Musicjsmith
Well-known member
After building the EQ pedal once I needed two more. I did one stock, and wanted another tuned a little lower for my bass. I play a 5-string most of the time, so being able to get the range down was part of the plan. I scoured the site to see if anyone had attempted a bass mod of this pedal but there wasn’t a complete build. There were a couple helpful threads that pointed me in the right direction, and a couple requests for Robert to put together a bass version, but nothing complete or fully thought through.
I took matters into my ignorant hands and went down the rabbit hole not knowing that most of the bands are gyrator circuits. After getting a little stumped, I found an online calculator for gyrator circuits and went to town. This build is the results of that for better or worse.
My aim was to lower the bands to have 2K Hz as the top end, followed by 1K, 500, 250, 125, and 63 as the six parameters. According to the calculator, I got them pretty close, but not exact. Close enough. Someone smarter than me can actually check the math. The mods required me to change resistors R10 through R20 and capacitors C5 through C14, and C16.
Also, pot values were lowered to B10K
R10 - 330R
R11 - 100K
R12 - 330R
R13 - 82K
R14 - 330R
R15 - 100K
R16 - 330R
R17 - 100K
R18 - 330R
R19 - 82K
R20 - 1K2 (although this looks to be the same as stock)
C5 - 82n
C6 - 2u2 (film capacitor)
C7 - 47n
C8 - 1u5 (film capacitor)
C9 - 22n
C10 - 470n
C11 - 12n
C12 - 220n
C13 - 5n6
C14 - 150n
C16 - 82n
All 6 Pots - B10K
The 2u2 and 1u5 box film capacitors were found at Tayda. Those were the only slightly out of the ordinary components.
I’ll try to get a playing demo soon, but in testing it did work and the low end was right in the meat of the low B. Here’s the photos.
The standard and bass version side-by-side
I took matters into my ignorant hands and went down the rabbit hole not knowing that most of the bands are gyrator circuits. After getting a little stumped, I found an online calculator for gyrator circuits and went to town. This build is the results of that for better or worse.
My aim was to lower the bands to have 2K Hz as the top end, followed by 1K, 500, 250, 125, and 63 as the six parameters. According to the calculator, I got them pretty close, but not exact. Close enough. Someone smarter than me can actually check the math. The mods required me to change resistors R10 through R20 and capacitors C5 through C14, and C16.
Also, pot values were lowered to B10K
R10 - 330R
R11 - 100K
R12 - 330R
R13 - 82K
R14 - 330R
R15 - 100K
R16 - 330R
R17 - 100K
R18 - 330R
R19 - 82K
R20 - 1K2 (although this looks to be the same as stock)
C5 - 82n
C6 - 2u2 (film capacitor)
C7 - 47n
C8 - 1u5 (film capacitor)
C9 - 22n
C10 - 470n
C11 - 12n
C12 - 220n
C13 - 5n6
C14 - 150n
C16 - 82n
All 6 Pots - B10K
The 2u2 and 1u5 box film capacitors were found at Tayda. Those were the only slightly out of the ordinary components.
I’ll try to get a playing demo soon, but in testing it did work and the low end was right in the meat of the low B. Here’s the photos.
The standard and bass version side-by-side
