This should be simple, but it ain't...

[aron]

Has that vero board layout been verified? I wonder if there are mistakes there?

[aron]

Hmmm if you look at the schematic, it does look like all it is doing is cutting the signal. There's no "gain" in any of the op amp stages (that I see). Please correct me if I'm wrong.

It looks like a lot of buffering and filtering. If I had to guess how to "fix it", I would add gain to the last op amp stages before the 20K linear pot.

[aro]

According to the author of the schematic the vero board layout is correct. I don't know more than that...

My rough understanding is that the purpose of this is to attain a -30dB around 7-8 kHz and a +??dB (not sure how many) around 2-3 kHz. The samples I heard show a definite difference in tone.

[aron]

OK, but assuming that you put everything together correctly, you can bring the level up on the last stages to bring back up what you may have lost.

[aro]

you can bring the level up on the last stages to bring back up what you may have lost.

Can I...??

What I'm saying is that I would like to do that but I wouldn't know how. 

Well, it seems I got it to work  I just figured out there was one more trace to cut. Once I did that the whole thing seems to do the job. The volume is a little bit lower when going through it, but not as much as before. The main thing is that there is a difference in the "fizzy" sound.

The more gain I use, the more noticeable the difference with the device turned on. I guess I did it... I was kinda expecting a more spectacular difference, but that's probably it. I listened to the samples again and I what I hear there is pretty much what I get. My wife and my cat protested a lot so I couldn't do a full blown test, but it seems to work. Too bad there is that volume difference, but it's not that much.

I don't know if I should pat myself on the back or be slightly disappointed with the results. Or maybe I still didn't do it right all the way...