Bring out yer Diptrace

Got a few on their way to me

New layout of the Sardine Tin Plus (modded superfuzz)
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A test board of a MPB forum member's project that I liked the sound of--with some value adjustments. SMD necessitated some top layer traces and vias, so not as pretty. And the pots aren't named like the original, my B :ROFLMAO:
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and a couple adapter boards
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Also, SBP has 13700 SMDs (made by coolaudio???) for 50% less than Mouser (TI)
 
Just sent this one off to JLC:
Standard Fuzz PCB.png
I've been playing around with the Ibanez Standard Fuzz circuit for the past couple weeks. It's an even gnarlier derivative of the Univox Super Fuzz, with a JFET input stage, a gainier phase splitter, and a more intense mid-scoop. The Tayda 2SK30A JFETs work well for Q1 in this circuit; all I had to do was make a slight tweak to the value of the source resistor (R3/R4), and it hit the bias voltages perfectly (and sounds right, too). I'd recommend making the source resistor a 5k trimpot if you plan on making more than one or two of these; otherwise you'll need to breadboard the input stage before each build. I made a few small modifications to the circuit:
  • Added an octave control to adjust the intensity of the octave up overtones
  • Added a resistor (R24) between the diodes and ground to soften the knee of the clipping a little
  • Removed the tone switch. Instead, I added an A100k pot between C11 and ground, which goes from full scoop to flat mids as you turn it up.
  • Changed the biasing of the output stage to increase the output volume
I also added ferrite beads to the DC and audio inputs. I'd seen this done in Spaceman pedals before, but I was curious as to whether it actually did anything. Turns out that, at least on the breadboard, it significantly reduces the noise level of the pedal without changing the tone at all. Here's the schematic:

Standard Fuzz Schematic.png
 
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Big Monk said:
I had the reverse issue up until you mentioned it: I did not even k ow there was a measuring tool.

The dimension tool is so much more useful I must have glossed right over it.
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I can see that haha. I don't see the ol ruler coming out much after this.
 
szukalski said:
Aren't the resdef / values on the wrong sides? Ie. you need values on the front for population, and the rear for troubleshooting.
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They’re on the right side for my workflow. I like to follow the schematic as I populate the PCB, so it’s easier for me if I keep the refdes on the top silkscreen layer. Additionally, for octave fuzzes with a differential pair like this one, I like to match the resistors in the octave section (R7-12, R15, R16) as closely as my Fluke will allow. This actually makes a big difference to my ears, and results in a stronger octave than just using a trimpot for the differential pair’s base to ground resistors. So for a circuit like this, it’s nice to be able to identify which 1k/10k/22k resistors need to be matched without having to flip over the board. The reason that I started putting values on the back is to serve as a backup of sorts in case the schematic is ever lost, rather than for ease of assembly on my part.
 
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PedalBuilder said:
They’re on the right side for my workflow. I like to follow the schematic as I populate the PCB, so it’s easier for me if I keep the refdes on the top silkscreen layer. Additionally, for octave fuzzes with a differential pair like this one, I like to match the resistors in the octave section (R7-12, R15, R16) as closely as my Fluke will allow. This actually makes a big difference to my ears, and results in a stronger octave than just using a trimpot for the differential pair’s base to ground resistors. So for a circuit like this, it’s nice to be able to identify which 1k/10k/22k resistors need to be matched without having to flip over the board. The reason that I started putting values on the back is to serve as a backup of sorts in case the schematic is ever lost, rather than for ease of assembly on my part.
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Since you're rolling your own boards, have you considered resistors arrays? 0.05% matched are just a few bucks.
Or maybe that takes the fun out of it.
 
I just got diptrace and finished my first "original" design, it's cobbled together from online schematics that I've fooled around with on the breadboard for the last 2 weeks, anyway, please point out any glaring errors you see in the schematic. I ran the electrical rule check and corrected the errors it found, connections I thought I had made but didn't, but I'm not sure I have the switch pads all done correctly, or anything else from that matter. Please and thank you!
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Congrats on making the leap! A few thoughts/questions:
  • I'd recommend changing the polarity protection diode to a series diode, rather than the parallel diode to ground. A series diode is more reliable.
  • I'm not sure if I'm reading the symbols correctly, but it also looks like your indicator LED is not connected to a switch pad and will always be on.
  • Does the box with "IN G 9v OUT" represents four pads for wiring the footswitch? If so, you'll probably want to remove the 9v pad and replace it with a switch pad that connects to the cathode of the indicator LED.
  • The clipping LEDs look questionable to me. A single transistor into a tonestack seems unlikely to produce a hot enough signal to reach the clipping threshold of the LEDs. I'd recommend moving them after the 1uF capacitor that follows the second transistor. you have a hot enough signal to clip the red clipping LEDs?
  • What is the -9V(T) net? It looks like it's the same as ground.
  • What is the difference between GND and GND(T)?
  • Which potentiometers are external controls? Which ones are internal trimmers?
 
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PedalBuilder said:
Congrats on making the leap! A few thoughts/questions:
  • I'd recommend changing the polarity protection diode to a series diode, rather than the parallel diode to ground. A series diode is more reliable.
  • I'm not sure if I'm reading the symbols correctly, but it also looks like your indicator LED is not connected to a switch pad and will always be on.
  • Does the box with "IN G 9v OUT" represents four pads for wiring the footswitch? If so, you'll probably want to remove the 9v pad and replace it with a switch pad that connects to the cathode of the indicator LED.
  • The clipping LEDs look questionable to me. A single transistor into a tonestack seems unlikely to produce a hot enough signal to reach the clipping threshold of the LEDs. I'd recommend moving them after the 1uF capacitor that follows the second transistor. you have a hot enough signal to clip the red clipping LEDs?
  • What is the -9V(T) net? It looks like it's the same as ground.
  • What is the difference between GND and GND(T)?
  • Which potentiometers are external controls? Which ones are internal trimmers?
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Thanks for all the tips, I definitely need to rework the power supply section.
The clipping LEDs occasionally pulse while I'm playing, so I assume they're working? They're just there to prevent hard clipping from the jfets.
-9V(T) is the pad for the negative connection from the DC jack, I wasn't sure how to represent connecting it to ground, so that's what I came up with.
GND is ground reference and GND(T) is the pad for connecting to jack ground, so that was just showing all of that hooked up. Maybe I'll try to find some example schematics where everything is shown, usually that stuff seems to be omitted. I do have everything labeled on the schematic, but turned off refdes and justed showed values for the print image because it wouldn't all fit, but I realize now it would've been more helpful to leave the labels on and the values off. Thanks again, I'll get back to work on this tomorrow!
 
pingpongcomputer said:
Thanks for all the tips, I definitely need to rework the power supply section.
The clipping LEDs occasionally pulse while I'm playing, so I assume they're working?
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It’s possible that there is DC that’s making them blink. Try putting a large capacitor between them and the rest of the signal path and see if they still pulse.
pingpongcomputer said:
-9V(T) is the pad for the negative connection from the DC jack, I wasn't sure how to represent connecting it to ground, so that's what I came up with.
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Gotcha. I use V- or DC- for that pad on my schematics. It might be worth changing the name because the negative connection is 0v, not -9v.
pingpongcomputer said:
Maybe I'll try to find some example schematics where everything is shown, usually that stuff seems to be omitted. I do have everything labeled on the schematic, but turned off refdes and justed showed values for the print image because it wouldn't all fit, but I realize now it would've been more helpful to leave the labels on and the values off. Thanks again, I'll get back to work on this tomorrow!
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I’d recommend keeping both refdes and values in your schematics. It’s difficult to discuss the schematic without refuses, and it’s hard to know what the circuit is doing without values. Check out the schematics that I’ve posted (or the schematics in the PedalPCB build docs, for that matter) for examples of schematics that include both.
 
PedalBuilder said:
  • The clipping LEDs look questionable to me. A single transistor into a tonestack seems unlikely to produce a hot enough signal to reach the clipping threshold of the LEDs. I'd recommend moving them after the 1uF capacitor that follows the second transistor. you have a hot enough signal to clip the red clipping LEDs?
Click to expand...
pingpongcomputer said:
The clipping LEDs occasionally pulse while I'm playing, so I assume they're working? They're just there to prevent hard clipping from the jfets.
Click to expand...

Runoffgroove is doing this in several of their circuits as well. The DC check suggested above is a good idea, but if you're not after the clipping character of the LEDs, I wouldn't recommend moving them. It also might be worth just keeping them in case you want to put a booster or something ahead of this circuit that might change the character.
 
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