Are new Sparks just being recieved coming with a grounded power supply



  • Wondering if PG is now sending new units with the proper power supply. Waiting for my replacement told today they are out but will ship when they receive some more.



  • @stinger0625 No, i just got mine on Friday and I had emailed them while my order was being processed after reading a lot of the feedback on here. They stated it is usually environmental factors that cause the hum noise some are experiencing. Mine doesn't have any issues. My guess is older electrical systems may be a factor or other electrical sources causing interference? I have no clue; just guessing.



  • @stinger0625

    Seems to me that there was a thread about grounded AC power supplies recently. It contained a reply with a link to a power supply that met the Sparks power requirements and a problem polarized plug. I'm a bit puzzled about the need for one, is there a grounding pin in the amps connection that ties it to the ground of the external power supply?

    https://forum.positivegrid.com/topic/4027/fixed-hardware-solution-for-humming-problem/17



  • While I wait, relatively patiently, for the Power Supply promised by Positive Grid I went ahead and picked up the one identified in a thread here in the forum. OH MY GOD (or whatever higher power you identify with (or not), you get the point), what a difference!! I noted the hum, even with the Clean settings and it got progressively worse with other presets but I didn't realize how much the new power supply would eliminate it. They gave me the same line about environmental factors but the only thing I changed was the power supply with a grounded plug and there is absolutely NO extraneous noise. All I get now is what comes from the guitar with the added effects from the selected tones. IT IS AMAZING!! I couldn't believe how much it cleaned up the sound. There is no question that the power supply is the issue.



  • @cmcwillieb

    Care to share your source and model for the power supply youre referencing? I’m curious about the pin configuration, and should I run into the same issue I’m not averse to getting it fixed fast with an aftermarket PS. The only thing that comes my mind even as I type is voiding the warranty by using a PS Not supplied by PG.



  • I was also confused about the power supply being the problem, as there is no earth coming from the spark input for the supply to connect with.

    So I guess it's a grounding issue inside the supply or lead itself, which is inducing an EMF that is then being picked up by the circuitry within the amp, as opposed to the amp being incorrectly grounded and it being resolved by being earthed out through a new power lead/supply.

    I dont know why they wouldn't make it a 3 prong in... it's an amp, you don't want noise, you want the supply and amp to have 0 potential.... tell me what amps you have that don't have a 3 pin IEC In. All my amps have the standard 3 pin IEC.

    After the 2 year warrenty period ill be mod-ing mine to 3 pin.



  • @sjdonahue13 Then why do most amps not have a similar noise/sustain problem in a wide variety of homes and buildings?



  • @n3g4tiv_1

    I doubt the amp itself needs a 3 pin (+, -, Gnd) connector at the amp as the voltage supplying the amp is DC voltage. If it were an AC powered amp plugged straight into the wall I doubt it would have gotten its safety certification labels without using double insulation which adds to the cost of the product. Fender used to use a two prong wall connector and a ground switch in the amp to eliminate ground hum. Nowadays one of the first things an amp tech will strongly suggest is converting that two prong cord to a grounding cord and disabling the old ground switch in the amp. After talking to my son, an engineer (great investment there) he felt that the power supply box, likely a very inexpensive one, is the source of RFI emissions (radio frequency interference), possibly from a ground loop. A power supply that uses a 3 prong AC connection would ground the power supply to the house's breaker panel ground and therefore the power supply transformer and rectifier inside the PS box. If you ground the amp by adding a ground wire connection at the amp as I've seen in another thread you're effectively grounding the power supply as well. I'm digging into this further.



  • I went and bought a "grounded" PS for my Spark months before it arrived. Ya know what I found out? I used the grounded PS (grounded with better amp specs than the factory PS) and had noise! So I unplugged and then hooked up the "Un-Grounded" factory PS sent with the Spark, and the noise was GONE!

    I agree, that this should NOT have happened, but it did. The Grounded PS with the better specs went back in its box and will be a "spare" PS if I ever need it...



  • @keoki This was my feeling as well -- it isn't a question of how many prongs on the plug, it's really a question of quality. I've also noted a few times in posts that the cable doesn't even have any ferrite core rings, which dampen RFI. There are plenty of quality-made two-prong power adapters that come with musical equipment. But this isn't one of them.

    I've already come across an example -- since you can mitigate the issue by using the included AC adapter while simultaneously plugging-in the USB to a computer, I've come across two different results, despite both scenarios having three-prong plugs. For instance, while using the included AC adapter and plugging the USB into a newer MacBook, the AC hum disappears. However, if I plug the USB into a 2011 MacBook Air that uses a non-Apple AC adapter I found on the internet (since the original one died), I still have AC hum, even though it is a three-prong plug. This again shows that it is a question of overall quality, and even a three-prong plug doesn't guarantee anything (although anecdotally, I think the chances are still better).

    I did end-up buying a 3rd-party AC adapter for this, since I didn't want the Spark tethered to a computer all the time -- but only because I knew of someone who already owned it and verified that it worked, so it wasn't as risky, and wasn't too badly priced. Like all 3rd-party stuff, YMMV.



  • @blueingreen & @Michael-Howell

    I should have been clearer with respect to my sons comments. He strongly felt that given the price point of the units that a cheap power supply would likely be sourced. Not necessarily by PG but the OEM in China. That’s not to say that every "ungrounded" power supply they sourced will create a hum, but that that inferior components would be used, and some PSs would be just fine and other would not. Michael, honestly I have no explanation for your own experiences with the grounded PS you tried..Conjecture? As @blueingreen experienced perhaps simply being grounded isn’t enough to eliminate hum but being a grounded with quality components might. In other words there are likely funky grounded units as well. His experiences seem to bear that out. I wonder if there’s a way to test the PS’s to determine the cause. I’ll see if my son has an Elect Eng classmate I can talk to. Meanwhile, as the King said in Rogers and Hammerstein’s “The King and I”....it’s a puzzlement.



  • @michael-howell

    Michael, I’m not sure I understand what you meant by “better amp” specs, Could you expand on that a bit? Are you talking about the DC output current?

    Gracias y Mahalo
    Keoki



  • @rexlarsenphoto said in Are new Sparks just being recieved coming with a grounded power supply:

    @sjdonahue13 Then why do most amps not have a similar noise/sustain problem in a wide variety of homes and buildings?

    because modern homes in modern areas have the neautral (black) earthed/grounded.
    and the original power supply only has two pins.. active(red) and neutral (black).

    if anyone has doubt about their power supply, I'd suggest to take the amp to a friend's house in another area and try it there



  • @crystalpit I may be able to shed some light on this.
    And @crystalpit, I do not mean to single you out. Your post was simply the last in my thread.
    Electrical Engineer here. There are different types of AC to DC power supplies (Inverter, rectifier, switching, non-switching, etc.) They all do roughly the same thing but work in very different ways. Then there is types of filtering. Most power supplies use some rudimentary filtering methods just to maintain even enough DC output voltage or to mitigate external influences on that voltage. However, as @Keoki's son said, it is a matter of price point. I don't know, as I have yet to receive my amp, but my guess based on what I am reading is that PG spec'd either a non-switching PS, or one that doesn't have a ferrite choke and/or filtering capacitors capable of evening out the noise generated in that circuit. So, depending on how much noise is in your nominal AC voltage source (your wall outlet), the nature of the EM field of your environment (your amps location in relation to sources of electrical noise) and/or the internal noise generate in the PS; it is possible that different people experience different levels of noise.
    I will make one correction to the myriad of above statements though:
    -An AC to DC PS will be bonded from the ground through the common or 0V position (sometimes called negative) internally on the PS as per UL ratings. Even if the PS doesn't have a specific ground terminal at the input, it is still chassis grounded and ultimately the incoming neutral line is bonded back to ground at the houses main and into earth. This is of course if your house is remotely up to code. This does not mean noise will be cancelled out, however that if a current carrying conductor internal to the PS is disconnected and touch the case or in this case anything that is ground (as these are usually injection molded plastic) that current is safely conducted to ground. In the case of a non-grounded plug, this is not grounded internally, but bonded back to neutral of the AC source. This is why polarized plugs are important. My ultimate point is that even though there are only two conductors on the barrel connector, on is still grounded. It is whether or note the grounding/filtering in the PS is adequate enough for your application and whether it is plugged in to the correct polarity in the wall socket. I will assume however that the two prong plug is at least polar. It wouldn't be able to bu UL listed if not.



  • @sarawson Excellent explanation. I have an electronics background with some education in electrical. I checked the AC plug on my Spark's power supply and it is non-polarized. I have NO AC hum what-so-ever no matter which way the plug is plugged in. My education was in old tube technology and it amazes me what advances in power supply technology that has taken place over the years. Not sure why some people are having noise problems, but think it could be low cost components in the power supply that may be defective.



  • @sarawson

    Thanks pal. That saved me some oxygen over the phone! @XBFOZ ? I didn't even think to ask if the plugs on the power supplies were polarized (one could insert the plug into an outlet in any orientation vs a plug with the larger Neutral prong). Now that I think back about it, we used flip the plugs on our amps in an attempt to stop humming. Particularly when there was no grounding switch a la Fender (yeah as I said in my bio, I'm an old guy! ;) )



  • @keoki said in Are new Sparks just being recieved coming with a grounded power supply:

    @sarawson

    Thanks pal. That saved me some oxygen over the phone! @XBFOZ ? I didn't even think to ask if the plugs on the power supplies were polarized (one could insert the plug into an outlet in any orientation vs a plug with the larger Neutral prong). Now that I think back about it, we used flip the plugs on our amps in an attempt to stop humming. Particularly when there was no grounding switch a la Fender (yeah as I said in my bio, I'm an old guy! ;) )

    I remember those days. After plugging my guitar into an amp, I would lightly touch the strings to see if the AC plug was in correctly. I hated the feel of the slight shock on the underside on my strumming arm. I betcha I am older than you, though...;)



  • @xbfoz

    Bahahaha! Lol, okay XB I'll pickup that gauntlet!! 1952?

    Keoki



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  • @keoki Yep, you are the same age as my younger brother!