Post by ashcatlt on Oct 1, 2012 22:34:01 GMT -5
I finally got around to building my booster pedal! I've had most of the parts laying around for over a year, but...you know...excuses...
If you look at the schematic:
you may notice that it's very similar to Dave's Boost A/B pedal with a couple of differences:
1) I didn't need the input switching, so I used that half of Sw1 for an LED indicator instead.
2) Added a switch (Sw3 "Scream" here) to drop a couple of back-to-back diodes across the feedback loop for "soft clipping" ala the TubeScreamer type OD pedals.
3) Added 1K in and out resistors (R4 and R6) for "best practice" reasons. Not sure exactly what R4 does, but the R6 will limit the current demand and help keep the opamp form destroying itself in the unlikely event that the output is shorted.
4) Added D1 (1N4002) for reverse polarity protection. This is not the way you normally see these things installed. I prefer real protection, rather than Boss's warranty gotcha scheme.
5) In Dave's I used a TL071 for the opamp which is internally compensated. In this one I used a TL080, and the 180pF compensation cap is the same that I used in my Rat clone. It's supposed to slow the slew rate down to somewhere close to the original Rats. Can't say for sure what it does to the sound here. The opamp is socketed. Maybe someday I'll drop in an 071 and see if I can hear a difference. I expect it's something very subtle, and only really has an impact at the highest gain levels.
6) C9 is 18pF rather than 15 because it's what I had. In Dave's I think I actually used 2 x 30pF in series.
Here's the gutshot:
Yes, that's without the opamp installed. No, you can't see the solder side nor the offboard wiring.
This is the first pedal I've done with anything resembling real graphics. Laser printed onto a sort of vinyl sticker stock. Eventually I might spray it with some clear coat, but I may have to re-print the sticker first. It is mildly NSFW, so here's a link.
I haven't really done much with it yet except to plug it in to make sure everything works as expected. It sounds pretty darn good through my AC4. The OD setting of the "Scream" switch is pretty cool. Not super distorted, just a bit edgy, with some interesting clarity that leaks through in a way that's pretty different from what my Rat does. I guess you could call it "transparent" or something. It doesn't sound much like the TS, though, until you flip the "Squeal" switch. Also, with the trimpots (R7 and R9) set where they are now the total gain doesn't get quite to where a TS would. All in all I'm pretty happy with it. I finally will have boobies on my pedalboard, and I can give my brother his Boss TurboFuzz back!
If you look at the schematic:
you may notice that it's very similar to Dave's Boost A/B pedal with a couple of differences:
1) I didn't need the input switching, so I used that half of Sw1 for an LED indicator instead.
2) Added a switch (Sw3 "Scream" here) to drop a couple of back-to-back diodes across the feedback loop for "soft clipping" ala the TubeScreamer type OD pedals.
3) Added 1K in and out resistors (R4 and R6) for "best practice" reasons. Not sure exactly what R4 does, but the R6 will limit the current demand and help keep the opamp form destroying itself in the unlikely event that the output is shorted.
4) Added D1 (1N4002) for reverse polarity protection. This is not the way you normally see these things installed. I prefer real protection, rather than Boss's warranty gotcha scheme.
5) In Dave's I used a TL071 for the opamp which is internally compensated. In this one I used a TL080, and the 180pF compensation cap is the same that I used in my Rat clone. It's supposed to slow the slew rate down to somewhere close to the original Rats. Can't say for sure what it does to the sound here. The opamp is socketed. Maybe someday I'll drop in an 071 and see if I can hear a difference. I expect it's something very subtle, and only really has an impact at the highest gain levels.
6) C9 is 18pF rather than 15 because it's what I had. In Dave's I think I actually used 2 x 30pF in series.
Here's the gutshot:
Yes, that's without the opamp installed. No, you can't see the solder side nor the offboard wiring.
This is the first pedal I've done with anything resembling real graphics. Laser printed onto a sort of vinyl sticker stock. Eventually I might spray it with some clear coat, but I may have to re-print the sticker first. It is mildly NSFW, so here's a link.
I haven't really done much with it yet except to plug it in to make sure everything works as expected. It sounds pretty darn good through my AC4. The OD setting of the "Scream" switch is pretty cool. Not super distorted, just a bit edgy, with some interesting clarity that leaks through in a way that's pretty different from what my Rat does. I guess you could call it "transparent" or something. It doesn't sound much like the TS, though, until you flip the "Squeal" switch. Also, with the trimpots (R7 and R9) set where they are now the total gain doesn't get quite to where a TS would. All in all I'm pretty happy with it. I finally will have boobies on my pedalboard, and I can give my brother his Boss TurboFuzz back!
