Fulltone - OCD  [traced]

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
User avatar
bajaman
Old Solderhand
Information
Posts: 4549
Joined: 26 Jun 2007, 21:18
Location: New Brighton, Christchurch, NZ
Has thanked: 595 times
Been thanked: 2056 times

Post by bajaman »

good quality caps = clear sound - mylar is shit :wink:
bajaman
be kind to all animals - especially human beings

User avatar
WormBoy
Information
Posts: 32
Joined: 23 Feb 2008, 20:24
Location: The Netherlands
Been thanked: 1 time

Post by WormBoy »

Ah, so tantalum and ceramic rate as quality cap material? :hmmm:

User avatar
bajaman
Old Solderhand
Information
Posts: 4549
Joined: 26 Jun 2007, 21:18
Location: New Brighton, Christchurch, NZ
Has thanked: 595 times
Been thanked: 2056 times

Post by bajaman »

Ah, so tantalum and ceramic rate as quality cap material?
Well Tantalum bead are better than aluminium in audio coupling circuits and the newer multilayer ceramics are a distinct improvement on the earlier low voltage ceramics, but I was meaning polystyrene and polypropylene foil capacitors not cheap shitty polyester (mylar) capacitors.
cheers
bajaman
be kind to all animals - especially human beings

User avatar
WormBoy
Information
Posts: 32
Joined: 23 Feb 2008, 20:24
Location: The Netherlands
Been thanked: 1 time

Post by WormBoy »

Thanks for explaining. But do you think that cap material would make the difference between a muddy and a sparkling pedal? Polystyrene caps would probably be difficult to find, but should I be able to hear a difference between polypropylene and (good quality) polyester caps, in a circuit like an OCD?

I once A/B-ed a tantalum and aluminium elco in a fuzz face clone for the input cap, but could not hear a difference (may be my ears though, which suffered from my guitar-playing "career" :( ).

User avatar
lohstah
Solder Soldier
Information
Posts: 237
Joined: 08 Jul 2007, 20:08
Has thanked: 214 times
Been thanked: 96 times

Post by lohstah »

baja, you got mail.

cheers,
lohastah

User avatar
MKB
Breadboard Brother
Information
Posts: 93
Joined: 06 Sep 2007, 12:03
Location: USA

Post by MKB »

WormBoy wrote:Thanks for explaining. But do you think that cap material would make the difference between a muddy and a sparkling pedal? Polystyrene caps would probably be difficult to find, but should I be able to hear a difference between polypropylene and (good quality) polyester caps, in a circuit like an OCD?

I once A/B-ed a tantalum and aluminium elco in a fuzz face clone for the input cap, but could not hear a difference (may be my ears though, which suffered from my guitar-playing "career" :( ).
It's true that tantalum and aluminum electrolytics are crap in audio circuits compared to a polystyrene, but the characteristics of the crap do make a difference tonally in circuits, especially simple ones with amplification. I first built my OCD clone as a VLOD with standard high quality parts, and it was totally dead and uninspiring. When it was rebuilt with the OCD values and the proper cap dielectrics, it was 1000% different (better). I suspect that the tantalum caps (which sound TERRIBLE in hi-fi coupling applications, the detail is smeared with a grinding treble) add an aggression to the high end and help shape the harmonics that pass through. And a ceramic coupling cap will have a different tone (more aggressive upper mids but less treble) than a silver mica. So for a bypass cap, if the tone is too bright and sizzly, try a silver mica instead of a ceramic as the silver mica is more efficient at the higher frequencies. All the cap types are like spices, too much of one type or the wrong one in the wrong place is nasty, but combine them properly and it gets really tasty. To me the real value of gut shots (other than reverse engineering) is finding the proper capacitor types for the circuit.

User avatar
WormBoy
Information
Posts: 32
Joined: 23 Feb 2008, 20:24
Location: The Netherlands
Been thanked: 1 time

Post by WormBoy »

MKB wrote: I first built my OCD clone as a VLOD with standard high quality parts, and it was totally dead and uninspiring. When it was rebuilt with the OCD values and the proper cap dielectrics, it was 1000% different (better).
But you changed both the values and the material, so the difference may be mainly due to the value ... It is not that I don't believe that cap material makes a difference, I'm just having a hard time trying to figure out how much and in what direction ... and to figure out for which (parts of) circuits I will have to source for exotic and/or expensive caps. As I said *I* could not hear a difference between a tantalum and an aluminium of the same value in an FF, but I should be able to hear a difference between a tantalum and a good quality film cap in the audio path.

Oh well, maybe I just have to breadboard the OCD and try all kinds of different caps in there ... that may be a fun project for summer vacation.

User avatar
Ghandi
Solder Soldier
Information
Posts: 162
Joined: 14 Aug 2007, 13:52
Has thanked: 14 times
Been thanked: 28 times

Post by Ghandi »

hi there again,
I made a mistake the cap across the diodes should be 1nF, like in the old voodoo labs overdrive, sorry... :roll:

User avatar
foo zen trader
Breadboard Brother
Information
Posts: 62
Joined: 09 Feb 2008, 17:46
Location: germany
Has thanked: 2 times
Been thanked: 10 times

Post by foo zen trader »

Does anyone have a verified layout?

regards,

Foo
JABBA DABBA DOOM

User avatar
tuemmueh
Solder Soldier
Information
Posts: 165
Joined: 26 Jun 2007, 23:30
Has thanked: 7 times
Been thanked: 2 times

Post by tuemmueh »

kusi offered to upload his, but didn't do it so far :(

User avatar
nokaster
Solder Soldier
Information
Posts: 153
Joined: 07 Oct 2007, 16:46
Contact:

Post by nokaster »

foo zen trader wrote:Does anyone have a verified layout?


i wouldn't mind a good vero layout myself! 8)

User avatar
MKB
Breadboard Brother
Information
Posts: 93
Joined: 06 Sep 2007, 12:03
Location: USA

Post by MKB »

You can take the Voodoo Labs OD vero layout and make it into an OCD with not too much effort.

User avatar
Jay
Information
Posts: 42
Joined: 17 Aug 2007, 03:04
Location: USA

Post by Jay »

foo zen trader wrote:Does anyone have a verified layout?

regards,

Foo

Isn't MarkM's OVD layout actually the OCD?
If it is I believe it is verified.

User avatar
Deric
Breadboard Brother
Information
Posts: 74
Joined: 04 Oct 2007, 03:04
Been thanked: 2 times

Post by Deric »

Started this layout a while ago - based on MarkM's. The OVD layout appears to have an error in the hp/lp switch wiring - the switch puts the 22k and 33k in series instead of parallel. The 220k from pin5 to vref was also missing - not sure if it should be there or not???? :scratch: I changed the switch wiring, added the 220k and added some pads for an extra diode for assymetrical clipping if desired.

Commenst/suggestions/corrections are encouraged/appreciated. :thumbsup

Image

For the record: I do not have an OCD. I have NEVER played an OCD. I have not traced an OCD. This layout was done from schematics, layouts and comments posted here.
Try not to be a dick when speaking about others; try not to be pussy when others are speaking of you.

User avatar
foo zen trader
Breadboard Brother
Information
Posts: 62
Joined: 09 Feb 2008, 17:46
Location: germany
Has thanked: 2 times
Been thanked: 10 times

Post by foo zen trader »

I asked Kusi... he's got much to do at the moment but he tries to finish/upload his version until next week...
cheers,
foo
JABBA DABBA DOOM

User avatar
stratotrasto
Information
Posts: 10
Joined: 07 Sep 2007, 15:02
Location: Avila Spain
Been thanked: 1 time

Post by stratotrasto »

Here I leave my offer you

Image

Image

A greeting

User avatar
tuemmueh
Solder Soldier
Information
Posts: 165
Joined: 26 Jun 2007, 23:30
Has thanked: 7 times
Been thanked: 2 times

Post by tuemmueh »

No 220k from Pin5 to Vbias?!

User avatar
drmathprog
Breadboard Brother
Information
Posts: 67
Joined: 02 Jan 2008, 23:16

Post by drmathprog »

Where did the images on photobucket go?

User avatar
oscarv77
Solder Soldier
Information
Posts: 181
Joined: 25 Aug 2007, 01:41
Has thanked: 11 times
Been thanked: 11 times

Post by oscarv77 »

Here you go...
Attachments
ocd.jpg
SCHMFXOCD.jpg

User avatar
snoof
Information
Posts: 36
Joined: 24 Aug 2007, 21:21
Location: KC
Has thanked: 2 times
Been thanked: 1 time

Post by snoof »

Jay wrote:
foo zen trader wrote:Does anyone have a verified layout?

regards,

Foo

Isn't MarkM's OVD layout actually the OCD?
If it is I believe it is verified.
yes it is. i've built it.

Post Reply