How do I know if my guitar amp tubes are bad?

Crackling, squeals and feedback, excessive noise and muddiness or low output are all evidence of tube problems. Power tubes. The two main symptoms of a power tube problem are a blown fuse or a tube that begins to glow cherry red. Either are typically indicative of a power tube failure.

How long do guitar amp tubes last?

Power tubes can last years in a light-playing situation while lasting only 6 months in heavy playing conditions. It is also dependent on how loud you play and for how long. Also if you don't correctly match up the impedances, this will put strain on the power tubes and wear them down much faster.

How often should you change tubes in a guitar amp?

You can expect a conventional amplifier tube to have a service life ranging up to 10,000 hours. Tubes with military specifications are built to last up to 100,000 hours.

How do you know when amp tubes need replacing?

What color should power tubes glow?

This type of glow is usually violet in color and most noticeable around the inside surface of the glass bulb. It is most pronounced on power tubes and is the product of electron bombardment of the glass taking place within the tube.

Troubleshooting Your Tube Amplifier

Can bad preamp tubes cause volume loss?

Use the wooden part to tap each of the preamp tubes and main power tubes. A good tube will be a dead 'thud' sound, so if you hear one that has a high ringing rattling sound, that's the bad tube. Bad tubes will make volume drop and tone sounds will be dulled. When a tube goes bad, this is exactly what happens.

What does a bad preamp tube sound like?

A bad preamp tube will become very noisy and produce hiss, crackle, and pop sounds, or create volume drops or loss. In some rare conditions, the tube can also lose its vacuum and fail completely. Bad preamp tube symptoms can lead you to the faulty one if you know what to look for.

Can you test tubes with a multimeter?

Open or shorted filaments can be detected using a multimeter, and should be done before plugging the tubes in. Set the multimeter to measure resistance and connect the meter's test leads to the filament pins. (You can consult on-line tube manuals for the pin configuration.

How do you test old tubes?

Put the tube into your guitar amplifier, tester, or other tube-using machine. Turn on the machine to activate the tubes, and look for an orange, red, or purple glow. If the heated filament inside the tube glows orange like a setting sun, it's usually a sign that the tube is healthy. The filament may be hard to see.

Why is my tube amp crackling?

Random Crackling and Pops

This typically signifies your amplifier has faulty power tubes. First, try swapping them one by one with a spare tube. If this does not fix it, then the preamp plate and/or cathode resistor need to be checked out (this is probably something to get a professional tech to do).

How long do 12AX7 tubes last?

Small signal tubes like a 12AX7 or 6922 will work well on average for about 10,000 hours. If you leave your equipment on 24 hours a day, well you do the math: There are 8,760 hours in a year.

How long do tube amps need to warm up?

As a rule of thumb, your tube amp needs to be warmed up for 20 to 30 minutes at least before you can start playing your guitar. Most of the time, tube amps have warm up specifications included in their instructions for use.

Are tube amps hard to maintain?

> Yes, tubes are generally more fragile than solid-state amps. They require more attention, so you can't be clumsy around tubes. > Tubes have a life span of about 3,000 to 5,000 hours before needing replacement, depending on usage.

How long do tubes in a tube amp last?

Depending on how often you turn on and turn off your gear, but tubes should last about 5,000 to 10,000 hours. For most people, they only need to be replaced every 2-3 years at most. But it's good to have at least a spare set around just in case one of them decides to die on you.

How often should you change preamp tubes?

Preamp Tubes are generally at their best 2 - 3 years. Power Tubes are generally at their best 1 - 1.5 years. Rectifier Tubes are generally at their best 3 - 5+ years.

How do you match tubes without tube tester?

Oh, you could use a preamp or power amplifier to match tubes, taking measurement of plate current, bias current but you really have to know what you are doing as you are working with 100 to 500 volts and enough current to kill, but this is a very accurate way to check tubes as they are "in" the circuit intended for ...

How do tube testers work?

The mutual conductance tester tests the tube dynamically by applying bias and an AC voltage to the control grid, and measuring the current obtained on the plate, while maintaining the correct DC voltages on the plate and screen grid. This setup measures the transconductance of the tube, indicated in micromhos.

How do you bias a tube amp with a multimeter?

Set your multimeter to DCV > 200m. Insert the black and red ends into the proper test points and note the reading on your multimeter. Locate the bias trim/knob labeled V1, V2, etc, (usually located on the top near the front of the amplifier) and with your screwdriver make very slight turns and watch the readout change.

Should a tube amp hum?

Tubes will make a myriad of strange and seemingly inexplicable sounds. The one thing they won't do is hum. It can, however, seem that way if one or more power tubes go out. When this happens, the natural hum from your power transformer is no longer being phase canceled by the tube that just died.

What happens when a rectifier tube goes bad?

Power and rectifier tubes can cause a fuse to blow when they go bad--often after volume fluctuations. They can glow a bright red and or spark if they are failing. If this happens, contact a competent tube amplifier technician or call us. Preamp tubes usually last for years.

Why are my tubes glowing blue?

Sometimes you may notice a blue hazy glow inside your amp tube. This glow is rarely a sign of a defect and is fairly common especially in modern power tubes. This type of glow is called Fluorescence. This phenomenon is due to electron bombardment of the glass taking place within the tube.

Should tubes in an amp glow?

A: That blue glow is just a side effect of a power tube — a fluorescent glow in the blue spectrum. The tube is fine! It actually indicates that the vacuum inside the tube is very good, which is what allows this phenomenon to occur. It will not have any effect on the performance or tone of the amp.

Should tubes glow orange?

Unfortunately the orange glow is just the heater element. It's often impossible to tell if a valve is working by simply looking at it. There are some exceptions however and I will explain below.

Is it OK to leave a tube amp in the cold?

It turns out that tube amps can be stored at reasonably cold temperatures without any issues. While temperatures of -40 degree Fahrenheit and beyond can be damaging to some electrical components, the biggest problem that results from storing tube amps in the cold is temperature fluctuation.