Link to build: https://tagboardeffects.blogspot.com/2016/11/earthquaker-devices-dephs.html
Link to Schematic: https://imgur.com/8R4keTO
So I've been working on this pedal (The first design with the offboard LED circuit) for a little bit and can't quite get it to work. I have signal passing through from input to output, but the signal isn't being effected by the LED pulses. The volume knob works, but nothing else seems to alter the sound. The LED circuit seems to work fine (Yellow diffuse LED with GL5539s) since the LED rate and intensity changes with the pots, and I can hear a white noise pulsing with the LED using audio probing. I can't seem to find where the input signal gets lost through the effect circuit. I haven't made any modifications. Here are my voltages to ground:
IC1 (Top):
P1 = 4.4
P2 = 4.4
P3 = 3.9
P4 = 0
P5 = 4.2
P6 = 4.3
P7 = 3.3
P8 = 8.9
IC2 (Left):
P1 = 7.6
P2 = 6.0
P3 = 4.4
P4 = 0
P5 = 4.4
P6 = 4.7
P7 = 1.3
P8 = 8.9
IC3 (Right):
P1 = 1.5
P2 = 4.5
P3 = 4.4
P4 = 0
P5 = 4.4
P6 = 4.4
P7 = 7.5
P8 = 8.9
Q1 (Top): Varies with LED Intensity
C = 1.0 - 6.7
B = 0.7 - 3.1
E = 0.1 - 2.4
Q2 (Bottom):
C = varied too much to measure
B = 0.6
E = 0
D1 (LED): works fine
D2 (1n5817):
Anode = 9.2
Cathode = 8.9
Any help would be greatly appreciated! I'm considering just replacing the bottom two ICs and the MPSA18s, but was hoping y'all might have a more precise fix. Thanks!
Welcome.
When a thing don't work right, a Schematic is clearer than a layout. I happened to find the Schematic:
https://i.imgur.com/8R4keTO.png
However this is notated for the TL074 version, and you appear to have TL072, so all pin numbers change.
First odd thought is: you do have the LED/LDRs covered, dead-dark? Room light will overwhelm the LED blink.
Is it on breadboard yet?
Voltages on chips' pins should not be too far away from 1/2Vcc (pins 4 and 8 aside).
Check there
IC2 pin 7 and IC3 pin 1 both having the same badly wrong voltage, and both being on the same vero strip raises some questions about your trace cuts and solder shorts.
as someone says I always say, post some photos of what you have built.
and welcome.
i had this exact problem with my build. make sure your voice and intensity pots aren't wired backwards.
to this day i see confusion as to which pin is 1 or 3.
should fire right up. if its passing signal, and the led is flickering, check your soldering for a bridge. this circuit doesn't need to be in total dark, it will kick ass even in broad daylight.
when ya get it working, you can parallel the led with another for an external flashing indicator with no issues. just run two wires between the external led and the one on the board. it has to connect to the two points, if you ground it it will kill the led pulse.
pics would be useful. i DO have a schem for this with a couple separate oa's i think. check FSB
I made an account to chime in. the second one works, made two of them. I would do the 2nd one.
also, its kind of thin as in trebly or icy and is there any mod to help thicken it up some? im going to try the external blinking led mod thanks
jimiphoton
Got it working! It's a bit finicky when I mess around turning the pots way up or down. It will stop pulsing for a bit but then start back up. I ended up having to replace IC2. I think there was a short underneath it. Unfortunately, some of the vero strip came up with the IC and I ended up having to do some lateral jumpers to salvage the circuit. Not the most elegant solution, but it works!
Thanks for the help y'all.
And Harry: I don't seem to have a very thin tone with my build. What kind of LED and LDRs are you using? You can really change the tone with different color LEDs and different LDRs.
Quote from: Harry Muff on September 15, 2017, 03:52:15 AM
I made an account to chime in. the second one works, made two of them. I would do the 2nd one.
also, its kind of thin as in trebly or icy and is there any mod to help thicken it up some? im going to try the external blinking led mod thanks
jimiphoton
should be completely transparent unless the depth and color knobs are pegged. this circuit is almost as good as the Black Cat, which is THE best vibe i've ever tried (and not cuz i work there).
i would check your signal path, cuz it should just be a buffer from in to out mostly. if its thin, check to see if you maybe used the wrong sized cap somewhere... hey, it happens!
I cant seem to get the external led blinking. parallel means the same two holes right? my throb doesnt do anything either. I have an ultr violet with cheap ldrs. I guess have to place a small bear order soon for ldrs
how come a cm7371 lamp will not work in this? i have 5-6 of them in the junk box
the ultraviolet led is your problem, wrong light spectrum for the ldrs to respond to. you want green for this one, not that blueish purple.
they also draw different current i think and it may just be me, but i believe they radiate noise into the power supply as well.
yes, connect the two leds to the same spots remember that if its on vero and ya tack it on the bottom of the board it may have to have its polarity reversed.
you could use a lamp, but it has a lot more current draw than what this circuit will allow i think. cold lamps are pretty high resistance, and it goes down as it heats up. you could try it. but it may blow something up. ;)
take the cathode to board and anode to a clr then to + rail for external lfo , seen the comments from gfx page and it works. throb does nothing at all still. going to change out led now and place ldr order with small bear! small bear looks to have 4-5 types of ldrs you know which would you recommend? any fix on the throb control? i would like the bottom end swoosh over the harsh bite. mine is pretty much transparent but still has an icy edge to it on the high B and E that is a bit to shrill to use the fx imho. i need to work out a fix somehow.
im not good at this but looking at the schematic then the vero , is the 220nf and 22k network in the right spot? looks like the 22k goes to neg inverter and the 220 to + out but backwards on vero as i cant follow the trade to the ldr like on the schematic. maybe a missing jumper there?
throb is fairly subtle it changes the "width" of the flash.
you don't need a current limiting resistor, just connect the led in parallel with the first one.
your problem is not the ldrs. your problem is the color led you're using. ultraviolet is about the worst color you can choose for this particular application. green is best, yellow or red will work, but blue or ultraviolet the cadmium or whatever in the ldr's won't react to.
changing the ldrs would be wasting your money.
just change the led. ;)
Quote from: pinkjimiphoton on September 15, 2017, 05:48:02 PM
throb is fairly subtle it changes the "width" of the flash.
you don't need a current limiting resistor, just connect the led in parallel with the first one.
your problem is not the ldrs. your problem is the color led you're using. ultraviolet is about the worst color you can choose for this particular application. green is best, yellow or red will work, but blue or ultraviolet the cadmium or whatever in the ldr's won't react to.
changing the ldrs would be wasting your money.
just change the led. ;)
will do! we need one of the resident experts to check that throb section of the scem and match it up to the vero , i cant follow it to tell but I suspecting something is off there maybe not though
jimphoton its the diffused yellow :icon_mrgreen: :icon_biggrin: yessir my friend. now excuse me for the rest of the night while I go pretend to be jimi hendrix and gilmour in my jam room with my new play toy!
just seen you said green, will have to make a quick mod lol
the thin,icy shril is gone and with new LED the natural tone of my amp is coming through pretty darn good now
yeah boy!!!!! that is AWESOME. i @#$%ing LOVE mine.
i put it in a crybaby shell. it sounds better than my @#$%in univibe by far, real close to the black cat one that's my all time fav.
if it sounds good, box it and rock it, green and yellow i think should be more than close enough.
watch the throb control on the external led... you'll see it does change the way the light flashes at higher intensity and voice settings.
in some settings its actually useable, others barely noticeable. it controls the pulse width of the flash < i think >
psyched ya got it going... good on ya!! its a good feeling when ya first figure something out and fix it.
welcome to the forum. ;)
I'd love to see a photo of that, Jimi! I bet it came out awesome.
hey aish,
seeing as how you made the board and popp'd it for me, here ya go!!
https://imgur.com/gallery/1zmXU (https://imgur.com/gallery/1zmXU)
(https://i.imgur.com/MnQEm8C.jpg)
(https://i.imgur.com/K1yLvrf.jpg)
(https://i.imgur.com/8lkKUHc.jpg)
(https://i.imgur.com/hiNPmvH.jpg)
(https://i.imgur.com/dn4IO49.jpg)
the big knobs are for the voice and intensity, the small ones are throb and volume.
works great, i call it the ashiewnivibe
some reports back from the 4 hour jam, went through two stoner/doom compilations; 18 volt no good with my set up, yellow better than green, green didnt seem to work. the icy shrill on my high E and B appears with full distortion and with medium gain the pedal gets wet and transparent with the twang gone.
I replaced the 10k pot with a modern/vintage toggle to switch the 10k resistor in or out
Kept the clr on the paralelled led
clr on the external led willl mean its also on the primary led and will likely affect its performance adversely
the icy shrill at full distortion means you're clipping the input of the effect most likely.
sounds like something else is wrong with your build, bugger if i can figure it out ;)
Quote from: pinkjimiphoton on September 16, 2017, 08:19:22 PM
clr on the external led willl mean its also on the primary led and will likely affect its performance adversely
the icy shrill at full distortion means you're clipping the input of the effect most likely.
sounds like something else is wrong with your build, bugger if i can figure it out ;)
yeah there is definitely something wrong. if I take out the clr the lfo led quits working when voice goes above 40-50 %. it works, but I would not put it on my board and use it as is. Its nothing like the 4000 video demos of just about every vibe on the tubes. could be my guitar set up and lousy guitar playing but I was hoping to at least get a similar tone to a Fulltn MDV or a MjM 60's vibe. you can get the mdv used for 120 bucks but im too poor to buy one. I really need to get this going if I can. but this build is just off, i was so eager to use a phase type effect last night , but after today concluded this aint worth it ..rather use a dod phase 45 from musicians friend for 35 dollars
hey harry
dude, yah, until the voice is about 40% it doesn't really do much. if ya subbed linear for audio anywhere or vice versa it would bunch everything up really funny at one end of the pot's rotation, too.
but diggit... you GOT it working. its just not dialed in right. that alone is a hell of an accomplishment, cuz its not the easiest vero project to do. i was lucky that aish burned and populated a board for me (lol and it didn't work when i first fired it up, had one of them internally decapitated resistors) and i misinterpreted the layout so had all the pots backwards ;)
but it worked. i was like... ah, fudge the damn thing. but i figured it out.
so will you.
i hear ya on the no money thing. i'm a professional musician (read: impoverished) too. ;)
listen. take a break from it for a few. go back with fresh eyes, and take a look at the project. go node to node, confirm everything's good.
make sure the values are spot on. sometimes mistakes happen, something can be off by a factor of 10 to a million ffs with very little effort. ;)
also check your soldering. look for bridges. run a knife or something thru the cuts on the back of the vero.
its passing audio... thats a plus. it probably sounds more like a tremolo with the voice and intensity backed off. its supposed to sound like that. if ya peg the intensity and voice its pretty much a colored phasey univibe sound. the throb control don't do shit really til the other two knobs are cranked up. there's a LOT of fine adjustment possible, i like it backed off a little so it sounds like almost real vibrato. this thing is transparent and beautiful when working.
post some voltages and we'll compare notes. i'm betting there's a solder bridge somewhere or an intermittent cold solder joint, especially cuz ya said it makes the e and b strings sound funky. do ya have it all the way up? this circuit has some gain to it. it could overdrive your amp in some cases easily.
you'll figure it out. start with voltages. and we'll go from there
Quote from: pinkjimiphoton on September 17, 2017, 02:43:19 AM
hey harry
dude, yah, until the voice is about 40% it doesn't really do much. if ya subbed linear for audio anywhere or vice versa it would bunch everything up really funny at one end of the pot's rotation, too.
but diggit... you GOT it working. its just not dialed in right. that alone is a hell of an accomplishment, cuz its not the easiest vero project to do. i was lucky that aish burned and populated a board for me (lol and it didn't work when i first fired it up, had one of them internally decapitated resistors) and i misinterpreted the layout so had all the pots backwards ;)
but it worked. i was like... ah, fudge the damn thing. but i figured it out.
so will you.
i hear ya on the no money thing. i'm a professional musician (read: impoverished) too. ;)
listen. take a break from it for a few. go back with fresh eyes, and take a look at the project. go node to node, confirm everything's good.
make sure the values are spot on. sometimes mistakes happen, something can be off by a factor of 10 to a million ffs with very little effort. ;)
also check your soldering. look for bridges. run a knife or something thru the cuts on the back of the vero.
its passing audio... thats a plus. it probably sounds more like a tremolo with the voice and intensity backed off. its supposed to sound like that. if ya peg the intensity and voice its pretty much a colored phasey univibe sound. the throb control don't do shit really til the other two knobs are cranked up. there's a LOT of fine adjustment possible, i like it backed off a little so it sounds like almost real vibrato. this thing is transparent and beautiful when working.
post some voltages and we'll compare notes. i'm betting there's a solder bridge somewhere or an intermittent cold solder joint, especially cuz ya said it makes the e and b strings sound funky. do ya have it all the way up? this circuit has some gain to it. it could overdrive your amp in some cases easily.
you'll figure it out. start with voltages. and we'll go from there
im going to breadboard it but I have some questions. the schematic is in 3 blocks. I know the power supply connects to vref, but how does the lfo connect to the rest of the circuit ? I have trouble with logic gates and assuming I can use any inverting/non inverting/out pins off the opamps ?
this vibe doesnt sound as good as all the other in the demos I been watching. I made two madbean harbingers and didnt like them at all either, would a GGG neovibe sound like a dry bell ? maybe I should order JD's pcb board but it uses a transformer I am not familiar with that method
the bell sounds just like woodstock tone with that chewy phase to it
if i had about 400 bucks I would buy one of these
i gotta dig out the schematic and look at it. aisha built mine for me as a gift, so not sure as i wasn't involved with much beyond boxing it and debugging one rogue resistor.
check the black cat vibe, this is my personal fav. but i suspect you and i are looking for different things in a vibe pedal
https://www.youtube.com/watch?v=nyyGSW_EdLQ
the strymon is hip, but i doubt its fully analog.
if ya want something you can have that much versatility with, check out rick holts (frequency centrals) causality 4 project. very tweakable, can do just about everything a phaser can do. does some nice chorusing and almost flanging, too.
Quoteim going to breadboard it but I have some questions. the schematic is in 3 blocks. I know the power supply connects to vref, but how does the lfo connect to the rest of the circuit ? I have trouble with logic gates and assuming I can use any inverting/non inverting/out pins off the opamps ?
harry, if we are still talking about the EQD depths thing circuit - the lfo connects optically to the phase stages. the lfo does nowt but flash a led. the phase stages all have a part of their phase-shift network in the way of the light produced by the led, those parts being light dependant resistors. there is no physical connection beyond the photons, and I don't think they count.
as for the opamp pins, no, you can't just willy nilly them. all the (-) inverting inputs in the phase shift string are connected to provide feedbacking loops, and all the (+) non-inverting pins have the cap/ldr combo attached, to do the phase shifts. and the ouput pins are for outputting.
Welcome Harry.
That EQD circuit should own the vibe sound.
Where it me I'd probably breadboard it first and experiment with led/ldr (vactrol)
First port of call would probably be a 5mm red led and 1M dark ldr. Then some 500k dark ldr.
I'm not sure what the circuit calls for. Not having researched it more than a quick squiz at the link.
Both of the sample videos you posted have a much bigger signal chain than just vide in the picture.
I'd probably buy the picture based on the recording and mixing.
But still end up disappointed with my playing compared to the video.
As Duck says the lfos sine wave output will make the led flash which shines right next to the light dependant resistor. ldr. The ldrs resistance will change depending on how bright or dull the led is.
Imagine that on each phase stage input is an RC filter
C4 R6 (R6 being the ldr) the filters corner freqauncy will change depending on the ldrs resistance.
I hope this explains a little of how the led/ldr combination plays it part.
Hello,
I am resurrecting this thread, because i built this circuit using a similar veroboard layout yesterday, and i am experiencing some issues :
- There is no audible effect;
- output signal is below unity gain;
- sometimes, audible input distortion is heard (a bit like crackles).
- The LFO seems to work fine, according to the LED blinking when I turn the pots.
I am using the layout with the external LDR daughterboard from here (https://tagboardeffects.blogspot.com/2016/11/earthquaker-devices-dephs.html)(which uses 3 x TL072).
The schematic is here (https://www.pedalpcb.com/docs/Abyss.pdf), or there (https://i.imgur.com/8R4keTO.png).
I have used 4xGL5516 and a yellow 5mm led.
I think that my build is quite clean (I checked several times, and didn't notice any trace or cut error), you will find a picture below.
I have measured the voltages at the IC and transistors pins : they all share the same "voltage pattern" (values between 1 and 1.4V, except pin4 which is 0 and pin 8 which is slightly below 9V) :
IC1
1.43
1.43
1
0
1.30
1.7
1.75
8.8
IC2 (left)
1.38
1.36
0.95
0
0.95
1.37
1.39
8.79
IC3 (right)
1.40
1.38
0.90
0
1.95
1.38
1.40
8.70
Both transistors have 0V at their Emitter, around 0.3 and 0.6 at the Base, and changing values around 3.5 and 4.80 at the collector.
(https://i.postimg.cc/nCXMf6cP/EQD-depths-vero-back.jpg) (https://postimg.cc/nCXMf6cP)
I have read on the net that i am not the only one experiencing such issues, but i couldn't find any hint to fix the issue. I'd be grateful if anyone could point me toward a direction where to look at...
Thank you in advance for any help
we do want to see the topside, and the offboards, but, I think you've done mirror image board cuts.
Hi, DuckArse, thank you for your kind help.
I think my cuts are ok : at least, when i was soldering every components fitted in their place (by lack of better words). But it's a somewhat big layout, so maybe that an error occurred indeed. I am uploading pictures to Imgur as we speak, and will post a link in a minute.
The wiring looks a bit messy, and it's quite difficult to take a good picture, but hopefully it will be good enough.
Here is an Imgur album with several pictures. (https://imgur.com/a/hS0JNB6)
Obviously, when I tried the effect, the led/ldr daughterboard was'nt exposed to light.
With your mirror suggestion, you made me curious to try an overlay with the layout and my build.
It's quite rough, but it fits... It fits enough to show me that i forgot a 1µF at the top right :icon_redface:
(https://i.postimg.cc/0M0g3G4f/vero-overlay2-front-B2.jpg) (https://postimg.cc/0M0g3G4f)
(https://i.postimg.cc/ppTNGFJf/vero-overlay1-back.jpg) (https://postimg.cc/ppTNGFJf)
yeah, I think I'm losing my mind, all this flipping and mirroring. well spotted w/ the cap.
Unfortunately, the missing cap didn't change anything...
Back to scratching my head and losing my mind, too ;)
This is how it sounds (DRY/WET/DRY again) : whyp.it/t/eqd-depths-issue-35826 (http://whyp.it/t/eqd-depths-issue-35826)
I'm thinking it might be either a faulty op-amp (i never experienced that yet), or the power path coming into the audio path (with a wrong wiring, or a trace, but i have checked a dozen times and didn't see anything suspect).
I have tried audio-probing, but the circuit is more complex than a fuzz, so it isn't that easy :icon_redface:
Hello,
Further attempt at debugging this circuit.
I have audio probed the TL072 pins :
- The only point where i get a WET signal (ondulating, pulsating) is at PIN 3 of chip 02 (on the left of the veroboard), but it is low, way below unity gain.
I also get some DRY signal at CHIP1 (upper part of the veroboard):
- PIN3 (of course, it's the input);
- PIN6 (DRY signal, low volume). Pin6 goes to the output of the circuit through the Level pot.
- PIN7 (DRY signal, very low volume).
I also get the DRY signal, very low volume at CHIP 2's pin 2.
(https://i.imgur.com/e5os6IW.png)
I will try to understand where the issue can come from by comparing my findings with the schematic, but i don't have a good understanding of the schematic, so it might not be easy :icon_redface:
If ayone has any hint or advice, i'd take it :)
I'm looking at some of your resistor colour bands, esp around the top right corner, 47k's and 10k's. can you please go thru ALL resistors with your meter and check those bands that look orange to me are in fact red?
Thank you for your answer, Duck Arse.
Quote from: duck_arse on April 06, 2021, 10:58:07 AM
I'm looking at some of your resistor colour bands, esp around the top right corner, 47k's and 10k's. can you please go thru ALL resistors with your meter and check those bands that look orange to me are in fact red?
Yes, I will do. But i am a bit unsure about what you mean : do you want me to
check the value of the resistors (especially around the top right corner, 47k's and 10k's), or to
check the continuity of the veroboard strips (and checking that the cuts in red are indeed cuts)?
By the way, in the meantime, I audioprobed each TL072 pins, and tried to make the vero match the schematic better (I mean that the veroboard layout uses 3 TL072, while the schematic uses 1X tl072 and 1x TL074).
So here is a picture of my findings :
(https://i.postimg.cc/CRY21S0K/EQD-The-Depths-PINS-probing.jpg) (https://postimg.cc/CRY21S0K)
My questions :
- Am I right to find suspicious to get no signal at all at any of the 3d chip ("ICA2A/B" on the schematic)?
- Is the sound arriving at chip2 pin3 (on the layout, and "IC2C pin 10" on the schematic) supposed to be that low?
Continuity test done:
- the DMM didn't beep, which is a good sign.
- However, I was surprised to see on a few rows values going above zero, but no beeping occurred.
I am measuring the resistors right now, and started by the upper right corner as suggested.
-most of the resistors gave the expected value...
-... but one 10k resistor kept rising its value (from something around 15k to... 100k, then i gave up but it was keeping rising) :icon_eek:
(https://i.imgur.com/fwLPdL6.png)
-With a green check mark : all the checked resistors (giving the expected value).
- circled in purple : the resistor with the "neverending going up value"
I am wanting you to be testing the resistance value of each resistor. that circled resistor is one of a pair of 10k's, except that the multiplier on one looks red, and the other, the one that counts to 100k, looks orange, which would be ...... 100k.
I also see red/orange confusing me on some 47k's, but I'm not going to tell you where. also, all your voltage measures are bad. please pull the IC's from the sockets, and then do another round of volts measures on the empty sockets.
one further, and expected by some, question - is there a circuit diagram that matches the dual opamps version of this circuit?
QuoteI am wanting you to be testing the resistance value of each resistor.
Ok
Quotethe multiplier on one looks red, and the other, the one that counts to 100k, looks orange,
What do you mean by "multiplier" (sorry if it is a basic question, but i don't get that term)?
[edit] ah, I understand : you are talking about the color codes of the resistors on my build, right? I thought you were talking about the veroboard layout. :icon_redface:Sorry about that!
Quotealso, all your voltage measures are bad. please pull the IC's from the sockets, and then do another round of volts measures on the empty sockets.
eerk! Yes, I will do!
Quoteis there a circuit diagram that matches the dual opamps version of this circuit?
I fear not. I searched the web, but I didn't find any. I think the regular circuit use one 72 and one 74, but this layout used 3 x 72 so the led/ldr combo could be put on a daughterboard to avoid ticking.
Some people said it was verified and working fine, but i am rather sure that the original schematic use 1 x 72 and 1 x 74.
I think I have posted above the sources :
-schematic here : http://guitar-fx-layouts.42897.x6.nabble.com/EQD-The-Depths-gut-shots-td34241.html (http://guitar-fx-layouts.42897.x6.nabble.com/EQD-The-Depths-gut-shots-td34241.html)
- and there : https://www.pedalpcb.com/docs/Abyss.pdf (https://www.pedalpcb.com/docs/Abyss.pdf)
- both layouts here : https://tagboardeffects.blogspot.com/2016/11/earthquaker-devices-dephs.html (https://tagboardeffects.blogspot.com/2016/11/earthquaker-devices-dephs.html)
- and there (unverified) : http://dirtboxlayouts.blogspot.com/2020/11/earthquaker-devices-depth.html (http://dirtboxlayouts.blogspot.com/2020/11/earthquaker-devices-depth.html)
"the orange multiplier"... I get it! thank you!
(https://i.postimg.cc/sGfPBYy6/10k-100k.jpg) (https://postimg.cc/sGfPBYy6)
Quote from: duck_arse on April 06, 2021, 12:07:58 PM
I am wanting you to be testing the resistance value of each resistor. that circled resistor is one of a pair of 10k's, except that the multiplier on one looks red, and the other, the one that counts to 100k, looks orange, which would be ...... 100k.
Duck Arse, thank you so much for your hawkeye and expertise : that silly little resistor is changed, and now everything seems to work fine ! :icon_biggrin:
Kudos!
mmmm, hang on a minute, you ain't finished yet. what did you find when you measured all those other resistors, any others out-by-10? and yes, that band on the [5 band] resistors is called the multiplier, sorry for the lack of explaining.
I think that 10k-100k is one half of the Vbias divider string for the opamps, which would have pulled the voltages way low, 10 to 100 instead of 10 to 10. but you've measured them all again since, haven't you? and you're going to post them here for us to check, aren't you? it seems only fair.
Hi,
When I measured the resistors, they all matched the expected values (except, of course, the wrong one. Also, I did not test the 2.2M and 3M, as my DMM doesn't go above 2M).
I spent some time yesterday playing with the effect, and so far, it seems to work fine.
Today, I built an enclosure for the circuit, but I will take some time tomorrow to measure the values once again (and yes, that's fair, given the help provided). By the way, did you mean the resistor values, or the voltage at the opamp pins (with the opamps removed)?
if you have a bad/wrong/backwards opamp, it will throw the voltages off. and because the opamp outputs follow the voltage on their inputs, they can confuse and confound when other errors are present. so, at times, we pull the opamps and measure the voltages on the empty pins. that can/will/should show things like correct supply connections and correct bias voltage and things shorting when they shouldn't. if you have, for example, a 10k//100k divider instead of 10k//10k, it becomes very apparent.
I keep looking at your board photo, and comparing the red bands I can see [that are actually red] to the bands on the 47k resistors, and they [47k's] seem to be very orange to me. and it looks possible, from how the circuit shows those resistors connected to the opamps, that if 470k's were instead fitted, in pairs, their would be no discernable audio difference [to if they was 47k]. but I only think this, I don't know it for a fact.
and now that you have experienced a resistor colour band reading problem build, I can tell you the professional pcb assemblers would/will always align the resistors such that the tolerance band was always facing the same direction. this shows you've taken the attention in the first place, and makes it less fumble for when you [or the testing tech that follows production] come to read the values when debugging, or when others have to read to debugg. and it counts double for the blue-bodied resistors, just because they are harder.
Quoteif you have a bad/wrong/backwards opamp, it will throw the voltages off. and because the opamp outputs follow the voltage on their inputs, they can confuse and confound when other errors are present. so, at times, we pull the opamps and measure the voltages on the empty pins. that can/will/should show things like correct supply connections and correct bias voltage and things shorting when they shouldn't. if you have, for example, a 10k//100k divider instead of 10k//10k, it becomes very apparent.
Thank you for the technical insight.
I'm going to check the voltages and report back.
QuoteI keep looking at your board photo, and comparing the red bands I can see [that are actually red] to the bands on the 47k resistors, and they [47k's] seem to be very orange to me. and it looks possible, from how the circuit shows those resistors connected to the opamps, that if 470k's were instead fitted, in pairs, their would be no discernable audio difference [to if they was 47k]. but I only think this, I don't know it for a fact.
I checked yesterday all the resistors, which measured as expected. I tested again all the 47k a couple minutes ago, and it was fine... So i guess it was maybe a lighting issue while taking the picture?
Quoteand now that you have experienced a resistor colour band reading problem build, I can tell you the professional pcb assemblers would/will always align the resistors such that the tolerance band was always facing the same direction. this shows you've taken the attention in the first place, and makes it less fumble for when you [or the testing tech that follows production] come to read the values when debugging, or when others have to read to debugg. and it counts double for the blue-bodied resistors, just because they are harder.
Thank you for the tip. I had never paid attention to that, but now it becomes obvious, and makes such kind of debugging way faster. After all, this is what these color strips are for :)
Now, I'll go measuring the pins voltage before boxing the circuit into an enclosure ;)
New chips measurement (errh, without the chips).
It's totally different than the previous measurements :
CHIP 1
0
0
2.20
0
0
4.30
4.11
882
CHIP2
0
0
moving (between 1.8 and 4.80?)
0
4.30 (changing slightly, around 4 and 4.50 it seems)
0
0
8.83
CHIP3
0
0
around 4.30 (varying slightly)
0
around 4.30 (varying slightly)
0
0
8.83
[just so we won't argue with you, it's always good to include the IC pin number itself.]
the four opamps non-inverting inputs connecting to the ldr's [pins 3 and 5] we can allow to wobble, because the resistance of the ldr will be changing and varying the way the meter measuring loads that reading. but they should all be the same, as the connections are identical - so "moving (between 1.8 and 4.80?)" looks out of place.
the input opamp non-invert pin (+) connects to Vbias via a 1M resistor, so measuring at pin 3 will again load down the reading - yours is ok. the other half of that oppie is connected differently, with Vbias to the (-) inverting pin, pin 6, and then thru another resistor to pin 7, so those readings, pin 7 a little lower than pin 6, seems right.
all ground and supply pins measure same, so that's good, and all the other pins are not connected to DC except when the IC's are fitted, so they are good. so, only pin 3 of chip 2 needs attention - perhaps remeasure to make certain.
but if it works and you're happy with the sound and it's in a box - forge on! and ignore me.
oh, and to really, REALLY belabour the point - this stuff is all apparent when you have a circuit diagram, complete and matching your build, at hand to refer to, to compare with, and to discuss at. none of this can be divined from a layout diagram.