Does FV-1 have what it takes to do a Rockman X100 simulation ?

[Ice-9]

I do think all this is possible within the 128 instructions but the problem would still be only 3 control pots. I would say it is definitely worth going over to the FX-Core DSP for the Rockman idea.

[marcelomd]

Regarding memory/instruction limitations. Is it possible to use multiple FV1s? Just set them up as multiple pedals.

[Ice-9]

Regarding memory/instruction limitations. Is it possible to use multiple FV1s? Just set them up as multiple pedals.

yes it is.

[ElectricDruid]

I do think all this is possible within the 128 instructions but the problem would still be only 3 control pots. I would say it is definitely worth going over to the FX-Core DSP for the Rockman idea.

Why? The Rockman uses a grand total of no pots at all, so it's not a big issue for a proper clone. Ok, there's a lot of knobs you *could* put on it, but then it's not a Rockman any more.

[Vivek]

Since the FV-1 does 128 instructions on each Audio sample

I started to guesstimate the size of each part


FET Compressor (with specific input output curve) :
steps

2 stage Distortion : A saturated Opamp feeding Hard clip LEDs
About 30 instructions

Cab Sim "Complex Filter" : 3 opamps as filters
About 15 instructions

Chorus : 555 LFO at 1.7Hz modulating VCO at 50 Khz thats clocking a BBD
LFO = about 6 instructions
delay ?

Reverb : MN3011
One of the sample progs "rom_rev1.spn" at http://www.spinsemi.com/programs.php had around 80 instructions for the reverb. Is that about right ?

Mixer : to generate a L and an R from the dry and wet signals
2 or 4 instructions

[Vivek]

The complex filter could most likely be described as a cascade of first and second order blocks.  FV-1 does 1st order easily in 2 instructions.  2nd order (implying a resonant structure) take more like 6 or 8.  And there are more filters sprinkled throughout the design.

yes "Complex Filter" or Cab Sim is 3 stages of filter blocks, they are resonant at about 400 Hz and 3K

There are many other filters to restrict the high frequencies before and after the chorus BBD, and also before and after the reverb MN

Will these be needed on a FV-1 ?


ie is the need to cut High frequencies related to deficiencies of BBD chips, or are they universal truths related to how delays work ?

[ElectricDruid]

There are many other filters to restrict the high frequencies before and after the chorus BBD, and also before and after the reverb MN

Will these be needed on a FV-1 ?

Yes, and certainly Yes if you want it to sound the same.

ie is the need to cut High frequencies related to deficiencies of BBD chips, or are they universal truths related to how delays work ?

It's a universal truth related to how sampling works. BBDs are one (rather unusual since it's analog) example of sampling technology, and the FV-1 is another. In short, if you put any frequencies in that are above half your sample rate (that's your clock rate for a BBD) then the frequency that comes out won't be the one that went in. This is "aliasing".
Once you have the signal safely inside the FV-1, you don't necessarily need to add more filtering unless you're about to do something that would add harmonics (like a distortion stage), but in this case, you'd probably add the filtering to try and get the most authentic sound.

[ElectricDruid]

Reverb : MN3011
One of the sample progs "rom_rev1.spn" at http://www.spinsemi.com/programs.php had around 80 instructions for the reverb. Is that about right ?

I'd say that's probably an over-estimate, because the Spin Semi reverbs are much more complex reverb algorithms with various stages of allpass filters and multiple delays.

The Rockman reverb is one MN3011 chip followed by a MN3007 chip, so it's just a multi-tap delay with a couple of mixers to mix the tap outputs and a bit of feedback. Not terribly complicated.
Of course, if you've got the code space, you could always start making improvements to the Rockman design and use a better reverb algorithm like some of the Spin ones. There's no reason your Rockman clone has to be totally authentic if you don't want it to be.

[Digital Larry]

I already posted the code for an MN3011 block I made, it's about 10 instructions.  Adding another delay tap is just one more instruction to that.  If you try this on your FV-1 be aware that the feedback is turned ALL THE WAY UP UP UPUPUPUPUUUPPP ahhhhhhhhh!

Someone else seems to be interested in that awesome sound as well: https://line6.com/support/topic/58178-free-bostonrockman-irs-zip-updated-nov-19/

DL

[Cybercow]

The Rockman reverb is just an MN3011. 

Actually, looking at a completely traced and verified X100 schematic, the MN3011 is directly associated with an MN3007 and are joined thru a stereo filtering network and tied to the same clock chip. So rendering an exact match to the X100 reverb/echo section is a bit more complex than just an MN3011 emulator.

[Vivek]

In the FV-1 world

Adding MN3007 functionality to a MN3011 model could be 2 extra lines of code and change in one constant value.

"Stereo summing" could be 2 extra lines of code

And "same clock" doesn't need any code

[ElectricDruid]

+1 what Vivek said.

The 3011+3007+filters+mixers really isn't the hard part at all. It's pretty trivial on the FV-1, since that sort of stuff was absolutely what the chip was designed for.