.... they trust...and this is what i need..their confidence to try my amplifiers.
They are other guy's ideas tuned (my amplifiers)....as i have not invented Class A , Class AB, or invented amplifiers nor transistors.... all i know was Klipsch, Self, Slone, Sinclair, Brice, Duncan ,Singmin, Davis, Patronis, Watkinson, Hugh Dean, Karris, Cordell, Pass and many others that helped me a lot and are sources of important information.
So...if distortion is higher than 0.009 % THD... then do not interest me anymore...as i will not succeed to tune it to my own ideas about sonics and to offer it built, tested and tuned..dedicated to DIY community, for them to build... i do think they will not be interested.
I will look forward to see this amplifier progress....maybe i will build to listen it in the future... if not too much complicated.
Carlos
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