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Orange 35RT humming/buzzing

Started by bsilverop, February 18, 2023, 05:57:42 PM

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I just started playing again after about a 20 year break. I bought a new Orange 35RT amp and plugged my old epiphone SG into it, and the amp makes a very loud buzzing/humming sound when I turn up the gain past 20%. I tried new cables as well without any change. It stops if I put my finger on the string or another metal part of the guitar. Thinking it was the old guitar, I went out and bought a new one, and the exact same thing happens.

Unfortunately I don't have any other amp to test on at home, but seems like the issue is with the amp. I'm thinking of returning it and exchanging for another one, but wondering if this has happened to someone else before. Thanks!


Is the amp being plugged into a working, properly grounded outlet ? Try a different outlet. If that doesn't work, take it back to where you purchased it and see if it works there.


Quote from: Loudthud on February 19, 2023, 12:26:26 AMIs the amp being plugged into a working, properly grounded outlet ? Try a different outlet. If that doesn't work, take it back to where you purchased it and see if it works there.
Yes I've also tried other outlets throughout the house and have the same issue. I'm going to take it to the shop where I bought my new guitar and see that everything works fine on one of their amps to rule out the guitar, and will probably take my amp with me. I requested a return on Amazon where I bought it but want to make sure it's not my guitars or outlets first. Thanks!


Is the pitch of the hum between a Bb and a B?


How can you play without touching the strings?


Not sure it is any note in particular. Ignoring the last comment, but here's a video of the issue as well.



Ok - if you hum along with the hum, that's right around Bb - B, which is 60Hz or 120Hz, so bad filter cap(s) would be my first guess. If it's been a long time since you played it, this makes a bit of sense, dried out electrolytics. If you know what you're doing, open it up and measure AC volts across the power supply filter caps (across the cap leads, NOT from each lead to ground). You should get 0.00Vac since caps pass ac voltage. If you get a measurable AC voltage across a filter cap, there's the culprit. If caps look good and clean, then I'd try to hunt down a ground problem, which by nature can be frustrating, so lots of patience... On occasion I've run across bad filter caps on op-amp supply pins, and FET drain pins (when bypassed), but that's been more rare for me. Hope that helps. If you have any trepidation at all about opening the amp or measuring those caps, take it to a tech, not worth getting hurt over a silly cap. - Will


Thanks for the reply. This is a brand new amp, so will likely return it before cracking it open. Don't want to be blamed for damaging it or voiding the warranty if I open it up. I wish I found this forum before giving away my 25 year old fender amp that wasn't working after plugging it in for the first time in almost as long. Thanks again!


Ah - OK, I think I had my threads crossed (someone who had just pulled an old amp out of a closet, on another one, sorry). Usually the bad cap issue takes time, but failures on new components can and do occur. For sure, this blatant problem would rarely get past QA. Or maybe it was a late day at the factory and someone wanted to go home. Could have been damaged/jiggled during shipping... This is a great site to bookmark - lots of knowledge here from some amazing techs with decades of experience (g1 and phatt, especially, have some serious chops!)


Sounds to me like poor grounding and/or picking up electric interference on your circuit.  If you touch the strings on your guitar does it change the hum?  What about pickup selection?  Tone/volume knobs on the guitar make it change?  Unplug the guitar entirely and try the amp again - same noise?
Life is what you make it.
Still rockin' the Dean Markley K-20X


When I touch the strings or tuning knob, the hum dampens a bit (maybe 75%) but is still there. If I adjust the pickup volumes, same thing. I ordered a new amp (same one) and hoping the issue goes away. Otherwise I'm clueless l, but ordered a circuit tester to check for any grounding issues in my outlets to rule that out.

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Quote from: bsilverop on February 19, 2023, 03:38:17 PMIgnoring the last comment

If you are referring to me, perhaps you misunderstand my comment, or I misunderstood the original post.
You said the hum goes away when you touch the strings.  I was trying to get you to think about the issue from a different angle, or re-direct the conversation to see if others here thought the hum could possibly be normal.
Does the amp perform normally while you play?  If so, it seems there is an issue with your guitar shielding or cable.  Or maybe a bad interference issue.
Without touching any metal parts on the guitar, turn the guitar's volume controls all the way down.  Does that make the hum go away?


The buzz on the video is most likely switchmode power supply high frequency switching.
IF these Smode supplies are not well grounded then the hi Freq switching will bleed through into you audio circuitry.
Some are horrendously noisy if badly designed.

Just one thing you may not have tested is the power cord back to wall.
If the earth wire is faulty (Open circuit) then even the best designed Smode system will bleed through.
  Swap the cord for another and report back.

One other possible issue, your house wiring may not be up to standard.
Try another house, see if the issue resolves.


I had considered trying another house before returning the amp, but have a new one on the way so I can report back then. I don't think the hum was present with the pickup volume turned down, but can't say for certain. I should have tried another power cable prior, but the manufacturer just suggested a swap before troubleshooting too much.

Hopefully the issue is just gone with the new amp, otherwise I would suspect the house as the culprit, since the issue happens on two guitars (one really old one, and one brand new Gibson LP Standard), and 3 different cables. 

I do have a few non standard things running in the home that I can try turning off in case of interference, so thanks for that suggestion as well.. I hadn't considered interference prior.

Thanks again!


Yes if you turn down the volume on the guitar you are grounding the audio input and hence no noise.

These Smode supplies radiate hash out into the air and the high Z input of the Guitar audio circuit picks this up.
And yes ANYTHING that uses Smode supplies in the room/house such as computers and like can wreak havoc on your sound because they travel back through the wiring of the house as well as into the air.

With the old Copper and Iron transformers any noise was low freq hum. but unlike Smode they did not radiate very far into the surrounding space.

With a Transformer you just had to keep the power Tx away from the sensitive input when you designed the layout of the chassis and usually there was no big problem.