"Enhancer" project

Hideki said:

This looks better. The high pass filters are still wrong. Swap + and - on the opamps.
You specify the value of the resistors, so why not do the same for the pots?

In your high shelf EQ, 10 uF and 6.8k will give you a cutoff of about 2.3 Hz. Try something like 1.5 nF instead. That gives you 15.6 kHz, and with a 100k pot you can turn it down to 1 kHz. Now, that's only the cutoff frequency of the filter. How you want to specify the frequency of the shelf is not as well defined, so it's up to you.

Either add a capacitor to the hot output or remove the one on the cold. The idea is to keep it impedance balanced, which means using the same impedance for both of them.

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Thanks for the very detailed pointers, Hideki! Makes the learning process so much easier.

I've flipped the sallen and key highpass filters now, funny thing is that if you look at the first post in this thread, I think the original schematic of the harmonic saturator has them the wrong way around. So that got me a bit confused.

The pot values were there in iCircuit, but for some reason they would not show when exporting (I've added them now manually).

I changed the capacitor at the EQ stage to meet with the requirements + added a cap at the output to keep the impedance balanced.

Does it look like I could start building it ?

Kokoroko said:

I've flipped the sallen and key highpass filters now, funny thing is that if you look at the first post in this thread, I think the original schematic of the harmonic saturator has them the wrong way around. So that got me a bit confused.

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Yes, the original is wrong

Does it look like I could start building it ?

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I believe so. It's not the most awesome design I have ever seen, but as drawn right now, it should work the way you want it.

Hideki said:

Yes, the original is wrong
I believe so. It's not the most awesome design I have ever seen, but as drawn right now, it should work the way you want it.

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Thanks! Not going for "awesome" with this anyway. More aiming towards "okay" or maybe "yup works"

I made an effort to create a pcb design in eagle for it, would any EAGLE pros be willing to give the files a look?
I have not used EAGLE before, so go easy on me

JPGs for mobile viewers --->

  You've got to be able to do better than that for your PCB layout, pro tip, don't use either  autoroute nor autoplace, with good placement you should get away with few long traces, nothing buckling around several components to get where it want's to.

  The autoroute might be ok for some very specific tasks where the software, well configured, does it similar to what you'd do or just good enough for something you don't care at all. Draw the schematic and let the software design a PCB for you is not even an option. A good PCB layout can take hours and it can totally worth it, in audio particularly, layout is where you squeeze the last few dB of X-talk, noise or THD.

JS

Kokoroko said:

I have not used EAGLE before, so go easy on me

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The problem isn't that you're not familiar with Eagle, but that you're clearly not familiar with PCB layout at all. This is a completely hilarious result. It doesn't really make me laugh, since I have seen this kind of nonsense so many times before.

The real problem here is placement. You seem to have lined up the components in neat rows with absolutely no thought of how they are connected. Proper placement makes routing so much easier. In some cases absolutely trivial once the components are put in the right place.

Beginners should never use autorouters. Even experienced designers will avoid them almost 100% of the time. Especially the one in Eagle, which is NOT very good.

The Hot and Cold inputs use the same net name (it probably got copied by accident) so they have all been connected together on the PCB. To fix that, rename the signals in the schematic.
The Hot, Cold and Ground connection of the output also use the same net name. Same problem there.

If you still insist on using the autorouter and the mess that it makes, you will have to fix any remaining airwires once it's done. In the file you posted they were all ground connections to isolated ground islands not connected to the rest of the ground plane.  It should be possible to fix it if you move some bottom traces and add one or more on the top layer. Or tweak some setting and hope the autorouter does a better job the next time.

The power and signal connections have 0.7 mm holes. It's going to be hard to fit any decent diameter wire in there.