doest it matter if Wuyit accepts it....To me I'am just as happy regardless.....🙂
Though this is the very point of the shunt like operation of the circuits you bring forward..
Though this is the very point of the shunt like operation of the circuits you bring forward..
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this was the big surprise for me, I thought the constant current arrangement was an obvious choice for a long time now, I remember seeing it on the net early in my DIY wanderings - I never realized 'til you said it and thought about it that it is in fact uncommon. Strange....
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Vladimir,
the DC current through both speakers in #119 is given by I = Vspeaker / Rspeaker. Since DC current through speakers is to be avoided, what is the point? When it is zero, the DC current through the amplifying device and the CCS will be the same in both cases, constituting a limit for the maximum AC current that can be produced. (In Fig. A, a varying DC current through the speaker would mean a varying DC current through the amplifying device as well).
the DC current through both speakers in #119 is given by I = Vspeaker / Rspeaker. Since DC current through speakers is to be avoided, what is the point? When it is zero, the DC current through the amplifying device and the CCS will be the same in both cases, constituting a limit for the maximum AC current that can be produced. (In Fig. A, a varying DC current through the speaker would mean a varying DC current through the amplifying device as well).
buzzforb,
You are is correct, due to the single-ended topology and the high (DC) quiescent current. It´s pretty meaningless to build an amp like this with poor quality power supply.
The diagrams in #119 are "block"-diagrams, consider instantaneous currents under AC signal, and look at instantaneous currents at the point where
active device
CCS
Load
are connected.
In the traditional approach: I (active device) = I (from power supply) = Iccs+I (load)
In the shunt approach: I (active device) + I (load) = Iccs = I (from the power supply), i.e. currents through active device and load are always sum-up to form the same constant = Iccs
I am viewing it as if it were a shunt regulator. This seems to be the main principle behind the design. Like the shunt regulator, it is very pure, but very inefficient. Walt Jung, has some nice articles on shunts that were helpful.
My main finding, after assembling and listening to dozens of prototypes and finished devices, is that the shunt-like concept, and constant total current concept for a given stage under ac signal (like diff pair) are the most basic grounds for good sound.
All THD simulations have nothing to do with good sound, also tested various low-THD schematics, that always suffer from "dull" sound of PS electrolytics, that sit in the signal chain. Snubber caps help a bit to improve the sound, but only partially. I tested from o,o1uF till 100uF. Radical solution provides only the shunt concept.
All THD simulations have nothing to do with good sound, also tested various low-THD schematics, that always suffer from "dull" sound of PS electrolytics, that sit in the signal chain. Snubber caps help a bit to improve the sound, but only partially. I tested from o,o1uF till 100uF. Radical solution provides only the shunt concept.
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Yes, a constant current draw from the power supply does have its advantages. For example it doesn't have to be a terribly low impedance supply, nor does it have to be particularly "fast." It simply has to supply the appropriate voltage and current.
se
se
My only issue is the live 32-volt speaker connection, which I would never run in anything other than a self-contained amp-speaker unit. This is easily solved by going p-channel and running the circuit "inverted", or running the supply 0-(-32) and adding appropriate mods. (double insulated is OK too I guess, not sure). I'd take any hints/knowledge/advice, in this regard.
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i didn't notice the floating nature of the whole circuit until after I posted, it appears its natural state relative to the signal of the input connection is 0-(-32). ug, should probably more thoroughly consider this in the morning.
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Vladimir....
Take the design a step further an have two active devices running in opposite phase...with the load suspended in between...thus removing the need for the coupling cap....
I know i have brought this forward once before and that it will make matters at bit more complex, as you'll need someway to balance the drive...But my gut feel is that you'll then create something really spectacular...
Take the design a step further an have two active devices running in opposite phase...with the load suspended in between...thus removing the need for the coupling cap....
I know i have brought this forward once before and that it will make matters at bit more complex, as you'll need someway to balance the drive...But my gut feel is that you'll then create something really spectacular...
I did like you are saying many times, and came to traditionally "dull" sound, as I mentioned in #129.
No output cap - it is a tricky trap, which most of DIYers and experienced designers fall to.
The EMI issues, related to pulsed currents, and electrolytics issues, lead always to the same "medium" sound impressions, irrespective of how linear and symmetric the schematics is.
As a real breakthrough, I would propose to use very good integrated class A amp with buffer-like output stage, and to provide an output from its preamp, and to use classe D power amp (with unity amplification) being connected to the preamp output.
I roughly tested this idea, and this really promises something (class D is unbeatable for the bass duty).
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yes, that is indeed the "next" stage. Pass has a few like this and Euvl F5x is also of this type. Fully balanced ClassA designs that draw constant current from the supplies.
I am also supporter of the balanced approach, but, nevetheless, I guess the bi-amped approach, with corresponding speakers equipped with fourth-order crossover and separate connection posts for every frequency band, will win.
The reason is that 100W amp will never win over dedicated 10W amp (all other being close) in transparency and sound immediacy. Better to take the best from different worlds (class A and class D), and sum up their benefits.
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Vladimirk,
I recently purchased some SS RO85 Jfets to try in various Pass designs, including the F3. although they have more input capacitance than these Jfets, It is not high at 250+pF. You menntioned in your earlier statements, that Ciss was of major importance to this design. What is the cutoff point for what you would consider a good candidate? Are there other ways to deal with Ciss, like bootsrapping. There are many RF jfets available stateside, but noise seems to be the major hindrance in most parts.
I recently purchased some SS RO85 Jfets to try in various Pass designs, including the F3. although they have more input capacitance than these Jfets, It is not high at 250+pF. You menntioned in your earlier statements, that Ciss was of major importance to this design. What is the cutoff point for what you would consider a good candidate? Are there other ways to deal with Ciss, like bootsrapping. There are many RF jfets available stateside, but noise seems to be the major hindrance in most parts.
But this here should not be any traditional push-pull design.. but merely a balanced or bridged version of your concept..not referenced to GND-..but with the speaker load floating between two of your shunts..then you still don't see any dull supply caps because you're dealing with two local current loops controlled by your power like J-fet
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