Chuck D. Bones
Circuit Wizard
Has anyone besides K Pedals built An FX-53? I have a breadboard in the works...
This Week on the Breadboard: DoD FX-53
- Thread starter Chuck D. Bones
- Start date
Yup. Here's a thread about some mods Mark Hammer made Mods FX-53
Chuck D. Bones
Circuit Wizard
Good Stuff! Thanks.
The tone network is strange and can make a lot of bass boost when turned all the way up. The only thing I've changed so far is I've ditched the buffers at the input and output. DoD put them there to support the soft switching, same as what Ibanez & Boss do. If the soft switching is removed, then the buffers are superfluous.
The soft clippers do most of the work until GAIN is dimed. At low gain settings, the hard clippers barely conduct.
The tone network is strange and can make a lot of bass boost when turned all the way up. The only thing I've changed so far is I've ditched the buffers at the input and output. DoD put them there to support the soft switching, same as what Ibanez & Boss do. If the soft switching is removed, then the buffers are superfluous.
The soft clippers do most of the work until GAIN is dimed. At low gain settings, the hard clippers barely conduct.
Aentons
Well-known member
I tore into one and the others that use the same board a couple years ago and made some notes
https://www.madbeanpedals.com/forum/index.php?topic=32722.0
https://www.madbeanpedals.com/forum/index.php?topic=32722.0
Chuck D. Bones
Circuit Wizard
The potential changes that come to mind at the moment are asymmetric soft clipping and retuning/rewiring the active tone circuit. Gonna spend some time with it in stock form first. A W-taper TONE pot might be good too.
Chuck D. Bones
Circuit Wizard
I've farted around with this for a few days, so it's time to share. I'm not done yet, but I'm getting close.
Knobs (L-R): LEVEL - TONE - GAIN The toggle switch shorts out D5 for selecting between symmetric and asymmetric soft clipping. I prefer to run it with asymmetric soft slipping.
The basic circuit topology is unchanged, but I fiddled quite a few component values. Most importantly, the pots. GAIN should be C-taper for a smoother sweep. I reduced it to C250K because I wasn't using the bottom end of rotation. TONE should be W-taper for a smoother sweep. B-taper works, but W is better. I didn't have a W100K pot, so I rescaled the impedances in the tone circuit and used W20K. I also retuned the tone network for more boost in the mid to low treble range. Pretty clever circuit and I may use it in future designs. This thing is certainly bass-heavy. I reduced C1 & R3 to roll-off the the bass below 275Hz. I reduced C4 to provide additional bass cut when GAIN is dimed. I reduced C3 to brighten things up a bit. I added D5 for some mild asymmetrical clipping. Makes for a slightly richer midrange. I ditched R13 and increased the LEVEL pot to A250K. I may end up putting C1 on a switch. At low signal levels and/or GAIN settings, the clipping is asymmetric and makes mostly 2nd & 3rd harmonics. Kinda like overdriving a tube preamp. At higher signal levels or GAIN settings, D3 & D4 dominate and the clipping is symmetric. Kinda like overdriving a push-pull output stage. The transitions from clean, to asymmetric to symmetric are smooth.
This is the gain sweep, looking at U1-1.
This is the tone sweep from LEVEL-2 to the output. Below noon, it's a Bass Boost. Above noon, it's a Mid/Treble Boost.
At the end of the day, it's just another dirt pedal. But it's fun to experiment with and it might make a tone you like.
Knobs (L-R): LEVEL - TONE - GAIN The toggle switch shorts out D5 for selecting between symmetric and asymmetric soft clipping. I prefer to run it with asymmetric soft slipping.
The basic circuit topology is unchanged, but I fiddled quite a few component values. Most importantly, the pots. GAIN should be C-taper for a smoother sweep. I reduced it to C250K because I wasn't using the bottom end of rotation. TONE should be W-taper for a smoother sweep. B-taper works, but W is better. I didn't have a W100K pot, so I rescaled the impedances in the tone circuit and used W20K. I also retuned the tone network for more boost in the mid to low treble range. Pretty clever circuit and I may use it in future designs. This thing is certainly bass-heavy. I reduced C1 & R3 to roll-off the the bass below 275Hz. I reduced C4 to provide additional bass cut when GAIN is dimed. I reduced C3 to brighten things up a bit. I added D5 for some mild asymmetrical clipping. Makes for a slightly richer midrange. I ditched R13 and increased the LEVEL pot to A250K. I may end up putting C1 on a switch. At low signal levels and/or GAIN settings, the clipping is asymmetric and makes mostly 2nd & 3rd harmonics. Kinda like overdriving a tube preamp. At higher signal levels or GAIN settings, D3 & D4 dominate and the clipping is symmetric. Kinda like overdriving a push-pull output stage. The transitions from clean, to asymmetric to symmetric are smooth.
This is the gain sweep, looking at U1-1.
This is the tone sweep from LEVEL-2 to the output. Below noon, it's a Bass Boost. Above noon, it's a Mid/Treble Boost.
At the end of the day, it's just another dirt pedal. But it's fun to experiment with and it might make a tone you like.
Chuck D. Bones
Circuit Wizard
I'm done with this one. I tried switching caps For C1 and even with single-coil pickups, I prefer 1nF.
Aentons
Well-known member
Chuck, The FX53 values for R8 and C10 in the tone circuit put the filter around 234Hz and you raised yours to around 482Hz. The other 3 variants fx50,52,55 have it at 2.2kHz. Does the higher cutoff affect the circuit in any significant way other than just brightening it up a bit?
Chuck D. Bones
Circuit Wizard
You can see what it does in the figure above. R7 & C8 determine the upper cutoff freq of the Treble range. C10 affects the lower cutoff freq of the Treble range. C9 affects the upper cutoff freq of the Bass range. C11 affects the lower cutoff freq of the Bass range. There are some interactions, so I use LTSpice to figure out the exact freq response the Tone network.
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