I’ll add that the polarity of C2 is reversed.
Also, it’s a bad idea to use the same bias circuit for the long-tailed pair current source and the Vas load current source. When driven into negative clipping it will latch up.

 

If this horse isn't all dead, then it is certainly mostly dead.

 

R2 is connected to GND, and the diode string and the two current source emitters are connected to -30 V.

Missed that.

 

Missed that.

My work is done.

ak

 

Without looking too close at it... Q8 has the collector and emitter reversed. Q4/Q5 form a cascode pair - this is usually done to reduce miler capacitance and improve high frequency response. Q2 base (without the resistor to ground) would the the 'opamp' non-inverting input.

 

Please edit the Wiki page I linked.

ak

There is nothing wrong with the Wikipedia page. It correctly says that the cascode configuration eliminates the Miller effect.
However, a three-stage amplifier can have a total phase shift of 270°, so it will require dominant pole compensation to keep it stable. Dominant pole compensation is generally achieved by placing a capacitor between base and collector of the voltage amplifier transistor, so it adds to the base-collector "Miller" capacitance of that device, and therefore is commonly called "Miller" compensation.
Eliminate the Miller effect from the VAS, and the amplifier still requires dominant-pole compensation. In fact it requires more compensation as some would be provided by the Miller effect of the VAS transistor.
The dominant pole compensation capacitor therefore needs to be placed between the base of the lower transistor and the collector of the upper for it to have the appropriate effect.
There may be applications where a decompensated op-amp can be used, and in that case the circuit can be used without the dominant-pole "Miller" capacitor.

 

There may be applications where a decompensated op-amp can be used,

Possibly at higher closed loop gains where the phase-margin is adequate.

 

Possibly at higher closed loop gains where the phase-margin is adequate.

RIAA-weighted responses came to mind.

 

OK, so the thing may be an amplifier, but with only one input connection available it is not similar to any OP-Amp that I have seen before.
In addition, the open-loop gain of most opamps is quite a bit greater than ten. So as circuits go, this one does not come across as an example of best choices.
And closing the loop on a low gain amplifier is not likely to improve much at all.

 

OK, so the thing may be an amplifier, but with only one input connection available it is not similar to any OP-Amp that I have seen before.
In addition, the open-loop gain of most opamps is quite a bit greater than ten. So as circuits go, this one does not come across as an example of best choices.

The closed loop gain is 10, obtained by the external feedback resistors R11 and R12.
There are two inputs available, one is grounded in a standard inverting amplifier configuration.