Yesterday I finished my Ember Boost, a clone of the TC Electronic Spark Boost (the four knob, full-size version). I tried to avoid electrolytic caps in the signal path, preferring film caps instead (for extra mojo). As you can see, this makes things a bit crowded. For the power supply filter, I didn't have a 220uF on hand, but I did have a 330uF organic polymer, surely the extra low ESR adds some mojo. The build doc calls for OPA2134 opamps, which I didn't have on hand, and are pretty expensive to boot. I initially started out with NE5532 chips, that's what's shown in the pictures. I later switched to the good ol' TL072, I thought maybe that made the pedal a bit "crispier" (I think I read, the OPA2134 is FET input, and I believe TL072 is also FET input, but if I'm not mistaken, NE5532 is BJT input, maybe there's something there?).
Anyway, in reality, I suspect capacitor chemistry doesn't make a massive difference here either way. And I don't think the opamps are a big part of the sound either. I did a few more mods though that might be more interesting:
Lastly, as you can see, I socketed all the clipping diodes. This pedal has three 1n914 diodes in series in each direction (total of six). My goal for this pedal is to have a kind of "swiss army knife" that can help me adapt to different guitars, amps, and even bands. I want something that can do some general boosting, some midrange boosting, light overdrive, and EQ. I haven't been able to test this pedal in a band setting yet, but at-home testing suggests it certainly has it's foot in all three roles (boost, EQ, light overdrive). I used sockets for the clipping diodes to experiment with shifting the pedal more into the overdrive category. With a single 1n914 in each direction, as you might expect, it basically becomes a straight-up overdrive pedal (still not super high gain, but considerably more than stock). The tradeoff is the boost capability is mostly lost, because it clips too much signal and therefore volume. I also tried with a single red LED diode in each direction, and I thought that might be the best compromise. But then I played side-by-side against the real Spark, and started second-guessing myself. If I was really motivated, I'd put another switch on the pedal to allow different clipping configurations to be selected on the fly. For now, I'm keeping the clipping diodes in the stock config (2x3x1n914), and just live with it for a while.
Anyone have any other suggestions for a pedal that can straddle three roles like this? There's lots that do boost, light overdrive and EQ (e.g. Timmy is popular for this), but few have the ability to tweak the mids on the fly.
Anyway, the cover art is the no-film waterslide decal on an unfinished aluminum enclosure. I think it looks decent!
Anyway, in reality, I suspect capacitor chemistry doesn't make a massive difference here either way. And I don't think the opamps are a big part of the sound either. I did a few more mods though that might be more interesting:
- I used a socket for C19, but left it unpopulated. This was mentioned in this thread. I haven't tested with a C19 populated. I own the actual COTS TC Spark Booster, and with C19 omitted, and my build sounds so close that I don't feel it's worth taking the time to experiment. Plus I'm saving a few pennies by using one less component!
- I socketed C10, per this thread. That's Chuck's post where he first suggested the C19 omission, and also the C10 mod, reducing from 1n to 100pF. I went straight to 100pF, and like the C19 omission, it sounds good and close enough to the real Spark that I don't plan to experiment with it.
Lastly, as you can see, I socketed all the clipping diodes. This pedal has three 1n914 diodes in series in each direction (total of six). My goal for this pedal is to have a kind of "swiss army knife" that can help me adapt to different guitars, amps, and even bands. I want something that can do some general boosting, some midrange boosting, light overdrive, and EQ. I haven't been able to test this pedal in a band setting yet, but at-home testing suggests it certainly has it's foot in all three roles (boost, EQ, light overdrive). I used sockets for the clipping diodes to experiment with shifting the pedal more into the overdrive category. With a single 1n914 in each direction, as you might expect, it basically becomes a straight-up overdrive pedal (still not super high gain, but considerably more than stock). The tradeoff is the boost capability is mostly lost, because it clips too much signal and therefore volume. I also tried with a single red LED diode in each direction, and I thought that might be the best compromise. But then I played side-by-side against the real Spark, and started second-guessing myself. If I was really motivated, I'd put another switch on the pedal to allow different clipping configurations to be selected on the fly. For now, I'm keeping the clipping diodes in the stock config (2x3x1n914), and just live with it for a while.
Anyone have any other suggestions for a pedal that can straddle three roles like this? There's lots that do boost, light overdrive and EQ (e.g. Timmy is popular for this), but few have the ability to tweak the mids on the fly.
Anyway, the cover art is the no-film waterslide decal on an unfinished aluminum enclosure. I think it looks decent!
