Coda
Well-known member
Add Black Books…
Help! My amp is buzzing!!!
- Thread starter giovanni
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Add Black Books…
SillyOctpuss
Well-known member
Coda
Well-known member
SillyOctpuss
Well-known member
I haven't watched black books in ages. I must revisit it.
Harry Klippton
Not Interested
C'mon no Keeping Up Appearances???
SillyOctpuss
Well-known member
I was just listing my personal favs. A list of every decent british comedy would be huge.
giovanni
Well-known member
Took a very short clip with my phone. I think you can hear the rattling on the E and A strings:
on.soundcloud.com
Rattling amp noise
Listen to Rattling amp noise by Giovanni X Botta #np on #SoundCloud
on.soundcloud.com
PunchySunshine
Well-known member
sounds like a loose screw to me, but I'm no amp tech!Took a very short clip with my phone. I think you can hear the rattling on the E and A strings:
Rattling amp noise
Listen to Rattling amp noise by Giovanni X Botta #np on #SoundCloud
giovanni
Well-known member
I spent a bit of time trying to debug this today. I tightened a few screws that were a bit loose, moved the box spring out of the enclosure and tried to audit the noise to better identify the source.
First off, the tubes are not rattling against the metal socket since they all have a plastic base, so I think that issue can be ruled out.
It’s hard to tell exactly where the rattling is coming from. I tried holding my hand against various parts of the amp to see if it would stop or change at all but I couldn’t find the right spot. It kinda feels like it’s coming from the top of the chassis but I think this kind of perception can be misleading.
I could try replacing tubes but from what I’ve learned this doesn’t seem like a symptom of a faulty tube, but please correct me here folks! I would venture into tube replacement if you guys think it’s a good idea.
PunchySunshine
Well-known member
I really don't think it's the tubes, but to finally rule it out (like Feline suggested) use a wooden chopstick or some other NON conductive stick to VERY lightly tap on the tubes while it running to make sure they aren't microphonic.
If you want to find out if it's mechanical or electric, you can always make a dummy load for for the speaker out. Then you run a sine wave generator in and a silly scope on the output to really nail down where in the circuit the noise is coming from. It's like an audio probe on steroids.
It sounds VERY mechanical to me. I know you said you weren't comfortable messing with the insides, and I respect that. 500 volts ain't nuttin fux wit. Could just be a loose screw on the inside though....just sayin.
I'm rooting for ya amigo!
RetiredUnit1
Well-known member
Have you tried a different guitar? Sounds like maybe a change in the humidity has altered the shape of your neck and you have fret buzz.
giovanni
Well-known member
I have tried two of them and I have tried them with my other amp so I can confidently conclude it’s coming from the amp.
Edit: it also occurs with open strings so no frets involved!
giovanni
Well-known member
Thanks for the suggestion! I tapped on all the tubes with the volume up but I hear no sound coming from the speaker when I tap.I really don't think it's the tubes, but to finally rule it out (like Feline suggested) use a wooden chopstick or some other NON conductive stick to VERY lightly tap on the tubes while it running to make sure they aren't microphonic.
If you want to find out if it's mechanical or electric, you can always make a dummy load for for the speaker out. Then you run a sine wave generator in and a silly scope on the output to really nail down where in the circuit the noise is coming from. It's like an audio probe on steroids.
It sounds VERY mechanical to me. I know you said you weren't comfortable messing with the insides, and I respect that. 500 volts ain't nuttin fux wit. Could just be a loose screw on the inside though....just sayin.
I'm rooting for ya amigo!
RetiredUnit1
Well-known member
Do you have a stethoscope? You can use a long screwdriver, or anything you can press against your ear. One side against the ear, the other side move it around until you can localize where the sound is originating. Got this tip from my Dad who used to use it on car engines.
It's how I found the vibrating staple and capacitors....
(edited: I DO have a stethoscope)
It's how I found the vibrating staple and capacitors....
(edited: I DO have a stethoscope)
giovanni
Well-known member
Alright I finally solved this, but I wasn’t the one to find the solution. I took the amp to a very highly rated local tech who opened it up and found nothing wrong with the amp, except this little plastic thing was stuck in the speaker (I couldn’t pick up the amp myself because I’m sick today so I am not sure exactly where). He cleaned the guts and removed and problem solved.
KR Sound
Well-known member
Oh man. Seriously?!
Harry Klippton
Not Interested
Too bad you didn't just look inside 
giovanni
Well-known member
I did! So many times! With a flashlight and all! I have no idea where that thing was and I really wish I could’ve picked up the amp myself so he could’ve showed me! He didn’t even find it at first! I really appreciate his honesty tho, could’ve replaced tubes and charged me or something. Great guy.Too bad you didn't just look inside
Wow - he really is a good tech if he didn't charge you.
It's crazy what happens with amps. There are so many things which can cause problems. 99% of the problems with tube amps though are tubes. I built an amp for a guy early this year and he lives two hours south of me. He drove up today to drop off the amp because the volume took a dive. I spent about 15 minutes swapping tubes and sure enough (and slightly unusually) it was the PI tube which was on the way out. Stuck a new one in and it's back to sounding great.
So while I had it I did a couple of minor tweaks for him because his needs have changed a bit. Now it's going to sit in my hallway for the week until he comes back next weekend to get it.
It's crazy what happens with amps. There are so many things which can cause problems. 99% of the problems with tube amps though are tubes. I built an amp for a guy early this year and he lives two hours south of me. He drove up today to drop off the amp because the volume took a dive. I spent about 15 minutes swapping tubes and sure enough (and slightly unusually) it was the PI tube which was on the way out. Stuck a new one in and it's back to sounding great.
So while I had it I did a couple of minor tweaks for him because his needs have changed a bit. Now it's going to sit in my hallway for the week until he comes back next weekend to get it.