Building the small clone, a few questions...

[deadlyshart]

Hey guys, I'm putting together a Small Clone pedal and I want to make this one my best yet. I'm following the schematic and PCB layout from this tonepad page. I've etched the PCB and soldered most of the parts, so here's where I am now:



You can see that some of the holes are horrifically large; this is because my damned carbide mini bits kept breaking while drilling (the shitty drill press is slightly off centered I think, causing lots of stress), and eventually I had to use a regular bit...



It worked mostly fine, but the solder really doesn't want to bridge the gap between the component leg and the side of the hole it's not touching, so there's some pretty ugly soldering.



I only had to do one "repair" though, where it became such a shitshow that it actually burnt the track off. Not good, but I've tested continuity everywhere and it seems good.

I don't want the stereo mod, so I'm ignoring that part.

Anyway, so I'm nearly there I think, but I have a few questions I'm stuck on that I'd really appreciate if someone could help me verify.

1) They show how to make 2 versions in the pdf, the original (with a depth switch) and their depth pot mod. They say "the original small clone had a depth switch instead of the potentiometer, this gave two depth options only." It appears they also modify the original switch method to have 4 depths. Is there any reason to do the original version? Intuitively, a continuous pot seems like it offers more tunability, but it's using a resistor rather than a capacitor (as the depth switch method does). Does the pot mod version have a different sound then?

2) Just so I understand it (I think I do), if you're doing the pot mod version (the one in the main schematic), Ra = jumper and Rb = nothing (as it says on the PCB), and if you're doing the depth switch version, you replace those with the appropriate resistors it says, right?

3) the circles/pads A,B,C,D,E are only if you're doing the stereo mod, right? So if I don't want the stereo mod, I just leave them disconnected, right?

4) So in the full schematic they show (the one with the depth pot mod, I believe), the depth pot mod is 10kOhm. In the BoM, they say about it "replace with SPST switch if building the stock version." This wouldn't be the stomp/bypass switch, would it (because I thought that was usually a SPDT switch)? Does this mean if I want that stomp switch, it's not included in this schematic and I just hook the input/output jacks up to it separately?

5) There were a couple values of caps in the BoM that I didn't have, so I had to improvise. For example, when it asked for a 2.7nF one, I used a 2.2nF and 470pF in parallel (=2.67nF), and for the 180pF one I used a 150pF and 33pF in parallel (=183pF). This should be fine, right? My understanding is that most caps don't have this precision anyway (about 1.5% for both), so it can't make too big a difference... is that right?

6) Lastly, in the BoM it asks for a 2.2uF tantalum cap, which I don't have any of... However in the schematic it shows one with polarity. Is it okay to use a 2.2uF electrolytic for that one, or does it really need to be tantalum? Will it affect the sound?

Anyway, sorry for the long post. Any help is appreciated, thank you!

[EBK]

1) They show how to make 2 versions in the pdf, the original (with a depth switch) and their depth pot mod. They say "the original small clone had a depth switch instead of the potentiometer, this gave two depth options only." It appears they also modify the original switch method to have 4 depths. Is there any reason to do the original version?

Nostalgia.  Some people seem to feel that a true-to-original reproduction must sound the best. (I'm not one of those people.)

Intuitively, a continuous pot seems like it offers more tunability, but it's using a resistor rather than a capacitor (as the depth switch method does). Does the pot mod version have a different sound then?

Not sure what you mean.  Depth switch appears to just switch Rb in and out of circuit.

2) Just so I understand it (I think I do), if you're doing the pot mod version (the one in the main schematic), Ra = jumper and Rb = nothing (as it says on the PCB), and if you're doing the depth switch version, you replace those with the appropriate resistors it says, right?

Sounds right.

3) the circles/pads A,B,C,D,E are only if you're doing the stereo mod, right? So if I don't want the stereo mod, I just leave them disconnected, right?

Again, sounds right.

4) So in the full schematic they show (the one with the depth pot mod, I believe), the depth pot mod is 10kOhm. In the BoM, they say about it "replace with SPST switch if building the stock version." This wouldn't be the stomp/bypass switch, would it (because I thought that was usually a SPDT switch)? Does this mean if I want that stomp switch, it's not included in this schematic and I just hook the input/output jacks up to it separately?

The SPST is the depth switch, not the stomp switch.  Tonepad has a separate document showing how to hook up a stomp switch (external wiring document).

5) There were a couple values of caps in the BoM that I didn't have, so I had to improvise. For example, when it asked for a 2.7nF one, I used a 2.2nF and 470pF in parallel (=2.67nF), and for the 180pF one I used a 150pF and 33pF in parallel (=183pF). This should be fine, right? My understanding is that most caps don't have this precision anyway (about 1.5% for both), so it can't make too big a difference... is that right?

You should be fine with those cap arrangements.

6) Lastly, in the BoM it asks for a 2.2uF tantalum cap, which I don't have any of... However in the schematic it shows one with polarity. Is it okay to use a 2.2uF electrolytic for that one, or does it really need to be tantalum? Will it affect the sound?

Not sure why tantalum is specified here.  Don't know if it affects sound.

[EBK]

That's a lot of ceramic disc caps, by the way.  In the future, you may want to consider using film caps (almost) wherever possible.  You might also consider machined pin sockets (like your transistor sockets) for your ICs for somewhat better reliability (I have no data to back this claim up, however).  I doubt you'll have problems specifically based on these things though, so I wouldn't suggest changing them in this build. 

[davepedals]

As to drilling , I use a cheap wen rotary tool, actually the best one I've ever owned, it's excellent!  The wand attachment for it is really tight and the bit doesn't wobble... well one bit!  Using PVC pipe, duct tape, and a few other odds and ends I mounted it in one of those old Sears and Roebuck drill presses. The kind where you have to use your own drill with it.


Do a search on Google or whatever for DIY drillpress and you'll see lots of ideas how to use a rotary tool with a wand attachment and make your own drillpress stand for it. I rarely ever break bits any longer even down to size 65.  Give it a try...  also put a piece of wood under your PCB and fasten it down tightly and adjust drillpress so that the bit just barely protrudes through the bottom of the PCB . Set your drill on high speed and let the bit do all the cutting, in another words don't put any pressure on it .


Dave

[deadlyshart]

1) They show how to make 2 versions in the pdf, the original (with a depth switch) and their depth pot mod. They say "the original small clone had a depth switch instead of the potentiometer, this gave two depth options only." It appears they also modify the original switch method to have 4 depths. Is there any reason to do the original version?

Nostalgia.  Some people seem to feel that a true-to-original reproduction must sound the best. (I'm not one of those people.)

Intuitively, a continuous pot seems like it offers more tunability, but it's using a resistor rather than a capacitor (as the depth switch method does). Does the pot mod version have a different sound then?

Not sure what you mean.  Depth switch appears to just switch Rb in and out of circuit.

2) Just so I understand it (I think I do), if you're doing the pot mod version (the one in the main schematic), Ra = jumper and Rb = nothing (as it says on the PCB), and if you're doing the depth switch version, you replace those with the appropriate resistors it says, right?

Sounds right.

3) the circles/pads A,B,C,D,E are only if you're doing the stereo mod, right? So if I don't want the stereo mod, I just leave them disconnected, right?

Again, sounds right.

4) So in the full schematic they show (the one with the depth pot mod, I believe), the depth pot mod is 10kOhm. In the BoM, they say about it "replace with SPST switch if building the stock version." This wouldn't be the stomp/bypass switch, would it (because I thought that was usually a SPDT switch)? Does this mean if I want that stomp switch, it's not included in this schematic and I just hook the input/output jacks up to it separately?

The SPST is the depth switch, not the stomp switch.  Tonepad has a separate document showing how to hook up a stomp switch (external wiring document).

5) There were a couple values of caps in the BoM that I didn't have, so I had to improvise. For example, when it asked for a 2.7nF one, I used a 2.2nF and 470pF in parallel (=2.67nF), and for the 180pF one I used a 150pF and 33pF in parallel (=183pF). This should be fine, right? My understanding is that most caps don't have this precision anyway (about 1.5% for both), so it can't make too big a difference... is that right?

You should be fine with those cap arrangements.

6) Lastly, in the BoM it asks for a 2.2uF tantalum cap, which I don't have any of... However in the schematic it shows one with polarity. Is it okay to use a 2.2uF electrolytic for that one, or does it really need to be tantalum? Will it affect the sound?

Not sure why tantalum is specified here.  Don't know if it affects sound.

Thanks for all the advice!

What I meant by the pot giving more control than the depth switch is, for the depth switch there are just 2 depths (4 if you use their version with the 4 capacitor settings), but if you use a pot that covers the same range, you can choose all the values in between.

[deadlyshart]

That's a lot of ceramic disc caps, by the way.  In the future, you may want to consider using film caps (almost) wherever possible.  You might also consider machined pin sockets (like your transistor sockets) for your ICs for somewhat better reliability (I have no data to back this claim up, however).  I doubt you'll have problems specifically based on these things though, so I wouldn't suggest changing them in this build.

You mean, those rectangular caps? Why are they better than ceramic disk caps?

thanks!

[EBK]

That's a lot of ceramic disc caps, by the way.  In the future, you may want to consider using film caps (almost) wherever possible.  You might also consider machined pin sockets (like your transistor sockets) for your ICs for somewhat better reliability (I have no data to back this claim up, however).  I doubt you'll have problems specifically based on these things though, so I wouldn't suggest changing them in this build.

You mean, those rectangular caps? Why are they better than ceramic disk caps?

thanks!

Ceramic disc caps are sometimes susceptible to piezoelectric noise,  i.e., they can convert mechanical vibrations to electrical fluctuations like a microphone.  There are stability concerns as well (capacitance varying with applied voltage, for instance), but overall, probably will make only a minor difference in your results.

Rod Elliott has written an impressively detailed article about capacitors that favors science over anecdote.  You may want to skip ahead to the section on ceramic capacitors, where he concludes that they are not recommended for audio signal coupling or filtering (but they are great for supply rail decoupling, which is why I bought a big bag of 0.1uF ceramic caps once).
http://sound.whsites.net/articles/capacitors.htm
  (His entire website is full of excellent material)

[hannibal827]

the depth control and the 1p4t capacitor switch are two different things.

the depth knob [or switch] basically controls the amount of chorusing you hear. the cap switch determines the delay time--how much separation (in time) there is between the dry signal and the vibrato signal. Think of this as "width" rather than depth.

[deadlyshart]

That's a lot of ceramic disc caps, by the way.  In the future, you may want to consider using film caps (almost) wherever possible.  You might also consider machined pin sockets (like your transistor sockets) for your ICs for somewhat better reliability (I have no data to back this claim up, however).  I doubt you'll have problems specifically based on these things though, so I wouldn't suggest changing them in this build.

You mean, those rectangular caps? Why are they better than ceramic disk caps?

thanks!

Ceramic disc caps are sometimes susceptible to piezoelectric noise,  i.e., they can convert mechanical vibrations to electrical fluctuations like a microphone.  There are stability concerns as well (capacitance varying with applied voltage, for instance), but overall, probably will make only a minor difference in your results.

Rod Elliott has written an impressively detailed article about capacitors that favors science over anecdote.  You may want to skip ahead to the section on ceramic capacitors, where he concludes that they are not recommended for audio signal coupling or filtering (but they are great for supply rail decoupling, which is why I bought a big bag of 0.1uF ceramic caps once).
http://sound.whsites.net/articles/capacitors.htm
  (His entire website is full of excellent material)

Huh, interesting. Thanks for the advice. This stuff is infinitely fractal...

[deadlyshart]

the depth control and the 1p4t capacitor switch are two different things.

the depth knob [or switch] basically controls the amount of chorusing you hear. the cap switch determines the delay time--how much separation (in time) there is between the dry signal and the vibrato signal. Think of this as "width" rather than depth.

Huh, okay, so I'm kind of confused...

So it seems like there are 3 total versions we're talking about, right? All have a rate knob, but they each do something different for the other control:

1) The original small clone, that had only a SPST depth switch. I guess this just selected between two values?

2) The SP4T cap switch in the tonepad manual version. So is this just the same thing as the original, but with 2 more settings?

3) The "depth pot mod" in the tonepad manual, with the potentiometer.

Is that all correct?

But you basically choose either the cap switch or the depth pot version, right? I'm not sure which to go for, though the depth pot is simpler... will it have a very different sound than the original small clone? I really like the sound of the small clone.

[EBK]

The depth pot more or less replaces the original SPST switch, but gives you a continuous range instead the two depth options on the original.  This is a slight simplification because the pot is changing both Ra and Rb, so you never exactly hit the two values of the original, but you'll run through something close.

1. You pick ONE of: the depth switch and depth pot.
2. You can optionally add the SP4T cap switch mod to either of the above two versions.  From hannibal827's description, it controls a different aspect of the sound.

[vigilante397]

I've built a couple small clones from that layout (your etch looks way better than mine did!) and loved them. I would definitely recommend going to the depth pot route for the reasons already discussed. The four-way switch with the caps is a voicing mod, which I personally didn't find that useful so I left it off when I boxed it up (plus that switch makes it impossible to put into a 1590B, which was my goal).

So if you're looking for solid recommendations, I would say yes on depth pot, no on four-way cap switch.

[deadlyshart]

The depth pot more or less replaces the original SPST switch, but gives you a continuous range instead the two depth options on the original.  This is a slight simplification because the pot is changing both Ra and Rb, so you never exactly hit the two values of the original, but you'll run through something close.

1. You pick ONE of: the depth switch and depth pot.
2. You can optionally add the SP4T cap switch mod to either of the above two versions.  From hannibal827's description, it controls a different aspect of the sound.

Ahhhh, I think I see now... thank you. I think I'm just gonna go with the single depth pot.

[deadlyshart]

I've built a couple small clones from that layout (your etch looks way better than mine did!) and loved them. I would definitely recommend going to the depth pot route for the reasons already discussed. The four-way switch with the caps is a voicing mod, which I personally didn't find that useful so I left it off when I boxed it up (plus that switch makes it impossible to put into a 1590B, which was my goal).

So if you're looking for solid recommendations, I would say yes on depth pot, no on four-way cap switch.

Thanks! It's a lot simpler so I'm glad I can just go for it instead, heh.