Lyrebird Recreation Project

I took a look at the schematic, but I'm having real trouble following it. It will benefit you greatly to use conventional symbols for op-amps etc., because otherwise there's a risk of errors. Also, it's not easy for users to follow so a review of the circuit is difficult.

Also, circuit conventions are needed, e.g. ground or 0V connections should be using the correct symbol, and going downward. On a huge circuit as you're creating, it's even more important.

I couldn't follow the above to comment one way or another. I took a look at the following part:

The above could be greatly simplified by replacing with a single amplifier chip. I can't see that it will work anyway. The top MOSFET appears to be permanently switched on (because the 'HIN' pin on the chip is connected to logic high, so the speaker will fry, or both MOSFETs. I'm guessing you were planning to use Q1 to provide an inverted and a non-inverted signal, but I still can't see how that would have worked. All this is solved by using any off-the-shelf amplifier chip.

it is still a work in progress, and yes Q1 is configured as an inverter, and those are the symbols that came provide by element14 website via the library loader.  And I use labels such as GND from ground/0V cause the symbol for ground is still broken in KiCAD, the one with the two zener diodes is actually a triangle wave oscillator for the class D amp, and the reason for not using an amp chip, is I have more freedom on the amp design this way.

I cannot tell what is incomplete and what is a mistake, so all I can do is identify and report anything I see that looks odd.

I'll wait until you're ready for a review, if you want it (but please use normal conventions, and change the symbols if you think it benefits the reader. If ground is broken in KiCad, please upgrade; I'm using KiCad 7 and I can draw ground symbols; if you cannot, then raise a bug on the KiCad GitLab page, otherwise no-one is going to fix it if it's just occurring for you if the developers have not realized). Anyway, it's good that you've published what you've got so far on GitHub so that people can scrutinize it.

You also need decoupling capacitors on every chip incidentally. Also, (you're going to hate me for mentioning it now, but at least it's now than later!), it would have been good to have your ground connections interspersed on the connectors, rather than at one end. Especially on the large ~80mm length connectors, it's a big return path for ground for each signal, unless you move the ground pins. It's a lot of effort to do it now but it's worth doing I reckon. Also, you could reduce the number of +15V and -15V and +30V pins to get some extra pins as ground.

You'll definitely need a review I think, because it is easy to miss stuff on such a large circuit, and it won't be pleasant to have to add 73 or 146 bodge wires etc. Mistakes are easily done. I still remember getting the pinout on a 0.4mm pitch 40-way connector wrong on a PCB, thinking the numbers were odd/even on opposite sides, simply because I didn't do a review. Every connection was wrong except pin 1, and it cost tons of effort to resolve.

One more point; not everyone can read KiCad files, so if or when you want more eyes to examine it, you'll need a high-res PNG/JPG or a PDF copy of the circuit and maybe also of the PCB layout, either at the GitHub link or uploaded here etc.

I cannot tell what is incomplete and what is a mistake, so all I can do is identify and report anything I see that looks odd.

I'll wait until you're ready for a review, if you want it (but please use normal conventions, and change the symbols if you think it benefits the reader. If ground is broken in KiCad, please upgrade; I'm using KiCad 7 and I can draw ground symbols; if you cannot, then raise a bug on the KiCad GitLab page, otherwise no-one is going to fix it if it's just occurring for you if the developers have not realized). Anyway, it's good that you've published what you've got so far on GitHub so that people can scrutinize it.

You also need decoupling capacitors on every chip incidentally. Also, (you're going to hate me for mentioning it now, but at least it's now than later!), it would have been good to have your ground connections interspersed on the connectors, rather than at one end. Especially on the large ~80mm length connectors, it's a big return path for ground for each signal, unless you move the ground pins. It's a lot of effort to do it now but it's worth doing I reckon. Also, you could reduce the number of +15V and -15V and +30V pins to get some extra pins as ground.

You'll definitely need a review I think, because it is easy to miss stuff on such a large circuit, and it won't be pleasant to have to add 73 or 146 bodge wires etc. Mistakes are easily done. I still remember getting the pinout on a 0.4mm pitch 40-way connector wrong on a PCB, thinking the numbers were odd/even on opposite sides, simply because I didn't do a review. Every connection was wrong except pin 1, and it cost tons of effort to resolve.

One more point; not everyone can read KiCad files, so if or when you want more eyes to examine it, you'll need a high-res PNG/JPG or a PDF copy of the circuit and maybe also of the PCB layout, either at the GitHub link or uploaded here etc.