Extra noise

  • This topic has 29 replies, 5 voices, and was last updated 1 month ago by mike335.
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  • #15115 Reply
    jrg320
    Participant

    I built my Quaverato a few months ago, and I generally really enjoy the sound pedal, but I have been getting an extra high-pitched frequency in the signal when I have the pedal in the signal, whether it is engaged or in bypass, and the sound corresponds to the rate at which the trem is set. Again, this is happening both in bypass and engaged mode, but won’t happen if the depth is all the way down, which of course is no longer a trem-pedal, but a very large boost (I’ve actually been using it as a last-stage boost lately, because the trem causes too much noise!)
    Any thoughts on how I can alleviate this?

    #15136 Reply
    brach
    Moderator

    This sounds like either the PWM is leaking into the signal path or the power supply is noisy. First of all, try to switch power supplies to a liner type (instead of switch-mode)…make sure it’s rated for at least 100mA. See if this helps.
    If the PWM is leaking into the signal path, this can usually be helped by adjusting the high and low trim pots down in volume. Also play around with the gain trim pot to adjust the ratio of high/low trim pot volume to gain trim pot volume. This noise should decrease as you get the trim pots set in a good ratio.
    Good luck.
    -Brach

    #15475 Reply
    mike335
    Participant

    I’ve been trying to optimize my Quaverato’s internal high, low, and gain trim pot settings to minimize noise and set the best tone for my tastes/purposes. I bought my kit and downloaded the owner’s manual and assembly instruction .pdf’s some time ago. After building it, it worked, but was a bit noisy, at least with my single-coil guitars.

    When I opened the case up some months after completing the build I reviewed the owner’s manual and assembly instruction .pdf’s and found that there appears to be a discrepancy between these two documents in regards to the gain trim pot. The owner’s manual says on page 13: “Turning this pot clockwise increases the gain, counterclockwise decreases the gain.” The assembly manual on the other hand says on page 44: “the volume output of the pedal should be roughly the same when the effect is bypassed or engaged [with the volume knob at 12:00]. If not, adjust the GAIN trim pot (VR10) until it is. Counterclockwise gives more gain, clockwise gives less gain.” The instructions for the high and low trim pots that I found on page 45 of the assembly manual state: “If you would like the tone to be a little brighter then turn up the HIGH trim pot (clockwise) and turn down the LOW trim pot (counterclockwise). If you would like the tone to be a bit darker do the opposite: turn down the HIGH trim pot (counterclockwise) and turn up the LOW trim pot (clockwise).”

    To tell the truth, turning the screw on the trim pots doesn’t really seem to do a great deal to change the gain with the gain trim pot or tone with the low and high trim pots. They don’t seem to have any stops, and the changes seem almost imperceptible. If rotating the screw on the gain trim pot counterclockwise increases gain, I would have thought that the same applies to the high and low trim pots, I gather this is incorrect, and that to increase the high or low end tone with the high and low trim pots requires turning the screws clockwise?

    Frankly I’m a bit confused about making the adjustments. I don’t really want to desolder the jumpers to reset the resistance with my meter according to the assembly instructions, but I guess it might be smart to do that and start over from the recommended baseline.

    #15517 Reply
    brach
    Moderator

    Mike335,
    I’m sorry for the confusion.
    Thank you for pointing out this discrepancy between the Quaverato user manual and assembly manual.
    The assembly manual is correct. The gain increases as you turn the gain trim pot counter clockwise. The tone trim pots are just the opposite, clockwise increases volume output.
    These are 25-turn trim pots…so you probably won’t notice much change if you only turn it a little bit…at least with the gain trim pot. You just have to keep turning it until you hear the volume change. As you keep turning it, there will be one area that it really starts to change and you’ll notice it. You’re right, they don’t have any stops to them so once you get to the end of the pot’s 25 turns it starts making a little clicking sound as you turn it, indicating it’s not adjusting anymore.
    You probably don’t need to unsolder the jumpers to reset the tone trim pots…just use your ears. It also may help to use “calibration mode” to set the tone trim pots. The gain trim pot can always be tested via test points 5 and 6, as long as the pedal is off.
    Once again, sorry for the confusion.
    Let me know if you have any more questions.
    -Brach

    #15526 Reply
    mike335
    Participant

    Brach,
    Thanks for clarifying how the Quaverato’s internal trim pots work. I’ve been making adjustments to them with the Quaverato powered up face down on my bed with the back off of the case so that I can play and hear how the adjustments affect the volume/tone. It’s been a bit confusing, probably because I didn’t know that these little pots are 25-turn pots, and the changes are subtle. I haven’t noticed any “clicking sounds”, presumably because I haven’t reached the end of the 25-turn range, I don’t know. At least now I can be sure of the correct direction to turn them.

    Thanks for the help.
    Mike

    #15546 Reply
    brach
    Moderator

    Mike,
    Once again, sorry for the confusion and the misleading/wrong info in the user manual.
    Keep playing with the trim pots. Hopefuly you’ll find a setting that works for you.
    Let me know if you have anymore questions.
    -Brach

    #15666 Reply
    jrg320
    Participant

    Brach, as far as the power supply, I have tried isolated power supplies (truetone CS7) daisy chained, or standalone wall-wart powering just the Quaverato, same results. I will mess around with the trim pots tonight.

    #15710 Reply
    jrg320
    Participant

    Brach, I’ve tried all of the trim pots and there seems to be no difference. The sound is especially more pronounced when I have other pedals in the signal chain, but it is the same if they are on or off, and whether the Quaverato is on or off. Even with nothing else in the signal or power chain, there is still the PWM leak.

    #16133 Reply
    brach
    Moderator

    jrg320,
    I’m sorry i missed your last posts…i just now found them….sorry for the delay.
    I have found that the pwm can leak into the ground path via extra capacitance anywhere from that part of the circuit…meaning that you don’t have to necessarily have a physical short. For example when i press and hold the solder joints for the tap tempo led i can hear some of the pwm leak into the audio path via the capacitance of my finger. So with this in mind, make sure that the solder pads on this pwm rail don’t have excess solder on them and that the components are standing upright and not bent over close to other components or solder joints.
    I’d be willing to look at for you if you can get it to me and back from me, somehow. If you live in the Chicago area you can come by the lab sometime, or you can mail it to me if you’d like. Depending on which model you have, I can possibly do some mods for you. I just want you to be able to use your Quaverato as a tremolo pedal.
    Let me know.
    -Brach

    #16135 Reply
    mike335
    Guest

    Brach,
    It’s been awhile since I assembled my Quaverato and I confess that I’m not sure what the “pwm rail” is. I reviewed the assembly instructions but it didn’t pop out at me. I guess I could send the pedal to you so that you could have a gander, but I live in Hawaii! I seem to remember that I initially assembled the Quaverato without placing the paper sheets under the pots to insulate their backs from the components. I opened it up again and inserted the sheets and that reduced the noise considerably. I then slid in some flattened heat-shrink insulation material thinking that that would help even more, but this didn’t reduce the noise anymore than the the paper separators already had.

    I could attach some photos of both sides of the board so that you could at least have a look, not sure if that would help—I guess I’d have to upload them to an image hosting site? I can’t seem to upload them from my hard drive here. Though the pedal seems to work properly, it would be nice to be sure that any extraneous noise is at a minimum.
    Mike

    #16136 Reply
    jrg320
    Participant

    Hey Brach, thanks for the update. I’m in Milwaukee, so I might be able to swing down to Chicago some day to have you take a look at the pedal. It’s certainly not an emergency, but I will get in touch if I am able to find my way down there.

    #16150 Reply
    brach
    Moderator

    jrg320,
    That’s good…you’re not too far away. Feel free to send it in the mail, if you’d like, and then plan a trip to pick it up…or vice versa…drop it off at our lab and then have us send it back to you….if any of that makes it easier.
    We’re here at the lab most weekdays from 7am-4pm. Let me know what works for you.
    -Brach

    #16151 Reply
    brach
    Moderator

    Mike,
    I’m not sure that the noise you are experiencing is the same kind of noise as jrg320. Would you classify it as a “high pitched whine” associated with the rate knob setting, that can be minimized by lowering the depth knob?
    If not, then you have an unrelated issue…how would you characterize the noise (a video might be helpful)?
    No matter what kind of noise you have, it is important to make sure you followed all the steps in the assembly manual…otherwise you can end up with a broken or noisy pedal.
    Pictures would help after I’ve seen video of your pedal and heard what kind of noise you are experiencing…so i know what to look for in the photos. Our forum is annoying in that you have to have a web link to post a photo. So use google drive/photos or another upload site. …actually email may be best (if the files are small enough): info “at” zeppelindesignlabs.com
    -Brach

    #16161 Reply
    mike335
    Guest

    Yes, my issue may be different Brach. I don’t believe it’s a particularly high-pitched whine, more like a hum or buzz I think. I’m away from home and don’t have the Quaverato with me, but I can make a video and email it when I get home next week so that you can offer an opinion. Thanks again for your help.

    #16721 Reply
    mike335
    Guest

    Brach,
    haven’t heard from you since I emailed the second video. Do you have any new thoughts on resolving the noise issue with my Quaverato build?

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