FV-1 Multi effect full forum project ready to go. (ShimmerVerb Also)

[cloudscapes]

edit: oops, posted in wrong thread

[Stroszek]

Hello people.
I'm new at this forum. I've spent LOTS of hours of the last weeks reading about FV-1 based stompboxes. I've read every page of this particular topic.
I don't know if I miss something, but I have a couple of questions:
-the effect discussed here digitise the entire signal, am I right?
-the bypass is TB, analog buffered or is even digitised?
-Is there a way to make the FV-1 act in an "only wet" way, so I can add an analog mixer circuit or a "split 'n blend" circuit?
I'm looking for reverbs and echoes, specifically, and maybe some flanging/phasing/chorus, so I think the analog mixing/blending must work. I clarify this because I've know a tremolo, for example, wouldn't work properly.
I've downloaded the one-sided PCB layouts (both, the one with pots and switch on board and the other), I know a local distributor who sells the fv-1 chip, so I'm almost ready.
In the other hand, I've got a friend who is also a DIY enthusiast and is an Informatic Engineer, so he can help me to program the chip. Of course every advance on this project will be shared with you in this forum.
Thank you very much.

[Ice-9]

Hello people.
I'm new at this forum. I've spent LOTS of hours of the last weeks reading about FV-1 based stompboxes. I've read every page of this particular topic.
I don't know if I miss something, but I have a couple of questions:
-the effect discussed here digitise the entire signal, am I right?
-the bypass is TB, analog buffered or is even digitised?
-Is there a way to make the FV-1 act in an "only wet" way, so I can add an analog mixer circuit or a "split 'n blend" circuit?
I'm looking for reverbs and echoes, specifically, and maybe some flanging/phasing/chorus, so I think the analog mixing/blending must work. I clarify this because I've know a tremolo, for example, wouldn't work properly.
I've downloaded the one-sided PCB layouts (both, the one with pots and switch on board and the other), I know a local distributor who sells the fv-1 chip, so I'm almost ready.
In the other hand, I've got a friend who is also a DIY enthusiast and is an Informatic Engineer, so he can help me to program the chip. Of course every advance on this project will be shared with you in this forum.
Thank you very much.

Hello Stroszek,

1. Correct the entire effect passes through the FV-1 chip so is all digitized.
2. The TB is true bypass and bypasses everything inside the pedal.
3. Yes you can design the circuit so that the dry signal is totally analogue and the effect (wet) is independent of the dry.
4. Check out the Spinsemi website and forums for lots of programs and code examples.

[micahvdm]

Hey Mick
Any chance you're selling the pcb's for this project? How much would you be selling them for?

[Ice-9]

Hey Mick
Any chance you're selling the pcb's for this project? How much would you be selling them for?

All the pcb's I had made are all gone now, and as I made quite a few updates to the original circuit I won't be getting any more made for now. I have uploaded the original pcb that goes with this thread to oshpark and they can be ordered from them if you want one.  Just search for ice-9 projects, the little switch daughter board and a fv! dev pcb is also up there.

[grenert]

Just want to report that another Ice-9 FV-1 Multi-effect is alive thanks to Mick and Ian!   
I followed the standard build (using the very nifty switch/resistor board) except for adding an extra switch to select the internal reverb programs on the FV-1.
A warning: I thought I could program the PIC in place using leads soldered to the appropriate pins, but this never worked.  I don't know if it was my incompetence or problems with having the other circuitry on the board.  In any case, I ended up removing it and soldering to a DIP adapter for programming off-board.  The EEPROM was easy to program in place with the instructions here (used PICkit2).
It's great!

[slacker]

Great to hear you got it working. I've never tried programming the PIC in circuit, could well be that it doesn't work.

[deadastronaut]

 Just curious,  are there any  full on distortions,with cab sim modelled...type srtuff with the fv1?

please excuse my ignorance with this programming lark..

[Ice-9]

Yeah glad you got it all working, If you followed my schematic then no, the pic can't be programed in circuit as I didn't add a pgm header for the pic. The reason was that as the code for the pic would never need updating I had no need to add a header for programming it. Saving space on a tight pcb.

@Deadastro, A few distortions exist but in all honesty the FV-1 strengths lie in modulation and delay rather than modelling distortion. It would be nice to have a go at some nice drive programming though.

[deadastronaut]

Cheers mick...

[Digital Larry]

I've goofed around with many but admittedly not all of the supplied examples of FV-1 code that I can find.  Regarding distortion, as Ice-9 said, this is not the chip's strong suit.  As far as whether it does "modeling", by which I take you to mean (intentionally or not), solving partial differential equations representing a circuit's behavior in real time, the answer is absolutely not.  One of the visitors to my forum has done some work with modeling of that sort and kindly shared some work describing how it works.  Were it not for that I would have had no idea how it is done.

I have obtained good results with the Spin supplied "Overdrive" block, which has 3 gain/clipping stages with a fair amount of low pass filtering distributed throughout.  Natural clipping in the FV-1 is hard.  You just run up to the max numeric value and the waveform flattens out.  But at least it doesn't flip polarity or chatter or grid block or anything like that.

There is a "Distortion" algorithm I found, that I haven't spent much time looking at, which sounds bad to me, like it has some splat/buzz on the attack which goes away as the note dies out.

There's a "cube" distortion algorithm that is touted as a soft clipping approach.  I've tried that and it's very subtle.  So subtle I can rarely tell it's doing anything.

Finally, Spin supplies a "t/x" algorithm which uses piecewise assembly of the waveform depending on the amplitude to give an actual soft clipping characteristic.  That one's OK too although I've had a hard time getting lots of gain out of it.  Maybe I need to add more gain between the stages.

In addition to delays and modulations mentioned by Ice-9, I've gotten what I consider to be some compelling sounds with filters, mostly second order state variable structure.  Those are the only ones that you can easily vary frequency or resonance in real time.  It also implements first order filters with an adjustable shelf very efficiently and this gives you a LOT of flexibility doing "tone control'.

[deadastronaut]

cheers larry..i was just curious.

i,ll stick with the old fet lark then..

[Ice-9]

Yeah ! Sorry Larry, I just used the word 'Modeling' in a general term for the question about distortion and amp/speaker sim and not in the way of amp modelling DSP. I should have been clearer, I blame that on a few beers and lazy typing.

While it won't do modelling as such I could see it coping quite well using filters to simulate a cab/speaker sim. It is not something I have tried though.

[grenert]

In case some of you might be interested, here's a "softclipping overdrive" algorithm (with Spin code provided) that Jeroen Korterik posted a while back.  Sound samples included.  Sounds pretty good to me!   
http://www.broekrock.nl/hosenlander/dsp_overdrive/index.php

[Ice-9]

In case some of you might be interested, here's a "softclipping overdrive" algorithm (with Spin code provided) that Jeroen Korterik posted a while back.  Sound samples included.  Sounds pretty good to me!   
http://www.broekrock.nl/hosenlander/dsp_overdrive/index.php

That does sound pretty impressive, I listened to the sound file but have not had time to look at the code, I will definitely give it a try

[TOPLEL]

I spent about 3 hours reading this thread, the Spinsemi forums, SpinCad designer stuff and i still doesn't get this:

Let's say i copy pasted 8 different code snippets for 8 different effects from different sources into a single txt file. Or let's say i made 8 different algorithms in SpinCad designer.

What kind of code should i write around them to make them selectable and recognizable by the FV-1 chip?

So basically i need the "skeleton" code without the effect algorithms, the code which will get uploaded to the EEPROM chip.

[slacker]

To make the file that you then upload to the EEPROM you take your code snippets or the output from SpinCad and use the SpinASM software, available here http://www.spinsemi.com/products.html to assemble them into a hex file that can then be written to the EEPROM.

Have a read of this http://www.spinsemi.com/Products/datasheets/spn1001-dev/SPINAsmUserManual.pdf pages 17 to 20 explain how you take up to eight programs and make them into a hex file, ignore all the stuff that talks about the dev board you don't need that.

[TOPLEL]

To make the file that you then upload to the EEPROM you take your code snippets or the output from SpinCad and use the SpinASM software, available here http://www.spinsemi.com/products.html to assemble them into a hex file that can then be written to the EEPROM.

Have a read of this http://www.spinsemi.com/Products/datasheets/spn1001-dev/SPINAsmUserManual.pdf pages 17 to 20 explain how you take up to eight programs and make them into a hex file, ignore all the stuff that talks about the dev board you don't need that.

Thanks!

[deadastronaut]

In case some of you might be interested, here's a "softclipping overdrive" algorithm (with Spin code provided) that Jeroen Korterik posted a while back.  Sound samples included.  Sounds pretty good to me!   
http://www.broekrock.nl/hosenlander/dsp_overdrive/index.php

cool, sounds good....i await the high gain version 

[caillan]

I'm finally making a start on building this - does anybody have a copy of the .hex for the PIC handy? I had a look through the forum but couldn't find it anywhere

Cheers,
Caillan