Author Topic: ADHD (ocd) : Dark sound, How to get more highs ?  (Read 637 times)

eh la bas ma

ADHD (ocd) : Dark sound, How to get more highs ?
« on: November 22, 2021, 12:21:11 PM »
Hello,

I am not sure if there is even an issue with this build. I notice it sounds much darker than the other overdrive and distorsion I built before.

https://www.pedalpcb.com/docs/ADHD.pdf

Everything sounds fine with the distorsion. Switches are effective, with a noticeable mid boost.

When the tone knob is fully CW, it feels like it is really at midrange, not much high frequencies audible. Going CCW it acts like a treble cut.

I checked the pots values, the soldering, resistors and caps values, nothing obviously wrong there.


Maybe the 22n capacitors are the wrong type (three brown caps located on each side of the IC) ?

Are C1, C8 and C13 affecting the signal ? Should they be replaced by film caps ?

Any help would be welcome !

Here is a picture in case someone can spot something I missed :



Edit : I checked and they are film caps, so I guess I will go and re-recheck the soldering...

Edit 2 : according to some posts on forums, there might be less high frequencies on this circuit than in the original :

" If you built the ADHD board according to the build doc it will be a little darker sounding than the original OCD, but the difference (At least from the one I built) wasn’t significant at all"

What would be the best way to get more treble from this circuit ?
« Last Edit: November 22, 2021, 12:57:37 PM by eh la bas ma »
"unity-gain non-inverting stage", "ground leg","post-pick moments", I love this colorful forum.

POTL

Re: ADHD (ocd) : Dark sound, How to get more highs ?
« Reply #1 on: November 22, 2021, 02:21:20 PM »
Hey I've also noticed that OCD sounds dark. My opinion is. 1) C3 has too much capacitance, the higher the gain, the less high frequencies pass, I would reduce the capacitor to 100pF or even 47pF, find a balance when there is not too much high frequency noise, and the sound becomes brighter. 2) C6 should also be reduced. 3) The tone control is not very good, due to the fact that R11 and R12 form a voltage divider with R14 + tone pot, the high frequencies are always slightly suppressed. 4) C1, C2, C5 are also worth trying to reduce, a large amount of low frequencies makes us hear the sound less bright, this is how our ears are arranged.

niektb

Re: ADHD (ocd) : Dark sound, How to get more highs ?
« Reply #2 on: November 22, 2021, 04:39:38 PM »
My problem with the OCD circuit was that the output impedance is rather poor. When I would put a buffer behind it, the sound was a lot brighter :)

I solved it by messing with the tone control and changing some values there :)

eh la bas ma

Re: ADHD (ocd) : Dark sound, How to get more highs ?
« Reply #3 on: November 22, 2021, 05:32:53 PM »
I solved it by messing with the tone control and changing some values there :)

Do you remember your custom values by any chance ?
"unity-gain non-inverting stage", "ground leg","post-pick moments", I love this colorful forum.

Mark Hammer

Re: ADHD (ocd) : Dark sound, How to get more highs ?
« Reply #4 on: November 22, 2021, 07:49:56 PM »
1) While the stock OCD says lowpass/highpass for the two switch settings, BOTH are lowpass, like the Filter in a Rat pedal.  The two switch positions are merely range settings for the lowpass function, one higher than the other.

2) If you want more upper mids and "bite", do what the Rat does: provide two different ground legs to set the gain differently for highs.  If you run a 47nf cap and 2k2 resistor in series, and place that pair in parallel with R4/C2 it will provide more gain for content above 1250hz (max gain of 463x, compared to 309x for stock), without changing anything for content below that frequency.

idy

Re: ADHD (ocd) : Dark sound, How to get more highs ?
« Reply #5 on: November 22, 2021, 09:16:00 PM »
I think the original description of the HP/LP was one was for single coils, the other Humbuckers... Low Peak/ High Peak.

fowl

Re: ADHD (ocd) : Dark sound, How to get more highs ?
« Reply #6 on: November 23, 2021, 10:55:00 PM »
The tone control is rather severe, it sometimes only sounds good all the way up.  A smaller cap or larger pot can help there.
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niektb

Re: ADHD (ocd) : Dark sound, How to get more highs ?
« Reply #7 on: November 24, 2021, 02:26:06 AM »
I solved it by messing with the tone control and changing some values there :)

Do you remember your custom values by any chance ?

I dó! I simulated the values in this topic! https://www.diystompboxes.com/smfforum/index.php?topic=124840.msg1185919#msg1185919
But before going down the same rabbit hole (had to replace a pot, can be a bit annoying) I would check that the problem you ran across is indeed a tonesucking/impedance-related problem  ;)


Edit: Aaah I opened the build docs and it's quite a different schematic, most notably a buffer at the end which I didn't have in mine! So I very much doubt thjat this is an impedance issue :)
« Last Edit: November 24, 2021, 02:29:26 AM by niektb »

niektb

Re: ADHD (ocd) : Dark sound, How to get more highs ?
« Reply #8 on: November 24, 2021, 02:41:35 AM »
I was comparing my schematic to yours, and I noticed that I have a little more bass cut in front. C2 is 68n in my case, and C1 would be 10nF (to get the same cut-off) but your tone section has a 22n rather than my 100n so that shóuld counter-act it I think.

In this case, the capacitor type doesn't matter. There are a couple of caps that could suffer from the DC bias effect if they're cheap ceramics (think X5R) but in this case that would all result in móre highs, not less :)

Elijah-Baley

Re: ADHD (ocd) : Dark sound, How to get more highs ?
« Reply #9 on: November 24, 2021, 05:14:44 AM »
I would like to put in the software schematic emulator this:



But everytime I look at this I has some difficults to follow the track, I can't understand that numbers into circle: (1) (2) (3) (4) (5). How I should connect it? Where does the signal go?
«There is something even higher than the justice which you have been filled with. There is a human impulse known as mercy, a human act known as forgiveness.»
Elijah Baley in Isaac Asimov's The Cave Of Steel

DIY Bass

Re: ADHD (ocd) : Dark sound, How to get more highs ?
« Reply #10 on: November 24, 2021, 06:15:33 AM »
Switch 2 changes between true and buffered bypass.  The numbered circles correspond to pads on the PCB that then connect to the stomp switch.  This is an OCD2, not an OCD

Elijah-Baley

Re: ADHD (ocd) : Dark sound, How to get more highs ?
« Reply #11 on: November 24, 2021, 07:04:55 AM »
Thanks.
Looking this layout http://effectslayouts.blogspot.com/2019/07/fulltone-ocd-v2.html I traced it, again. ;D

I built the OCD following the very first version.
I didn't find it dark at all, and in case the tone pot help me to bright it up without I need to put at max.
The OCD push mid, but it don't cut much bass like the TS808, so it seems more flat. Actually, like the TS808, the OCD cut some high, too. I found the TS808 a duller than the OCD, probably because the TS808 is not so aggressive. Did you tried a TS808?

Anyway, if you want a more open sound you could change the tone pot with a B20k or B25k to cut less high. My software emulator says that if you change C8 22nF (ton cap) with a 47nF cut some mid bass.
Even the asset C2 100nF and R4 3.3k push some lower mid, comparing it with the previous version of the OCD, 68nF + 2.2k.

[...] If you run a 47nf cap and 2k2 resistor in series, and place that pair in parallel with R4/C2 it will provide more gain for content above 1250hz (max gain of 463x, compared to 309x for stock), without changing anything for content below that frequency.

This will help you to push higher mid, indeed, instead push lower mid. :)
«There is something even higher than the justice which you have been filled with. There is a human impulse known as mercy, a human act known as forgiveness.»
Elijah Baley in Isaac Asimov's The Cave Of Steel

eh la bas ma

Re: ADHD (ocd) : Dark sound, How to get more highs ?
« Reply #12 on: November 29, 2021, 05:39:19 AM »
2) If you want more upper mids and "bite", do what the Rat does: provide two different ground legs to set the gain differently for highs.  If you run a 47nf cap and 2k2 resistor in series, and place that pair in parallel with R4/C2 it will provide more gain for content above 1250hz (max gain of 463x, compared to 309x for stock), without changing anything for content below that frequency.

Thanks, so I first soldered together a cap and a resistor. I connected (via a switch) the side with a 47n cap to the 100n (C2) on the pad opposite to R4. I connected the 2k2 resistor's free leg to R4 3k3's ground pad.

I can hear a real difference when i use the switch, it is brighter with surely more high mids and a new balance in the gain sound.
 It sounds a bit less noticeable with Drive fully CW, but on 90% of the rotation, the new frequencies are expanding the distorsion sound in a very pleasant way.

Great idea, thank you very much !
« Last Edit: November 29, 2021, 05:42:00 AM by eh la bas ma »
"unity-gain non-inverting stage", "ground leg","post-pick moments", I love this colorful forum.

Elijah-Baley

Re: ADHD (ocd) : Dark sound, How to get more highs ?
« Reply #13 on: November 29, 2021, 05:52:54 AM »
That was the easier trick you could try. ;)
«There is something even higher than the justice which you have been filled with. There is a human impulse known as mercy, a human act known as forgiveness.»
Elijah Baley in Isaac Asimov's The Cave Of Steel

eh la bas ma

Re: ADHD (ocd) : Dark sound, How to get more highs ?
« Reply #14 on: November 29, 2021, 10:00:57 PM »
I built an other circuit that I love but have the same dark calibration : a Wampler Velvet fuzz clone, Corduroy Fuzz.

https://www.pedalpcb.com/docs/Corduroy.pdf

...and i already added this mod (bypassing fuzz part) :

https://forum.pedalpcb.com/threads/bypassing-fuzz-part-in-corduroy-fuzz.2951/#post-54081

I wonder if I could do a similar trick on this one, adding high-mids in the signal to get a more open sound ?

I also noticed 2 caps and a resistor around the Bright pot. Maybe I can try some other values on C18, C19 and R27... should I try to increase or decrease their values ?
« Last Edit: November 29, 2021, 10:13:26 PM by eh la bas ma »
"unity-gain non-inverting stage", "ground leg","post-pick moments", I love this colorful forum.

Elijah-Baley

Re: ADHD (ocd) : Dark sound, How to get more highs ?
« Reply #15 on: November 30, 2021, 04:12:23 AM »
We could talk about it, but we will go off topic.
Do you wanto to open a new thread about it? I'll try to help you.
«There is something even higher than the justice which you have been filled with. There is a human impulse known as mercy, a human act known as forgiveness.»
Elijah Baley in Isaac Asimov's The Cave Of Steel