Single Knobby FV-1 Reverb

[jighead81]

Sorry, been out of the game for awhile just lurking about when I get the chance.  But the dreamtime pedal I saw demo'd on facebook recently got me thinking.  Those chips can do so much, as Brian had demo'ed.  But how about just a badass "spring reverb" setting?  One knobby of awesomeness.  Isn't that all the EHX Holy Grail is?  Sure there's more, (hall, flerb), but I'm ready for the bashing if I'm way off course, lol.  I love my big box Holy Grail, but it's lost some sparkle and charm over the last 10 years.  That's either my playing, ears, or circui.... naww, probably my playing, lol.

[somnif]

Sorry, been out of the game for awhile just lurking about when I get the chance.  But the dreamtime pedal I saw demo'd on facebook recently got me thinking.  Those chips can do so much, as Brian had demo'ed.  But how about just a badass "spring reverb" setting?  One knobby of awesomeness.  Isn't that all the EHX Holy Grail is?  Sure there's more, (hall, flerb), but I'm ready for the bashing if I'm way off course, lol.  I love my big box Holy Grail, but it's lost some sparkle and charm over the last 10 years.  That's either my playing, ears, or circui.... naww, probably my playing, lol.

There is a Spring Verb that I found on.... I want to say it was Spin's own forum, but I could be wrong? I'm pretty sure it was the basis for a few FV-1 "Spring" verbs floating around, but it could just be a case of conceptual convergent evolution.

I haven't burned it to a chip myself (I hex'd it up but never got around to it, for some reason), though, so can't compare it at the moment. By default it's only got a "level" control, as well as a built in tremolo with rate/depth controls.

The opening comments of the file:

Code Select Expand

; SPRING REVERB         (c) 2016 Don Stavely
;            Please, not for commercial use!
; Description:
; Spring reverbs sound "boingy" because of dispersion in the spring -
; higher frequencies travel slower than low frequencies.
; A "spectral delay filter", consisting of many (100's) of unit allpasses
; will produce the desired "chirp" impulse response.   
; The number of APs can be reduced by "stretching" the allpass filters,
; using delays larger than one.
; Using different chirp AP lengths spreads the eigentones (?)
; Reverb loop looks like std X-coupled AP-AP-DELAY loops, but inputs
; and outputs moved so first echos straight out of delays, not APs.
;
;           +-------------------------------------+
;           |                                     |
; in---[+]- | --[  D1  ]--[lp]--+--[AP1a]--[AP1b]-+
;       |   |                   |
;       |   |                  [+]---------------->[CHIRP APs]--->
;       |   |                   |
; in----| -[+]--[  D2  ]--[lp]--+--[AP2a]--[AP2b]-+   
;       |                                         |
;       +-----------------------------------------+
;
; Delay, AP lengths scaled from GA reverb, modded close to Accutronics
; 2-spring delay lengths of 33ms and 41ms.
; Filtering inside the loop and sin/cos LFO smearing of the reverb APs
; also reduces ringing.
; Oh, and it has tremolo so my son can use it for surf rock.  You could
; add tone and reverb time controls instead.
;
; Pot0 = Reverb Level
; Pot1 = Tremolo Rate
; pot2 = Tremolo Depth

; Declare constants

[oip]

if i remember right the FV-1 doesn't do spring as well as plate/hall/shimmer etc.  i've got some plate reverbs from somewhere or other which sound pretty excellent and thought about making a pedal just for those.  given the FV-1 is about the same price as belton bricks and there are plenty of those floating around.

definitely a case to be made for making FV-1 pedals with just a single effect (or maybe 3) and optimising the code + surrounding circuitry to play nice together. 

[selfdestroyer]

if i remember right the FV-1 doesn't do spring as well as plate/hall/shimmer etc.  i've got some plate reverbs from somewhere or other which sound pretty excellent and thought about making a pedal just for those.  given the FV-1 is about the same price as belton bricks and there are plenty of those floating around.

definitely a case to be made for making FV-1 pedals with just a single effect (or maybe 3) and optimising the code + surrounding circuitry to play nice together.

I'm going to have to disagree with you there.. The main problem is there has not an "easy" way to make a good spring reverb sound on the FV-1 with something like SpinCAD. There is plenty of ways to do it with ASM programming but that can be very difficult to pick up with out some diving in. There are many factors to getting the FV-1 to emulate the spring reverb algorithm. You want that "chirp" sound on the attack of the reverb and that beautiful "ring" like quality of long decay.

Check out the Catalinbread Topanga Spring Reverb, which is FV-1 based.

The header of the reverb code that was posted is a good file (if you find it around) to start with. I know SpinCAD added a chirp block in the reverb section but I have yet to play with it.

-Cody

[somnif]

Oops, I had actually meant to attach the whole file of the reverb I mentioned. Well, thats easily remedied.

One issue, it just BARELY fits into a SpinHex file as is, and can actually fail to compile for some people (Windows 8 and 10 users reported the issue). One could likely cut out the Tremolo blocks and work from there to make life a little easier, but I don't want to hack the dudes file without attribution and will leave that to others. It's in .spn format, which is basically a text file. Needs to be compiled to hex to use with a chip.

Source link: http://www.spinsemi.com/forum/viewtopic.php?f=4&t=598&sid=f189fd77a81918a3dc93e4f0236163fd

[selfdestroyer]

Oops, I had actually meant to attach the whole file of the reverb I mentioned. Well, thats easily remedied.

One issue, it just BARELY fits into a SpinHex file as is, and can actually fail to compile for some people (Windows 8 and 10 users reported the issue). One could likely cut out the Tremolo blocks and work from there to make life a little easier, but I don't want to hack the dudes file without attribution and will leave that to others. It's in .spn format, which is basically a text file. Needs to be compiled to hex to use with a chip.

Source link: http://www.spinsemi.com/forum/viewtopic.php?f=4&t=598&sid=f189fd77a81918a3dc93e4f0236163fd

Just wrote that to my FV-1 Dev Kit and it does sound really good. Tested it with my eurorack. I will try to get a sound snip uploaded. I wonder if the tremolo portion was removed if it would free up some of the mem/resources headroom to add a little more char to the spring algorithm. Time to tinker with it..

Thanks again for the post!

[selfdestroyer]

I used SpinASM IDE v1.1.31 on Windows 10 and comiped it without issues.

I'm leaving the pot1 and pot2 all the way down to leave the tremolo off. Just messing with pot0 for the reverb level.
Now introducing fat sausage fingers and hairy hand time!

[jubal81]

I used SpinASM IDE v1.1.31 on Windows 10 and comiped it without issues.

I'm leaving the pot1 and pot2 all the way down to leave the tremolo off. Just messing with pot0 for the reverb level.
Now introducing fat sausage fingers and hairy hand time!

That does sound nice. Drip is pretty convincing, too

[oip]

I'm going to have to disagree with you there.. The main problem is there has not an "easy" way to make a good spring reverb sound on the FV-1 with something like SpinCAD. There is plenty of ways to do it with ASM programming but that can be very difficult to pick up with out some diving in. There are many factors to getting the FV-1 to emulate the spring reverb algorithm. You want that "chirp" sound on the attack of the reverb and that beautiful "ring" like quality of long decay.

Check out the Catalinbread Topanga Spring Reverb, which is FV-1 based.

The header of the reverb code that was posted is a good file (if you find it around) to start with. I know SpinCAD added a chirp block in the reverb section but I have yet to play with it.

-Cody

interesting thanks - forgot about the topanga.  will definitely load up that file when i get home, the write up in the spinsemi thread and code annotations are great too.

i'll try to find the sources for the plates i was mentioning, they are super nice reverbs

edit:  ok so i loaded it up (issue i found with compiling is that some of the characters are subbed with html versions, breaks one line of code where a colon renders in html as &#58, changing 'endinit:' to 'endinit:' fixed it).  it's nice!  like a cleaner sounding belton brick a little bit.  taking out the trem and putting maybe a tone control and room size/reveb length would be fantastic but i have nothing approaching the skills to do it..

also somewhat sheepishly, the plates i was thinking are the free ones from the spin site.  they are fun though: http://www.spinsemi.com/programs.php

[nzCdog]

Jeesh that sounds great Cody. I've been so interested in this FV1 platform, but have zero headspace to learn it right now.  A project I'd love to do would be a Cab SIM kinda like the impulse response convolution options out there, for direct recording.