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Ben,
From looking at the schematic in the assembly manual, you can see 2 noninverting opamp stages and one non-inverting…resulting in an inverted output….so you are correct. If you want to mod your Quaverato, you can turn that last inverting opamp stage into a non-inverting stage by cutting 3 traces, running 2 jumper wires, and adding 1 resistor (10K ohm, or so). The first picture shows the traces that you need to cut (in purple) and the jumper wires you need to run (in green). The second picture shows where to solder the resistor (sorry for the horrible artwork)…soldered to pin 9 from the V/2 rail.
Let me know if you have any questions.https://zeppelindesignlabs.com/wp-content/uploads/2024/05/noninverting-quaverato.jpg
https://zeppelindesignlabs.com/wp-content/uploads/2024/05/noninverting-quaverato-2.png
https://zeppelindesignlabs.com/wp-content/uploads/2024/05/ORIGINAL-MODDED-circuit.jpgBenjamino1979,
Email me and I can give you the latest Arduino code package…info “at” zeppelindesignlabs “dot” com
-BrachNeil,
I’m sorry about this trouble.
I’m not sure what is happening here. Does the frying sound happen when the treadle is stationary, or just when it is moving through the lowest part of its action? There are some interesting things that are happening at the very lowest volume setting that may be causing some sonic artifacts. I’ve never heard of this happening, but I suppose it’s possible.
A question that follows is how much gain are you using on the VPM-1 or after it? If you use a lot of gain, then some of the normally inaudible artifacts might be more audible if the volume is turned up enough.
Also, it may help to re-set the volume level table in your pedal’s software by running the “stereo setup routine” discussed in step E-3 of the troubleshooting guide (if you haven’t done this already).
I hope this is helpful.
-BrachMathias,
I’m sorry about this noise problem. This problem has to do with some of the PWM frequency leaking into the ground path of your power supply. Certain power supplies, (mostly regulated switch mode power supplies) don’t have much filtering on their output, so these frequencies can leak into the audible part of the circuit. Other power supplies (like linear powers supplies) help filter these frequencies out of the audio path. You can verify that this is a power supply issue by using a battery to power up the Quaverato (with a 9v battery snap to barrel adapter). So one thing you can do is try a different power supply. I recommend using a linear power supply for this application.
Another thing that you can do is add a filter capacitor across the microcontroller as described in this post: https://zeppelindesignlabs.com/forums/topic/extra-noise/page/2/#post-25412
This capacitor helps filter the frequency at its source.
Another thing you can do is make sure all your solder joints are not too large and then clean off the flux from the circuit board (as described in another post on that same forum).
I hope this is helpful for you. Please let me know if you have any other questions.
Good luck.
-BrachI’m glad to hear you were able to get the new one working…although I still think you could have successfully repaired the first one. There is a table in the owner’s manual that shows the crossover frequencies based on the dip switch settings. When the phase switch is on the “in” setting, the crossover frequency doesn’t matter because both sides are going up and down the same…there are no frequencies crossed over. But you still can determine the amount of highs and lows you hear based on how the trim pots are set.
I hope that answers your question.
Enjoy your Quaverato!
-BrachThat’s good to hear. I guess as you discovered, it’s important to pay attention to the details of the instructions.
Take care and enjoy your Quaverato.
-BrachIf your bypass circuitry is working correctly (step 5-C in the troubleshooting guide) and the LEDs are flashing but you aren’t getting the tremolo effect then you must have a short somewhere in the analog signal path or you are jumping the jumpers wrong. Please check for shorts and make sure the jumpers are soldered correctly (step 6-A in the troubleshooting guide).
-BrachBen,
Write to us at info “at” zeppelindesignlabs.com
…or just send us a note through our contact page form. Please include your Quaverato’s serial number. I’m out of town right now, but I can send you the hex file as soon as I get back.
Thanks.
-BrachBen,
Thanks for reaching out about these issues.
As far as I can recall (it’s been a while since I looked at this code), I do think that the RATE is a saved parameter in the presets. When this happens, does it sound like the saved rate is a multiple of the intended rate?…In other words, is it being multiplied by the multiplier knob? That’s the only thing that I can think of that might be part of this issue.
The idea of having the assigned expression parameter saved in the preset is a really good idea. I can’t believe that we didn’t think of this earlier. I will add this to our change log for the next update. Thank you for the suggestion.
I think in our latest version of the Quaverato software we implemented your third suggestion. In this latest version we have the bypass function split across the data range…0-63 is on (or off, I can’t remember at the moment) and 64-127 is off (or on).
In this latest version of the code we also made updates to the tap time functionality, which keeps the tempo from drifting over time as much. We actually haven’t put this version of the software into production yet, but I can send you the hex file if you want to install it on your pedal. You’ll need a USBtiny ISP programmer and a PC.
I don’t know that we’d be able to update the code anytime soon to adapt the other change you suggested, because our software guy is on an extended break, but I will put it in the future change log.
Thank you for your suggestions. Please let me know if you want that hex file to update your pedal.
-BrachIs the depth knobs set to the maximum value (fully clockwise) when doing your tests? If it is…
Try it in calibration mode to see if both the harmonic mix knob is working and also if the optocouplers are working.
It seems that the analog signal path is working through the pedal but since there is no tremolo effect the LEDs in the optocouplers seem to be on at all times…as if the depth knob is not working somehow (check that the voltage is getting really close to 5V on the center pin of the depth knob). Ensure that the high and low trim pots are set to give maximum LED brightness. You can also check that the LEDs are fully flashing by going through the process described in appendix A.
-BrachAre you making it all the way through step 7 in the troubleshooting guide? If so, where on step 8 do you get stuck?
-BrachThanks for you interest in the Percolator. To answer your question, it’s won’t damage anything in the amp if you use a 16 ohm speaker, but you won’t get the same wattage/volume level out of the Percolator. Also, I can’t guarantee how it will sound because I’ve actually never driven a 16 ohm speaker with the Percolator, but you are welcome to experiment.
-BrachI’m glad you are enjoying your Percolator. We don’t have any plans to release another amp anytime soon, but we do have several other things in the works.
Good luck with the Quaverato!
-BrachAlex,
Feel free to use a socket if you would like. I just usually don’t prefer to use sockets because they can become oxidized and add resistance to the circuit…it’s just one more questionable connection (or 14, in this case). Soldering a component to the board is usually a much better option if you know you’ll never have to replace it. The reason the uC is in a socket is because some people may want to re-flash the software and sometimes it’s easier to remove the IC to do that…otherwise that would be soldered to the board too. That is just my opinion, but you can do what you’d like.
Good luck.
-BrachLordHamlet,
No, you were correct in your first post, it is a photo resistor. We call it an LDR, which is a light dependent resistor. We actually sort these components through a proprietary sorting process, so the pair is matched with each other. So you’ll probably need to get a new pair from us. You can try to use pre-manufactured optocouplers, but I can’t guarantee the results. You’ll want to find optocouplers that get under 10k (under 5k is better) in the light and over 5M in the dark. The should respond relatively quickly too, within 1 second they should reach these values. If you can find some optocouplers that respond in this way, that will probably work. But feel free to experiment too…pretty much any optocouplers will work, but how well they work just depends how close they are to the proper specs. Email us if you want to order some new LDRs from us.
Good luck.
-Brach
