To enhance the efficiency of the amplifier, you need to take care of it. If you observe that your amp’s volume has decreased, it’s general performance has reduced or it is not working smoothly, you need to check these factors.
Changing the Amplifier tubes
There are two main reasons why amp tubes would need to be replaced. The first reason is that these tubes break down. Amp vacuum tubes do not have an extensive lifespan so that these tubes can burn out at any time. If these tubes burn out, it is essential to get them to repair immediately. If it’s not done, it can deteriorate the functioning of an amp transformer.
The other fundamental reason is the amp’s tone. The tubes in the amplifier are similar to the strings on your guitar. If you use them aggressively, these tubes will break down faster. This means if you want to play loud or consistently push your amplifier, you will observe a noticeable effect in the sound until the tubes finally fall out.
The deterioration and change in the tone are prolonged, and hardly you will notice any problem. It is useful if you change your tubes at once, so the wear on them remains equal. This will give you a more even tone, and you will have backups during a practice session.
Dealing with Preamp tube noise and hissing
If you have ever switched on your tube Amplifier and noticed a hissing, even no guitar plugged in, you might have a problem of microphonic preamp tube. It is a widespread problem, but luckily we have an easy way to fix it up.
First, be sure that amp is unplugged. Now remove the back panel. Once that’s done, you can turn the amp on and wait until the tubes warm up. Then take a pencil and lightly tap each preamp tube. Notice any sound or loud cracking. Each will ring a bit, but any defective tube will be much noticeable. If it is not helpful, you can swap out one tube at a time with a new one until you can detect the worn-out tube.
Unlike power amp tubes, preamp tubes do not need any biasing so that you can do it yourself. Be aware that you take all the precautionary measures.
Insertion of different circuit formats
Over time different circuits have been developed to improve the efficiency of an amplifier. These circuits formats are called as Class A, B, C, D, E and F configurations with different biasing arrangements.
Class A Amp
In class A amp, the output current flows continuously, and the power transistors are conducting for the full 360 degrees of the input signal. Active devices are powered on all the time. The DC input power supplied to the machines must be constant. An ideal class A amp has 50% efficiency when delivering peak envelope power(PEP).
Class B Amp
In class B amp, the power transistors are conducting at 180 degrees of the input signal, so that the active devices are switched on for one-half of the time. As a result, this amp format uses applied power more effectively than Class A amp, with 78.5% efficiency at PEP. But it is less linear than Class A amp.
Class AB Amp
A class AB uses the two approaches, with an angle that is between 180 and 360 degrees. So, that the active devices are on for the three-quarters of the time. It produces proficiency, that is between 50% and 78.5% at PEP. The savings in power causes a reduction in the linearity.
Class C Amp
In class C amp, power transistors are biased at less than 180% conduction angle. This approach produces 85% efficiency that is higher than Class A, B or AB amp. This amp is useful for the signals that turn on and off, such as pulsed waveforms. It can provide challenging operating conditions for transistors that are switched on and off at high frequencies.
Class D, E and F Amp
Class D and E use multiple or single transistors that produce output signals with high efficiency but poor linearity. Class F aims for high efficiency and output power. This class has complex input and output requirements.
Spotting a deterioration
The best way to know when your tubes need to be changed is by listening. If you begin to observe any noticeable changes such as loss of high end, little or no treble, crackles, pops, blows a fuse or a muddy bottom end with no clarity, hearing changes in the volume or excessive noise. If your amplifier tube does not work, you should replace your tube and consult your technician.
It would help if you examine all these factors for the efficient working of an amplifier. If you observe any noticeable breakdown in the amp, you need to consult your technician. It would help if you wisely choose amp according to your needs to get the best results. If you keep notice of these things, you can detect deterioration.