Biggus Dickus PTP think-along

[comradehoser]

Build Rating

5.00 star(s)

Here's my next PTP project, inspired by @GizzWizzKing 's build report of @Nostradoomus ' one-knob version of this @Chuck D. Bones Boneyard circuit, here.

I reverted back to the OG layout because as much as I like one-knob jobs, I like switches and potentiometers and doodad parameter controls more, and internal trimpots and PTP might not be the best at playing together. I'll be doing this in stages and updating after each, because if there's one thing to eff up a PTP build, it's excessive "off-board" elements. And we have 5 pots, 3 toggle switches, 3 jacks, and a 3PDT, for a total of 12 things that have to be routed and laced into the central circuit. Jesus. Good thing I chose a 1590BBS enclosure.

Here is the schematic:



I'll be deleting R13/C15 leg because I don't have an "eye" LED effect (had to ask nostradoomus what that was, thanks, bud!), and I'll also be leaving R2 and C16 out, as they are super easy to add in any event if I need them.

So here we have a typical distortion circuit, with everything arranged pretty symmetrically around a ground line on the bottom and a power line on top. I note that we are going to have fat right after the in, and fat and brite are pretty much in the neighborhood of the gain pot. We'll also have to save some room around there for the transistor array, and somewhere around "bright" and "crush" before tone controls we'll have to also include the IC array. Neither of those on their own needs excessive real estate, but we'll see. Layering is a possibility if things get crowded. The three tone controls are tightly related, so probably it makes sense to keep them together, even if they are in a strange order, but I'm not going to mess with it because I'm having trouble spatially dealing with this circuit and I don't need more complications at this point. Maybe I can fold/flip one of the loops to reorder, we'll see. Then we go to Level and out.

 

[comradehoser]

So, I recommend doing all of your layout and graphics before you assemble the pedal, because removing a PTP circuit is possible but maybe not ideal. I broke a 9v jack doing it to paint my friend's Corroder build.

I tried many, many different ideas for this: landscape orientation, portrait orientation, pots along the top switches at the bottom, switches diagonally, etc., and the issue I kept running into is clearance around the stompswitch for yer dawgs. Hitting a toggle with your toe is a real thing. Oh, and also circuit flow. We have to designate some spaces for related groups of pots and toggles. This is what I eventually settled on that made the most sense from both of those priorities--I think it looks decent too. It's very rational and aligned, in any event.

The circuit will flow from 3PDT to fat (bottom toggle), over to transistor array above the LED, to gain (leftmost pot in the middle row), to brite (middle toggle), back to the right to where there's space for the IC, up to the top toggle (crush), to the top row of three pots (tone controls), down to the rightmost pot in the middle row (level) to 3pdt out.

It kind of crowds everything over to the left when there is the most real estate right around the 3PDT, but we will see.

If anyone has layout better ideas, let me know.

Next is trying to find the aesthetics in the assembly.

 

[GizzWizzKing]

I love it.

This would maybe be a case where having your ground line go physically around the entire circuit could be useful. You're gonna need to ground like 30% of the components so having that ground thought out or at least easily accessible all over the circuit is gonna be critical.

I like the layout. The pot placement make sense. When you actually start the circuit my plan of attack would definitely be going from the output first and knocking out your level and tone stack connections. Then I would lay my ground line near the back plate of the enclosure and make all those grounds. I find that helpful too because I can actually hang anything I want connected to the ground from the loop without soldering them just so I have some frame of reference for where the blocks are going to physically end up.

Once that's done you should find you have a decent amount of space left for your transistor loom and ic. For me those are the hard parts though. The off boards stuff is how I orient it all in my brain so more doodads/switches/pots make the circuit build itself.

Disclaimer: I've built 2 ptp circuits (nothing nearly as big as this) and I know absolutely nothing.

 

[comradehoser]

Hahaha... but what you say makes sense! Maybe more IS better! I like the ground loop idea. I might also try just laying down some copper shielding foil and soldering all grounds directly to the "floor."

And, I might try attaching everything to the pots and switches to see what shakes out, but backing into the circuit is not a bad idea to start.

 

[Feral Feline]

Super impressive that you're doing this circ P2P!

 

[comradehoser]

Super impressive that you're doing this circ P2P!

Well, thank you! It looks more complex and intimidating than it is-- the circuit itself is pretty straightforward and linear. I'm saying this to encourage you and anyone else to give PTP a shot. As GizzWizzKing stated in another conversation, you just gotta wade into it, and it's way more fun and less crazy than you'd think.

There's some complexity around the transistor loops and what's tying into the IC, and of course, the offboard tie-ins, and as GizzWizzKing pointed out, a heckuva lot of grounds. It looks sprawling, but as we go, you'll see that we can get it pretty tight. I might have been able to cram it in a 125B, but I just wanted a little bit more breathing and soldering room, especially for the controls layout. You can create the subunits independently and then relate and arrange them in the enclosure, which helps.



Drilled and stamped the enclosure last night--I need to find/make/buy a proper backing block for stamping. Don't try stamping without some kind of metal block behind it, you'll wreck the enclosure.

Decided to name the pedal Mandrake (the man-shaped root--had to keep the manly root connection-- that screams and kills you when you uproot it), and looped the e over the 3pdt, like Mandrakeeeeeee. Then decided that the latinate word Mandragoraaaaaaa works way better for the scream since the E in Mandrake is silent duh. Mandrakekekeke, hahaha. Would also make not a bad metal band name. Tried to overlay it, but didn't work--it just looks messy, but whatever, learning experience. Stamping works best when it's slightly off anyways--even if this is like way more than slightly off. I also played with sanding patterns. Too much going on, I feel, and not well planned. Well, it's not the first enclosure I've mangled... Like I said, functionality ain't my issue, it's aesthetics.


I also tested soldering to a copper foil sheet for grounds on a spare enclosure cover. It was interesting. A tad stinky because of the conductive adhesive. Of interest is that the excellent thermal conductivity of copper and large surface area makes it pretty difficult to get a nice looking solder joint. You can get the joint very solid on there, but it instantly freezes into an irregular blob. Also leaches the heat away from the soldering iron, so reworking just makes it look worse, even with a good amount of flux..

 

[comradehoser]

Alright, let's go! We're gonna lay the led line, 9v/5817 line in and jack ins and outs to the 3pdt. Looks sweet...


...and it's so wrong. We can't do that, dude! We have to solder a bunch of stuff for those three tone pots at the top. Also the orientation of the last (mid) pot doesn't even make sense. [edit: it's more elegant just to have them 3-in-a-row since we have to jumper pins 2 and 1 of one pot and connect to pin 3 of the next pot. Except the Treble pot! Pin 2 is the signal in from the 386. Oops. Will snip and correct in the pic after next.]


Muuuucho better above. Tone stack done, LED line rerouted. Still can't put the jacks back because we have to figure out the crush switch and the line coming off the treble pot as well the line to ground from pin 1 of the far left pot.

I'm working backwards into the circuit, as @GizzWizzKing suggested, but I haven't found an opportunity to suss out the ground line or 9v supply line.



Alright, connecting treble pot pin 2 to volume pot pin 3 and pin 2 to board out on the 3pdt in the pic above.

There's a 4n7 that needs a ground off the treble>vol pot line, and that pin 1 left over from the mids pot too. Hmm. Well, they're both really close to the input jack ground, so I just grounded both directly to the jack.



While I'm there, I'll ground the 9v. Installed out jack, and the initial 2 caps for 9v supply, as well as made the crush switch.

Things are getting real, now. Time to connect to the IC and/or the transistor/fet array. Both will require a lot of grounds, so now might be the time to decide about the line placement. [edit: situated the ground loop, but I desoldered it and took it out because it's impinging on all of the subunit assembly and location I'm about to do with the transistors and IC. Desoldering is much more fun when you don't have to worry about lifting pads and traces. You just have to worry about melting the rest of your assembly. I'll just leave the leads long on the ground side of things and have my ground line as the top layer.]

The transistor/fet array is also a bit spatially complex, what with the different connections necessary. It's hurting my brain along with the first switch, I don't know why.

 

[Hal Harvey]

Some of your bus wire looks tinned and some does not?

If you have some romex around you can strip out the conductors, put one end in a drill chuck and the other end in line man’s pliers and twist it. It’ll get straight and stiff. Perfect for a structural ground wire.

Also is using Teflon tubing considered cheating? Apex Jr has 100ft rolls of milspec 18 gauge for 1/10 the retail price right now. Looks like this on 18 guage bus wire:


Your build is looking good!

 

[Feral Feline]

THIS IS TOTALLY WICKED!

Thanks for letting us be flies on the wall.

 

[comradehoser]

Some of your bus wire looks tinned and some does not?

If you have some romex around you can strip out the conductors, put one end in a drill chuck and the other end in line man’s pliers and twist it. It’ll get straight and stiff. Perfect for a structural ground wire.

Also is using Teflon tubing considered cheating? Apex Jr has 100ft rolls of milspec 18 gauge for 1/10 the retail price right now. Looks like this on 18 guage bus wire:

Your build is looking good!

Thank you, The artist formerly known as Zanshin (Aikido connection?).

Romex is a bit thick to use--I mean you could, but it's hefty and harder to work with. I think GizzWizzKing used something similar in his Distortion+ PTP "WolfMan" build. It was girthy. Good tip on the straightening, though, I could probably use that to get those "pro" @Erik S -style lines.

I use a mix of silicone-sheathed 20 or 22 or maybe 24 AWG solid-core just for bottom layer/where needed, a fatter unknown gauge of copper wire (18 or 20AWG maybe) a friend left me, and component legs. Gotta use em for something. I wish I had the equipment to melt them down and make a backing block for enclosure stamping.

 

[comradehoser]

Wooo.... epic build. Stayed up late til 2 finishing this one. I just got in the problem solving flow and it happened.

As usual, I will write way too many words of dubious interest. Sorry it's not just pretty pictures, folks.

So, here I have my transistor/fet array and IC. I actually soldered the array WRONG, so PTP rule 1 is double check EVERTHANG, and rule 2 is
take.
your.
time.
Be patient with the circuit, and graceful with yourself. Near the end, I was feeling tired and started rushing and doing dumb things.

Rule 3 is respect the transistor and IC legs. They DO NOT like to be bent more than twice, support at the body so if the leg breaks at least you have a stub you can solder onto. This will be important later.

Here are my baby pictures:



Below, this is what the IC looked like after I sussed out the connections and decided on how I would relate the stubs I had left before to where they needed to connect on the IC. Pin 2 and 4 to ground, 3 to the transistor array, 1 to the crush switch, 6 to power, and 5 to the tone stack stub I had established before.

I most definitely DID NOT bend to fit on the IC. That's way too much stress on the legs. I desoldered, sussed it, bent the link where necessary, resoldered and cut to size. I forgot pin 7: it goes to a 47u to ground. The pin broke off, so I have to solder to the big flat part of the pin. Did I mention IC legs really don't like to be bent?

Here is also a good time to mention rule 4 of PTP: flux is your friend. I usually don't bother with flux in PCBs. I can't solder PTP without first daubing the join ends of components with flux. It's what allows "touch soldering" so that your circuit doesn't overheat, travel up the components, and melt your other beautifully and painstakingly arranged joints. Flux, position the joint, load a bead of solder on the iron, and touch and go. You really don't want to touch your joint longer than a miss of a mississippi. Maybe mississ on a big copper deal.



Here is the IC in circuit, and I'm pondering how to join the transistor array. I chose to put the 47u electrolytic off pin 7 *under* the IC because it was getting way too crowded.

I had also installed and uninstalled a ground loop, if you will recall. That was actually a very useful thing to do, as I could put it in there as a reference for situating components to ground, but take it out of the way so I could get in and do the assembly.

I also ended up being opportunistic with grounding and didn't actually end up grounding too too much directly to the line. I'm not sure electronically if the location of ground makes a difference. I've been operating under the assumption that it doesn't. So I feel free to just put grounds at any ground point, join grounds together. Doesn't seem to matter. For example, in the top right hand corner, I aggregated the grounds from the two switches and pins 2 and 4 of the IC. I also like the look of many lines joining together. Looks organic.

I finally tackled what was really hurting my head, the line-in to fat switch to transistors. The schematic was just not jibing with my spatial situation at all, and I had to slow down and think--"ok, what does the signal see first, and then what" etc. Basically, the in signal has to cross the 1M pulldown resistor before it hits the 1nf cap, and the 1M also has to make it to pin 2 of the fat switch. The 47 nf film cap on pin 1 has to make it to the other side of the 1nf before the signal hits the 10k/390k resistor intersection, and then it's into the transistor array. I decided to run the 1M resistor long so I could bring the line back over to the left, where there just happened to be space just the right size for the transistor/fet array.

 

[comradehoser]

Here is the pedal in final form, with the ground loop installed and the transistor array all connected. I chose to put the final power line cap gleaming there in the corner because I like diagonals. It's connected to ground via the mid pot ground looping over the input jack. I could have run the transistor array a bit further over, but I just figured it wasn't worth the bother with a jumper and all. I also had to join the line from that little 1.5k resistor over to the 220nf wima cap.

At this point, I was getting tired and trying to finalize the pedal by straightening my lines and was making a hash of things. Aesthetically, I'm pretty happy with how the circuit turned out. Still don't have that pro-quality @Erik S line quality, though. So I'm just going to say... this my style, man.




Plugged this guy in and-- NO SOUND>>>> WTF????

Will this be my first PTP pedal requiring extensive troubleshooting? At 2AM I was feeling kind of done. Well, instead of doing a good visual inspection like I should have (I wear reading glasses and my eyes were toast), I poked around at stuff. Just so happens that pushing on the IC gave me intermittent signal. Can y'all see what is the matter?



In moving around the circuit and straightening lines, I broke pin 3 off the IC. Yup, IC legs REALLY REALLY don't like to be bent. Resoldered it ugly, but the pedal "works".

Here is the stuff:

@GizzWizzKing warned me that transistor and IC selection might be important in this circuit, so did I breadboard it and audition components? Eff no. I just ploughed ahead like a dum-dum, because hey, Chuck didn't say and there wasn't a lot of selection discussion on the board, even though I'm sure it's something that's just understood as SOP. Also, I am lazy, and an opportunistic breadboarder. This circuit looked like a bit much to do. (I will breadboard my next PTP--the Fuzz & Burn V.2--'cause it's easy peasy).

In retrospect, do like GizzWizzKing says, not like I do. Even though he only has 2 PTP builds, he knows what's up. It's always a good idea to breadboard PTP because it's not as much fun taking stuff out than putting stuff in, and you avoid problems and sort out misconceptions before you actually build (see tone stack discussion below). And sockets are not really a great option in PTP.

I tested in a shitty digital emulation practice amp set to clean with a touch of reverb, so I have to wait for the chance to play in something for real in order to know for real. Keep these shortcomings in mind with these first impressions:

Crush and low switches make an immediate and obvious difference, Bright not so much. Crush toggles between middle position kind of mid-gain cleanish breakup amp, to mid-high gain to the right, to crushing on the left, which is what I assume @Nostradoomus chose as fixed for his one-knob board built by GizzWizzKing.

Gain and level operate as normal. Gain makes a difference within the gain range selected by crush, so there's not really "clean up" per se in the right and left positions, it's just saturated or really saturated. This has, I think, a whole LOT of volume on tap. Will test later, though.

I might have effed up the EQ wiring as I tended to rely on Robert's numbered pin designations for pots, and don't grasp the "CW" designation. I just went with "pin 3 is the incoming signal, pin 2 is out, pin 1 is ground" pattern. Seems like the bass pot works in reverse--not a huge deal to me, but generally, the tone stack looks to be interacting in ways I'm unused to, so I might have indeed effed something up.

Hopefully, I won't have to get at that bottom layer of the tone stack. ARG.

This was definitely a "teaching moments" and "level up" pedal for me. It ended up being pretty intricate and posing lots of interesting spatial challenges--not something I would necessarily recommend to a first timer, but still, like most PTP, very very doable. GizzWizzKing's ideas were clutch, and present us with PTP rule number 5:

Just get in there, the build puzzle will work itself out.

Thank you so much @Chuck D. Bones , @GizzWizzKing , and @Nostradoomus for the source, insights, and encouragement. It's a really fun pedal.

 

[Erik S]

So good.

 

[jcpst]

Holy moly. Do not leave that wonderful creation unattended.

 

[comradehoser]

So good.

That's what I can do. Think about the radittude YOU could do...

 

[comradehoser]

Had more time with this.

Like what I feel with most Boneyard circuits, this is tuned to be amp-like. Cleans up amazingly and with beautiful breakup when you back off the guitar volume knob. A LOT of different sounds from this circuit.

Treble toggle definitely works, I just failed to grasp that it's the subtraction of the 47nf that makes the bright, so the cap needed to be on the other lug of the switch

The bass pot works backwards. Not a bother, really, but not really sure how that happened.

 

[Feral Feline]

Very cool!

Learned a lot on this ride-along.

I know the pain of IC-legs rebuking any bending (and that's without P2P!), so I went hunting.
Was just looking for metal-can variants of the LM386 or metal-can alternatives — there aren't any.

 

[Nostradoomus]

dude hell yeah

 

[comradehoser]

Very cool!

Learned a lot on this ride-along.

I know the pain of IC-legs rebuking any bending (and that's without P2P!), so I went hunting.
Was just looking for metal-can variants of the LM386 or metal-can alternatives — there aren't any.

Glad to know somebody got something useful out of it.

I think it's just the state of modern electronics and not much to do about it.

Actually, come to think of it, fitting the ICs into sockets prior to soldering might not be a bad idea just to make things more stable. Transistors--- maybe less useful.

 

[GizzWizzKing]

This just looks so satisfying. Impressed. As soon as you started orienting pots both ways was lost and it came out looking great inside and out. I will be back to study as I do more. This has some cool stuff and it sounds like it was a good challenge.