Can someone help me understand a few parts of the Boss Dimension C circuit?

[alanp]

Oooo. That's caught my eye

You're not using the normal Eagle "pinhead.lbr" header pins?

[solderfumes]

Still may have been heterodyning, breadboards aren't a quiet place.

Yeah, fair enough.  I'll investigate further, but I still kind of doubt it; if it were heterodyning, I think I'd be noticing more of an oscillating pitch, whereas this is mostly static.

I don't mean to drop in and advertise... just one of those "if it were me I'd wanna know" situations

And I do!  That looks very cool.  I'll pass this time, but thanks for the offer.  Maybe if I want to build another one though!  Looks like you've gone with three mode switches, much like the original; I'm planning to go with depth and rate knobs.  I've also identified a few mods that work better for me, such as decreasing the gain on the compressor and increasing it on the expander to avoid BBD distortion, and I'll include spots for the capacitors that I talked about previously.  I'm also going to put in a CV input, to go with a tap tempo unit I built based around the TAPLFO chip.  Mostly, though, I'm looking forward to making my own layout, because fitting all the components onto the board is like crack for an old Tetris addict like me.

[aion]

Oooo. That's caught my eye

You're not using the normal Eagle "pinhead.lbr" header pins?

Nope, didn't even know about that one! Just a bunch of individual square pads. This method does have the advantage that you can put the pins anywhere on the schematic that you want - the pinhead library looks like it wants you to run the wires to it which could get a bit messy.

And I do!  That looks very cool.  I'll pass this time, but thanks for the offer.  Maybe if I want to build another one though!  Looks like you've gone with three mode switches, much like the original; I'm planning to go with depth and rate knobs.  I've also identified a few mods that work better for me, such as decreasing the gain on the compressor and increasing it on the expander to avoid BBD distortion, and I'll include spots for the capacitors that I talked about previously.  I'm also going to put in a CV input, to go with a tap tempo unit I built based around the TAPLFO chip.  Mostly, though, I'm looking forward to making my own layout, because fitting all the components onto the board is like crack for an old Tetris addict like me.

Wow, you're all in! That's going to be fun. I'm tossing around the idea of doing another "deluxe" version with stereo in/out and a few other enhancements, but I'm so drained from working this layout every day for the past month that it might be awhile before I have the mental energy to tackle it.

Let me know if you come up with any new mods or tweaks you want to share and I can include them in the docs!

[dan.schumaker]

Not sure what your plan is for getting it off the breadboard and into a box, but if you can wait another 6-8 weeks I'll have a DC-2 DIY project ready to go. Just sent off for the prototypes this past Friday.



The PCBs are double-decker: signal & switching on the top PCB, clock & LFO on the bottom (with holes for top trimmer adjustment). 125B enclosure, all 1/4w flat-mounted resistors and standard box caps. Supports either stock buffered bypass (signal goes through pre-emphasis and de-emphasis filters) or minimally-buffered bypass (signal only goes through the first op-amp stage and is split to each output).

I don't mean to drop in and advertise... just one of those "if it were me I'd wanna know" situations

That looks like an amazing layout, I can see why you are so drained after working on it.  Excited to build it up when it is released.

[solderfumes]

Let me know if you come up with any new mods or tweaks you want to share and I can include them in the docs!

Probably the biggest thing I've found yet is to add some resistance in series before the input of the first NE570 (this is the compressor portion) to lower the gain of the compressor stage -- I used 62k.  This will help with the BBD distortion.  To compensate, change the jumpers connecting pins 6-7 and 10-11 on the second NE570 (the expander stages) to resistors, to increase the gain -- here I used 19.1k.  I might go even higher than these values too, as I'm still getting a tiny bit of distortion when I use a guitar with P90s.  Putting it after a distortion pedal could be ghastly!

For whatever reason, as I mentioned above, my BL3102s really want a small capacitance to ground hanging off their pin 7s, so that might be useful to include.  Not sure if that's just my board or not.

Maybe you've already figured this out, but somewhere I found a mention that pin 9 should not be tied to pins 10 and 11 on the first NE570.  I also got uncontrollable noise until I tied pin 12 to pins 10 and 11 on that NE570.

Lastly, I replaced R39 with a 10k resistor and R38 with a trimpot (which will be the depth knob on the finished product) to get my depth control, and I replaced R37 and R36 with a 10k resistor and a 500k reverse audio taper pot to get a rate knob.  Note, though, that you get lots of unusable settings with these values, so I leave it to someone with better taste than me to suggest better values for those

[alanp]

Nope, didn't even know about that one! Just a bunch of individual square pads. This method does have the advantage that you can put the pins anywhere on the schematic that you want - the pinhead library looks like it wants you to run the wires to it which could get a bit messy.

Easy fix for that is to use netlabels