<Debug> JHS TwinTwelve buzz and hiss

[Lord9000]

Hello everyone!

I think there always comes this time in life of a diy pedal maker when he runs out of internet resources and has to ask for help.
This is my first post here, so please correct me if I do something wrong. 

Ok, straight to the point!
I've decided to build a JHS Twin Twelve clone for my friend using this source: http://effectslayouts.blogspot.com/2017/07/jhs-twin-twelve-v1.html
This is my 6th pedal build, so I have some experience but by no means I consider myself an expert, or even good in this field.

I've etched my own PCB, assembled it and hooked it up externally with some alligator wires to test if I did everything right.
Of course, it turned out I didn't. As the old saying tells: "It never works on the first try".
I grabbed a multimeter and started checking if I had any shorts in the circuit. And I found out I had a short between the gate and source of Q1.
I fixed it and started setting up the trimmers. For some reason I was able to reach the recommended 9V only on the two "right" ones. The max setting on the left pair of trimmers only reached about 6-7V. Not discouraged by this fact I hooked up my guitar and started testing. A slight hum was noticeable on higher drive setting, but as long as I didn't exceed the 1/2 of the volume and drive range everything was fine (or at least bearable). The effect sounded as it should, the problems started then I disconnected the guitar. The moment I unplugged the jack, a loud buzz started to come from my amp. The higher the drive and volume, the more aggressive the buzz became. To make it worse, when I tried to max out the controls with guitar connected, an unbearable hiss started. The his would go away (mostly) when I started playing, but it wasn't of any help to me.

Something was not right. I tried to analyze the circuit with a audio probe, and created this image for later reference:


Something must be generating this noise and I have no idea what to do next. My only idea is to scrap the board and start over, as I don't have enough electronics knowledge to be able to fix the problem.

Below I leave some photos of the wirings and the board (please don't judge me for my soldering skills). I also leave you some audio clips I've recorded with diferrent settings on the effect both conneted to and disconnected from the guitar:
https://drive.google.com/drive/folders/1OTFnVl68p4cXfFs_mobtq4YNQXAJReJR?usp=sharing

My greatfulness will be immeasurable if you'll manage to help me. I'll provide any data you need if provided is insufficient.

[JustinSelf]

Is this all happening with the circuit still  hooked up externally?  If you don't have it in the enclosure, you're going to get a lot of noise, especially at higher gain. Also, be mindful of your input and output wires interfering with each other. If they're too close, you can get some noise. Shielded input and output wires can help too for naturally noisy circuits. But it could just be from not having the enclosure function as a faraday cage. I've had circuits that were noisy in the breadboard/test box that were quiet once I boxed them up.

[Lord9000]

Yep, I still haven't put it in the enclosure. Maybe I'll give it a try as soon as I get some time to work with it. But I don't think it will do much, since the buzz generated with guitar unplugged is way too loud to be just the enclosure problem.

[JustinSelf]

That could actually contribute to noise more than it being plugged into the guitar, because your guitar is likely shielded. Have you ever unplugged to switch guitars or something and noticed a humming sound until you plugged back into your guitar?  The pedal is going to amplify any noise that the cable picks up, as well as any noise the circuit picks up from not being shielded including radio frequencies, static, etc. so the more you turn up the gain and level, the more noise you'll hear.  When it's boxed, and enclosure properly grounded, all that background noise gets dumped off to ground and kept out of your signal.

I should also add that while I think this is likely a source of noise, it may not be the only source. If you box it and it's still giving you more noise than it should, we can work through other possibilities, and some folks way smarter and more experienced than myself might chime in. Power supply, signal wires, etc could also be culprits but IME, unboxed dirt pedals are always noisy.