Fulltone - OCD  [traced]

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pgm
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Post by pgm »

kungpow wrote:I've built off the layout you posted and it sounds great! Can't speak for the others...
alright cool!
thanks for all the advice will post comments after build :D

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Post by Grendahl »

nooneknows wrote:Btw, I think the switch is not that useful, since I always used mine on Hi, I just took out the switch, connecting the two resistors in parallel.
Any reason you didn't just throw a single 13K resistor in there to lower component count?
Resistance is futile...
( if < 1 ohm )

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Post by borislavgajic »

I made it like this..... :thumbsup

nice sounding pedall......and it is completely handwired by robot :block:

Boris
Attachments
oced1.jpg
oced2.jpg
oced4.jpg
oced5.jpg
oced7.jpg

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Post by Liquitone »

ooh that looks very nice :o
nice how the colour of the resistors match that of the enclosure.
I've never seen those flat leads before on resistors,.. but then again neither have i seen those resostors before,. what type are they?

I've been working on a point to point OCD aswell,. I haven't got the parts yet but have made a layout,
It uses those small pins instead of the normal turrets they use in amps,.I think the moolon Class-A boost uses those aswell.
After building a univibe this way I'm more confident in this building method, only thing I'm worried about is the ic sockets,.
Point to point building doesn't seem to be very IC friendly.
still working on a better method than seen on this layout.
Image

btw I didn't name it Vintage-Drive to cover up its origins,. since it wont be for sale.
I'm building one for myself, our bass player and as something to give to befriended musicians as birthday-presents :)

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Post by borislavgajic »

https://www.freestompboxes.org/viewtopic ... 75#p105875
here are resistors

thanks for kind words!

I love green paint.....

Boris

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Post by Reintz »

MarkM's layout, that 95strat posted, works very well. I used ceramic capacitors as C3 and C6 and tantalum as C10.

Image
Image

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Post by robotsdocry »

Hi,
I can see in the layouts that their are two mosfets. In gutshots of real OCD's their are 3. What is the difference?

I have built an OVD last year as a hobby project. It sounds nice. But when A/B with a 'real' OCD their is a difference: the OCD is tigher!

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Post by okgb »

I built one that had a 10uf on the output and i had .27uf around so used
that on the input . these maybe contributing to the overall
bass heaviness mine seems to have , anyone experienced this ?
being more used to tube screamers my ego [ madbean pcb ] build
has a softer slight fuzzy quality to it that i'm not really digging

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Post by B_of_H »

i've built 3 of these now.

I prefer .068u for the tone cap (add's a little bass), .047u seems to be closer to unity but it doesn't sound like a cranked up amp as much to me. I may try .056 next.

I prefer 1uf tantalum for the cap prior to the HP/LP switch. electrolytics of various values seemed shrill and harsh to me.

the tlo82 is by far my favorite IC so far. I've tried a lot including the tl072, burr browns, 4558, 2272, 4559, lm1458 and a few others that I can't think of off the top of my head.

I tried a lot of different values and types of caps around the circuit and found that the stock ones were the best for me other than the above mods.

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Post by Güero 2.0 »

Image

Image

Image
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Post by B_of_H »

pgm wrote:
Image

i've been trying to get the madbean egodriver to match up sound wise with this layout. I've built two of each with precisely the same parts. Both of the vero boards on the layout above sound more open and articulate than the 'egodriver'.

the only differences I see are:

- stratotrasto's has a 1uf NP cap to ground and no 100r resistor in series (power filtering section)
(I already swapped a 1uf tantalum cap for the egodriver's c10 which is 10u electrolytic)

could the 1uf NP to ground and lack of 100r in series be causing the difference? I've tried swapping out resistors, mosfets etc... The vero layout sounds better to me for some reason.

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Post by Liquitone »

I've finished turret-OCD. It was a pain fitting it in a relatively small box, with the big caps and all. it sounds great on the recent champ 600, which i use at home, but behaves very different on the amps i use in the studio (fender 75 and Engl richie blackmore).
While at home the toneknob is in perfect balance about halfway in LP mode,but too low and muffled in the studio. cranking the tone-knob adds adds unpleasant highs while somehow still sounding muffled,.
I also need to keep the volume down more and dailing it just a little higher gives a way bigger volume-boost than it does on the champ.
so im not really sure if it the pedal or the amps that need tweaking, though im planning building my own amp since this is not the only pedal sounding worse on the big amps than it does on the sweet little champ.

also it had a high pitched squeal when bypassed,.after trying everything to fix it, a simple wire from the input cap to ground when bypassed
completely solved that.

here's the result;
Image

and the enclosure;
Image

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Post by mictester »

pgm wrote: Does schematic sound good?
No. You have to build the circuit!!! :wink: :lol:

It's a fairly standard "diodes to ground" clipper effect, which tries to "soften" the onset of clipping by the use of MOSFETs instead of simple diodes. This does have some marginal sonic benefits, but you're probably unlikely to hear much difference unless you're very careful with the way you play so that the level of the instrument fits perfectly to just the curved part of the MOSFET characteristic.

The tone switch has a very marginal effect, and this kind of effect really needs a much more effective tone control to be musically useful. The values chosen in the circuit give a fairly useful over all frequency response for guitar, but it's really not at all special (and doesn't really warrant the huge number of posts discussing it!)

As an experiment, in a recording studio recently, I had a box with me that allowed switching between different types of clipper. The basic circuit was a low noise Tubescreamer type (circuit in another post elsewhere here on this forum), with the option of differing diodes, MOSFETs, transistors and LEDs for clipping. The clippers could either be connected to the inverting input of the first op-amp or to the mid-rail (which is AC ground because of the large electrolytic from the midpoint of the bias potential divider).

I had several musicians and engineers "audition" the effect, and we did "blind" testing of the different means of clipping. In each case, the levels were carefully adjusted to remain the same, so that "loudness" wouldn't be a factor in their comments about the sounds. We found that there were three discernible types of clipping, and all the rest sounded much the same as one of these three:

Diodes in the feedback loop of the op-amp (like a basic Tubescreamer)

Diodes to ground after the op-amp

Asymmetrical diodes in the feedback loop (very marginal difference to the first).

It didn't really matter what kind of clipper you used!!!! In most cases the only differences are the point at which distortion starts - germanium diodes clip at 0V2 p-p so will seem more "sensitive" than silicon one which clip at 0V65 p-p. LEDs are even less "sensitive" because the take even higher voltage to conduct. There was a slight difference audible with asymmetrical clipping (though, on average, only three out of ten listeners could hear the difference!).

After the experiments, I was really quite disappointed - I felt sure that there would be a noticeable difference in sound between differing types of clippers (not just the point at which clipping starts, which is what I found). The most important part of the over all sound of the effect is the frequency response before and after the clipper stage (a low pass filter before the clipper makes your effect really smooth), and the best we can really do is to put a really effective tone control circuit after the clippers. We also need to keep the noise down!

I plan to repeat the experiment with a set of "Fuzz Faces" and "Tonebenders", and see how much variation people find.
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Post by ansil »

I have version 4 of the ocd, no. 40,001 and thought this was the biggest crapfest i have ever witnessed [i traded a broken sm-58 though so considering i had nothing in it it didn't really matter] however after seeing the tl082 i thought wow way to go with the cheapness mike.

I put a socket in this thing can i can attest to this fact the latest version of this pcb have really really thin foil on them and pull up even on low heat settings. I am using a 1000dollar soldering station with de-soldering station built in and it fell apart in my hand.

but alas i put in a socket finally re wired the stupid thing and was going to get rid of it till i put in an burrbrown chip in it and thought this is usable albeit if only slightly. lastly i slapped a tlc2262 in it now and although i cannot use the 18V mod anymore i can finally achieve decent tone out of it.

thinking of stacking opamps in it utilizing a jrc4558 BB opa and tlc2262 and running it at 16v. should be a hoot.

if you put a socket in your let me know what you think of the 2262

ed

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Post by jg »

I kind of like the TL082. With its jfet inputs and bipolar output it sounds good in a lot of circuits. The 2262 being all MOSFETs can sound good on their own being overdriven as they clip nicely, but as a buffer they always sound 'flat' to me. Plus there's the max 16V supply issue.
I've reworked 100s of OCD boards with my $80 soldering iron and have never had a problem with lifted traces. Maybe your technique could use a little work? The PCB looks to be the standard CE approved FR-4 with 1oz copper.

I think you will find that stacking it with a 4558 will make it sound just like a 4558 alone. The lower gain (slew rate) and max voltage swing of 7 volts (9 volt supply) means it will probably dominate the response.

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dozen tube screamer fulldrive whatever you call them variants

hell i can't type this long it will piss off people what can i say i have been doing mods on toyz appliances gear sex toyz computers and such for 27 years. i started when i was 6 taking stuff apart.

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Post by ansil »

i think we can always improve our technique but as i stated before this is a version 4 not sure if you have seen these yet but if you have i do certainly apologize. but they contain NO copper near the IC. these are very tiny silver [not sure what the hell they are actually] but even under the microscope after scraping away what i thought was where it was pre tinned it contained no copper. currently i am out of acid or i would like to see what it is. i have seen one of each of the first three generations and each one was indeed a nice copper board with no problems. however this isn't one of them.

to give you an idea of how bad the traces on this board i can remove the trace from the board with my fingernail with less pressure than it would take to remove a paint fleck from glass.

my Fulldrive isn't like this nor any other of my fulltone products

[edit] after re examining this board i found by the pots and switch there is pre tinned copper but everything by my socket is what appears to be a silverish foil. almost like it was factory second that got new foil traces?? i am unsure if it didn't mean taking it all apart again i would post some pics and well lets say its sold anyway.

i have emailed mike just to ask him about it although it is working fine now.

i do like your idea about the buffer though i have noticed in designs that they seem to avoid them for buffer stages. so i may just try another trick via halving the opamp.

ciao for now

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Post by jg »

I'm very familiar with version 4 boards. More than you know. Since you sold the pedal and therefore cannot illustrate your point with pictures, I guess the point is moot.

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Post by BennyB »

What might cause a slight overall lower voltage reading for the pins of the empty chip socket?

I built one of these, and it sounds mostly good, but with a faint, sizzly, sputtery high end on the decay of a ringing chord.

It kinda sounds like when you starve the voltage of a fuzz. But REALLY slight and faint.

Some voltage measurements: (with the chip out)
Battery: 9.2
Pin 1: 4.15
Pin 2: (with the drive all the way) 4.15
Pin 3: 4.39
Pin 4: 0
Pin 5: 4.15
6-
7-
Pin 8: 9.2

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dozen tube screamer fulldrive whatever you call them variants

hell i can't type this long it will piss off people what can i say i have been doing mods on toyz appliances gear sex toyz computers and such for 27 years. i started when i was 6 taking stuff apart.

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Post by ansil »

did you check the continuity of the pins to make sure they are reaching all the way through the board?? there are quite a few jumps from top side to bottom side of the board i had a trace fall off that was never heated or even touched anywhere near it.


JG meant to tell ya, you were right i tried it and i never noticed about the 2262 as a buffer before but you blew my mind with that.

but you know i am starting to think that this thing was monkeyed with before i got it. i picked up another one at guitar center to do a different mod to it and this one is so much better. so i am thinking the guy i got it from may have tinkered with. which happens

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Post by BennyB »

ansil wrote:did you check the continuity of the pins to make sure they are reaching all the way through the board?? there are quite a few jumps from top side to bottom side of the board i had a trace fall off that was never heated or even touched anywhere near it.
Well mine's from a pcb.

The thing sounds great, cleans up and no one can really tell that something's wrong. But there's this minute, niggling sizzle sputter on the high end of a sustained barred chord.

Just wondering if those voltages were indeed too low, and what might be a culprit... I realize it's a vague question, but...

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