Holy Stain mods for flanger chorus and extra pots

[Ice-9]

I am going to outline some mods to this cool pedal which will unleash the full potential of the DSP chip used inside. The mods include addind a switch to allow all the effects to be selectted instead of the being restricted to the 4 effects EH have allowed. These extra effects include the flanger and chorus.
As well as the extra effects I will outline how mto add two extra pots for controlling the FV-1 parameters.

Here are some gut shots of the Holy Stain front and back PCB.
The pedal is mono in mono out and as well as the 4 programs (Room - Hall reverb, pitch shift and tremolo) has a built in fuzz effect as well.




The units digital effects are made with a Spin Semi FV-1.

I have traced out some of the FV-1 circuitry and its pretty much application sheet stuff as expected but only having one pot to control the digital parameter of the FV-1. The one pot does link to 2 of the controls pins, so adjusting the pot  is adjusting 2 parameters at once.

It would be quite easy to mod this to pop in an external eeprom that we could put our own code on which would open up more possibilities for the pedal.

[Ice-9]

Ok here is a very cool thing that can be done to add these extra effects to the Holy Stain

Flanger
Chorus
pitch with echo

All that is needed is a SPST toggle switch and a bit of wire.

This is all that is needed to modify this :-
Pin 17 of the FV-1 is tied to 3.3v as standard, to access the extra effects pin 17 needs to be able to be switched either 3.3v or gnd

1. This can be done by lifting pin 17 of the FV-1 chip from the pcb, to do this heat up the solder on pin 17 and with tweezers or a stanley blade lift the pin until its floating off the pcb contact.
2. you then need to solder a wire to this pin (thin kynar wire is best) The wire is best glued down to the top og the chip or the pcb as we dont want this wire flexing and breaking the pin from the ic.
3. The final bit ! take your spdt toggle switch and solder a wire to each outer terminal. Now solder one end terminal to ground and the other to 3.3v. The centre terminal from the switch goes to the pin 17 wire that was previously soldered and glued down.

So when the toggle switch is in one position the effect select footswitch selects the 4 effects as normal, when the toggle switch is in its other position the effect select footswich will select the other 4 effects.

[Ice-9]

Here is Mod number two, the second control mod.

EH in there wisdom wired up one pot to two control parameters, what this means is that on there Tremolo patch as you turn up the speed of the tremolo it also adds in the reverb. At minimum setting of tremolo speed there is no reverb but as you increase the tremolo speed the reverb increases to max. As my first mod added some extra effects like chorus and flanger the use of the second control pot comes into it's own as you have independant control over the rate of chorus/flange independant of reverb. On the reverb only programs the second pot will adjust the high freq filter of the reverb.

I didn't bother adding the third control pot as in the programs all it does is change the effect output mix, EH added a seperate mix control for this anyway.

Here is the second pot mod. In the first picture i have highlighted the track that need modding in white. This is the centre pin of the pot to the two control pins on the FV-1 chip



First of all we need to remove the resistor R18 circled in red.

After the resistor follow the trace down under the FV-1 chip to the two pins on the chip that are connected together, the bit circled in GREEN , this track needs to be cut seperating the two pin of the chip (20 and 21). Even after cutting the track between the two pins we can still reverse the mod if needed by placing a blob of solder between the two pins on the chip . (nothing in these mods can't be put back to standard)

Next a wire from the top pad of the removed resistor need to soldered from there to pin 20 ( the lower pin in the white trace) This just recconects the pot to its original control pin.

Adding the second pot now is just as easy. Using  100k linear pot solder one end to the 3.3v and the other end to gnd or just conect each end to the ends of the pot that I have put the white trace on. The centre pin on the pot then goes to the other end of the R18 pad ( bottom pad R18)

If any of this is confusing just ask and i can answer every question, this second picture with the mod done should make it clear.

[Mark Hammer]

Many thanks for this!

The EHX Holy Stain is often available for a very reasonable price, perhaps precisely BECAUSE it does not fully exploit all the options of the FV-1 chip.  Nice to know that it can be more than it already is, and based on knowledge easily and historically shared here.

[Govmnt_Lacky]

Why do I feel that sometime in the near future we will be seeing a Holy Stain 2 with "Improved Control, Functionality, and more choices of Effects!"  

Exceptional work and contribution Mick!

[culturejam]

I followed Ice-9's mod instructions and converted a cheap used Stain to something a lot more usable.

[MikeH]

This is awesome info!  I'm going to start trolling ebay for one of these now.

[puretube]

some guys want ALL the KNOBS...

and then again they want even more control over teh FUZZ, too    :icon_rolleyes:b


(a.o. the wisdom of E-H sometimes is the ART of REDUCTION !!!)

[Ice-9]

Right then !! If you want all the pots, You got-em.

1. lift pin 22 of the FV-1 from its solder pad so its just floating.
2. solder a wire from pin 22 to the centre of a 100kB pot.
3. One end of the pot to 3.3v, the other end to 0v.

Note.
EH put a 10k resistor from the centre pin of the pot to the control pin of the FV-1. (This isn't in the data sheet for the FV-1 but might be worth adding anywa to all the pots)

HINT.
It wouldn't be difficult to knock up a little daughter PCB for an external eeprom allowing you to put in your own programs like wah, distortion, phaser etc. or some of the many available programs to download from the Spinsemi site.

[Govmnt_Lacky]

HINT.
It wouldn't be difficult to knock up a little daughter PCB for an external eeprom allowing you to put in your own programs like wah, distortion, phaser etc. or some of the many available programs to download from the Spinsemi site.

Hey Mick,

Brilliant work on this by the way! 

I was under the impression that the programs for download on the Spinsemi site were only "partial" programs 

I thought they were only for testing and the sorts. I was unaware that they were fully-functioning programs that could be used with the FV-1. Am I wrong?

[slacker]

There's mixture of things in the "free DSP Programs" section some are just snippets of code for incorporating into other things, but there are some full programs in there, the Disco/DJ ones for example.

You can also download the programs for the Guitar amp and mixer applications, these are full ready to go programs. There's some nice effects in the guitar amp section, I haven't looked at the mixer ones so I don't know how suitable they are for stompbox use.
http://www.spinsemi.com/guitar_amp_application.html
http://www.spinsemi.com/mixer_application.html

The forum also has a few full programs posted in it.

[Hides-His-Eyes]

some guys want ALL the KNOBS...

and then again they want even more control over teh FUZZ, too    :icon_rolleyes:b


(a.o. the wisdom of E-H sometimes is the ART of REDUCTION !!!)

You worry about making a successful product and we'll carry on tweaking things for extra options.

[Govmnt_Lacky]

You can also download the programs for the Guitar amp and mixer applications, these are full ready to go programs. There's some nice effects in the guitar amp section, I haven't looked...

Ian,

I looked at the files. All of them seem to have the "DEMO" tag in them. They read "GA_DEMO_****....." This leads me to believe that they are not COMPLETE programs and are only suitable for demo applications. I suppose you could disect them and use the parts to form a complete code.

Am I still wrong?

[slacker]

I guess they call them demo programs because they're designed to showcase what the thing can do, in the same way as the internal programs the FV-1 ships with. They're fully working programs though, they just need compiling and burning to an EEPROM and they're ready to go.

[Ice-9]

I guess they call them demo programs because they're designed to showcase what the thing can do, in the same way as the internal programs the FV-1 ships with. They're fully working programs though, they just need compiling and burning to an EEPROM and they're ready to go.

+1, they are indeed fully working programs, I have tried them all, some are great and some are not to my taste but you can either use them as they are or try and improve them. The good thing about them is that you can use these as a base to learn how the code works.

For instance the flanger/reverb patch, If I wanted to use the flanger and maybe i don't want the reverb in with the effect I could re-write that patch and just remove the reverb code.

There is also the internal chip effect programs available for download.

[culturejam]

some guys want ALL the KNOBS...

and then again they want even more control over teh FUZZ, too    :icon_rolleyes:b


(a.o. the wisdom of E-H sometimes is the ART of REDUCTION !!!)

Riddle me this: Why does the "Clean" setting on the Holy Stain clip so much? That pedal would be really awesome if the clean setting was actually clean, and not set to "amp about the break up". I really don't understand that.

[puretube]

Just wait until people find out that they`ll have "digital" dry
plus "analog" dry in their mix
@ "chorus" & "flanger"
(like @ tremolo, already...) 

[Ice-9]

Riddle me this: Why does the "Clean" setting on the Holy Stain clip so much? That pedal would be really awesome if the clean setting was actually clean, and not set to "amp about the break up". I really don't understand that.

I'm not 100% sure, but from memory when I was modding the Holy Stain I think mine was clean when the fuzz section was set to clean. I sold the pedal some time ago so can't check.

[culturejam]

I'm not 100% sure, but from memory when I was modding the Holy Stain I think mine was clean when the fuzz section was set to clean. I sold the pedal some time ago so can't check.

Mine is gritty, and so is the one I just moded yesterday.

But I just saw this on TalkBass:

When running the clean setting, you need to have the color NOT on Warm, and the tone knob close to all the way counter-clockwise or else it will still distort somewhat.

So I fired mine up and played around with the "color" switch. Warm is definitely the grittiest of the three. But all of them have some grit if I hit a chord more than somewhat lightly. And with the Tone control any brighter than 12 o'clock, I get grit. And even at 12 o'clock, there is a little grit, and the tone is quite dark even with my bridge pickup.

I suppose if I only played with vintage single coils (~5k), I'd never notice. But I'm a humbucker dude.

The fuzz and drive on the Stain are pretty decent, but I sure would love to be able to play clean without tiptoeing around the grit. That's why I'm anxious to see how the Ice-9 "Forum FV-1 Project" turns out. I'm all over that.

[Ice-9]

I'm not 100% sure, but from memory when I was modding the Holy Stain I think mine was clean when the fuzz section was set to clean. I sold the pedal some time ago so can't check.

Mine is gritty, and so is the one I just moded yesterday.

But I just saw this on TalkBass:

When running the clean setting, you need to have the color NOT on Warm, and the tone knob close to all the way counter-clockwise or else it will still distort somewhat.

So I fired mine up and played around with the "color" switch. Warm is definitely the grittiest of the three. But all of them have some grit if I hit a chord more than somewhat lightly. And with the Tone control any brighter than 12 o'clock, I get grit. And even at 12 o'clock, there is a little grit, and the tone is quite dark even with my bridge pickup.

I suppose if I only played with vintage single coils (~5k), I'd never notice. But I'm a humbucker dude.

The fuzz and drive on the Stain are pretty decent, but I sure would love to be able to play clean without tiptoeing around the grit. That's why I'm anxious to see how the Ice-9 "Forum FV-1 Project" turns out. I'm all over that.

Yeah the fv-1 project is still on but the last 2 months i've been struggling just to keep my head above water so haven't had any spare time to put to it. Soon hopefully.