Looking For Digital Octave up

daeg

Well-known member
Also, this wasn't brilliant or anything. It was stupidly simple to rectify your signal (analog octave up) on the FV-1. You just ran through the absolute value instruction which IIRC was called MAX. The part that I got lost tweaking for days was the envelope detector and control to fade one signal out as the other came in.

I still think the concept has promise as both 'analog' and 'digital' octaves octaves have something that the other needs.
 

phi1

Well-known member
Yeah absolute value is ABSA, very simple, I’ve added that as an octave up to a couple patches with One of the knobs to blend it in. That’s clever though I never thought to try to combine with pitch shift to get the latency better.
 

RobertJay

Member
Another day... another question. I did order the arachnid and curious about the 1uf MLCC. What the hell is this? Monolithic? Multi layered? I have plenty of the small ceramic discs and the dipped yellow ones, but what are these? Are these those little box looking ones? Does it matter?
An online search for them keeps bringing up surface mount, those box looking ones I mentioned...
another edit....
I found them, small yellow caps that look just like the Ceramic dipped I have in stock. But, because I assume this is something I don't know... I'll buy them.
 
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phi1

Well-known member
Multi Layer Monolithic Ceramic. The dipped yellow ones (not the disc).

electricially the box film would work the same, but 1u size box type would be too big for the layout.

Search the build reports section, there’s lots of finished arachnid projects there with gut shots.
 

Dali

Well-known member
Multi Layer Monolithic Ceramic. The dipped yellow ones (not the disc).

electricially the box film would work the same, but 1u size box type would be too big for the layout.

Search the build reports section, there’s lots of finished arachnid projects there with gut shots.

Was doing it last night. Still smell solder (not really ;) )

1600357378743.png
 

RobertJay

Member
Hey, how do ya know what pot does what on this Arachnid for which effect? Is there a master sheet? A decoder? Instructions?
 

zgrav

Well-known member
it all depends on what program you are running on it at the time. You can see a list of the different programs in the drop down boxes here. I do not recall if there is a quick reference for what each of the controls does with each program.
 

RobertJay

Member
So, it's an octave up I suppose, but it sounds like a terrible attempt at 80's video game sounds. It flutters, sounds oscillating if that's the right word. Am I expecting too much from this? Suppose I should build another one, cuz that's whatcha do, right? haha. I did get the chip loaded with other effects, I'll test them tomorrow.
 

phi1

Well-known member
Yeah that’s just the way the fv-1 octave up patch is unfortunately, (I think we had a PM conversation about this a while back).

that fv-1 patch uses a pretty rudimentary form of octave up processing, which by nature has some latency and tremolo type artifact. DSP algorithms for higher quality octave up pedals use more advanced techniques (PSOLA for example). Maybe something like that would be technically possible on the fv-1, but likely the fv-1 wouldn’t be powerful enough.


so building another one would most likely give you the same result.
 

zgrav

Well-known member
the Daisy will eventually be a better platform for octave-up effects. will it be good enough for virtually no delay and clear sound? I don't know, but it will absolutely outperform the FV-1.
 

Dali

Well-known member
the Daisy will eventually be a better platform for octave-up effects. will it be good enough for virtually no delay and clear sound? I don't know, but it will absolutely outperform the FV-1.
My bet is also on "good enough" at least.

We just need to convince a coding Wizard to join the Terrarium platform ! (or maybe @PedalPCB ... It's a synonym) ;)
 

phi1

Well-known member
The daisy will definitely have more power, should be enough power for a very good octave up sound. But, as far as I understand it, the quality depends on the sophistication of the algorithm.

so if you ran the same type of rudimentary algorithm on the seed, I think you’d get a similar result, higher power alone (sample rate, resolution) wouldn’t fix it (again, my understanding).

But the daisy will have way more code lines allowed so a more advanced algorithm should be doable. Maybe there’s already some really good octave up algorithms for c++ that could be adapted for use with the seed?
 

RobertJay

Member
So, it's shit. We can agree on that. Digital, polyphonic, all that jazz...... Shit. It's ok. But the past year has taught me that I will be taking the guts out of 30 dollar harmony pedals and a 79 dollar TC Electronics Sub n Up so I can have an octave up in my build. BUT!!!! I now have quite the collection of octave fuzz's. I'm a real lemons into lemonade guy who can easily through these "failures" into a box with another Mod effect and get use out of em and 7 more prototypes. so.... yay? haha. Thanks . everyone here is always awesome.
 

RobertJay

Member
The Parentheses isn't what you want... The octave in that is essentially a Green Ringer.

This is the Arachnid project:

And this is where you get the custom EEPROM with the Dual Pitch Shifter algorithm:
And what say you?... The PEDALPCB admin who had chimed in with the original recommendation.... Might I have a defective chip? is this a reported issue? Clean sounds fuzzy and pitch shifted up sounds pingy and electronic.
 

phi1

Well-known member
If the clean sounds fuzzy then probably a build error. The dry signal has an analog path through and should never distort.
 

RobertJay

Member
Here's the build for comparison. I k ow wee were also talking caps back in the day. Maybe I used the wrong type of cap? Idk
 

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phi1

Well-known member
Couple things I noticed,

-the volume area seems weird. More Resistance between lug 1 & 2 boosts the output. Since you don’t have lug 1 connected, you Have infinite resistance, which would boost the op amp to being unstable I think. Unless you have it connected some way underneath the board.

-not having the control pots connected may do weird things to some of the patches. I don’t know exactly how it would behave, but I would look into that. For control 2 & 3 you only have 2 pads connected. Connecting all three pads to a potentiometer is the normal way (voltage divider sets the voltage going to the fv-1 pin).
 
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