October 2, 2023 at 12:42 pm #41376
First off, building this pedal was an absolute joy, I’ve never seen better documentation with more attention to detail than with this kit.
It does work, and I very much like the over all sound of the effect. The depth however isn’t quite how it should be if I compare it to the demo videos on YT.
Normally maximum depth should result in the typical choppy sound that goes from 100% to 0%. This isn’t the case with mine, which goes more like 100%-30%, so there’s always some of the signal continuing, as if it’s leaking through underneath the effect. Still sounds good and usable, but I’d prefer the pedal to work as intended.
I have punctured the black tubing a tiny little bit to see if the LEDs are actually working, and they are. But for some reason with maximum depth it doesn’t fully shut off the signal.
What could be the reason? I’ve been very careful not to make any mistakes soldering the parts, and I checked a couple of times, but couldn’t fine any. But something has to be wrong.
Maybe you guys can point me into the right direction!
Thanks, IkeOctober 2, 2023 at 1:01 pm #41377
I’m glad to hear you are liking the Quaverato, but I am sorry about this issue.
It sounds like you may have some leaky optocouplers. It seems like light is somehow making its way into the heat shrink, causing the signal not to shut off all the way. Please make sure you seal the ends very well with some opaque substance (even poster putty/sticky tack will work). Also, make sure you optically seal the holes you made in the heat shrink.
You can use calibration mode to tell what side (high or low) is leaky. Also, it’s best to use the square wave setting with the depth all the way to 100% (fully clockwise) and the LFO rate set relatively slow, so you can easily hear if the sound is not shutting all the way off on each cycle.
-BrachOctober 2, 2023 at 6:33 pm #41379
Wow, that was quick 🙂 Thanks for your speedy response 🙂
Do you mean that maybe light from the other LEDs might be interfering with the optocouplers? I would have thought once the box is fully closed, it should be pretty dark in there.
I had poked these minute holes in there after I realised the problem, and poking them in didn’t have any detrimental effect. They are really minute anyway, so I can barely see the light inside them. Maybe I should take them out and redo them with a fresh piece of shrink tubing.
If it’s not that, what else could it be?
I’ve also noticed that there’s no trem effect whatsoever if I turn the Mix knob all the way to Hi. The signal only gets quieter and maybe a bit muffled. If I turn it all the way to low, the lower frequencies do trem, the high frequencies remain steady. That’s the same in both phase settings. So that seems to me that something on the treble side isn’t quite right.
Again, both optocouplers seem to work, they both emit a pulsating light through those tiny holes. Covering them up doesn’t seem to make a difference.
In Calibration mode thanks to my tiny holes I’m observing that the low LED flashes and goes dark when I turn the mix to “hi”, the other way round the hi LED is constantly on and doesn’t change when I turn the knob to “lo”. Somehow the high frequ. part isn’t affected by the effect… Band solder joint somewhere? If so, any obvious places to look for it?
Very mysterious! I hope my description makes sense to you.
Thanks for now, let’s hope it’s something really simple and obvious 🙂October 2, 2023 at 6:46 pm #41381
Here’s a little sound sample of what it sounds like:
http://www.falckenberg.com/downloads/Trem.mp3October 3, 2023 at 11:25 am #41382
That’s really good information to have…the high side audio is not pulsing (thanks for the audio clip, that was very helpful). The other piece of good information to know is that the high optocoupler LED is working. So there must be a problem around the LDR, like it’s possibly shorted. So from looking at the schematic, make sure TP1 and TP2 (or JP1 and JP2) aren’t connected/shorted. You can use your meter’s continuity tester to check this (with the pedal’s power off).
Let me know what you find.
-BrachOctober 3, 2023 at 3:53 pm #41383
Hm, that would have been too easy I suppose 🙁 No, it’s not that, TP1 and 2 are not shorted 🙁
Could the LDR be defective?October 3, 2023 at 5:03 pm #41384
If you haven’t measured the resistance (with the power off) across the test points (1 and 2), please do that…just to ensure there is no short or near-short on those pins. There may be a short on a part of the board that isn’t visible.
To find out if the LDR is defective you can always measure the resistance across TP1 and TP2 (with the power off), while you shine a flashlight in the hole you made earlier in the heat shrink. I’ve never seen an LDR short out or go bad, so it’s probably not that.
-BrachOctober 3, 2023 at 6:43 pm #41385
Resistance across TP1 and 2 is roughly at 1700k. If I shine a light onto the heat shrink, it goes down significantly (to ±70k) Quite amazing, given that the hole is really really small 🙂October 4, 2023 at 8:43 am #41387
Yes, the LDRs are very sensitive to even the tiniest amount of light.
So by that test we now know that the high LDR is not shorted and it is working, at least on some level. Just to clarify, when you cut the high optocoupler open, did you see that the LED was pulsing at any time (or at any knob setting), or was it just staying on all the time? Because the pedal is behaving like it’s just staying on and never flashing, at least according to the symptoms that I’m aware of. If this is the case then there could be a problem with the mix pot. Please ensure that the center pin of this pot is scrolling from close to 0 volts to close to 5 volts as the knob is turned from one end to the other. Otherwise, there could a problem with Q1…ensure it’s in the correct orientation and soldered correctly, without any shorts.
-BrachOctober 4, 2023 at 6:33 pm #41388
This is getting weird now. So the LEDs are both pulsating, when the pot is in the middle position, if I slowly turn it to one side, one of the two will stop pulsating and go steady, depending on which way I turned. But both LEDs behave in the same way.
As for the pot, it does exactly what you say, it goes from 0 to 5 volts measured from the middle lug to ground.
Q1 is soldered in the correct orientation, which was to be expected thanks to those nifty little drawings on the board, that indicate the direction 🙂 I will however resolder those 3 legs anyway, to make sure they make good contact.
I’m aware that the transistor probably doesn’t like heat that much, but I believe was taking great care to use only moderate heat and make sure to solder it quickly. It might still be fried, who knows. Maybe I should order a few more of these and check if that’s the problem. What do you think?
The three legs are not shorted as in “they don’t produce a beeping sound on the continuity tester”. Also there seems to be a resistance of roughly 600Ω between the middle leg and one side leg. I don’t know if that’s the way it’s supposed to be. Q2 is the same BTW.
I’m also considering the possibility that I’m just too stupid to use the pedal correctly, and that’s actually how it’s supposed to sound! But I don’t seem to be able to create that choppy sound that goes from on to off.
Hey man, I appreciate your help!!October 5, 2023 at 8:33 am #41389
From what you are describing, it seems like it’s working as it should. The mix knob is behaving correctly…when it’s turned to one side or the other it causes only one side to pulse while the other lets the signal through without pulsing. When it’s in the middle position (12:00) both sides should pulse the same amount.
This is making me wonder if you had the mix knob turned to one side when you recorded the sound sample. Can you test that again with the mix knob in the middle?
If you are looking for the pulsing sound, the phase switch needs to be set in the “in” position. Once you get the pedal working correctly, you’ll probably need to adjust the tone trim pots (high and low) to dial in the proper amount of both signals.
-BrachOctober 5, 2023 at 9:26 am #41390
The recording was made with the mix knob in the middle. I will check again. My mix knob is at its most effective setting, that is with the most extreme pulsating a little to the left of the middle position, so that’s what I chose. My idea of recording the signal came from my observation, that it’s kids difficult to hear if the signal really shuts off during the down phase of the cycle, as the natural sound of the guitar tends to confuse the ear (unless I turn up the volume to neighbour-unfriendly levels) The recording gives me an visual representation as well as the option to listening back in isolation.
I watched some example videos on youtube, and there the effect indeed goes from full to silent, so I assume, that’s how the pedal is meant to work.
Also the high portion of the effect not pulsing is consistent throughout my tests. It never goes down to 0, like the direct signal is constantly leaking through.
Let me do some more tests and get back to you.October 5, 2023 at 10:12 am #41391
Ok, did some comparison with your very own video.
First off the settings I copied on my box:
Secondly, the waveform as recorded, both from your video and my Quaverato:
Here’s the audio off your video:
And finally from my box:
On my recording there’s always an underlying constant tone, it never shuts off completely. And that’s with wave shape set to square wave, full depth, spacing in the middle, harmonic mix where the effect is the strongest (my pot ends up in the 11 o’clock position when the separation is strongest).
Should I replace the transistors in question?October 5, 2023 at 10:45 am #41392
Here’s a short video to illustrate how my mix control reacts from LO to HI, coming from the same settings I used for the comparison with your video. On the LO position the effect is fairly subtle, the middle position is actually somewhere around 11 o’clock, and if I turn towards the HI position the effect gets less and less until it’s completely gone in the HI position. That can’t be right, can it?
http://www.falckenberg.com/downloads/Quaverato/Harmonic-Mix.MOVOctober 5, 2023 at 11:04 am #41393
It gets even weirder.
Here I turn both the depth and the Mix knob. Note how the depth know does rather weird things, while interacting with the Mix knob:
Could the pots be defective I wonder?
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