Hi Struth,
I still have difficulty understanding what you mean. Could you draw an example of a topology you don't like?
If you mean that in general, one needs to consider common-mode stability in differential circuits, that one sometimes has to add common-mode loops to get defined common-mode levels and that if the input signal happens to be perfectly balanced, you can avoid these complications by using two identical (ground-referred) amplifiers driven in antiphase, then I agree entirely.
How much these things complicate the design is really very dependent on the circumstances. For example, in the attachment AMP.pdf all I needed to do to ensure common-mode stability was to add the 1 nF capacitor in the bottom middle. (By the way, this is indeed a high-gain circuit.) In the balanced to unbalanced and vice-versa converter of schema.pdf I needed to add two common-mode loops together comprising four transistors (Q7, Q8, Q11 and Q12), a bunch of resistors and a capacitor just to get defined common-mode bias points.
Best regards,
Marcel
I still have difficulty understanding what you mean. Could you draw an example of a topology you don't like?
If you mean that in general, one needs to consider common-mode stability in differential circuits, that one sometimes has to add common-mode loops to get defined common-mode levels and that if the input signal happens to be perfectly balanced, you can avoid these complications by using two identical (ground-referred) amplifiers driven in antiphase, then I agree entirely.
How much these things complicate the design is really very dependent on the circumstances. For example, in the attachment AMP.pdf all I needed to do to ensure common-mode stability was to add the 1 nF capacitor in the bottom middle. (By the way, this is indeed a high-gain circuit.) In the balanced to unbalanced and vice-versa converter of schema.pdf I needed to add two common-mode loops together comprising four transistors (Q7, Q8, Q11 and Q12), a bunch of resistors and a capacitor just to get defined common-mode bias points.
Best regards,
Marcel
If I remember correctly the Pathos is a hybrid single-ended amplifier tube-mosfet with source's output is loaded with an inductor.
In fact it is precisely the use of this choke the much-vaunted technology "INPOL". A renewed scientific worthy of being patented !!!!
Now it is born "INPOWER", that is, two single ended circuits connected in bridge and driven by two balanced signals (that is in phase opposition).
I do not doubt that it will sound good, but I doubt that it can counted among the differential circuits.
Otherwise all bridge circuits could be defined differentials.
Unfortunately these clarifications should be made to define exactly what types are true differential, and then check if it is not worth it to be used in audio field. If in doubt, some simulation should be done.
Technical-brain is brilliant, two separate circuits inside one circuit, balanced differential circuit with the bridging placed at a very late symmetric place in the circuit, if build as the schematic extreme matching is needed, no emitter resistors must give a very fuzzy circuit right on the edge
Hi Guys
Marcel - your circuits are very interesting. The ESL driver could have been simplified somewhat inasmuch as it could have been done as separate amps, one with gain, the other inverting unity. That's how I did mine. But there are lots of interesting approaches.
The solid-state is just a preamp? Should likely have buffering on each output if you want to drive any kind of a load.
Technical brain may be brilliant but what are its specs? Lots of novel mediocre stuff...
Have fun
Marcel - your circuits are very interesting. The ESL driver could have been simplified somewhat inasmuch as it could have been done as separate amps, one with gain, the other inverting unity. That's how I did mine. But there are lots of interesting approaches.
The solid-state is just a preamp? Should likely have buffering on each output if you want to drive any kind of a load.
Technical brain may be brilliant but what are its specs? Lots of novel mediocre stuff...
Have fun
My high-voltage amplifier sounded quite nice, but was only useable for soft background music. Its maximum output voltage was really too small for for my colleague's home-made loudspeakers. How did you make the high-voltage supply?
The solid-state circuit is a cheap alternative for a line level signal transformer. Due to the indirect voltage feedback and the deliberately slow and weak common-mode loop at the output, its output stage acts more or less as a floating voltage source. In theory, it can deliver 10 mA peak output current, which is more than enough for a 10 kohm single-ended or differential input. It is indeed a bit on the low side for 600 ohm loads or for very long cables.
The solid-state circuit is a cheap alternative for a line level signal transformer. Due to the indirect voltage feedback and the deliberately slow and weak common-mode loop at the output, its output stage acts more or less as a floating voltage source. In theory, it can deliver 10 mA peak output current, which is more than enough for a 10 kohm single-ended or differential input. It is indeed a bit on the low side for 600 ohm loads or for very long cables.
Hi Guys
Marcel - the ESL circuit you posted can have its output increased in many ways. The main issue, though, is that the output impedance is too high and asymmetric. This is a flaw in most such drivers, even for ES head phones.
Have fun
Marcel - the ESL circuit you posted can have its output increased in many ways. The main issue, though, is that the output impedance is too high and asymmetric. This is a flaw in most such drivers, even for ES head phones.
Have fun
Struth, please do your duedilligence before you label technicalbrain mediocre... Have you ever heard them..??
Hi Guys
MiiB - I did not say the technical brain is no good, simply that we have no way to tell without seeing its specs. A schematic cannot tell you if the amp is any good at all, only if it is interesting. If you have specs please share them.
Have
MiiB - I did not say the technical brain is no good, simply that we have no way to tell without seeing its specs. A schematic cannot tell you if the amp is any good at all, only if it is interesting. If you have specs please share them.
Have
From my diy experience, the bridged output stage is better sounding than traditional output, supposed that both have similar specs.
Not all listenable features are reflected among specs. In case of bridged output stage, the same PS rails are used for both bridge components, and, since any signal-induced variation of current consumption by one half of bridge is accompanied by opposite current consumption variationof the other half, output signal current does not pass through the PS circuitry. This produces a lot of positive for sound consequences.
The impedance is kept small by the shunt feedback. The positive peaks of the output voltage are limited, though, by both the supply voltage and the voltage drop across the anode resistors. That's why there is only 2 kV peak differential voltage coming out at 2660 V supply. I could win a dB or two with an SRPP-like output stage or any other stage that can get closer to the positive supply rail.
Still, I would be interested to know what kind of supply voltage you used and how you made it.
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