DOD - FX25 Envelope Filter  [schematic]

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
tubehead123
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Post by tubehead123 »

Mbas974 wrote:Hi all, I'm very happy with my pedal I built some time ago, everything is working well.
One question related to this circuit but O.T.

Will it be possible tweak the circuit in order to not have the envelop ?
Let me explain... this pedal is extremely silent that only when I play sound come out... in other words it is a GREAT GATE pedal.
So I was wondering whether I can mod it to change it in a standard GATE without the envelop.

...hope it is clear.

it has low noise prolly due to two things - low gain to not make self-noise or increase any incoming noise and a filter to cut out any high frequency noise. also, the filter is at its lowest position with no input signal which is what you want for a noise gate. if you wanted to make it into more of a gate you would want the filter to be a lowpass (see my lowpass mod) and instead of using an envelope derived from the input signal level, use a square wave instead, e.g. as long as you have signal the filter is at max position.

HullorHell
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Post by HullorHell »

Hi All,

I've just been given a DOD FX25 pedal from a friend who got in a pickle trying to fix a broken wire and ended up doing a really bad job of rewiring it. I don't understand wiring schematics so I wondered if anyone had any pictures of the guts of this that they could share so I could trace where each wire should be?

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Gila_Crisis
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Post by Gila_Crisis »

I got again after ages a DOD FX25B, and I did few mods to it.
- C11 up to 22uF to have a better, not so quick decay.
- changed R5 from 20K to 10k, this solves the volume drop and gives the filter the bite many says is missing in the FX25B.
- BP/LP switch (with a volume trim on the LP side to have unity volume)
- since this filter is very similar to the Korg MS20 VCF, I added a switch to select betwenn the DOD envelope, or flipped it becames a fixed filter with the additional pot to set the cut frequency.

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Ichabod_Crane
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Post by Ichabod_Crane »

I built the circuit of the DOD FX25 on veroboard sometime ago, but I got a sort of huge boost of the bass just in the tail of the decay, making my amp vibrate! Then I completed the Snow White, veroboard. It's nice, but I guess the decay pot doesn't do anything. :hmmm:

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Gila_Crisis
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Post by Gila_Crisis »

Ichabod_Crane wrote:I built the circuit of the DOD FX25 on veroboard sometime ago, but I got a sort of huge boost of the bass just in the tail of the decay, making my amp vibrate!
That's the magic of the FX25 :mrgreen: :mrgreen: :mrgreen:
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