EHX - Holy Stain

Post by **Ice-9** » 05 Jan 2011, 13:40

I was wondering if anyone has any gut shots of the EH Holy Stain, is there any interest in reversing this pedal at all ?

HEAD · Post by **HEAD** » 05 Jan 2011, 14:08

So you are able to do some seriously DSP programming, smd 0805 soldering and sot 48 ic soldering? No, seriously, forget about that unless you have the above mentioned skills and/or the sourcecode for the dsp.
I even would go so far to say that any of the newer EHX products isn't diyable. Do a little search at this forum here and you will find some gutshots. And hey, what's the price of that little gadget? 89€ is the cheapest offer I found in Germany. For that money something like that could hardly be built by your own.

Post by **Ice-9** » 05 Jan 2011, 14:50

HEAD wrote:So you are able to do some seriously DSP programming, smd 0805 soldering and sot 48 ic soldering? No, seriously, forget about that unless you have the above mentioned skills and/or the sourcecode for the dsp.
I even would go so far to say that any of the newer EHX products isn't diyable. Do a little search at this forum here and you will find some gutshots. And hey, what's the price of that little gadget? 89€ is the cheapest offer I found in Germany. For that money something like that could hardly be built by your own.

Yes i can do all that smd stuff 48pin TSOP etc no problem, I was under the impression that this pedal uses the Spin Semi FV-1 DSP chip which i am familiar with and which is a very DIY chip to use. Yeah £59 here in the UK for the pedal isnt much. I was considering buying one to reverse just to help in my development of an FV-1 project as i dont think the Holy stain offers enough if it does in fact use the FV-1 chip.

I done a search and couldn't find any info on the forum for the holy stain, I will have another search !

HEAD · Post by **HEAD** » 05 Jan 2011, 15:12

... ok, yes the FV-1 is pretty diy-able. But as far as I know EHX don't use the FV-1.
Edit: This is taken of the freeze but should be pretty close to what most of the modern EHX gadgets look like: download/file.php?id=8346&mode=view
Multilayer, 0805 etc.... pretty unlikely that something like can be traced by as average "cloners" I guess.

Post by **Ice-9** » 05 Jan 2011, 15:40

Thanks Head for the picture, if the Holy Stain uses this instead of the FV-1 then yes, I agree not worth the effort. Multilayer would be a problem to trace but if its dual layer it would be easy enough, although the dsp would need removing to trace.

I have been told that the Holy Stain does use the FV-1 chip, but the only way to be sure would be to check it myself. Probs just best to do my FV-1 from scratch.

In the meantime if anyone does have a gut shot picture of the Holy Stain that would be nice.

Post by **MarcoMike** » 05 Jan 2011, 15:42

https://www.freestompboxes.org/viewtopic.php?f=1&t=4305

my guess is they all share the same "brain" inside different boxes, and with different programming...

Hides-His-Eyes · Post by **Hides-His-Eyes** » 05 Jan 2011, 17:10

I doubt that; the holy stain being so uch cheaper, and having an analogue fuzz section... It'll have some things in common, but I don't think it's the same unit.

Post by **MarcoMike** » 05 Jan 2011, 17:34

well, seems like you can set the distortion to fuzz/drive/clean... this looks like too much to be analog to me... of course not impossible... but...

EDIT: I listened to it... drive and fuzz sound kind of similar... and also sound like they're very simple... well... I have no idea, let's wait for some guts to show up!

Post by **Ice-9** » 05 Jan 2011, 17:43

MarcoMike wrote:well, seems like you can set the distortion to fuzz/drive/clean... this looks like too much to be analog to me... of course not impossible... but...

EDIT: I listened to it... drive and fuzz sound kind of similar... and also sound like they're very simple... well... I have no idea, let's wait for some guts to show up!

Right bollocks with it, i just bought one, will reverse it if poss when i get it, i'm pretty sure its a simple fuzz face type circuit with a switchable cap or summit to change the tone, and an fv-1 reverb, time will tell when it arrives.

HEAD · Post by **HEAD** » 05 Jan 2011, 18:08

Found on the EEHX YT-channel as a comment: The fuzz circuit in this unit is analog all other features are digital.
EHX vor 3 Monaten
So, who knows. Maybe it's realy too cheap to use a (higher priced) DSP-IC as in the pics above.

Post by **Ice-9** » 05 Jan 2011, 18:38

HEAD wrote:Found on the EEHX YT-channel as a comment: The fuzz circuit in this unit is analog all other features are digital.
EHX vor 3 Monaten
So, who knows. Maybe it's realy too cheap to use a (higher priced) DSP-IC as in the pics above.

Thanks for that info , I will get some pics posted as soon as it arrives.

Post by **modman** » 05 Jan 2011, 19:24

I will move discussion on pedals based on DSP to the proper folder - it will turn out there is a lot more DSP discussion going that we would think. good thread, even if only for reference...

the wizards beard · Post by **the wizards beard** » 06 Jan 2011, 17:32

HEAD wrote:... ok, yes the FV-1 is pretty diy-able. But as far as I know EHX don't use the FV-1.
Edit: This is taken of the freeze but should be pretty close to what most of the modern EHX gadgets look like: download/file.php?id=8346&mode=view
Multilayer, 0805 etc.... pretty unlikely that something like can be traced by as average "cloners" I guess.

I think people are really overestimating the difficulty in working with modern boards like this. 0805 requires some sort of magnifier, a bright light and a tweezers, certainly not impossible for a hobbyist. Multilayer boards are not nearly as difficult as people make them out to be, most of the inner layers are usually just power and ground planes. Besides, continuity meters still work even if you can't see the traces. The current trend is to move towards using fewer passive components and using a small number of ICs in reference designs, which should be much easier to trace than a lot of complicated analog stuff.

Post by **Ice-9** » 10 Jan 2011, 22:43

There has been a slight delay on getting this pedal for an RE, and i would like to let everyone know whats happening.
I bought this pedal from Andersons Music in the UK. It was in stock and bought on next day delivery. FIVE days later i get an email from them saying the only one they have is in the display unit and is in good condition (Read used) and do i still want it otherwise they can get a new one in 6 weeks.
Now don't get me wrong a display unit would have been ok but when i paid for next day delivery why has it taken 5 days to email me that they don't have a new pedal and unlike other shops they took the money from my credit card instantly.

Principal tells me i should get my money back and buy one elsewhere.

Scruffie · Post by **Scruffie** » 10 Jan 2011, 22:46

Ice-9 wrote:There has been a slight delay on getting this pedal for an RE, and i would like to let everyone know whats happening.
I bought this pedal from Andersons Music in the UK. It was in stock and bought on next day delivery. FIVE days later i get an email from them saying the only one they have is in the display unit and is in good condition (Read used) and do i still want it otherwise they can get a new one in 6 weeks.
Now don't get me wrong a display unit would have been ok but when i paid for next day delivery why has it taken 5 days to email me that they don't have a new pedal and unlike other shops they took the money from my credit card instantly.

Principal tells me i should get my money back and buy one elsewhere.

I always have good service from Hotroxuk, they do a price match too so if Andersons is cheaper...

I ordered a Pedal once from Dolphin Music, waited 3 months without any contact and even E-Mailed the company that produced it who said they'd shipped several orders to Dolphin so just told them where to stick it, ordered from Hotrox the same day, next morning!

Hides-His-Eyes · Post by **Hides-His-Eyes** » 11 Jan 2011, 11:22

Ice: I don't put up with crap like that. What if it'd been for your kids birthday present or something?

Explain to them exactly why you wish to cancel the order and add that you're insulted they'd wait 5 days to try to sell you the floor model without even offering a discount on it!

mrpickle · Post by **mrpickle** » 12 Jan 2011, 10:35

Ice-9 wrote:In the meantime if anyone does have a gut shot picture of the Holy Stain that would be nice.

If you type holy stain gutshot into Google, you get one on the fourth hit and save further guesswork and inaccurate assumption.

U1 is the FV-1. It's one of puretube's creations - there's stuff on diystomps including pictures of his perf+daughterboard prototype.

Post by **Ice-9** » 12 Jan 2011, 11:18

mrpickle wrote:
Ice-9 wrote:In the meantime if anyone does have a gut shot picture of the Holy Stain that would be nice.
If you type holy stain gutshot into Google, you get one on the fourth hit and save further guesswork and inaccurate assumption.

U1 is the FV-1. It's one of puretube's creations - there's stuff on diystomps including pictures of his perf+daughterboard prototype.

Haha ! goto laugh, I have just recieved the pedal and just taken pictures of both sides of the pcb myself. Just about to post them when i see your post.

Post by **Ice-9** » 12 Jan 2011, 11:26

Here are two pictures I have just taken of both sides of the PCB.

A few thought on first impressions

1. As stated above it does indeed use the FV-1 chip
2. It looks like the Holy Stain patches have been burnt directly to the FV-1 as it looks like there is no external EEprom, if this is the case then the FV-1 will have been made for EH with there own programs built into the chip and as such is not the same as a standard FV-1 that is available to us diy'ers. No big deal as the programs are not so good anyway.

I will be trying to do some reverseing of the circuit as soon as i get a bit of time.

Should I start a new Thread as in the forum as now there are some gutshots ?

Post by **Ice-9** » 12 Jan 2011, 22:53

Here are some gut shots of the Holy Stain front and back PCB. I have had a little time at work to look at the pcb and do a little bit of tracing, but mostly at the moment I just have a few observations.

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 which seems like it has the EH algos burnt to the chip as opposed to being selected by an external Eeprom. I susspect EH sent there dsp code off to Spinsemi to be put directly on the die so the FV-1 in these units isn't what we Diy'ers can purchase. This is not really a big deal.

I've managed to start tracing the patch selector circuitry which is controlled by a momentary stomp switch through a dual D-type flipflop circuit set up as a 2 bit binary up counter based around a 74HC74c chip and another chip wihich i cant find a datasheet for (ST microelectronics markings of 393 and EF921 or EF92L) possibly a couple of nand gates ? Schmitt trigger ?

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 I assume 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.

EHX - Holy Stain [schematic]