Swap EEPROM in PedalPCB Octagon (FV-1)

[DLW]

The module8 and Octagon use the same board and BOM apparently, so swapping EEPROMs should be work no problem. Similarly, the kaleidoscope, unison, threeVerb, pythagoras, and radium springs all seem to use the same board/BOM. I was wondering if anyone has taken an unmodded Octagon and swapped in a different EEPROM - for example Unison.

I just put an Octagon together last night. Sounds good with the matching EEPROM. I threw in a Unisom EEPROM. It didn't light on fire, and it makes noises that I assume sound similar to a Unison. Just wondering if there is a fatal flaw in the schematic that would never allow a Unison EEPROM to function properly in an Octagon board.

[Willybomb]

I have 3 octagons here, with 3 different eeproms courtesy of BuGG, each has 8 different effects on them.  I should probably let him do the talking though....    My understanding is that if they share the same board, then the eeproms can be swapped like between like.

[sonnyboy27]

I believe Willybomb is correct. If the boards are the same then you can swap the eeproms. If they're different then the programs in the chip may not be selected properly so it won't quite work right. You may be able to get some sounds out of it, but since the octogon is trying to select 1 of 8 programs and the chip only has 3 it may freak out sometimes.

[BuGG]

The EEPROMs are fairly interchangeable...

If you put an 8-program EEPROM into a 3-program PCB you'll be able to access the first three effects on the EEPROM.

If you put a 3-program EEPROM into an 8-program PCB the last 5 "positions" on the mode knob will pass no digital signal, the first three will function as expected.


The exception is the DMD-2, Organ Donor, VHS, and upcoming "Leprechaun".    These have slightly different external (analog) circuitry so won't quite function as expected in any other PCB.

[DLW]

Thanks everyone!

The more I play with it, the more I love this pedal! Great job, BuGG!

[oip]

just to add on, i use my octagon build as a swiss army knife for a whole bunch of FV-1 effects from around the place.  the main differences i've run into which can cause issues are:

* some algorithms use both L and R channels, or have output routed to one over the other

* some use an external feedback, some delays especially and they won't really work without it

* some use a little circuit around crystal to adjust clock time and thus sample rate

* analog mixing and balancing around the effect might be customised and it can be difficult to match levels with a generic setup

and yes agreed it's a great PCB!  very handy and versatile platform