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after digging deeper into one of the unobtainable components, it seems that it is a 24 bit DSP with onboard ROM  . at this point i think i better give up because there is no way to get the firmware thats flashed on that ROM. i think i will probably just make a digital pitch shifter. another option i thought about was buying an xp-100 someday then copying all of the programmed ROM so that i can duplicate the build. so pretty much like how people copied the code from the EPROM (for the XP-all mod). my only constraints with that are 1. i can't afford one right now and 2. how would i get it onto my computer? i thought about using a USB reader interface but i would have to firstly figure out the ROM's location then figure out how to actually read it via the USB adapter.

To be fair, i probably should if anything make a digital pitch shifter since thats really all i am after. I would buy a second hand wh-4 but where i live im looking at minimum  £80 (about $105). Since i have most of the digital ICs i would in theory be making the pedal for cheaper.

right, i just found a link to an old thread where someone asks how a whammy works and i found a massive detailed reply explaining the use of SOLA and PSOLA. i actually found a PSOLA audio shifting algorithm in C++ but i highly doubt it would work with an XP-100 as there are other programs on the XP-100. not only that but im not too sure how it would interact with the other IC's etc.

appreciate the reply, i took a look into the fv-1 and it looks quite promising for what i want to do however the reason its more ideal to try and clone the xp-100 is because i already understand the circuit (and have lots of the digital stuff from a POD). looking deeper into the fv-1 makes me think it would actually be significantly easier to make a pitch shifter but after going through the link, it seems it suffers from bad lag. i'l keep my eye on the fv-1 in case i can't make the xp-100.

also for anyone else who might see this, when i say 'XP-100' i generally mean i am making an XP-xxx circuit (they are all the same with the only difference being that different code is flashed onto the EPROM)

Totally agree that the whammy is much superior to the XP-100 however i cannot find any schatics for the whammy plus it uses even more obsolete parts. Since its also slightly different i assume it will have different firmware that nobody has. I would make one instead if anyone had a schematic but i think if i could make anything at all, it would be the xp-100 since its the pedal that has most information on it.

Hey guys

Ok so i'l get straight to the point and not justify why i am doing this: i am going to attemp the impossible. A complete DIY xp-100. I've done research and I'm confident it's doable. The thing I'm not so confident on is the digital side. I get that the EPROM contains the firmware/code for the effects but what i need to know is what else has firmware/is custom programmed? More importantly, does anyone have the other firmware? I have had no luck from messaging a few people who are known for modding xp-100s so i don't expect much more insight here (no offense  )

thanks, i'l give it a try. no, the adapter does not have a ground/earth pin. also, all the pedals apart from an envelope filter pedal cause the noise. i think the EF blocks out all the low frequency or something. let me try some new cables as now i think about it, I've only used one cable to run from the pedal board to the amp.

my bad, i should've mentioned i already tried with similar results. there any chance it could be a bad ground / connection? although i checked, maybe i should go over it again

alright so i did some more testing. i powered all the pedals and turned all the pedals on. i unplugged the jack that runs to my amp and moved the tip of it near the power cables. this caused lots of 60 cycle hum but that is somewhat expected since it's a powersource. also when the amp is unplugged, and i touch the footswitch (so any grounded metal) it causes a very loud hum. i think maybe its just interference but why would it be different frequencies? i think i might use some shielded cable to jumper the input and outputs inside the pedal.

finally, i suspect one of my pedals (Boss SD-1) is buzzing is because i removed the clipping diodes. it did not do this before. the only other thing i did was add two footswitches so maybe there is some interference or poor grounding on that one.

yeah, if the pedals are bypassed, there is no noise. i've not touched the enclosures yet so i will try. also, when the pedals are disconnected from the signal chain but on, there is no noise so i doubt the pedals are causing dirty grounds.

Hey guys,

just finished my pedal board with a decent 2A 9v power supply. when i tested the pedals:
1 pedal on: some buzz when i stop playing
2 or more pedals on: serious buzz that changes frequency depending on what pedals are on. for example if i combine distortion with fuzz i get horrendous high pitch squealing where as if i use a compressor with both, it makes the squealing low frequency.

i feel confident that it is the power supply but after i tried a different one and used a noise filter, i still get buzz.

the buzz mainly occurs when i use my multi effects unit (4 guitar pedals inside an old Marshall ValveState foot controller)

I have checked most connections etc but i don't think it is directly related to the wiring since A. it happens with other pedals in my chain B. it does not matter what combo of pedals are on.

I understand that without pictures, diagrams etc it's hard to find the problem but i am confident it's something i'm missing.

thanks

~Aran

thanks for the replies,

i'l have to look at that site and see if i can see anything myself.

also Midwayfair, i never actually thought of it like that. i took a look at the datasheet and it makes sense. i suppose it would make sense that it is a 7 too. i would test it to see if it's npn but for some reason the transistor socket on my DMM is blocked up.

i also got in touch with the semiconductor museum and this is what they had to say: "The other unit, type "3621A" is similar to many other RCA "in-house" numbers made for a specific customer, often a computer manufacturer.    I haven't seen the CIA text before, so this type might be actually a special order for the CIA."

i suppose the only real way to know would be to contact RCA but considering they shut down in the 80s makes it impossible. another thought i had was asking the original seller where he got them from buy he said he bought them from someone years ago.

i would still love to know what the CIA means. i think its just RCA's markings as most of my RCAs have random letters on them.

bump

still no info at all

that pic reminds me of an old teacher i had. he came from Canada to the UK for a year to teach electronics. he had this cabinet in his classroom so he decided to show me inside when he found out i love electronics. it was filled with this HUGE collection of germaniums

thanks for the replies guys, much appreciated.

i searched in the discontinued transistors and i found a '2N3621' but it seems its not the same

as for the small signal transistors pdf, yeah, its actually nice to have as i never thought to search for it before.

i'm sure we will figure it out