Seppuku FX

[K2000]

I bought a Pinch Delay. I'm not great at digging deep into equipment features (or explaining equipment) but my initial report:

There's no Level or mix knob. Also no EQ knob. My unit has a "bonus feature" toggle switch for 100% wet (versus wet/dry mix). The default wet/dry mix seems to be well balanced, and the default EQ seems to let the repeats sit nicely with the clean signal (seems like a slight rolloff on bass frequencies). It's a nice sounding delay at normie settings, and the mild-to-medium 'pinch' settings sound cool. But there are some settings where the pedal makes terrible clicks and clacks (seems like the Sensitivity and Modulation knob going above noon can cause this). I'm not sure - the knobs are interactive - but there are some unusable settings. I think that's fine, as milder settings are still pretty interesting. But it's a pedal that you can't just turn knobs up all the way and be delighted - you have to pick your settings more carefully than that. Otherwise there are clicks and clacks that are unworkable.

Mine has a 2nd bonus features: a pushbutton for a circuit bend which "removes the hystersis on the comparator making it flicker/glitch as it changes states". I don't know what that means. I haven't experimented with this very much yet, it's more of a tabletop feature and I'm currently using it while playing guitar so both hands are busy.

I'm a total noob with this pedal and I'm hoping there will be some YouTube demos so I can get a better handle on this unit. I'm a long-time user of the Kassette which I love, but the Kassette's most interesting effects aren't always useful... for example when playing regular music in an ensemble, it's more suited to playing experimental stuff. The Pinch seems like it can do some strange and delightful things while playing in a conventional music context.

[Chankgeez]

https://reverb.com/item/89018354-seppuk ... nd-painted

[Pepe]

I already saw that and I told the seller that I suspect that the PT2399 needs to be swapped - as so often in Rhys' models! His circuits seem to tickle the delay IC in a matter that is not always too safe. I have a few PT2399 around in case that something bad happens.

[Chankgeez]

[moid]

I already saw that and I told the seller that I suspect that the PT2399 needs to be swapped - as so often in Rhys' models! His circuits seem to tickle the delay IC in a matter that is not always too safe. I have a few PT2399 around in case that something bad happens.

Hi Pepe
If the PT2399 has stoped working you might not need to swap it out - you might just need to perform an anti latch up trick instead. I've only built two of Rhys' pedals from schematics I've found online (Mind Warp and Memory Loss) but both of these seem (to my inexperienced eyes) to not apply enough resistance to pin 6 of the PT2399 when the pedal is powered on. I'm sure this is deliberate to help the pedals behave in that marvellously 'seppuku' fashion, but some PT2399 chips can handle this and some can't. What should happen (if you are using a PT23999 chip in a sensible, boring fashion) is that the circuit should contain a 2K resistor that connects pin 6 of the chip to ground. When the pedal is switched on, this extra resistance (which is only required for 400ms after powering on) tells the chip to work 'properly' and that everything is OK. From what I can tell neither of the above mentioned circuits that I've built have this because adding the 2K resistor limits the minimum time delay on the pedal. With some of Rhys's designs, setting the delay pot to be in the middle of its turn will ensure that the resistance to ground for pin 6 should be well above 1 -2K for the 400ms the chip needs it to be - you can then change the delay time to whatever you like (the delay pot is connected to pin 6 of the PT2399 in both theabove mentioned circuits)

Another technique (if the pot doesn't work) requires you to open the pedal up and temporarily connect a 2K resistor from pin 6 to ground in the pedal (you'll probably want to use some crocodile clips on leads to do this). Hold that in place, plug the power in and turn the pedal on and that should jump start it - you can now remove the 2K resistor and put the backplate of the pedal back on, and everything will be fine until you remove power to the pedal. Hmmm just had a thought, just connecting pin 6 to pin 3 with the 2K resistor might achieve the same effect, because pin 3 of the PT2399 needs to be connected to ground, and that's such a short distance that you wouldn't need any extra leads and crocodile clips!

If this is a persistent issue, some people have built anti-lockup or anti-latch up daughter boards to solve the problem - there is a schematic for one on the electrosmash website, scroll down to anti-latch up circuit https://www.electrosmash.com/pt2399-analysis. I could probably draw that on a vero layout if that would help you? That circuit fixes the resistance issue just when the pedal is turned on and then does not affect the circuit afterwards so the delay time can go as short as the circuit can go.

[Pepe]

If the PT2399 has stoped working you might not need to swap it out - you might just need to perform an anti latch up trick instead. I've only built two of Rhys' pedals from schematics I've found online (Mind Warp and Memory Loss) but both of these seem (to my inexperienced eyes) to not apply enough resistance to pin 6 of the PT2399 when the pedal is powered on. I'm sure this is deliberate to help the pedals behave in that marvellously 'seppuku' fashion, but some PT2399 chips can handle this and some can't. What should happen (if you are using a PT23999 chip in a sensible, boring fashion) is that the circuit should contain a 2K resistor that connects pin 6 of the chip to ground. When the pedal is switched on, this extra resistance (which is only required for 400ms after powering on) tells the chip to work 'properly' and that everything is OK.

Wow, that's great information! Then it could also be sufficient to install a small momentary switch that connects the 2k resistor (soldered to pin 6) with the ground, right? So for powering the pedal on, hold the momentary switch button, put the power plug in and release the button after a second. Could that be an elegant solution?

[moid]

Yes that sounds possible! I would test this before drilling a hole in the enclosure though. Also check to see if there is space inside the enclosure for a switch. Which pedal of yours has issues?

By the way I read last night that some people think you only need a 1k resistor. Not sure if that matters to you or not!

[Pepe]

None of my pedals is having an issue, because they are equipped with solidly working PT2399 chips. But it is great information for problems that might occur in the future. I threw a few Princeton chips in the bin, because they simply didn't work in my Seppuku Dynamic Echo Modulator. I wonder if that jumpstart method had worked with any of those chips.