Fulltone - OCD  [traced]

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Re: Fulltone OCD

Postby Blues Lyne » 02 Mar 2008, 00:45

The links don't seem to work. They just end up here http://f.defaut.free.fr for me.
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Re: Fulltone OCD

Postby gnognofasciani » 02 Mar 2008, 02:24

He removed the pics :? , if anyone wants them just pm me
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Re: Fulltone OCD

Postby bajaman » 02 Mar 2008, 02:40

He must have been pressured by Aron or maybe MF had a hissy fit :P :lol: :lol:
I always download this stuff double quick - all safe on my drive :lol: :lol: :lol:
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Re: Fulltone OCD

Postby gnognofasciani » 02 Mar 2008, 14:23

http://rapidshare.com/files/96427890/Pappice.zip.html

Save it fast, i don't know how long it will last...
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Re: Fulltone OCD

Postby bajaman » 02 Mar 2008, 20:31

Hey thanks gnognofasciani :wink:
At last a hand drawn schematic for the OCD :applause:
BUT - Do not try and build it from this schem - it will NOT work.
Take a look at that 10k resistor feeding the non inverting input of the second stage op amp :wink:
It should connect to the junction of the preceeding 10k resistor and mosfet/germanium diode clippers, NOT the half rail voltage as it is drawn :slap: :slap: :slap:
Great photos though - more than enough info to create a DIY project from this :lol: :hug:
cheers
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http://www.freestompboxes.org/members/bajaman/OCD/OCDschematics.jpg

spot the mistakes :hmmm:
Last edited by bajaman on 02 Mar 2008, 20:41, edited 6 times in total.
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Re: Fulltone OCD

Postby gnognofasciani » 02 Mar 2008, 20:35

I didn't have the time to check the schematic drawn by the autor of the photos, but I had the same impression at first look that something was wrong :)
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Re: Fulltone OCD

Postby gnognofasciani » 02 Mar 2008, 20:37

gnognofasciani wrote:I didn't have the time to check the schematic drawn by the autor of the photos, but I had the same impression at first look that something was wrong :)


I was more interested in the components values than the schem itself
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Re: Fulltone OCD

Postby Gila_Crisis » 03 Mar 2008, 08:57

are you sure the schem is wrong?
look here: http://s17.photobucket.com/albums/b72/m ... CDv2-1.png
this is another schem found for the OCD, and it looks preatty similar to the one posted above. there's a lovely mess in the part of the schem (the other posted here above) where there are the transistors... but the rest seam look ideantical
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Re: Fulltone OCD

Postby oscarv77 » 03 Mar 2008, 09:25

Gila_Crisis wrote:are you sure the schem is wrong?
http://s17.photobucket.com/albums/b72/m ... CDv2-1.png


I take it this schem is unverified? :whappen:
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Re: Fulltone OCD

Postby bestegw » 03 Mar 2008, 10:57

I've been watching the discussions over here and decided that now's about time to join in. So, first and foremost: thanks for being such a great platform for DIY-people :applause: !!!

I've read somewhere that the OCD is based on the Shaka Bradda III as designed by Aron Nelson. That design uses IRF510 or IRF520 trannies for clipping, while this design uses 2N7000's. :scratch:

I'm thinking about building something that's based on clipping Mosfets. Anybody have a clue about the sonic differences between these two types of trannies??

Thank U!

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Re: Fulltone OCD

Postby bajaman » 03 Mar 2008, 11:28

are you sure the schem is wrong?

positive :wink:
check out Markm's photobucket schem - the two 10k resistors :wink:
Then tell me that there is no mistake on the hand drawn schem :roll: :roll: :roll:
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Re: Fulltone OCD

Postby Gila_Crisis » 03 Mar 2008, 11:35

then makm's schem is right?
i still must see a schem of this OCD that says Built verified and working like the real one!
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Re: Fulltone OCD

Postby kusi » 03 Mar 2008, 12:00

hi,

markM`s schematic is nearly correct. only one 220k resistor from the second non.inv.input to Vref is missing.

i could post my schematic with the different versions incl. pcb (verified) if someone would like to see it... ;)

regards, kusi
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Re: Fulltone OCD

Postby gnognofasciani » 03 Mar 2008, 12:03

The markm schem is right (just a little "messy" in the tone control section), but you have to change values according to the hand drawn schem :wink:

Edit: hand drawn schem corrected

Image
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Re: Fulltone OCD

Postby gnognofasciani » 03 Mar 2008, 12:22

I think that the 1nF cap in the clipping section could be a 10nF, it would have much more sense...maybe a misreading?
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Re: Fulltone OCD

Postby tuemmueh » 03 Mar 2008, 12:50

kusi wrote:hi,

markM`s schematic is nearly correct. only one 220k resistor from the second non.inv.input to Vref is missing.

i could post my schematic with the different versions incl. pcb (verified) if someone would like to see it... ;)

regards, kusi


yep, there is someone who's interested, especially in the pcb.
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Re: Fulltone OCD

Postby Ghandi » 03 Mar 2008, 13:36

@ gnognofasciani,
that 1n cap parallel to the diodes should be a 10n.

@kusi
how is it going?
some friend of us told me that 220K resistor was removed in version3, it gives a bit more dynamics.

cheers
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Re: Fulltone OCD

Postby MKB » 03 Mar 2008, 14:52

kusi wrote:hi,

markM`s schematic is nearly correct. only one 220k resistor from the second non.inv.input to Vref is missing.

i could post my schematic with the different versions incl. pcb (verified) if someone would like to see it... ;)

regards, kusi


Several other differences, R3 should connect to pin 3 of U1A (might not make much of a difference), C7 should be 1nF, and C11 should be 10uF. Other than that it looks pretty close. I've built one of these and have used it on every gig for months now, haven't compared it to a real one but it is the best distortion pedal I've ever heard or used. It sounds exactly like the manufacturer's sound files to me, it especially gets the clarity right. Keep the gain knob at 12 o'clock or lower, higher than that it starts sounding bad. Set the gain at 12 o'clock, and overdrive it's input with a Tube Screamer or other overdrive pedal for a special treat. :thumbsup

It's basically a modified Voodoo Labs overdrive with a few tweaks and carefully selected part types (especially cap dielectrics, some of them are a bit out of the ordinary). I'm convinced the tweaking is where the magic lies.
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Re: Fulltone OCD

Postby JHS » 03 Mar 2008, 15:28

Kusi traced a V1, a bit different from the V2 and V3 circuit.
Maybe there are some transition circuits too and acc. to Fuller all 220p are 330p. I've seen a gutshot of a V4 prototype with asym. clippers and some altered values.

I don't bother about V1, V2, V3, and V4 anymore, 'cos I designed the OCD++ (rev. H) which is able to emulate all the sound of the different versions due to some jumper and other mods. Furthermore I replaced the HP/LP switch with a pot for a continuous blend between the HP and LP mode.

The clarity comes from the mixture of multilayer, tantal and ceramic caps. With Mylar and NF caps it will sound a bit muffled w/o the clarity.

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Re: Fulltone OCD

Postby snoof » 03 Mar 2008, 22:36

that is the complaint i had with the version that I built, muffled high end, no sparkle.
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