Understanding the EHX Y-Triggered Filter

Started by Mark Hammer, April 21, 2016, 09:37:36 PM

Previous topic - Next topic


OK, now really FINAL schematic and PCB files:

Most of 1u, 2u2 and 10u capacitors are MLCC. If you want to use electrolytic, please check polarity according to schematic. Please note that there are two SMD 100n caps beneath both ICs.

I still have some glitches on lower settings for C12 (Speed switch), which can be omitted increasing R40, or you can use DPDT On-Off-On switch and add some resistances at the second pole to change R40 value according to C12, so to maintain maximum range for Up/Down pot.

Please note that I have added R42 at the Filter switch, to reduce pop. It minimally affects the sound, but pop is significantly reduced. Maybe this could be done another way, I don't know?

Also, there are a few final notes not shown in a schematic:

  • R40 (9k1), R45 (22k) and R46 (jumper) are to be set to your taste, so the pedal doesn't pop when Up/Down pot is turned all the way CW.
  • C12 and C13 can be 2u2, 3u3, 4u7 or 6u8 (or any combination of those), just choose to your taste, but you can as well omit all of them together with Speed switch, C27, R46 and R40, in which case you simply install 15u at C12 and some resistance (in my case 5k1 was OK) at R45.
  • Depth can be any value from 2k to 10k, I used 5k. But you can also omit it and put a fixed value instead of it and R19, in which case I suggest 4k7 there, but you can also try lower values, to 1k.
  • I have finally installed R37, but it didn't affect the sound or filter behavior in any way, so I thinks it's safe to leave it out.
  • Width switch can be also omitted, in which case I suggest to short pins 2 and 3.
  • There's no BOM (I don't have time for that), so please note that all switches but Width and Range are On-Off-On, they are On-On.
  • All unmarked transistors on PCB are 2N5088. In case u want to use some from the BC family, remember to rotate them. PNP transistors are BC307/327 (I had a lots of them, so put them here), but you can use 2N5089 as well, in which case rotate them.
60 pedals and counting!