Trouble understanding offboard wiring diagram for first perfboard build

[Woysy82]

Hey all, long time/first time and all that :-)

I've built 5 pedals from pre-printed PCB's with relative success so thought I'd try a perf board build and chose the colour sound one knob fuzz as an easy starting point. I also added an SPDT with two different caps attached in place of that 100NF cap. I've used a 47nf and a 1UF. You can hear a difference when you flick the SPDT over but not as much as I'd hoped for.

Everything went fine and the pedal tested ok, it was a bit noisy but I find they generally are until they're in the enclosure.

Now it's boxed up and it does work, it's really fuzzy but it's quite noisy too. When chained with other pedals (via isolated power supply) I would say it's TOO noisy, but when plugged in separately (via the same supply) it's a lot better.

I've been through all my solder joins and as far as I can tell they're ok I'm no expert, but they're up the standard that I'm used to them working with previous builds), and I think my biggest area of suspicion is my 3PDT wiring. That diagram is the one I've used on all my other builds with no issues, but my concern is this:

• On the layout, tang 2 of the volume pot goes to output, so I've wired that middle tang to the output jack tip.
• Top tight lug on the 3PDT also goes to output so I've wired that onto the middle tang of the volume pot too
• Middle right lug on 3PDT goes to output jack tip so I've wired that to output jack tip

My gut tells me that's where I'm wrong....

I know it's an absolute rats nest in there...but as far as I can tell nothing is shorting out. I was getting a lot tidier with these but I think making the move to perfboard has had me not really think a couple of things through, like where the PCB would sit, and how the wires would flow around the case if that makes sense. I also picked an enclosure that was really deep because it seemed cool, but the reality is it's just been a nightmare trying to get in there with the iron...

Anyway, here's hoping someone can assist, thanks for reading

**Edit, have just tried it again and noticed that when the pedal is off, the volume pot still affects the guitar sound, and the guitar in general sounds a little quieter than I'd expect it to**

Cheers
Woysy

[Dormammu]

It need to make sure the box and the ground of the output connector has contact the ground of the circuit.
It would be nice to hear the samples — what's that noise.

[Woysy82]

The ground from the PCB is going to the shield of the input Jack and I thought that with a metal enclosure you didn't need to attach anything to the shield of the output Jack?

Audio clips might be tricky, what's the best way to share?

And thanks for the reply, I'm really stuck

[bluebunny]

Welcome Woysy. 

Snip that wire that you have from volume 2 to the output jack.  It should go to the footswitch only.

The assertion in the wiring diagram that you don't need the ground connection because it's a metal box is asking for trouble.  It will surely fail in the middle of a song in front of 10,000 punters, and all for the sake of a solder joint.

[Woysy82]

Thanks so much man, anything else that might be tripping me up?

So I'll snip the wire from tang 2 to the output Jack tip, that leaves my current situation with tang 2 connected to the top right lug of the 3PDT

Then I've got middle right lug of 3PDT going to tip of output Jack

Then I've got nothing going to the shield of the output Jack but you're saying I should ground that @bluebunny? Forgive my ignorance but is taking something to ground as simple as hooking it to the negative of the DC? Could I just shoot a wire from the shield of the output to the shield of the input that's already connected to the ground of the PCB and negative of the DC?

Apologies if this is all very elementary stuff, I'm trying to learn about all the electronics side of things and it's all coming very slowly but I'm super keen to progress!

Thanks for the help again

[bluebunny]

You can make the ground connection from anywhere convenient.  You might find the tab on the DC jack can't accommodate two wires.  The tab on the other jack may have more room.  Or else the volume 1 tab is close by.

[Woysy82]

So a ground connection is just taking it to a negative source? Or are you saying that the 1st tang of the volume pot could also be utilised to make a ground, that wouldn't stop the 1st tang doing what it's already supposed to be doing?

Also, does this mean that my top right lug of the 3PDT is just vacant?

[Dormammu]

What I meant was to check the connections by the multimeter.

[GibsonGM]

So a ground connection is just taking it to a negative source? Or are you saying that the 1st tang of the volume pot could also be utilised to make a ground, that wouldn't stop the 1st tang doing what it's already supposed to be doing?

It's fine.
Ground is a 'common reference point', of which you'll learn more later. Actual schematics will tell you what 'ground' is.  Some circuits use positive ground, and some use some other defined voltage level as ground, internally - but they are a very small minority - generally, ground WILL be 'zero volts', the negative terminal of the power supply.  That's the standard for the 'pedal system', the enclosures are all at zero, the cable shields, back to the amp.   Points directly connected to this terminal (there could be a few) are all ground points...the runs of wire between them present such low resistance, they're essentially the same, BUT -

At times, issues can develop from using 'any grounded point' to connect to, but for basic low-voltage builds, we're not going to worry about that just yet  

Welcome to the forum!

[bluebunny]

What Mike said ("ground" is just a label), and ...

Or are you saying that the 1st tang of the volume pot could also be utilised to make a ground

Yes.  Because:

. . . that wouldn't stop the 1st tang doing what it's already supposed to be doing?

No it wouldn't.  If you look at the vero layout, you'll see that it's already ground.  It's on the same row that's marked "Ground" at the other end.

Also, does this mean that my top right lug of the 3PDT is just vacant?

No.  Don't touch that.  It's doing fine as it is.

[Woysy82]

It's fine.
Ground is a 'common reference point', of which you'll learn more later. Actual schematics will tell you what 'ground' is.  Some circuits use positive ground, and some use some other defined voltage level as ground, internally - but they are a very small minority - generally, ground WILL be 'zero volts', the negative terminal of the power supply.  That's the standard for the 'pedal system', the enclosures are all at zero, the cable shields, back to the amp.   Points directly connected to this terminal (there could be a few) are all ground points...the runs of wire between them present such low resistance, they're essentially the same, BUT -

At times, issues can develop from using 'any grounded point' to connect to, but for basic low-voltage builds, we're not going to worry about that just yet  

Welcome to the forum!

Thanks so much for your help man, glad I found this place!

. . . that wouldn't stop the 1st tang doing what it's already supposed to be doing?

No it wouldn't.  If you look at the vero layout, you'll see that it's already ground.  It's on the same row that's marked "Ground" at the other end.

Ah awesome I see that now, thanks for taking the time to explain the 'why' as well as the how :-)

Thanks so much for all your help guys, I'm in Australia so have to go to work now but to summarise:

• I'm going to try snipping the wire I have going from tang 2 on the volume pot, currently going to the output shield
• I'm going to find a suitable ground connection for the output jack shield, given the proximity I may just go for tang 1 of the volume pot

Thanks again for all your help guys, I'll report back once I get a chance to tinker!

[Woysy82]

What I meant was to check the connections of the multimeter.

Ah you mean the scary yellow box that I use to check my resistors!

I really need to get better with that thing! Thanks Dormammu

[Woysy82]

So I got some time to tinker this arvo and it went pretty well. I snipped that wire going from tang 2 on the volume pot to the output jack, and added a ground going from the output jack shield to tang 1 of the volume pot. I played around and kind of twisted the board a little to see if I had any dodgy spots and I was getting some noise whenever I touched my 2 caps that I'd wired into the SPDT. I was using a 47NF cap and a 1UF cap and I wasn't hearing much difference at all when I flicked the switch - that was really bothering me so I decided to just rip it out and plug the hole with a bolt, nice and ghetto :-). Wondering if I did something wrong with my SPDT wiring and that's why I wasn't hearing any real difference in sound?

I was also hearing a bit of noise from my ground wire into the PCB so I replaced that and did a fresh solder.

I think the pedal sounds really cool, it almost goes into bit crusher territory at certain points, not sure if that's my dodgy work or just how it sounds, but I like it all the same. It really doesn't like being stacked with any other pedal I have which makes me think maybe I've done something wrong somewhere?

Having said that, when you plug it in on it's own it sounds fine, minimal hum etc. It also now doesn't make any excess noise when connected through the other pedals on the board, it only freaks when you turn another one on.

I'm really keen to have another crack at this  and this time make the switch really effective. I had the centre lug wired into one of the PCB holes, and the other two joining up to go through the other hole. The cap I was trying to double up on was the 100n on the 5th and 7th rail as a friend told me that cutting that from 100 to 47 would increase the treble





Cheers
Woysy

[Dormammu]

In such circuits, the use of a cap 100nf gives a sufficient frequency range. To get a greater difference, it is better to reduce the capacity of the smaller cap. Try the combination of 100nf and 6,8-22nf

[Woysy82]

In such circuits, the use of a cap 100nf gives a sufficient frequency range. To get a greater difference, it is better to reduce the capacity of the smaller cap. Try the combination of 100nf and 6,8-22nf

Ah ok? So it wouldn't really matter how high I went, the trick would be go for a much lower one  instead of the 47nf

Am I understanding that right?

[Dormammu]

Ah ok? So it wouldn't really matter how high I went, the trick would be go for a much lower one  instead of the 47nf

Am I understanding that right?

Basically — yes.
The number of highs will be the same, and the number of lows (basses) we will customize to taste.
The level of humm 50-60 Hz will also decrease slightly.

[Woysy82]

Ah ok? So it wouldn't really matter how high I went, the trick would be go for a much lower one  instead of the 47nf

Am I understanding that right?

Basically — yes.
The number of highs will be the same, and the number of lows (basses) we will customize to taste.
The level of humm 50-60 Hz will also decrease slightly.

Interesting, so when I make another one, was the way I had the SPDT wired correct? Would there be a better way of wiring the switch in at all?

I'd like it to really offer two distinctly different sounds of possible

[bluebunny]

The way you wired the two caps is fine.  Not pretty, and could probably be done "better"^*, but if it works...  As Dormammu says, choose different cap values to hear a difference.  You definitely want one to be way smaller to sound "trebly" (actually, "less bassy").



* You could do it with an SPST switch.  Have the low-value cap always in the circuit and use the switch to add the big one in parallel.  Caps in parallel add up, and if the big one is an order of magnitude bigger than the smaller one, the smaller one becomes insignificant and you "hear" just the big one when it's switched in.  More or less.  (Which is enough: this is rock'n'roll, after all.)

[duck_arse]

....... I'm in Australia ......

they don't let us use that as an excuse for anything around here, except upside-down jokes.

yeah. like blue sez. cut your 100nF and put that on the switch, and solder a new, much smaller value to the board.

and a circuit diagram is always helpful to all concerned.

[bluebunny]

they don't let us use that as an excuse for anything around here, except upside-down jokes.

We also take the opportunity to ask "ooh, what's the future like?" on New Year's Eve.