# Looking For Digital Octave up



## RobertJay (Sep 15, 2020)

I am looking for an Octave Up PCB to be used in a combo pedal for bass distortion. I am unhappy with Green Ringers and other Octave Fuzz circuits. I want Digital Octave up with blend feature, or at least octave up and dry signal being out out. 
What happens when I turn the Dist down on the Parentheses Mini Fuzz? Is it clean octave?
Any Suggestions?
I was referred here to look at the Arachnid V2 with custom EEPROM patch - PIT001, but can't find it...
and another recommended I look into the FV-1 boards to use as a dual pitch shift for octaves, but can't find that specifically either.....


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## Robert (Sep 15, 2020)

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

This is the Arachnid project:








						Arachnid MultiFX Platform - PedalPCB.com
					

FV-1 Digital MultiFX




					www.pedalpcb.com
				




And this is where you get the custom EEPROM with the Dual Pitch Shifter algorithm:








						EEPROM Builder - PedalPCB.com
					

Custom Programmed EEPROM




					www.pedalpcb.com


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## zgrav (Sep 15, 2020)

Also note you will have some delay on a board that uses the FV-1 chip for any pitch shift.


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## RobertJay (Sep 15, 2020)

Robert said:


> The Parentheses isn't what you want...   The octave in that is essentially a Green Ringer.
> 
> This is the Arachnid project:
> 
> ...


Thank you. Such a big help. With that extra chip, I noticed the options to purchase and have installed up to 10 digital effects, yes? And would these different effects all work independently one at a time? Or can I have the pitch shift, with chorus and a digital delay all at the same time off of this? I'm assuming it's a one at a time selector switch type of use.


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## RobertJay (Sep 15, 2020)

zgrav said:


> Also note you will have some delay on a board that uses the FV-1 chip for any pitch shift.


Delay as in it sounds as if I'm using a delay effect? Or a lag or latency between the original note and the affected note?


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## Robert (Sep 15, 2020)

You can have up to eight.    One at a time, selected by the 8-position rotary switch.

What zgrav is referring to is a fair amount of latency in the pitch shift algorithm.     It's not _horrible_, but it's noticeable.

It won't perform in the same league as a DigiTech Whammy or anything like that, but it's pretty much the only true clean octave you can get as a DIY project.


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## zgrav (Sep 15, 2020)

Sorry for not being clear.  I should have said latency instead of delay.


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## RobertJay (Sep 15, 2020)

zgrav said:


> Sorry for not being clear.  I should have said latency instead of delay.


I was also just turned on to the Octagon multi fx build. It boasts 8 point rotary switch but doesn't offer one with the 20 dollar chip. Comes with? 
And I see more than 1 build can get me there. The Arachnid with the eeprom or the Octagon that comes w the ability built in?


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## zgrav (Sep 15, 2020)

the arachnid is the PCB that uses the FV-1 chip but it does not include the eeprom chip with the 8 different sound programs.  you order one or more of those separately and select the programs from a list that you want to have on the eeproms. 

the octagon is the same PCB but it comes with one eeprom chip that has 8 programs already on it.  you can also order extra eeproms with custom programs to use with that board by changing the eeprom in the socket on the board.

when you order the PCB for an FV-1 project you can order it with the FV-1 chip already soldered in place by just paying the extra charge for the FV-1 chip.


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## RobertJay (Sep 16, 2020)

Sorry for the confusion, but do both of these pcb's require the EEPROM IC? I see spots on each board for one, The arachnid has advises that the additional IC must be purchased, the Octagon comes pre loaded, but how? Is an EEPROM included? not needed? please advise.


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## RobertJay (Sep 16, 2020)

And... Do both pcb's require the purchase of additional 8 point rotary switch? The Arachnid offers the 2 dollar addition at purchase the Octagon does not.


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## phi1 (Sep 16, 2020)

I think zgrav summed it up well, but it is confusing, I had to ask a lot of questions the first go too, So no worries.

both require purchase of the fv-1. Both require the 8way rotary switch. The octagon includes the eeprom as part of the order (Hence the higher cost). For the arachnid, you need to go the the eeprom section and build a custom eeprom (pick out your patches). You can also order more eeprom chips from that page and swap them in and out in your build, just be sure to put a socket where the eeprom chip goes.

the arachnid, octagon, module8, and spatialist reverb are all the EXACT same pcb and are constructed the same way. They all have the same build doc. The only difference is the eeprom chip where the code for the patches is stored.


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## RobertJay (Sep 16, 2020)

Man O Man! Thanks. I thought so, but have to ask to clarify. Now that we have that established. If you can believe it, I'm interested in this just for the digital octave capability. It's very hard to find a good octave circuit that isn't fuzz, needs to be played around the 12th fret and the bridge pickup to hear the effect. I'm building a prototype for a bass distortion pedal with octave and chorus, maybe even some delay.  Too bad I can only get 1 effect at a time out of this. haha. Now, if I only want to use this circuit for the octave up and dry signal.... Do I even need the rotary switch? I'm sure I can place a jumper between 2 pads and call it a day... thoughts?
also, I would say that there is absolutely NO way to use more effects at one time, but if I could.... How? 
Thanks again to all, very helpful.


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## phi1 (Sep 16, 2020)

For sure, you could leave out the rotary switch and diodes. This would default the fv-1 to read patch 0. Just load that the pitch shift patch as patch 0 on your custom eeprom.

there’s a lost the Pythagoras board, which is designed to only have 3 modes instead of 8.

look into the organ donor project, it has octave and kind of a chorusy type thing built in, check out the videos of the eqd organizer.

you can’t use more than one patch at a time. But, you could write a patch that has multiple functions within it. There is some limitation in the amount of code you can jam into one patch, but I think octave up and chorus or delay would be very doable. There is also the limitation of only 3 controls. But there are some ways to work around that.

I’ve gotten pretty handy at writing fv-1 code from scratch, PM me and if that sounds interesting to collaborate on.


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## RobertJay (Sep 16, 2020)

More answers and another question. Leave the diodes out? Sure, I won't be using them. I was going to ask about these builds and their instructions. Do they come with any? Is there a guide to tell a builder what components are being used for what? Do I need the Crystal if not using the reverb? What about the 78L33. And as with the diodes, if omitting them... a jumper? or simply omit? Suppose the schematic would tell me, but why not ask to confirm? 
Yes I am curious about custom eeprom code. Will discuss. Thanks


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## phi1 (Sep 16, 2020)

Study the fv-1 datasheet (just google for it) to understand how each component in the arachnid functions. The Pedalpcb build docs do go into any detail about the “why” because they’re assuming you’re building as designed.

but basically, you need the crystal and 3v3 supply to run the fv-1 regardless of patch. For single patch 0, just omit rotary and those 9 diodes, no need for jumpers.


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## zgrav (Sep 16, 2020)

If you are not an experienced builder, I would suggest finding the project that best fits your ideas and build it according to spec.  the differences in parts cost for what you would change or leave out are very small, and the likelihood of messing something up when you build it is much higher if you are changing things along the way. It is a bit more difficult to get help from others on the forum if you need it if something is not working.

the suggestion to look at the Organ Donor was a good one.  take a look at the project, look at the build doc and you will see you basically get a parts list and schematic.  you do not get an assembly guide, nor something thatanswers the kinds of questions you are asking and explains how the circuit works.  you can find general information like that if you do some searching on the internet.    see if you can find some videos of the organ donor being used, or for the EQD Organizer that it is similar to.  https://www.google.com/search?client=firefox-b-1-d&q=eqd+organizer

After you successfully build some kind of FV-1 pedal you will be in a much better position to know if the latency in the chip is acceptable for how you want to use it, and you will have an idea of what other kinds of effects, if any, you would like to have in your next version of the pedal.


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## RobertJay (Sep 16, 2020)

AWESOME AWESOME!!!!


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## phi1 (Sep 16, 2020)

Good advice from z. If you get a custom eeprom, consider trying out 2 different chorus types to see which you like.

MOD001 is a standard type chorus, where pitch vibrato is mixed which dry signal.

UNI001 is a different type of chorus where a slight detune up and down is constantly applied, but it doesn’t warble back and forth. Comes from the unison Double tracker project, which is not a copy but some similarities with the Keeley 30ms pedal.


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## daeg (Sep 16, 2020)

A couple months ago I was playing around with FV-1 code to use an envelope controlled rectifier to hide the latency of the crossfade pitch-shift / digital octave algorithms.

Basically, a (filtered) Green-Ringer esque sound would be over your attack, then fade out as the delay based Pitch-Shift faded in. No perceived latency. Gave the attack a touch of that screaming analog octave punch, but without the nasty intermodulation on sustained notes, double-stops, chords, etc that make analog octaves unusable in most musical contexts.

Got busy with work and never finished it. I'll be moving onto the Daisy soon and probably won't look back.


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## daeg (Sep 16, 2020)

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.


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## phi1 (Sep 16, 2020)

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.


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## RobertJay (Sep 17, 2020)

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 (Sep 17, 2020)

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.


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## Dali (Sep 17, 2020)

phi1 said:


> 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  )


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## RobertJay (Feb 9, 2021)

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


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## zgrav (Feb 9, 2021)

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.


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## phi1 (Feb 9, 2021)

EEPROM Builder - PedalPCB.com
					

Custom Programmed EEPROM




					www.pedalpcb.com
				




there’s a chart at the bottom


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## RobertJay (Feb 10, 2021)

YES YES YES, thank you! There it is!


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## RobertJay (Feb 10, 2021)

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.


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## phi1 (Feb 10, 2021)

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.


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## zgrav (Feb 10, 2021)

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.


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## Dali (Feb 10, 2021)

zgrav said:


> 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)


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## phi1 (Feb 10, 2021)

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?


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## RobertJay (Feb 12, 2021)

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.


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## RobertJay (Feb 12, 2021)

Robert said:


> The Parentheses isn't what you want...   The octave in that is essentially a Green Ringer.
> 
> This is the Arachnid project:
> 
> ...


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.


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## phi1 (Feb 12, 2021)

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


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## RobertJay (Feb 12, 2021)

phi1 said:


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


Dry is good. Dry is Dry. Bypass is clean. But the Mod FX like chorus and phaser sound fuzzy.


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## RobertJay (Feb 12, 2021)

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 (Feb 12, 2021)

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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## Robert (Feb 12, 2021)

RobertJay said:


> Clean sounds fuzzy and pitch shifted up sounds pingy and electronic.



It shouldn't be fuzzy.   Definitely look into the things phi1 suggested, especially the (possibly?) missing volume pot.   

The pitch shifting may never meet your expectations.  Like I mentioned back in post #6, it's far from perfect, but it shouldn't be fuzzy.


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## RobertJay (Feb 16, 2021)

All very interesting. I have the same performance with and without the pots. This circuit is for a multi effect box and one of them being an octave up w the dry out too. So, pitch 1 is off, pitch 2 is max, blend is set for the pitch 2. I used my meter and then gave the terminals to same as if I had the pots. 0 ohms where fused and Infinity where I left open. No? Does it not work like that? Because my removal of the pots changed nothing. It did exactly what I wanted it to do. It sounded pingy and weirds anyway. 
That's an interesting question though... Can I remove pots if they are just gonna sit at max or min. All or nothing... So just solder it like t hat.... That's what we have here.


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## RobertJay (Feb 16, 2021)

phi1 said:


> 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).


Yeah those pots are either all the way min or all the way max, set it and forget it. So I jumped the 2 pads that give me 0 ohms and left the one that was infinity. Maybe not that simple? Made total sense to me the other day. haha


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## RobertJay (Feb 16, 2021)

Robert said:


> It shouldn't be fuzzy.   Definitely look into the things phi1 suggested, especially the (possibly?) missing volume pot.
> 
> The pitch shifting may never meet your expectations.  Like I mentioned back in post #6, it's far from perfect, but it shouldn't be fuzzy.


And the vol pot, in particular actually confused me. It never did anything. It had no control or changed a thing with this build.


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## zgrav (Feb 16, 2021)

try connecting the unused control pins to ground and see if that changes anything.    what is your expectation for the pitch shift function with the fv-1?  if you are hoping for a real-time pitch shift the chip cannot deliver.  it is good for shifting any delayed repeats but falls a bit short for real-time shift.


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## phi1 (Feb 16, 2021)

For the vol pot area, the resistance that matters is between lug pad 1-2. Lugs 2-3 are connected together. If you don’t want to adjust the volume, you can put a resistor between lugs 1-2 (experiment to find the value resistor for the volume you want).

for the control pots, I didn’t know if leaving them unconnected would make a difference, just seems like bad practice to leave them open. Link either lug pad 1-2 (control at minimum) or lugs pads 2-3 (control at maximum). I think that’s maybe what you described.


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