Adding a compression indicator LED to an opto comp

[DC9V]

I've decided to build a Demeter Compulator clone for my next project, and I'd like to add a second LED indicator that will light up when the signal is effectively compressed.
The schematic made by Bajaman can be found here.
I understand the LED should be connected in parallel with the LED side of the optocoupler, but should I change anything else for the response of the compressor not to be affected by this mod?
Also, the LED would be connected to 1/2V. Is there a simple way to connect it to ground instead so I can use a single common cathode bicolor LED both for this function and as the on/bypass indicator?

[PRR]

> understand the LED should be connected in parallel with the LED side of the optocoupler

Poor. LEDs have a voltage threshold. Whichever LED has the lower voltage will light first and steal all the current.

Series ensures equal current, but you may not have enough room under a 9V supply. The LF353/TL074 has losses, the signal is symmetric, so you may have only 2.5V peak swing and it takes 3V to light two red LEDs.

Use another resistor. Duplicate the 619(??) ohm and LED with another R and LED. Actually make the visual LED's resistor smaller, like 330 ohms, because the opto-cell is more sensitive than the eye.

The V/2 buffer can stand eating this power LED's drain. Reduce the 10K to 5K (4.7K).

(??) Somebody had excess 619 ohm resistors. 620 ohms works exactly the same, and I bet 560, 680, or even 470 will work the same.

[DC9V]

Thanks a lot for your help. I really appreciate it.

So I should put a smaller resistor and the compression indicator LED in series with what's already there (the 619 ohm & LED side of the opto), right?
Sorry if I still sound confused , but I just want to make sure that I've got this right since I can't test it right away (haven't received the components yet). I think I understood the rest correctly, though .

The reason why I thought the LED had to be connected in parallel is that I saw a schematic for another opto compressor where this was the case, also I read this on the "other" forum:

The LED is connected to the out of the op-amp that controls the photocoupler. It is not in the signal path. The power splitter should be stable enough to drive an extra led without any problem. I used a low-current led though, it probably helped.