OR15 - constant 50hz hum

[WDeranged]

Orange mentioned that it might need the hum balance tweaking but as you said, they surely would have checked this when I sent it back.

You would think so, but who knows? If they didn't hear any hum/buzz when they were using it, they may not have even broken it open.

I don't want to be one of those nuisance customers.

Why not? You're the one dishing out the dough...don't settle for anything less than satisfaction! Like others have said, based on what you're describing, I can't imagine what you're hearing is normal.

If you're still able to get a refund, is there a situation where you could just swap it for a different OR15 and see if you hear the same thing?

They haven't had another OR15 in stock since I bought this one, I'd love to just sit down and compare two of them to settle the issue. I'll get on the phone with them tomorrow and see what I can do, it just feels difficult to argue over such a low level noise rather than something that everyone and their horse can spot.

[OrangeBoy]

My OR15 hums (in my case it’s 60 Hz) and it has a higher frequency constant sizzle over the hum too. My Micro Terror does exactly the same thing, and the CR60C as well (but without the sizzle).

I find the OR15 is very sensitive to interference, especially when the environmentally friendly new age overhead room lights are on. Those damned things are very noisy. I put it down to the gain structure of the amp because it amplifies any unwanted signal. The effects loop is especially sensitive and amplifies buffer noise and the cycles of modulated effects if they aren’t true bypass and not engaged (the end result being an audible modulated hiss). The effects loop is very quiet when shorted. The constant hum is normal transformer type hum, no biggie. I’m certain the sizzle is valves (but it could be picking up interference from somewhere else in the house).

I’ve tested different cables/guitars/effects and the hum and sizzle are fairly constant and is always at the same level regardless of volume and gain control positions (and the tone controls have no effect on how it sounds). To me it’s unobtrusive, doesn’t annoy and is normal.

[Phlowen]

I'm pretty sure the OR15 is assembled in China. Does it use Chinese transformers? I know those are real loud and very sensitive to interference (at least the Chinese Dual Terror PT & OT are - they come stock in the TH30 and once I switched them out, lots of noise went away).

[WDeranged]

So I eventually got a refund and ordered another OR15 online, pretty much the same hum and fuzz

My OR15 hums (in my case it’s 60 Hz) and it has a higher frequency constant sizzle over the hum too. My Micro Terror does exactly the same thing, and the CR60C as well (but without the sizzle).

I find the OR15 is very sensitive to interference, especially when the environmentally friendly new age overhead room lights are on. Those damned things are very noisy. I put it down to the gain structure of the amp because it amplifies any unwanted signal. The effects loop is especially sensitive and amplifies buffer noise and the cycles of modulated effects if they aren’t true bypass and not engaged (the end result being an audible modulated hiss). The effects loop is very quiet when shorted. The constant hum is normal transformer type hum, no biggie. I’m certain the sizzle is valves (but it could be picking up interference from somewhere else in the house).

I’ve tested different cables/guitars/effects and the hum and sizzle are fairly constant and is always at the same level regardless of volume and gain control positions (and the tone controls have no effect on how it sounds). To me it’s unobtrusive, doesn’t annoy and is normal.

You'd be the first person to spot exactly what I'm hearing, FX loop included. Thanks for replying as it's kind of put my mind at ease that this is "normal", though strangely enough I tested a Tiny Terror at the music store which only had the hum, no sizzle. I'm thinking the noise tolerance on these Chinese amps is pretty wide, it's a shame but I'll consider living with it, at least buying online makes it easier for me to get a refund.

*edit*

I do have one question for another OR15 owner, if you turn up your master volume in 7w mode and roll the pre-amp gain knob, does it cause a fuzzy "zipper" noise?

[Moonstone]

So are you sure this is normal? Because I also have the hum in my OR15 (you can hear it here: http://forum.orangeamps.com/viewtopic.php?f=3&t=54413) and I'm not sure if it was there the day I bought it.

[BobJM]

Hello,

Just wanted to say I'm new here and while I don't own an OR15, I do have a Tiny Terror and a Micro Terror, and an awesome Crush 20RT as well actually...

I do have some experience with the OR15 and may be able to help.

The hum noise in Moonstone's clip is most likely caused by the FX loop 12AT7. Hum balance noise tends to have a grainy higher pitched buzz to it. The hum may be louder when you plug a guitar in because when there is nothing in the input, the input jack mutes the signal going into the first gain stage and after the FX Send stage (one half of the 12AT7) simultaneously. So when you plug in, you un-mute half of the tube that could be an issue.

If you're getting a swooshy noise when running in 7 watts, its probably because there is some DC voltage appearing on the input to one of the stages fed from the gain pot. The lowering of the high voltages in the amp can make this happen. I don't think it will cause any issues other than that noise but swapping the valve may help. I think JJ tubes are a little prone to this.

You can also get some hum if you have badly matched or bad output valves or some other issues, but assuming those things are ok I'd say what I've mentioned above is easy to rule out before getting into checking that stuff.

[WDeranged]

I came across this old thread and decided to post a quick update in case it helps anyone else who had a similar issue with their OR-15. Eventually I got brave and cracked open the amp to find this mysterious 'hum balance' control.

It's clearly labeled and is the only adjustable control on the circuit board, after an evening of tweaking I managed to almost totally remove the 'sizzling' high end hiss that was bothering me. The 50hz hum is not affected by this control but as it's far less noticeable without that hiss riding on the top of it.

[shedivineswater]

I had an idling hum among other hums with mine and strangely enough it was the FX tube (???)... it was the 12AT7 that was the culprit and I never even used any pedals. I don't know how the tubes mesh together but I couldn't figure out how it could be that tube, but it was. If this is at all pertinent to your problem.

[WDeranged]

I had an idling hum among other hums with mine and strangely enough it was the FX tube (???)... it was the 12AT7 that was the culprit and I never even used any pedals. I don't know how the tubes mesh together but I couldn't figure out how it could be that tube, but it was. If this is at all pertinent to your problem.

My first OR-15 had this exact fx loop issue. The tube was replaced and the hum was significantly reduced. There was still an underlying sizzle/hiss and because I wasn't aware of the hum balance pot I ended up returning the amp

[pedecamp]

I hope the guy got this sorted out, these amps are too expensive to have to live with a lemon. I would have returned it for another one straight up.