Check this guy out:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7338501507&category=41419&ssPageName=WDVW&rd=1
I'd be really interested as to how this is achieved. I've got one of these pedals, and to be honest they're not great. If they could be modded i'd consider not getting rid. Ideas??
I'm guessing its probably DSP but we can hope!
*b
theres a sticky about it over at the guitar geek fx forum...]
guitargeek.com
Yes, it's DSP. However, the four XP models are very similar and that mod is analogous to swapping out component values in a tube screamer. Only here, the component is a chip rather than some resistors.
Swap out the EPROM and maybe add some memory depending on the unit (some have more than others). Bam! your XP has transformed. I haven't seen one of the ones from the guys at guitargeek, but I think the switch would just switch between the eproms. Make sure it has enough poles to cover the read/write lines; you can probably share the power and ground between all the chips. I'm pretty sure that the control logic and treadle handling is identical between models.
Maneco helped out with that mod over at guitargeek; perhaps he can give you more information. He actually provided a lot of information in a thread over there a few months (or a year?) ago. The newer thread doug mentioned is advertising and doesn't contain any technical information.
Jacien - I agree with you; I have the Modulator and it's not so great. I'd be interested in checking out some of the patches on the XP100, and of course the XP300 simply because people seem to pay ridiculous prices for those. I have an RP-12 collecting dust, and I believe it does most of what the XP series does... if the sound quality is the same, then I honestly don't get the fuss over them.
Something like the Boss GT-6 will do pretty much everything the entire XP series will do, aside from the bitcrushing algorithms on the Space Station (and we have Peter's Soma DSP box to do those :D). The wah, reverbs, arpeggiators, and pitch shifters are better... plus the modulation effects on the GT-6 absolutely kill those on the modulator, and every last parameter is controllable. Many newer multi-fx boxes are better and cheaper than the $300 space station (I think that's the going rate)--but that's just my opinion :). And I digress. That would take the fun out of modding this pedal :)
Anyway, I believe it's a fairly simple mod if you can get the EPROM files. You can build a cheap programmer; I use one I built for my PIC needs. I only have the one for the Modulator. I might try to do a similar mod if I can get the EPROMs for the 100 and 300. I'm personally interested in picking and choosing effects from different XP series to have on one chip, rather than having to switch through the four EPROMS with a rotary switch. Easier to use live.
The schematic for the XP100 is available around here somewhere, and even if you don't have it, it's pretty simple to open up the unit and see exactly what's missing on the PCB if you have one of the ones with less memory. If there's enough demand, I can try to work everything out at the start of the next school year, given that I can obtain the program files.
I don't want to step on any toes over at GG (doug, I forgot-are you the admin there? edit: sorry, you're mid-fi electronics, right? I'm confusing everyone), but it's a fairly simple mod and I doubt that the people here are the target market.
I wonder if any of this is grounds for breaking the DMCA :)
It would be amazingly cool to have one in a rack enclosure with the best patches from each of the XP series.
I would guess an eprom for each effect box and a switch leg to each enable pin on the eproms.
I would think this could be a copyright violation just like some of the mame stuff.
Forgot about the EN... sounds like that would work. I don't think any of the parts in there are too rare, so some SRAMs, caps, and the new prom's and you're golden. The hard part is tracking down the EPROM code to burn onto new ones.
And I agree, it gets hairy here - yeah, they're out of production but it really does amount to a ROM image as Gus mentioned. Distributing the "software" - in fact, copying and selling it - could be trouble if Digitech isn't friendly about it. With the prices those modded ones are going for on ebay, I doubt they're lifting Digitech-made chips from other devices. Still, it's arguable whether it would be in digitech's financial interest to even care anymore. An Xp300 reissue would appeal to too few people.
Edit: before that last paragraph causes the thread to erupt, I'm only referring to the mods that are out there, not what we should all go out and do ourselves :)
marduk - check out the digitech 2120 (2112 might be a slightly lesser version). I think it'll do just about everything in the XP series, and more. I had an RP-12 very briefly at one point, and it was a floor unit based on one of the S-DISC processors. Personally, I don't care for the way digitech units seem to color the sound (make it "glossy" for lack of a better word), but perhaps the newer ones are better.
from what ive heard the XP-300 is the only one out of those 4 thats really any use and then only for some really far out sounds, definatelly not subtle. id love one but atm im poor :(
ive heard about reflashing the ICs inside of the XP series to turn one to another but i heard it was a bit more extensive because one or two of them need more memory than the others. maybe its the XP300 that has more RAM and so thats why its the one thats modded
Johnny - you're correct. The XP's have from one to four memory chips each. The XP300 has four, the XP200 (modulator) has one, and I think the other two have one or two. I believe the XP300 has some reverse delay-based effects which accounts for the differences.
The one thing is that any of the four can be modded to each other. It's hypothetically the easiest to go from the XP300 to the others, because as you mentioned, it has the most RAM.
However, you can "upgrade" to the XP300 if you put more RAM in it. The circuit boards for all XP's are the same, just that some of them are not fully populated (from each according to his abilities, to each according to his needs ;))
The one on ebay is an XP300 simply because it's an XP300. I think that the modder is buying up the XP units that float by on ebay to mod them and sell them. He's stated that the modded XP300 does sell for more simply because it's more expensive for them to acquire. After the mod, they'll be identical, though I think the font on the space station looks the best ;)
Because I've posted a few times here, I should mention that I haven't done this myself. I started to look into it when Maneco mentioned it about a year (?) ago, before guitargeek put it out as a commercial mod.