Tricked-out older Arachnid (relay bypass, clock module, dry/wet out)

[p_wats]

I've got a couple of the older Arachnid boards laying around (pre-rotary switch), as my wife really prefers the rotary knob for selection patches for her synth setup (I built this double pedal for her a while back), so I figured I'd box one up for myself and try some mods.

• I added the relay bypass board and connected it with pin headers, which makes it super convenient to do. I also did some changes to the filtering to make it more like the newer boards in that regard (not sure i notice a huge difference compared to the super old one I have, but worth a shot).

• The clock module is something I've had kicking around for a while. In this case I added an external pot instead of the trimmer and used a switching jack to allow for an expression pedal input, which is a lot of fun.

• I also used a stereo output jack with the ring connected to pin 1 of IC1 in series with a 1k resistor and 1UF capacitor, for a dry output via an insert cable, which is great for some of the weirder FV-1 patches I've been playing with.

Nobody needs to see the under side of the board . All told, it's a full build that is a lot of fun to mess with.

 

[p_wats]

I decided there was room to cram a toggle behind the last row of pots under the input jack, so I added an SPST to give the option of grounding Pin 13 (at R5) to enable stock FV-1 programs. This way I can load up the EEPROM with weird nonsense, but still have access to a reverb or tremolo if needed.

 

[Chuck D. Bones]

Looks great! Cool paint job. Snug fit.

 

[p_wats]

Looks great! Cool paint job. Snug fit.

Thanks! Unfortunately I think I may have killed it while attempting one more mod (adding a daughter board to switch between 2 EEPROMS). We'll see if I can revive it. I've got another old Arachnid board kicking around I could use to recreate it the same guts if needed.

 

[Chuck D. Bones]

You'll fix it. Probably just a solder splash or broken wire.

 

[p_wats]

You'll fix it. Probably just a solder splash or broken wire.

Thanks for the vote of confidence. I wish! Signal goes in to the FV-1 (pins 1 & 1), but none comes out (pin 28). Power seems to be getting to the chip fine (confirming via where power/ground is supposed to be on the schematic). Alas.

 

[SYLV9ST9R]

On a side note, how would I go about making the clock module switchable (connections and switch I would need? Just ordered the arachnid and the clock module and I would like that option, but I'm still pretty new at this.

 

[zgrav]

honestly, I don't see a benefit to making the clock module switchable, at least if you select a spot on your pot rotation to be your default position. probably 12 o'clock so you can speed up or slow down. switching to the crystal would be equivalent to just not moving the pot from your default position.

 

[Chuck D. Bones]

Check the clock.

 

[p_wats]

Check the clock.

Good idea. I'm pretty sure my problem stemmed from the expression jack for the clock not connecting properly.

Things are a little better now, but there's a loud squeal with the wet signal that I need to track down.

On a side note, how would I go about making the clock module switchable (connections and switch I would need? Just ordered the arachnid and the clock module and I would like that option, but I'm still pretty new at this.

I agree with @zgrav. I was going to try to switch the clock module in/out, but upon testing it didn't seem worth it, as it's not hard to get a "normal" sound with the module left in a stationary position.

 

[Chuck D. Bones]

honestly, I don't see a benefit to making the clock module switchable, at least if you select a spot on your pot rotation to be your default position. probably 12 o'clock so you can speed up or slow down. switching to the crystal would be equivalent to just not moving the pot from your default position.

The advantage of the XTAL is frequency stability which translates to a lower noise floor. If the variable clock module sounds good enough, that's all that matters.

 

[SYLV9ST9R]

Thanks for the reply guys, will go with only the clock.