What do tubes in an amp do

Look below for visual signs that a tube has failed. This one may be straightforward. The problem is usually a connection breaking somewhere in the tube. Read below for identifying the bad tube or try one of your old stock tubes in each position until you find the culprit. Your amp could be working fine but then have a sudden drop in volume, or even turn off completely.

This may be the first sign of a tube slowly giving up. However, it could also be the sign of something else. Try testing with an old stock tube and see if that solves the problem. The first thing you should do is check the fuse. These exist for safety reasons and to protect your amp. If too much current flows through the device the wire in the fuse melts and breaks the circuit.

If they have both blown then it could indicate a problem with your amp. It may be an idea to get an amp tech to look at your amp. If you find that is is just one tube, then replacing the fuse and blown tube could sort your problem easily.

So you think a tube may be bad, but how do you know for sure? And which tube is it? After reading how a tube works above, it becomes obvious why. But if you replace with another tube, and it starts to glow, you can be pretty certain it was the tube.

This one is an easy diagnosis. Red plating is when the plate in addition to the filament glows red and looks kind of sinister. This means too much power is flowing through the tube and is a bad sign. Very soon the tube will die. Red plating is the result of a bad bias adjustment or a bad tube. If you notice this after a bias adjustment, or on more than one tube, then take it back to the amp tech.

Certain tube brands just deal better than others with a bad bias adjustment, so may not red plate. Microphonic tubes are annoying because they add noise into your tone from small vibrations which are created in your amplifier. Sometimes the sound from the amp vibrates them enough to hear the microphonics. All you need to do is take a pen and gently tap the tube while in use.

Sometimes tubes can arrive microphonic usually damaged through transportation. Or they can develop the fault over time. It could be something else. So, a part or component will need to be replaced. Although, most of the time it will be a biasing issue and the fuse should stop damage in most cases.

Tube amps are pretty complex and it could be any number of things for an experienced amp tech to diagnose. Any potential contaminants on the surface of the internal tube are removed during the burn in phase. JJ tubes do come pre burnt in, as do many other brands, but they should improve within the first several hours of using the tube.

Tube rolling - Tube rolling is where you try out different tubes in the same slot. This means you could end up with a range of brands in your amp. With experience, you'll get to know the brands. NOTE - when rolling power tubes, it's best to replace a whole set at a time, and not just replace an individual one. This is well done and easy to follow.

I took an electronics class in college so we studied and experimited with some of these devices. Your article put it in perspective for music. Thank you. Well done! Thanks for the info :. Thank you for giving me an intro into tubes. I had bought a box of tubes at an estate sale and, in the wee hours of the morning, found an electric guitar that had been given a mini Pete Townsend.

I fixed the guitar and want to make an amp out of the tubes I bought. Just added to your cart. Continue shopping. Close search. Free Delivery on all UK Orders. Contents 1. What is a vacuum tube? What do they do 4. How they work 5. The types of tube 6. Brands 6. Tube amps vs solid state 8. Other terminology Extra resources. The output transformer transfers the signal load without any major alterations to the tone and color of the sound output.

This allows them to work like a single, more powerful tube. There are advantages and disadvantages to each of these common modes of operation. There are other classes of amplifiers as well such as Class G and Class H, but they are not used for audio applications. Talking of Fender, the company still makes the best tube amps that are favored by professional musicians and music directors the world over.

Featuring high-end, all-tube performance, it is a highly portable unit with two speaker outputs and an 8-ohm primary tap. Audio Tinker has a simplified schematic showing how everything comes together in a tube amplifier. If you are not familiar with the symbols, the labeling will help you figure things out.

You can check out the full instructions on the AudioTinker website to learn more about the circuit, assembly, and specifics of the components used.

Now that you have a basic idea of how tube amps work, it is important to compare their performance with that of solid-state amplifiers. Solid-state amplifiers amplify signals using transistors and diodes.

Tube amps are warm and produce a pleasant, full-bodied result. In more technical terms, tube amps produce audile with a good bass and midrange response. When you overload a tube amp, the effect is even more pronounced. They cause a distortion of sorts that makes the sound even better, especially when playing loud guitar music in genres like rock and roll.

If you play heavy metal and rock, take a look at these top 8 amps for metal you can buy today. In comparison, solid-state amps are more faithful to the original signal and produce a cleaner sound. An amplifier without natural harmonic distortion sounds unnatural, however, so some modern amps called modeling amps tend to mimic the sound of tube amps. On paper, it would seem that solid-state amps beat tube amps squarely.

However, the warm and mellow sound produced by tubes makes them worth all the extra expense and effort required to use them. Tubes require regular checking and swapping depending on the frequency of playing. That could be anything from 6-month intervals to a couple of years. Vacuum tubes wear out naturally with time. They can simply burn out, or gas can form inside the tube and make them less effective.

This causes them to become less effective. Here are some signs of bad tubes. When you have a faulty valve, it is advisable to replace all of them at once. This ensures correct biasing and restores full performance. You should always have replacement valves with you in case of failure because sometimes playing with a bad one can damage the other internal components. This should be a problem, however.

They are designed to resist feedback and make a lively upgrade to your old tube amp, and are some of the most popular 12AX7 preamp tubes out there. Once you have determined that you have a bad vacuum tube, the next step is to remove and replace your tubes following the recommended safety guidelines.

Yes, most manufacturers account for this in their design. The vacuum tubes in a tube amp generally last 5, to 10, hours of play time. However, this depends on the intensity of use. Yes, tube amps certainly sound better than solid-state amps and any other alternative technology.

Even without being a purist, you will hear the difference in the warmth and character of the sound they make compared to the cold, clean sound of solid-state amps. Vacuum tubes wear out with use, so it is better to always turn off your amp when you are done using it. They also tend to overheat and use up a lot of power, so it is safer and cheaper to have them off until they are needed. If you just need an amp for practice or move around a lot, a tube amp is not worth the money or effort required.

You might want to check out our top five bass practice amps for this instead. Yes, tube amps need about minutes to warm up properly before you can start playing on them.

Your manufacturer will have provided guidelines on this. This will give you maximum character even at relatively lower volumes. It is always advisable to buy high-quality tube amps from recognized manufacturers in the first place, such as Fender or Marshalls. Century-old technology still trumps the most advanced transistor and microchip technology when it comes to amplifying guitar music. The natural harmonic distortion that tube amplifiers produce is what makes them worth all the effort required in maintaining and using them.

Hopefully, now you understand how tube amps work from this simplified explanation. The amps themselves are so simple that you can build one yourself given the right parts, but the technology behind them is simply ingenious. You can also now take better care of your old tube amp, and perhaps even perform a few minor upgrades to get the best sound.

Remember to enjoy the mellow sound of these antiquated units before impostor technology sweeps them all to the graveyard. In class AB operation—which is typical for many amps with two power tubes—each tube handles more than half, but not the full wave. Any amp with a single power tube aka "single-ended" amps will always be class A—that single tube must handle the entire wave.

That means our AC4 is class A, too. That said, amps with four power tubes typically pair two sets of class-AB-operating tubes, working much like a two-tube amp but adding power to each half of the sine wave.

Similarly, amps with more than one power tube can still achieve single-ended, class-A operation by wiring two tubes in parallel. This allows them to essentially act as a single, more-powerful tube the Gibson GA-8 is a good example of this.

Note that the arrangement of elements in a tube diagram is schematic, not actual. In the EL84, for instance, the cathode sits in the center of the tube, with the filament located inside the cathode.

The other elements grid, screen, suppressor, and plate surround the cathode, in that order. The cathode and plate are made from bent metal. The grid, screen, and suppressor, however, are wrapped wires. That's how the electrons can travel almost unimpeded from the cathode to the plate—there's space between the wire wraps.

Dotted lines in the tube diagram for the grid, screen, and suppressor reflect the fact that these elements are wire wraps, not solid metal. Now that you know the fundamentals of a tube amplifier, take some time to study the amp schematic. The AC4 schematic shown here has been redrawn, color-coded, and notated to help clarify the concepts. It'll probably take several times of going over it to get things down, and you should always be very familiar with the schematic of any amp you're working on.

Again, keep in mind that the voltages stored in amplifier capacitors are lethal. If you're not familiar with how to safely drain them of their charges, make sure you get a qualified amp technician to perform any mods or repairs. If you'd like to start your journey toward being more proficient with amps, there are lots of great books and online sources that will help. If not, then simply warm up those tubes, crank the volume, play a power chord, and listen to those electrons flow!

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The Vacuum Tube First, let's talk about some basic principles of electricity. Cathode vs. Fixed Bias A Vox AC4, like many amps, is designed to make the power tube's cathode slightly positive—a state that is commonly referred to in the guitar universe as cathode biased.

The Voltages The first and largest component in an amp circuit, aside from the speaker, is the power transformer. The Guitar Signal We all know your guitar's signal comes from your pickups, but to understand the amplified signal, let's start at electrical ground. Components in More Detail Now that we've got our quick overview of how an amp works out of the way, let's get into some more detailed descriptions, component by component. Power transformer The power transformer is the amp's larger transformer.

Capacitors aka caps Capacitors are shown in the schematic as two parallel lines perpendicular to the wiring. Resistors These are the small, cylindrical components with color-coded stripes indicating their value. Preamp Tubes The first tube that your guitar pickups' signal will get to is the first preamp tube. Power Tubes Just as the guitar signal is amplified by the preamp tube, the signal from the preamp tube is amplified by the power tube. Output Transformer It may seem strange, but an amp's output transformer doesn't just provide power in any old way— it's critical to shaping the amp's sound.

Class-A Operation The designation of "class A" is often a topic of hot debate for some tube-amp enthusiasts. Tube Diagrams Note that the arrangement of elements in a tube diagram is schematic, not actual. Let the Electrons Flow Now that you know the fundamentals of a tube amplifier, take some time to study the amp schematic. Spaceman Delta II Review. Rig Rundown: Torres. Enter Email Address Subscribe. Rig Rundown: Thrice []. Rig Rundown: White Reaper. Rig Rundown: Eric Clapton.

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