ADHD (ocd) : Dark sound, How to get more highs ?

[eh la bas ma]

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 ?

[POTL]

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]

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]

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

Do you remember your custom values by any chance ?

[Mark Hammer]

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]

I think the original description of the HP/LP was one was for single coils, the other Humbuckers... Low Peak/ High Peak.

[fowl]

The tone control is rather severe, it sometimes only sounds good all the way up.  A smaller cap or larger pot can help there.

[niektb]

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

[niektb]

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]

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?

[DIY Bass]

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]

Thanks.
Looking this layout http://effectslayouts.blogspot.com/2019/07/fulltone-ocd-v2.html I traced it, again.

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.

[eh la bas ma]

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 !

[Elijah-Baley]

That was the easier trick you could try.

[eh la bas ma]

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 ?

[Elijah-Baley]

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.

[rankot]

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?

1-5 should be connections to 3PDT switch. I suppose you don't need to emulate that. In case you use ltspice, here's the code (w/o input and output buffers):

Code Select Expand


Version 4
SHEET 1 4708 728
WIRE 1200 -32 1168 -32
WIRE 1328 -32 1328 -80
WIRE 1328 -32 1280 -32
WIRE 1360 -32 1328 -32
WIRE 1328 -16 1328 -32
WIRE 1168 16 1168 -32
WIRE 1632 48 1616 48
WIRE 1792 48 1776 48
WIRE 1840 48 1792 48
WIRE 1936 48 1904 48
WIRE 976 64 928 64
WIRE 1072 64 1040 64
WIRE 1328 80 1328 64
WIRE 1456 80 1328 80
WIRE 1504 80 1456 80
WIRE 512 96 480 96
WIRE 608 96 592 96
WIRE 784 96 672 96
WIRE 1328 96 1328 80
WIRE 1456 112 1456 80
WIRE 1168 128 1168 96
WIRE 1792 144 1792 48
WIRE 1824 144 1792 144
WIRE 1936 144 1936 48
WIRE 1936 144 1904 144
WIRE 480 160 480 96
WIRE 688 160 480 160
WIRE 784 160 784 96
WIRE 784 160 752 160
WIRE 816 160 784 160
WIRE 928 160 928 64
WIRE 928 160 896 160
WIRE 960 160 928 160
WIRE 1072 160 1072 64
WIRE 1072 160 1040 160
WIRE 480 192 480 160
WIRE 1328 192 1328 176
WIRE 1456 192 1456 176
WIRE 1456 192 1328 192
WIRE 1328 208 1328 192
WIRE 1792 256 1792 144
WIRE 1808 256 1792 256
WIRE 928 272 928 160
WIRE 944 272 928 272
WIRE 1936 272 1936 144
WIRE 1936 272 1872 272
WIRE 1952 272 1936 272
WIRE 2032 272 2016 272
WIRE 2144 272 2112 272
WIRE 2208 272 2144 272
WIRE 2304 272 2288 272
WIRE 2352 272 2304 272
WIRE 1072 288 1072 160
WIRE 1072 288 1008 288
WIRE 1120 288 1072 288
WIRE 1264 288 1200 288
WIRE 1328 288 1264 288
WIRE 1472 288 1328 288
WIRE 1504 288 1472 288
WIRE 1616 288 1504 288
WIRE 1680 288 1616 288
WIRE 1808 288 1760 288
WIRE 2144 288 2144 272
WIRE 416 304 384 304
WIRE 496 304 416 304
WIRE 592 304 496 304
WIRE 672 304 656 304
WIRE 848 304 752 304
WIRE 944 304 848 304
WIRE 1472 304 1472 288
WIRE 416 336 416 304
WIRE 496 336 496 304
WIRE 1328 336 1328 288
WIRE 848 352 848 304
WIRE 2304 368 2304 272
WIRE 1616 384 1616 288
WIRE 2144 384 2144 352
WIRE 1504 400 1504 288
WIRE 1504 400 1472 400
WIRE 1264 416 1264 288
WIRE 1280 416 1264 416
WIRE 1552 416 1520 416
WIRE 416 448 416 416
WIRE 496 448 496 416
WIRE 496 448 416 448
WIRE 416 464 416 448
WIRE 848 464 848 432
WIRE 2144 496 2144 464
WIRE 2304 496 2304 448
WIRE 2304 496 2144 496
WIRE 2304 512 2304 496
WIRE 1328 528 1328 432
WIRE 1472 528 1472 496
WIRE 1472 528 1328 528
WIRE 1552 528 1552 416
WIRE 1552 528 1472 528
WIRE 1616 528 1616 448
WIRE 1472 560 1472 528
WIRE 1472 656 1472 640
FLAG 416 464 0
FLAG 976 320 0
FLAG 1328 -80 9V
FLAG 1168 128 0
FLAG 2352 272 Out
IOPIN 2352 272 Out
FLAG 976 256 9V
FLAG 384 304 IN
IOPIN 384 304 In
FLAG 1504 80 Vr
FLAG 1328 208 0
FLAG 848 464 Vr
FLAG 1424 -32 0
FLAG 1472 656 Vr
FLAG 1840 304 0
FLAG 1840 240 9V
FLAG 1616 48 0
FLAG 2304 512 0
FLAG 480 192 Vr
FLAG 1616 528 Vr
SYMBOL voltage 416 320 M0
WINDOW 123 24 124 Left 2
WINDOW 39 0 0 Left 2
SYMATTR Value2 AC ac 1.
SYMATTR InstName V1
SYMATTR Value SINE(0 .07 100)
SYMBOL cap 656 288 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C2
SYMATTR Value 22n
SYMBOL res 656 320 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
SYMATTR InstName R2
SYMATTR Value 10k
SYMBOL Opamps\\LT1057 976 224 R0
SYMATTR InstName U3
SYMBOL voltage 1168 0 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V3
SYMATTR Value 9
SYMBOL res 1344 -32 M0
SYMATTR InstName R5
SYMATTR Value 15k
SYMBOL res 1344 80 M0
SYMATTR InstName R6
SYMATTR Value 15k
SYMBOL cap 1472 176 R180
WINDOW 0 24 56 Left 2
WINDOW 3 24 8 Left 2
SYMATTR InstName C4
SYMATTR Value 10µ
SYMBOL res 832 336 R0
SYMATTR InstName R1
SYMATTR Value 470k
SYMBOL res 944 176 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
SYMATTR InstName DRIVE
SYMATTR Value 1Meg
SYMBOL cap 1040 48 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C1
SYMATTR Value 100p
SYMBOL res 1104 304 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
SYMATTR InstName R4
SYMATTR Value 10k
SYMBOL cap 752 144 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C5
SYMATTR Value 47n
SYMBOL res 800 176 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
SYMATTR InstName R7
SYMATTR Value 2k2
SYMBOL res 496 112 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
SYMATTR InstName BASS
SYMATTR Value 25k
SYMBOL cap 1600 384 R0
SYMATTR InstName C6
SYMATTR Value 1n
SYMBOL res 2304 256 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName VOLUME
SYMATTR Value 40k
SYMBOL res 480 320 R0
SYMATTR InstName R8
SYMATTR Value 1Meg
SYMBOL res 1296 -48 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R9
SYMATTR Value 33
SYMBOL cap 1360 -16 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName C8
SYMATTR Value 100µ
SYMBOL zener 1488 304 M0
SYMATTR InstName D1
SYMATTR Value 1N34A
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL cap 672 80 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C7
SYMATTR Value 1µ
SYMBOL nmos 1280 336 R0
SYMATTR InstName M1
SYMATTR Value 2N7000
SYMBOL nmos 1520 496 R180
SYMATTR InstName M2
SYMATTR Value 2N7000
SYMBOL res 1664 304 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
SYMATTR InstName R10
SYMATTR Value 10k
SYMBOL Opamps\\LT1057 1840 208 R0
SYMATTR InstName U1
SYMBOL res 1808 160 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
SYMATTR InstName R11
SYMATTR Value 147k
SYMBOL cap 1904 32 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C3
SYMATTR Value 100p
SYMBOL cap 1776 32 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C9
SYMATTR Value 100n
SYMBOL res 1728 64 M270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
SYMATTR InstName R12
SYMATTR Value 39k
SYMBOL cap 2016 256 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C10
SYMATTR Value 1µ
SYMBOL res 2016 288 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
SYMATTR InstName R13
SYMATTR Value 22k
SYMBOL cap 2128 352 M180
WINDOW 0 24 56 Left 2
WINDOW 3 24 8 Left 2
SYMATTR InstName C11
SYMATTR Value 47n
SYMBOL res 2128 368 R0
SYMATTR InstName TONE
SYMATTR Value 100k
SYMBOL res 2288 352 R0
SYMATTR InstName R14
SYMATTR Value 10k
SYMBOL res 1456 544 R0
SYMATTR InstName SATURATE
SYMATTR Value {ST}
TEXT 584 464 Left 2 !;.tran 0 .3 .1
TEXT 584 496 Left 2 !.ac oct 100 10 30k
TEXT 944 528 Left 2 !;.step param Rvol 10k 100k 30k
TEXT 944 496 Left 2 !.param Rvol 500k
TEXT 944 560 Left 2 !;.step param ST list 1 10 100 500 1k 5k 10k
TEXT 944 592 Left 2 !.param ST 1



[Elijah-Baley]

I emulate schematic with Tina TI, but thanks.
I guess I finally find out how the buffers work on this pedal, I just forget it sometime, and I have to read my notes, again.
But I'm ok with it, now.

[antonis]

I guess I finally find out how the buffers work on this pedal,

What buffers..??

[Elijah-Baley]

The newer OCD version, the one in the last schematic, has an output buffer that the older version doesn't have, and the bypass is true bypass or buffered thanks to an internal switch.