Fulltone - OCD  [traced]

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
User avatar
bluesky636
Information
Posts: 21
Joined: 01 Sep 2015, 04:53
Has thanked: 1 time

Post by bluesky636 »

[smilie=a_goodjobson.gif]
Bill, "The Piranha"

User avatar
george giblet
Resistor Ronker
Information
Posts: 346
Joined: 30 Dec 2008, 17:27
Has thanked: 171 times
Been thanked: 240 times

Post by george giblet »

So clearly he doesn't have all his facts straight, but that doesn't change the fact that he felt he had to modify the power filtering in order to deal with noisier power supplies - which is perfectly plausible.
For audio generic adaptors are a pain in the butt for noise. You have no idea what you are dealing with. The old transformer wall-warts never had a problem (except for hum in the early days, as the pedals were designed for batteries).
The worldwide market for power supplies has changed because of modern regulations and technical innovations and the race to make things inexpensive. Switching supplies are far more common now for pedals than they were ~20 years ago.
There's no doubt about that. IMHO the cost saving don't always make it to the customers. The advantages of SMPs are regulated output, light weight and you can pack a lot more power into the same space. Weight and power aren't really selling points for pedals. A 12V 4A wall-wart with a conventional transformer just wouldn't exist, even 12V at 1A is on the verge of ridiculous. The SMPS wall-warts don't last either as the caps dry out. I've still got conventional wall-wart from the 70's.

User avatar
dmc777
Information
Posts: 45
Joined: 02 May 2010, 20:14
Has thanked: 6 times
Been thanked: 4 times

Post by dmc777 »

I had V2 for a few months and was really disappointed. Might have been rev1 of V2 but it was just wooly and full of bass. Had to crank the presence. Also, too much gain. Found to best way to use it was the gain around 9 and to slam it with a klon clone with the treble up. Seems like my little AMZ mini booster worked great after it as well which is wierd because my mini booster has a good bit of bass as well but it also has that top end sizzle that topped it off nicely.

What’s the general consensus on the “best” OCD? How’s v1.3? I believe I owned a 1.7 for a while which I liked but wasn’t in awe over it.

User avatar
bluesky636
Information
Posts: 21
Joined: 01 Sep 2015, 04:53
Has thanked: 1 time

Post by bluesky636 »

Sounds like you have a faulty pedal.

I have a V2.01 and run the gain at about 2:00, volume at 9:00, and tone at 10:30. Sounds glorious with both my R8 or Strat.
Bill, "The Piranha"

User avatar
aionios
Solder Soldier
Information
Posts: 203
Joined: 22 Mar 2012, 00:12
Location: Des Moines, IA
Has thanked: 6 times
Been thanked: 363 times
Contact:

Post by aionios »

I traced a V2 (details forthcoming) and mine had a 4n7 cap in parallel with the clipping diodes. Normally this is 1n, including in PPCB's trace of the V2, so they seem to have reverted this change at some point during V2's production. It was also really dark and honestly sounded pretty bad compared to a 1.4 or 1.7. But overall the V2 is definitely more bassy and less trebly than any of the 1.x versions, even without the 4n7 cap.

User avatar
bluesky636
Information
Posts: 21
Joined: 01 Sep 2015, 04:53
Has thanked: 1 time

Post by bluesky636 »

I do not find my 2.01 to be too bassy. In fact, if anything it is bright. I set the tone control to about 10:30 even with humbuckers. I've never turned it above noon.
Bill, "The Piranha"

User avatar
smear
Information
Posts: 20
Joined: 26 Mar 2018, 05:09
Has thanked: 1 time
Been thanked: 8 times

Post by smear »

Here's a simulation of the V1.4 using 1nF (green) and 4.7nF (blue), with the tone knob at noon (5k). The cap adjusts a lowpass in conjunction with the 10k series resistor. I don't show it here, but turning up the tone control can't get you those frequencies back, instead it gives a bigger peak at ~1.5kHz. Even with the tone at max, the 4.7nF version has a noticeable treble cut above ~8kHz.

I wonder why he wanted to make the pedal darker with the V2.

EDIT: got the colors mixed up.
Attachments
Fulltone OCD V1.4 frequency response Blue=1nF Red=4.7nF.png
Last edited by smear on 24 Jan 2023, 20:33, edited 1 time in total.

User avatar
bluesky636
Information
Posts: 21
Joined: 01 Sep 2015, 04:53
Has thanked: 1 time

Post by bluesky636 »

As I have stated previously, my 2.01 is not dark. I know nothing about the base 2.0
Bill, "The Piranha"

User avatar
ggbb
Information
Posts: 38
Joined: 12 Jan 2011, 22:16
Completed builds: Monte Allums Boss CS-3 Opto-Plus Mod
Run-Off-Groove Improved EA Tremolo (modified)
Modified Fuzz Face
Orange Smoothie Compressor
OCR (Modified RAT)
BSIAB2/Pinnacle Hybrid
Cardinal Tremolo
Bluesbreaker
Notorious OD (Modified Bluesbreaker)
Timmy
Boss CS-2 Compressor
Scarab Deluxe
Mini Copy Chorus (Modified Small Clone)
PAiA Gator
Hot Cake
ODR-1
Mostortion
OCD v2
Straight Up Clean Boost/Cut
Location: Toronto
Has thanked: 10 times
Been thanked: 15 times

Post by ggbb »

smear wrote: 24 Jan 2023, 20:04 I wonder why he wanted to make the pedal darker with the V2.
Since apparently there is a trace of a v2 using 1n not 4n7, unless we know which came first, it's possible that 4n7 was an early production run and he switched to 1n to make it brighter - maybe based on initial feedback that v2 wasn't bright enough. I built a clone sans input and bypass buffers (EDIT - the input impedance is raised to 1M anyway due to the larger bias resistor) and using 1n in parallel with the clippers and it's not at all dull (sounds great IMO).

That would still leave the question of why it started out as 4n7, which could be explained as compensation for the higher input impedance leading to less treble loss due to input loading.

v1 was continually being "tweaked" - so why not v2 as well?
bluesky636 wrote: 24 Jan 2023, 20:21 As I have stated previously, my 2.01 is not dark. I know nothing about the base 2.0
bluesky can you tell us whether your "not dark" v2.01 is using 1n or 4n7 for the cap in parallel with the clipping MOSFETs? Any details about the .01 mod would also be nice to hear about.

User avatar
bluesky636
Information
Posts: 21
Joined: 01 Sep 2015, 04:53
Has thanked: 1 time

Post by bluesky636 »

Sorry. I'm not interested in taking apart a perfectly good, working pedal.
Bill, "The Piranha"

User avatar
ggbb
Information
Posts: 38
Joined: 12 Jan 2011, 22:16
Completed builds: Monte Allums Boss CS-3 Opto-Plus Mod
Run-Off-Groove Improved EA Tremolo (modified)
Modified Fuzz Face
Orange Smoothie Compressor
OCR (Modified RAT)
BSIAB2/Pinnacle Hybrid
Cardinal Tremolo
Bluesbreaker
Notorious OD (Modified Bluesbreaker)
Timmy
Boss CS-2 Compressor
Scarab Deluxe
Mini Copy Chorus (Modified Small Clone)
PAiA Gator
Hot Cake
ODR-1
Mostortion
OCD v2
Straight Up Clean Boost/Cut
Location: Toronto
Has thanked: 10 times
Been thanked: 15 times

Post by ggbb »

bluesky636 wrote: 25 Jan 2023, 01:34 Sorry. I'm not interested in taking apart a perfectly good, working pedal.
Understood. That can be a bit intimidating.

User avatar
bluesky636
Information
Posts: 21
Joined: 01 Sep 2015, 04:53
Has thanked: 1 time

Post by bluesky636 »

Not intimidated at all. I build vacuum tube guitar amps as a hobby. I just don't feel like taking my pedalboard apart after just rewiring it a few weeks ago to fix a noise problem.
Bill, "The Piranha"

User avatar
ggbb
Information
Posts: 38
Joined: 12 Jan 2011, 22:16
Completed builds: Monte Allums Boss CS-3 Opto-Plus Mod
Run-Off-Groove Improved EA Tremolo (modified)
Modified Fuzz Face
Orange Smoothie Compressor
OCR (Modified RAT)
BSIAB2/Pinnacle Hybrid
Cardinal Tremolo
Bluesbreaker
Notorious OD (Modified Bluesbreaker)
Timmy
Boss CS-2 Compressor
Scarab Deluxe
Mini Copy Chorus (Modified Small Clone)
PAiA Gator
Hot Cake
ODR-1
Mostortion
OCD v2
Straight Up Clean Boost/Cut
Location: Toronto
Has thanked: 10 times
Been thanked: 15 times

Post by ggbb »

Understood. That would be some effort.

User avatar
aionios
Solder Soldier
Information
Posts: 203
Joined: 22 Mar 2012, 00:12
Location: Des Moines, IA
Has thanked: 6 times
Been thanked: 363 times
Contact:

Post by aionios »

All right, I took apart a v2.01 (serial ~221000, December 2021) and the preliminary findings are as follows: Mike is, once again, either a liar or an idiot (I would lean toward liar).

So far the only difference I can see is that there are two SMD LEDs (red waterclear) labeled D6 and D7:

Image

These are in an anti-parallel configuration and are connected to the outer pins of the Drive pot (pin 1 and pins 2/3), which means they're TS-style opamp feedback clipping, the only difference being that they are inside of the 18k minimum-gain resistor instead of directly between the opamp's output and inverting input as usual. The purpose seems to be to prevent the opamp from going into clipping at high gain settings. Maybe this impacts the bass, I don't know, but certainly it's not "tuned" in any way that is selective of bass frequencies like a capacitor would be.

This would both confirm & clarify the photo posted in another thread. I looked at a bunch of Reverb photos and it appears that there was a span of just a few thousand with the LEDs soldered on like this, around serial 215000 to 219000. (In that photo you can't tell from the angle, but I've seen a few others where it's more clear that there is a 2nd LED underneath the first one in the hot glue.) Earlier ones don't have these LEDs on the back, and later ones don't either, so my best guess is just that there was a shortage of the SMD LEDs for a few months.

I haven't done a full trace yet, but I don't see any new capacitors at all, and certainly none near the clipping section. C4 (the one in parallel with the clipping diodes) is 4n7. The tone cap is back up to the v1 value of 47n (earlier V2s had 22n here). The opamp highpass capacitor is still 100n as in other V2s, but the series resistor is back down to 2k2 (it was 3k3 in both PPCB's and my trace of V2 units). There are some changes to the input buffer, dropping the bypass capacitor on the source, though I haven't spent much time looking at this section of the PCB yet.

So why the BS? Mike likes to spread misinformation, and I was suspicious when he said he "found a way to isolate the clipping via a smaller separate pair of caps" (viewtopic.php?p=293561#p293561). If it was connected in the obvious way (cap in series with diodes, which should theoretically only make them clip the higher frequencies depending on the capacitor value) then you wouldn't need two capacitors unless you were an idiot, since the clipping diodes share the same audio path. You could use a single cap before the clipping diodes or after, but it's the same either way.

Unless... you were originally typing out something true and then decided to change one word at the last minute to avoid giving something away - in other words, he really meant "pair of diodes" but decided to say "pair of caps" instead. That's the best I can do to make sense of it.

User avatar
bluesky636
Information
Posts: 21
Joined: 01 Sep 2015, 04:53
Has thanked: 1 time

Post by bluesky636 »

Since Fuller built the 2.01s himself, I'm sure he knows what he put in them. Perhaps he is tired of people copying his work and posted misinformation to throw people off. Can't say I would blame him since he shut everything down.
Bill, "The Piranha"

User avatar
smear
Information
Posts: 20
Joined: 26 Mar 2018, 05:09
Has thanked: 1 time
Been thanked: 8 times

Post by smear »

bluesky636 wrote: 29 Jan 2023, 22:01 Since Fuller built the 2.01s himself, I'm sure he knows what he put in them. Perhaps he is tired of people copying his work and posted misinformation to throw people off. Can't say I would blame him since he shut everything down.
i thought he only build the Candy Apple Red ones himself? and when most of your pedal is machine-populated SMD, i do wonder what it means when he says he build it. soldered the pots himself?

from what i can tell, he didn't shut down because people stole his designs. more likely the reverb/guitar center thing...

User avatar
bluesky636
Information
Posts: 21
Joined: 01 Sep 2015, 04:53
Has thanked: 1 time

Post by bluesky636 »

smear wrote: 31 Jan 2023, 05:38
bluesky636 wrote: 29 Jan 2023, 22:01 Since Fuller built the 2.01s himself, I'm sure he knows what he put in them. Perhaps he is tired of people copying his work and posted misinformation to throw people off. Can't say I would blame him since he shut everything down.
i thought he only build the Candy Apple Red ones himself? and when most of your pedal is machine-populated SMD, i do wonder what it means when he says he build it. soldered the pots himself?

from what i can tell, he didn't shut down because people stole his designs. more likely the reverb/guitar center thing...
He said that he built the 2.01 versions himself and signed them. Exactly what that means I don't know.

I don't know what the "reverb/guitar center thing" is.
Bill, "The Piranha"

User avatar
smear
Information
Posts: 20
Joined: 26 Mar 2018, 05:09
Has thanked: 1 time
Been thanked: 8 times

Post by smear »

on their own, adding those LEDs doesn't change the frequency response. however, since the LEDs cause soft-clipping, they will give a warmer and bassier sound from the opamp clipping section when the gain is turned up high. that means more bass hits the diodes shunted to Vb. in theory the amount of soft-clipping could be fine-tuned by adding another resistor in series with the LEDs. the 18k does that a bit already, the soft-clipping doesn't kick in as early as on a TS for example.
bluesky636 wrote: 31 Jan 2023, 06:19
smear wrote: 31 Jan 2023, 05:38
bluesky636 wrote: 29 Jan 2023, 22:01 Since Fuller built the 2.01s himself, I'm sure he knows what he put in them. Perhaps he is tired of people copying his work and posted misinformation to throw people off. Can't say I would blame him since he shut everything down.
i thought he only build the Candy Apple Red ones himself? and when most of your pedal is machine-populated SMD, i do wonder what it means when he says he build it. soldered the pots himself?

from what i can tell, he didn't shut down because people stole his designs. more likely the reverb/guitar center thing...
He said that he built the 2.01 versions himself and signed them. Exactly what that means I don't know.

I don't know what the "reverb/guitar center thing" is.
https://www.guitarworld.com/news/reverb ... e-products

Post Reply