Fixed: hardware solution for humming problem



  • Are we chasing a grounding issue or poor dc rectification resulting in excessive ac ripple in the power adaptor ?



  • This fix works. It is a preposterous solution but effective.

    I've posted since the beginning that it is a grounding issue. I contacted PG explaining in great detail the symptoms, they sent me a replacement with same problem (of course). I already had tried Hum-x, and an isolation transformer, neither helped. So time to void the warranty...

    I just made a video clearly demonstrating the problem and how grounding the chassis makes an immediate improvement.

    https://youtu.be/6QtXJDLx-vA



  • Before you drill a hole in your Spark, consider trying a grounded power supply.
    It worked well for me, see how the hum goes away when I change the power supply: https://streamable.com/clk9l0
    Also, you could just attach that wire to the outer usb plug instead of drilling a hole.



  • @incognito-v Ok but also with this solution that eliminate the noise humming problem, when I play distorted power chord on bass strings the amp is cracking just like the cpu is overloaded or there is a wrong capacitor... 😢



  • I'm really concerned that this issue might be a deal breaker (still waiting on my Spark). Software issues like the low volume from the audio interface and app bugs can be fixed via updates but if this is a serious design flaw then I'm not sure I want to take a chance.

    What about running a grounding wire from the chassis (would still have to drill a hole to let the grounding wire out) to a grounding plug by cutting off the Positive Grid plug and replacing it with say a Leviton grounding plug (i.e. [Leviton 515PV 15 Amp, 125 Volt, Grounding Plug, Yellow(https://www.amazon.com/Leviton-515PV-07196000501-Pack-Yellow/dp/B0015P708Y/ref=sr_1_3?dchild=1&keywords=electrical+plug+with+ground&qid=1591917253&sr=8-3) and attaching the grounding wire to the grounding screw of the Leviton plug? Would this work?

    Thanks in advance for helpful replies.

    @incognito-v Very encouraging that you got results with a different power supply but a previous post said it wasn't a power supply problem. In that it worked for you, could you post a link to which power supply you purchased, please?



  • This is really hard to believe. These amps were rushed to production now they have who knows how many amps out there with this same problem. And the big question is if it took a half a year or more to get the amp, how long will it take to get the fix ?



  • Ac adapter : Fujitsu limited adp-90be d

    Tried the power ac from this post and I confirm Hum and buzz are gone. Everything woks perfectly.



  • @incognito-v Which power supply did you end up using?



  • @mark-pashalis Any 19V grounded power supply that can deliver 2.5 or more amps and has a ferrite choke and a 5.5mm 2.5mm connector would do as long as you power socket is properly grounded.
    Fujitsu and Asus laptops typically use such power adapters.
    I purchased a universal adapter as I needed a power adapter for my Dell laptop too:
    https://www.amazon.fr/TAIFU-Universel-Adaptateur-Ultrabook-TouchSmart/dp/B07MKJ2Z32
    But if you only need it for spark you can get a cheaper one like:
    https://www.amazon.com/Adapter-Computer-Charger-Notebook-ASUS/dp/B074QLP7WF/
    or something else.
    Yes, your Leviton grounding plug solution might work, but as I said you can test by attaching that wire to the outer usb plug case before of drilling a hole in your amp.

    Hope you'll get your spark soon.



  • Confirming what @incognito-v said. A couple days ago I ordered the power supply he linked and received it today: https://www.amazon.com/Adapter-Computer-Charger-Notebook-ASUS/dp/B074QLP7WF/

    Hum/buzz/static resolved.



  • @ezeje I'm guessing/hoping support is sending out replacements as this is a design flaw? Are you guys just not wanting to wait that long, because I imagine you can get the power supply from Amazon a lot quicker. I have a Spark on order and am crossing my fingers they are shipping grounded power supplies now. Seems like an easy fix and I'm surprised this got through quality control. Or maybe that's all they could get in bulk at the time. Regardless, glad to see there's a relatively inexpensive fix if I run into the same issue. I'd rather get another power supply that drill into the amp. Also, if plugging in to a USB port grounds it, I can live with that until support sends a replacement.



  • @cbrandst I had a replacement sent to me by positive Grid, it is exactly the same one that's supplied with the amp, no use at all same problems



  • Hi All,

    I can confirm that using a 3 pin earthed laptop power supply fixes these issues. For those in the UK I would recommend this https://www.amazon.co.uk/gp/product/B00EZNJYT6/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

    So, just a report. High gain amp with no noise gate loads of buzz. Touch string/ bridge on guitar or plug in usb cable buzz reduces/ changes. Using the linked PSU, absolutley no buzz. Even with a high gain amp (no noise gate) no more buzz, just the hiss/whoosh you would expect from such an amp.

    @mike Positive Grid, no expensive amp redesign required, just change the PSU supplied to a 3 pin earthed version and all is solved. I adore this amp now.

    Cheers

    Rob



  • Hi all, I received my Spark amp about a week ago or so. Was working perfectly both HW & via bluetooth using my Samsung tablet, up until 2 days ago. I turned it on today, everything looks normal, but no sound from guitar!!!! Instead, I hear a hissing sound that gets louder as I change amps/presets with more gain/dist. Nothing I do with the guitar affects the hissing sound, also same exact thing from headphones. I did a factory reset to no avail. I already emailed support.

    Any idea what is going on here? Is it the power supply?



  • In the meantime it is undoubtedly clear that there is a problem with the amp in terms of hum and this is due to the original power supply.
    A grounded power supply belongs to this thing and everything is good.
    It cannot be that we users start drilling holes in our brand new devices in order to properly ground them. Or we have to lay additional cables in our apartments to plug sockets in order to clamp them to contacts there with an alligator clip.

    This can be fatal !!!



  • @cbrandst I’m too impatient to wait for support to evaluate and respond. $18 on Amazon, arrived 2 days later. I’ll contact support at some point to report it but I imagine others have already and that they’ll either do something to make it right someday or I just ate $18 to get the amp working without jumper cables. It’s a pretty ridiculous issue to have to deal with though. PG leadership ought to be embarrassed that after all this bs they sent a bad power cord and fumbled the rollout. I’d be pissed off and all over it with my customers if that were my company. On the flip side, I dig the product. The amp is really fun and is exactly what I was wanting, so all in all (factoring in major tolerance for the delays and complications) I’m satisfied.



  • @ezeje I got the same adapter as you, but it had no impact on the buzzing issue. You still having luck with yours?



  • Some suggested you can plug the USB connection into a PC and ground it that way. Is that not working? Seems like the easiest way to work around the issue if so. I'm no electrician, but I thought the purpose of grounding a device is so you don't shock/kill the user. So if the AMP has a grounding issue, somebody could get seriously hurt or killed if there's some kind of failure inside the device and the current goes through the user and not to ground. So this may be more than just an hum issue.



  • i just plugged in wireless transmitters and now the hum is gone ,,go figure



  • @thomasid58 I've also connected my wireless system and improved a lot, however not 100% :(

    Increase the gain, pick a string and let it ring.. I can hear that damn noise after few seconds :(