Loud Buzzing From Monoprice Stage Right 5W Amp

[BobY]

I purchased a Stage Right 5W tube amp right before Christmas. I haven't played it much since then but now that I started playing it longer periods of time it has a noticeable loud hum/squeal that occurs after it has been played an hour or so. Not sure if this is an electronic component (I had a Blackstar make weird noises that had a diode issue) or a bad tube. I have only played the amp a few hours so unsure if it could be a tube unless the ones that come with it are junk.

I hear Monoprice is excellent in regards to RMA's but wanted to get opinions if I should buty replacement tubes or just exchange it. Here is a video of what is happening:

 

[northernguitar]

Not sure if Monoprice has any warranty on its tubes. Might be worth looking into. Regardless, you just bought it; my inclination would be to return it. If something goes on bargain equipment, it usually goes quickly. Better to be safe than sorry.

 

[stormsedge]

Send it back.

 

[bender66]

If you have spare tubes it wouldnt hurt to replace them before going through the hassle of returning. The stock tubes are bunk. They'll ship you another and you'll just repeat the process again.

I replaced mine from the get go. Didnt care for the harshness from the stock tube. Trying to remember what I put in.

 

[BobY]

Thanks for the replies. Do you think the tubes are the issue? If so I don't mind grabbing a good set.

 

[bender66]

Thanks for the replies. Do you think the tubes are the issue? If so I don't mind grabbing a good set.

If I were a betting man I'd say yes they are.
Not 100% sure, but that's where I'd start. If you have a gear buddy that could loan you tubes to test or take your amp to him if they're lazy (just to save the hassle of purchasing) Bob's your uncle.

I think I took a 12AX7 out and replaced with a 12AY7 or 12AU7? Sounds right.

 

[Chiogtr4x]

My stock tubes in mine ( bought mine Dec. 2021) sound fine to me.

No noise, clean/ bright tone at low-moderate Volume knob rotation ( NOON and lower), and great R&R grind with some nice sizzle and sustain with both Tone and Volume knobs cranked.
Not really deep low end from the amp and speaker, but not flabby either.
My stock tubes are unmarked (and I have good backup set) so I'm leaving them alone.

 

[dan40]

The fact that it doesn't start until the amp has been played for an hour would suggest that a solder joint is bad and losing connection once it gets warm. That buzzy noise certainly sounds like a bad connection in the circuit. I would send it back for a replacement.

 

[BobY]

The fact that it doesn't start until the amp has been played for an hour would suggest that a solder joint is bad and losing connection once it gets warm. That buzzy noise certainly sounds like a bad connection in the circuit. I would send it back for a replacement.

Thank you Dan! It will send it back and hope the replacement works out..

 

[MuddyWolf]

Life with tube amps.
Rule #41 you don't ditch an amp with a bad tube, you get a new tube. Preferable a couple new ones because sooner or later tubes can go bad. Power tubes can go maybe a 1000 hours. Preamp tubes can last ALOT longer but there is no guarantee.
This ain't a modeler this is a TUBE AMP.

 

[BobY]

I figured I may as well try some working tubes from my HRD to troubleshoot before sending back. Needless to say the ones shipped with the unit were not of the best quality. The power tube has some sort of rust and has what looks to be crack or two under the glass and from the scratches, scrapes and slightly bent pins appears to be used. Disappointing.

If my known good tubes work I will be requesting a new set of tubes fromt he Manufacturer. If they are started tubes that should a

t least be new

 

[bender66]

Dont request tubes from them. Kindly ask them for $ to reimburse you for quality tubes that you chose.

 

[dan40]

The power tube has some sort of rust and has what looks to be crack or two under the glass and from the scratches, scrapes and slightly bent pins appears to be used. Disappointing.

The rust you see is actually the glue used to hold the plastic base onto the glass envelope. The lines that look like scratches and cracks are caused when they insert the tube's into the glass envelope. there is a black coating on the interior of the glass that gets scratches in it when they insert the tube's internals during assembly. That internal coating can get pretty scratched up if they aren't careful during assembly. I have some NOS Sylvania 6v6's that also have those same scratches in the grey coating they use inside of the tube. Then bent pins are simply carelessness when they installed the tubes at the factory.

Please report back and let us know if new tubes fix the problem. I hope they do but that buzzing really sounds like a faulty connection to me.

 

[doof]

I bought my 5W Monoprice a couple years back, and the 6V6GT it came with was a Marshall-branded tube that did not look at all new. Luckily my amp works great, but they seem to be sourcing some shady tubes.

 

[Dirty Dave]

Did you manage to get this resolved?

 

[Tarkus60]

I found some NOS GE tubes for mine. I like that amp!

 

[BobY]

Did you manage to get this resolved?

Sorry for the delay. My out of town travel has been crazy! It has been resolved. I sent it back via the RMA process. I was afraid it was more than tubes and didn't want to risk it. I did notice the replacement had no hum or buzz at low volume vs. the original.

 

[Wildeman]

Sorry for the delay. My out of town travel has been crazy! It has been resolved. I sent it back via the RMA process. I was afraid it was more than tubes and didn't want to risk it. I did notice the replacement had no hum or buzz at low volume vs. the original.

Excellent, that was my thought, use that warranty while you got it. If that thing only needs a tube, let them deal with it and sell it as B stock.

 

[G Stone496]

I got one a coupla years ago and never had no problems before yet.

 

[Dwightcarr11]

I purchased a Stage Right 5W tube amp right before Christmas. I haven't played it much since then but now that I started playing it longer periods of time it has a noticeable loud hum/squeal that occurs after it has been played an hour or so. Not sure if this is an electronic component (I had a Blackstar make weird noises that had a diode issue) or a bad tube. I have only played the amp a few hours so unsure if it could be a tube unless the ones that come with it are junk.

I hear Monoprice is excellent in regards to RMA's but wanted to get opinions if I should buty replacement tubes or just exchange it. Here is a video of what is happening:

Had a fender bassbreaker do the same thing. New tubes and it was a new amp. At the time it was only 3 or 4 months old.