Dear Christer:
>The basic idea is to introduce complementary dummy circuitry to make the supply-current demand constant.<
OK, here is the Tomita RIAA circuit that I mentioned previously, which I think fits your description to a T. This being the case, I doubt the need for myself to explain how the circuit works. But I do believe that you will quickly come to the conclusion that, as far as the power supplies are concerned, the operating principles of this circuit are very similar to those of a folded cascode (but not where the amplification function is concerned).
The pass-element of the regulator is currently just a simple open-loop follower, but this could be much more elaborate, if you so choose. Personally I would be interested in feeding an opamp circuit from this type of arrangement (making the complementary negative regulator would be required).
The core amplifier circuit is ultra-simple, so it may be educational to build it in three different flavors - 1: Normal resistive loading, no local regulation. 2: The circuit as I have drawn it, with local regulation. 3: Folded-cascode, with constant-current sources. My guess is that flavors 2 & 3 will sound moderately similar to each other, with flavor 1 being the odd man out.
best, jonathan carr
>The basic idea is to introduce complementary dummy circuitry to make the supply-current demand constant.<
OK, here is the Tomita RIAA circuit that I mentioned previously, which I think fits your description to a T. This being the case, I doubt the need for myself to explain how the circuit works. But I do believe that you will quickly come to the conclusion that, as far as the power supplies are concerned, the operating principles of this circuit are very similar to those of a folded cascode (but not where the amplification function is concerned).
The pass-element of the regulator is currently just a simple open-loop follower, but this could be much more elaborate, if you so choose. Personally I would be interested in feeding an opamp circuit from this type of arrangement (making the complementary negative regulator would be required).
The core amplifier circuit is ultra-simple, so it may be educational to build it in three different flavors - 1: Normal resistive loading, no local regulation. 2: The circuit as I have drawn it, with local regulation. 3: Folded-cascode, with constant-current sources. My guess is that flavors 2 & 3 will sound moderately similar to each other, with flavor 1 being the odd man out.
best, jonathan carr
Jonathan,
thanks for posting the Tomita schematic. Although not exactly
what I meant, it certainly achieves the same effect and that in
a more general way. I actually only had in mind those cases
where it is possible to do exact cloning of subcircuits, which
would typically require access to both inverted and non-inverted
signals. The Tomita method is closer to what you described
earlier in the thread and is probably a better choice in most
cases, since it should be almost generally applicable. Whichever
way it is done, it makes a lot of sense to do this, since we get
a circuit that looks like a constant current sink to the regulator.
All circuits designed in this way should be able to share a
common regulator (or pair of regulators) with minimal or no
mutual interference. Just as you say, it seems also reasonable
to try this method with open-loop follower regulators or other
straightforward simple regulators.
------------
Werner,
your circuit is also interesting, and a little bit closer to what I
had in mind, since you use the inverted signal to feed a dummy
circuit. However, since the signal levels differ and the dummy is
not a true clone of the active circuit, it is yet a variant on the
constant-current idea. In your case, I would expect there to
be some problems to match up the JFETs and the Q points so
the two circuits show a true complementary supply draw. How
well have you managed to achieve this in practice?
--------------
I think the common philosphy behind all these slightly different
approaches could be expressed as: "Instead of designing a
super-regulator that can tame any load, make the load itself
be well-behaved and nice to the regulator."
thanks for posting the Tomita schematic. Although not exactly
what I meant, it certainly achieves the same effect and that in
a more general way. I actually only had in mind those cases
where it is possible to do exact cloning of subcircuits, which
would typically require access to both inverted and non-inverted
signals. The Tomita method is closer to what you described
earlier in the thread and is probably a better choice in most
cases, since it should be almost generally applicable. Whichever
way it is done, it makes a lot of sense to do this, since we get
a circuit that looks like a constant current sink to the regulator.
All circuits designed in this way should be able to share a
common regulator (or pair of regulators) with minimal or no
mutual interference. Just as you say, it seems also reasonable
to try this method with open-loop follower regulators or other
straightforward simple regulators.
------------
Werner,
your circuit is also interesting, and a little bit closer to what I
had in mind, since you use the inverted signal to feed a dummy
circuit. However, since the signal levels differ and the dummy is
not a true clone of the active circuit, it is yet a variant on the
constant-current idea. In your case, I would expect there to
be some problems to match up the JFETs and the Q points so
the two circuits show a true complementary supply draw. How
well have you managed to achieve this in practice?
--------------
I think the common philosphy behind all these slightly different
approaches could be expressed as: "Instead of designing a
super-regulator that can tame any load, make the load itself
be well-behaved and nice to the regulator."
Tomita RIAA circuit
This is kind of a convoluted circuit whose main virture could be acomplished with considerably more ease by an inverted cascode circuit. The collector load resistors would be referenced to ground with the inverted cascode topology. The signal currents then return to ground which is the lowest noise and lowest impedance power supply connection you can get. The basic topology of the Tomita is very close to an inverted cascode as it is other than the addition emitter followers for the supply regulators for collector resistors R1 and R6. Q2 and q5 act as regulators and do not have a constant current load. Q3 and Q6 act in a manner very simular to a shunt regulator.
The constant load on the supply is one of major advantages of both inverted cascode and balanced circuits. A balanced circuit has the antiphase current circuit built in, and it is the same circuit as the first half of the circuit, for excellent matching with the other half.
This is kind of a convoluted circuit whose main virture could be acomplished with considerably more ease by an inverted cascode circuit. The collector load resistors would be referenced to ground with the inverted cascode topology. The signal currents then return to ground which is the lowest noise and lowest impedance power supply connection you can get. The basic topology of the Tomita is very close to an inverted cascode as it is other than the addition emitter followers for the supply regulators for collector resistors R1 and R6. Q2 and q5 act as regulators and do not have a constant current load. Q3 and Q6 act in a manner very simular to a shunt regulator.
The constant load on the supply is one of major advantages of both inverted cascode and balanced circuits. A balanced circuit has the antiphase current circuit built in, and it is the same circuit as the first half of the circuit, for excellent matching with the other half.
Re: Tomita RIAA...
Hi Tube_dude,
Yeah, that must be noisy as hell.
But how does it sound is the 100000$ question.
Emittor feedback or feedback to the emittor of the first transistor, it sounds oldfashioned to me, but who knows...
The proof is in the pudding. In order to know how it sounds I have to build it.
Tube_Dude said:For a phono preamp so many undecoupled zeners references(the zener is one of the best generator of white noise) and active RIAA
equalization...
Hi Tube_dude,
Yeah, that must be noisy as hell.
But how does it sound is the 100000$ question.
Emittor feedback or feedback to the emittor of the first transistor, it sounds oldfashioned to me, but who knows...
The proof is in the pudding. In order to know how it sounds I have to build it.
>so many undecoupled zeners references<
Guys, when I post a schematic, I post first and foremost for conceptual simplicity and clarity. I encourage you to modify the details in any manner that you see fit - especially when it is something exceedingly rudimentary.
>active RIAA equalization<
The RIAA network used is very similar to the Kaneda phono stages, which have been well-regarded in both Europe as well as Japan for the past 30 years. As an approach, I feel that active RIAA has its strong points and weak points, just like passive RIAA.
Besides, at the end of the day a builder of audio equipment is judged ultimately by the quality of results that he can deliver. Whatever components, design approaches or fancy concepts that you choose to use are merely a means to an end, not the end unto itself.
What I find interesting about the circuit that I posted is that the quality of the components in the power supply appear to exert a noticeably smaller effect on the sonics than normal. The typical sonic differences between boutique power supply capacitors and industrial-grade capacitors seem to be reduced here. So I do encourage you to simulate, modify, build and listen.
regards, jonathan carr
Guys, when I post a schematic, I post first and foremost for conceptual simplicity and clarity. I encourage you to modify the details in any manner that you see fit - especially when it is something exceedingly rudimentary.
>active RIAA equalization<
The RIAA network used is very similar to the Kaneda phono stages, which have been well-regarded in both Europe as well as Japan for the past 30 years. As an approach, I feel that active RIAA has its strong points and weak points, just like passive RIAA.
Besides, at the end of the day a builder of audio equipment is judged ultimately by the quality of results that he can deliver. Whatever components, design approaches or fancy concepts that you choose to use are merely a means to an end, not the end unto itself.
What I find interesting about the circuit that I posted is that the quality of the components in the power supply appear to exert a noticeably smaller effect on the sonics than normal. The typical sonic differences between boutique power supply capacitors and industrial-grade capacitors seem to be reduced here. So I do encourage you to simulate, modify, build and listen.
regards, jonathan carr
Tomita
Of course!...thanks for charing !
I realy apreciate your fair play...is normal here when a person post a schematic and other people make any remark (after all is for discuting audio that we are all here) the reaction is not so elevated as yours! They find it as a personal attack!
You are a exception !
Regards
Of course!...thanks for charing !
I realy apreciate your fair play...is normal here when a person post a schematic and other people make any remark (after all is for discuting audio that we are all here) the reaction is not so elevated as yours! They find it as a personal attack!
You are a exception !
Regards
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