Is this a very loud blues junior III? Should I swap the tubes?

[Peng1026]

Hi folks,

i always find my blues junior III has too much noise, and whatever i tried, (different power outlet, different power strips, with EMI-RFI Filters, shut down the led lamps ) , i couldn't get rid of it.

Today I recorded the noise into my daw, added about 25dB gain to the audio, and let a multimeter show the frequencies, and I got this diagram. I took a video as well with my phone, when i measured the volume of the noise with a app directly in front of the grid, it showed about 34dB. I didn't plug the guitar into it as i did the recording.


https://youtube.com/shorts/2-zlG6uGdtM?feature=share



The noise doesn't quite bother me by practicing, but by recording. I couldn't record the playing with a high volume at home. I read in this forum, that many record them at home too and with a low volume, but when I do this, I get a very low SNR. How did you do it?


I own and play only mostly with this amp for like over 12 years, and never swapped the tubes, because I felt nothing wrong with the tubes (but maybe I am quite wrong about this).

Do you think if it worth a try to swap the tubes? Or do you have some other hints for me? Many thanks!

[enalnitram]

Twelve year old tubes could be a likely culprit for noise, and sure, should be replaced, like, years ago.

Beyond that, there could be other things and/or contributing to your noise. Filter caps. E-caps. Etc. Take it to a trustworthy tech.

[rpjazzguitar]

A couple of easy and zero-expense things to try.

1. Reseat the tubes in their sockets. Make sure they're solidly held.

2. Visual inspection. There's info on line about what to look for.

3. If there are two of the same tube in different sockets, swap them and see if the noise changes.

4. See if turning off the reverb makes a difference. If it does, make sure the leads to the tank are solidly making contact. If it's an RCA style jack, the wings might need to be very slightly bent out.

5. Wiggle wires (gently and carefully) and press on things like the faceplate and see if the noise changes. Don't forget wiggling the input jack and turning pots. If the amp has the pots, jacks and tubes soldered into a PC board, those solder joints are subject to mechanical stress and can crack.

[Jimmy Mack]

GOOD ADVICE ABOVE.
My buddy had similar trouble with a PRO junior. (No reverb). I went over there with a handful of pre-amp tubes, 12ax7's.
Changed one tube and BAM! Noise gone.

[vintagelove]

I would advise going to YouTube, look through this guys videos and see if there are any about your amp. Long story short, there are several common, minor faults on many of the modern fender amp. He definitely knows things the average tech does not. I wouldn't rush to replace tubes just yet.

Psionic Audio - YouTube

[Sam Sherry]

i always find my blues junior III has too much noise, and whatever i tried, (different power outlet, different power strips, with EMI-RFI Filters, shut down the led lamps ) , i couldn't get rid of it.

It looks like you have been thorough but sometimes the room just get dirty power.
Try a different room, or bring it to a friend's house.

FWIW the noisiest power in my house is in . . . my music room.

[enalnitram]

I wouldn't rush to replace tubes just yet.

This depends. If the tubes have never been replaced and are still the stock (Chinese) tubes the amp was shipped with...then replacing them, could transform the amp into something he likes into something he loves. Twelve years of heavy use... preamp tubes typically last longer than power tubes. Guesswork is guesswork. Taking it to a tech that can test tubes and assess the amp, is IMO the best idea.

[nevershouldhavesoldit]

This depends. If the tubes have never been replaced and are still the stock (Chinese) tubes the amp was shipped with...then replacing them, could transform the amp into something he likes into something he loves. Twelve years of heavy use... preamp tubes typically last longer than power tubes. Guesswork is guesswork. Taking it to a tech that can test tubes and assess the amp, is IMO the best idea.

Noise originates in many components - plate resistors, grid resistors, solder joints, press fit connections (e.g. tube pins in their sockets and RCA plugs in their jacks), tubes etc. Older tubes need not be bad - I replaced the original tubes in my '78 Boogie at about 20 years for no reason other than that I wanted to minimize the risk of failure on a gig. There was no problem with the old tubes and no change with the new tubes, so I never made that mistake again. The tubes in my '76 Princeton and '71 Twin are years old, and they'll remain in place unless they fail.

Chasing noise can be a long and arduous task. If you're not fairly sure where it originates, a tech is a sound investment.

[JazzNote]

Also make sure you got the exactly right tube types in their places. Here's a good address to understand things about tube amps in general: Amp Stuff

[vintagelove]

This depends. If the tubes have never been replaced and are still the stock (Chinese) tubes the amp was shipped with...then replacing them, could transform the amp into something he likes into something he loves. Twelve years of heavy use... preamp tubes typically last longer than power tubes. Guesswork is guesswork. Taking it to a tech that can test tubes and assess the amp, is IMO the best idea.

I stand by my suggestion. Tubes have many failure modes, true... but with power tubes, generally you don't just go "oh, that's kinda noisy". And if you did, you would notice it from one day to the next. All of a sudden there would be something different, the "pfft pfft pfft" or the "whoosh".

Furthermore, with some very basic troubleshooting, he could narrow down if it's actually an issue with the tubes, etc.

The gentleman I linked isn't your average guitar store tech. He's seen hundreds of each of these common amps and knows the stuff that always goes wrong, and more importantly when it's a manufacturing flaw that's easy to fix. Dumping $75 on new tubes on a crapshoot is a bad idea, when the problem might be a 10 cent PSU resistor that fender never gave enough clearance to which is slowly burning up the traces and will lead to an actual expensive repair down the road.

PS, cough cough IC caps cough cough...