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Troubleshooting tube amplifier hum

Sizzling noise from tube amp, tilting kills spring reverb. Joined: Apr I play it upside down since I want the tubes to release heat upwards PCB is on the top in normal position and tubes are attached to it. The tubes have clips that hold them in place.

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WATCH RELATED VIDEO: Tube Amplifier Troubleshooting Tips

Electronic – Troubleshooting Hum in a Tube Guitar Amp


By jackallahan , March 3, in Amps. However, when I was about 20 minutes into my practice the volume dropped and became flappy, and a noticeably loud hum came over the speaker, which persisted despite any manual volume adjustments. It would only go away if I turned the amp off entirely. I checked my guitar lead and it seemed fine.

I decided to leave the amp off for a while. I came back to try it again, but with a different guitar. It seemed absolutely fine, and then it happened to me again after a comparable passing of time as earlier. I noticed that if I turned off the amp it will stop, and Immediately turning it back on seems to correct the problem until I start playing loudly. I was doing some research on the net and found tubes can be at fault for sudden reduction in output.

It's interesting that the problem doesn't occur until the tubes are warmed up. Any thoughts on this issue? Thanks in advance. First and most important, Have you been running it with matching impedance. IE if you're using an additional cab does it properly add up in parallel when running the internal speaker. Chances are the internal speaker is 8 ohms, and if you use an external speaker of 8 ohms, you'd have to set the selector for 4 ohms.

I'd look and see if the tubes are turning cherry red. If they are the tubes are bad and possibly the grid resistors that set the bias.

I suggest this because this kind of problem comes and goes in the beginning before the amp blows possibly taking out the transformers when it does. Similar issues can occur when you replace tubes with an unmatched pair, a set that cant handle this dual wattage design or replacing the tubes without setting the bias properly.

Add to that tubes in combos take a beating. I usually suggest changing them at least once a year or more if you play regularly. This particular amp doesn't use a dual set of tubes and cut wattage by turning a set off, so it must be done by either dropping the voltage or using a resistive load. A resistive load is brutal on tubes because it acts like a brick wall.

Voltage drops make tubes run at lower voltage ranges and tubes behavior may change radically. Preamp tubes can be swapped out easily and require no biasing. They usually get noisy when they start going bad. They don't usually make a loud AC hum. That hum is coming from your power amp and its a clear indication something is majorly wrong. I'd check the manual as see if the tubes are self biasing some amp designs have this feature If so, buy a solid matched set and don't run the amp till they are replaced.

I'd also give the amp a nose test. See if you smell anything that smells like a cooked resistor. If so I'd open it up and inspect the resistors and caps. I'd also look for any cracked solder joints.

Combos vibrate badly and it wil literally shake the solder joints apart if they were weak from the factory. I always do this and reflow any solder joints that even have an appearance of looking weak. Wiggling components can often reveal a cracked solder joint too. You have to view the back of the PC board and see the legs move when you wiggle them.

This is especially true on amps that have tube sockets mounted to PC boards. The heat from the tubes and the vibration can turn solder into dust.

Just another issue with mass manufactured wave soldered boards. Just be careful doing this. Also let the amp sit for a day so the voltage drains off. You can even wear rubber gloves just in case some of those caps retain some of their high voltage. Use on hand too. Electricity needs a path to ground to discharge so don't grab a water pipe with your left hand while checking things with your right. If you don't feel comfortable getting in there, take it to a good tech who knows his stuff.

For him this may be a quick 15 minute repair that costs. If you let it go till it completely blows out it may be too expensive to repair, and cheaper to just buy another one. This is the price you pay for tube tone however. Tube amps are high maintenance and if you haven't got the money to maintain them properly with regular tube changes and setups, you may want to think about switching to solid state. My first thought is that one of the power tubes is acting up and causing an imbalance in the push pull circuit.

Something you can try with that type of amplifier is plugging your guitar perhaps through a pedal into the effects return jack. This will eliminate the preamp from the signal path and, if the hum persists then the problem is in the power amp section and not the preamp section.

One way to drain the capacitors is to use a small jumper cable to connect pin1 of V1 to ground. This is my preferred method because it discharges the filters through resistors so it is a more gradual way to bleed of the dangerous high voltages that may still be present after the amp is powered off.

I don't have any other cabs connected, so it shouldn't be an impedance issue. I plugged my guitar into the effects loop and the hum was still persisting, so it must be part of the power tube section. I went ahead and bought a pair of 6v6's and installed them, only to find that it didn't work.

The hum is still there. I even did a test with new preamp tubes, and still nothing. I took a look in the chassis and inspected all of the solder joints. At this point I'm ready to just take it to a technician.

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Guitar amp noises and faults: solutions

Always remember, guitar amplifiers hold large amounts of voltage and can kill you. Keep the following in mind when troubleshooting amp noise:. If you are new to guitar amplifiers, especially tube amps, you may be thrown off by the natural humming that these analog amps create. Rest assured, a low, steady hum from your tube amp is quite normal. Typically speaking, the noise floor will momentarily disappear once you start playing your instrument. Another thing worth mentioning is that higher wattage aka higher power amplifiers will create a louder noise floor than small, low-wattage amps. Noise Gate or Noise Suppressor pedals are a quick and easy fix if you play a lot of high-gain music.

Here is a list of possible causes: 1. A "cold" solder joint. Very easy problem to create with lead free solder. Check all of your joints for any.

How To Tell If Your Tube Is Bad


These vibrations can pre-exist in the instrument, particularly if it's made out of wood, or they may only appear when the instrument is amplified. Regardless of what is causing your instrument to hum, a few simple tips can help eliminate guitar humming. The first step to eliminating the noise is to determine the source. To do this, you will need to play the instrument while the amp is on. Most of the time , the noise will not come from the instrument but from the speaker or the amp itself. If this is the case, the vibration will only be heard when playing the instrument, and not when the amp is unplugged. If the sound is coming from the speaker, the buzzing will be heard whether or not the instrument is plugged in. This particular frequency hum comes from normal household electricity and is a byproduct of the power grid. It is not the result of harmonics produced by your amplifier.

Troubleshooting Hum in a Tube Guitar Amp

troubleshooting tube amplifier hum

This article gives several common symptoms and some ways to find out what the problem is. You will need a basic meter for most of these tests. Watch Tangent Tutorial 5 to see how to do this properly. If your amp is powered from a wall supply, is the voltage what you expect? See the chips' datasheets to find out which pins these are.

Hum in tube amp.

Motorboating (electronics)


You might have been practicing some heavy riffs on your tube amp. But what happens when your tube amp loses volume a day before your next gig? And after that, you can use that money saved on easy repairs and use it for scoring some new FX pedals instead. That first day you plugged it in and it was roaring at full-blast just at 3 or 4 on the main volume. Let me tell you how it works. As soon as you start to hear the sound is dropping-out, you need to turn off and unplug your amp.

Corded Headsets: Basic Troubleshooting

Last Updated: October 19, References. This article was co-authored by wikiHow staff writer, Hunter Rising. He has more than three years of experience writing for and working with wikiHow. There are 10 references cited in this article, which can be found at the bottom of the page. This article has been viewed 13, times. Learn more It can be really annoying when you plug into an amplifier and it starts humming.

I have a Gibson GARVT tube amp here, circa mid 's, with a hum problem that seems like a no-brainer, but I'm completely stuck on it.

Crackling Tube Amp? (5 Common Causes & Fixes)

First, start with the basics. Check if the amp or PA you are plugged into is turned on. If using a mixer, make sure it's not muted and that all cords are plugged in all the way.

However, he might be dealing with other issues than you. Noise is mainly caused by two things — outside interference and noisy components usually a combination of both. Noise caused by the components them selves is often as a result of cheap or faulty parts, bad assembly etc. Quick guide: — Make sure your guitar and amp is connected to ground that has a clear path out of your house in into ground. In case of a power failure or short circuit, the ground connection will lead the electricity out of your rig, through the wall and outside into the ground, rather than the electricity going through your body, which is a substantial conductor.

Single-coil pickups in guitars are essentially receptors for electrical interference of all kinds.

We are a brand born of a love for the beauty of restraint in design, the inherent grace of feminine strength, and the necessity to treat our environment and each other with love and respect. Each of our carefully researched, styled, tested and distributed collections reflects a particular aesthetic and ethos. We hope some of these speak to your own style, and help you refine and redefine your own look and style philosophy in the process. Beyond pouring sweet, sweet honey into your ears, even modern tube amps can make some unwanted noises, hums and buzzes. First thing to remember though is that this is often a problem of system matching and not the amp by itself. The good news though is that once you've solved the issue the resultant sound is in no way compromised, so you can keep your system. So why a system issue?

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