People into electronic music usually own an amplifier capable of shaking their room inside out. Amplifier heads are really for a guitarists because that is what helps them achieve different musical effects that we all love to hear in a rock concert. They are only to be used in conjunction with speaker cabinets, tube amp heads have to be plugged in to run. Most guitar amp heads have up to 3 distortion channels. To choose good quality amplifiers we need to know the distortion channel performance, the gain, the adjustment settings on the front panel, and learn about additional features that come in the box. There can be amp heads dissipating low power while others can throw more than 100W at you. In this article, we are only going to look at the 100 Watt tube amplifier heads which would lie in the price range of £400 to £1000.
Hell, that is a long name. The first thing to notice is the TRIREC. Now this is a feature which lets the guitarist use either the semi-conductor rectifier, the tube rectifier or the combination of both. For those who are very particular about the output from amplifier would definitely know the difference between the semi-conductor rectifier and the tube rectifier. When you start slamming chords they will not be immediately heard in full volume on the speakers, this is because the tube rectifier takes a little while to step up its power output. Although, it gives a distinguishing punch at the very moment you slam it and then slowly begins to build the desired volume. On the other hand, semi-conductor rectifiers do not have the sagging effect because they are more efficient with power delivery and thus, produce softer tones unlike tube rectifiers. You also get to smoothly change the power amplifier tubes without requiring to adjust the bias voltages and impedance matching. This is because of the INFINIUM feature. It automatically adjusts the bias voltages to the correct value without human intervention. This is especially useful when the tubes heat up and the bias voltage drifts with time. It is also very good feature for those who like to use the best performance tubes instead of the ones that come in the box because INFINIUM takes care of adjusting the bias voltage and impedance matching automatically. Maintaining bias voltages also helps the tubes last longer. You can easily run the 6L6s, 6550s and the EL34s on this beast. Obviously, you can also use a combination of the 3 tubes if you would like to. The amplifier produces crisp sound on the clean channel without any unwanted distortion, just the way we want it. You also have the remaining two distortion channels to produce sounds suitable for you. As usual, there are other audio controls such as presence, mid, high, low, reverb, etc. Another noticeable thing on the control panel is the Varipower knob which can vary the power output from 1W to the max power of 100W. The build quality is excellent and all the knobs and switches are firmly attached. Like all other amp heads, this one is also heavy and emits the glow coming from hot tubes. You can produce a variety of tones and tune the amp to suit your preference. The flexibility to adjust a lot stuff is something that I would definitely prefer while buying an amp head and Bugera Trirec gives me that flexibility. An additional point to take note of is that every channel has its own pre-amplifier independent of each other which is another reason for superior audio quality.
Engl are known for the amazing amp heads. One can easily notice the difference between an ordinary amp and an Engl amp. Engl Fireball 100 is in fact an evolution from their 60W amplifier. They are known for producing amp heads to be more inclined for bass and highly focused on the mid range. Unlike the Bugera TRIREC INFINIUM, Engl Fireball 100 has only 2 channels and it is meant for rock/metal kind of music. The focus on mid range is obtained through what they call “mid boost” feature which you can turn on whenever you need. This amp head does not have all those sophisticated features. It is simply an amp head with basic controls and 2 channels, it works great for what it is intended for. The front panel has the basic controls to adjust the gains for mid, high and treble ranges. The bass, mid and treble is common for both the channels. There is the clean channel gain and it’s power can be controlled by the Master A knob. If you raise the clean channel gain to maximum, you start to get overdrive distortion. The Master B knob controls the second channel power output and you can also control the distortion by adjusting the Lead gain. The Engl Fireball 100 uses four 6L6GC matched set tubes to deliver a monster 100W power output and four ECC83 pre amplifier tubes. By default, the Engl Fireball 100 is made to output deep, dark bass frequencies, but when you need to give a little bit of punch to your music there is the mid-boost switch at your disposal. Engl Fireball 100 is a huge amp head. It requires a lot of space and it is definitely not made to be moved very often. On the backside, you also have the foot switch connectors which remember your settings even when you remove them and plug them back in.
Having a tremendous amount of features is not always the key to a great amp. The Marshall JCM800 is just a single channel amp with not many features to offer, yet it is one of the popular amps out there. There are very few amps which perform well at one thing; they do not need necessarily need multiple features to make them liked by a lot of people. One thing to remember with JCM800 is that it is not meant for bedroom rehearsals and it is not meant to be used on low volumes. The low volumes will not produce all the tones correctly and thus it is recommended to be used on higher volume. The front panel has 6 knobs to control the presence, bass, mid, treble, master volume and gain. The back panel has the power connector, the fuses and the effects loop connectors. The simple control panel makes it to be a good choice for many beginners. The amp begins to distort the sound when you crank the volume knob to mid way. However you cannot play at this volume in your bedroom or your garage. The volume is too high on this one and you need a large space to actually feel the power this amp can provide. If you still want to listen to all the glory this amp has to offer, then you will have to resort to stuff like attenuators, distortion pedals and what not. JCM800 uses three ECC83s in the pre amplifier section and four EL34s in the power stage. For the price it comes, it is too expensive to buy this amp unless you intend to use it for professional purpose.
This is another 3 channel amp head in the list. There is also a 50W version of the same EVH 5150 III model. It is known that EVH 5150 III is a result of joining hands by two popular amp manufacturers; Fender and Eddie Van Halen. As usual, the channel 1 of the amp delivers clean sound with no distortion. EVH is not really known for the clean channels and nor have they done anything about it on this model either. Although, you can achieve quite a crunchy overdrive by turning up the gain. The channel two and the channel one share some of controls. The EQ, channel gain and volume are some of the shared controls. The clean channel begins to overdrive just after approximately 40% pre-amp gain. Anything under that is clean but it would not give a very bright mid range. On the other hand, the crunch channel really works great giving woody, crunchy tones. The dynamic range of the crunch channel is amazing. It can deliver classic rock at the lower end of the gain limit and begin moving towards hard rock tones as you turn the gain higher. Hence, the crunch channel is apparently the most versatile channel of all. The third channel will really start to produce the roughest possible tones. The dynamic range is not that great. You will barely notice any difference in the tones if you go above 50%, it all sounds the same. In short, the first two channels are pretty useful while the third channel is not well optimised. This amp head uses a whopping eight 12AX7 tubes in the pre amplifier section and four 6L6s in the power section. The channel which is suitable for you will decide if this amp is the right choice. Most users have also said that this amp is suitable for use in bedroom rehearsals or at a small gig, but definitely does not have the punch to shake a large audience.
This is probably a different kind amplifier in the entire list because of the hybrid design. It uses solid state devices as well as tubes inside the box. Like the Bugera TRIREC amp head, Line 6 is loaded with plenty of features. Unlike many other amp heads which are basically analog in nature, Line 6 takes a step forward and includes modern semiconductor technology into a traditional looking box. Features such as Quick loop, smart harmony, and programmable presets are possible because of the advanced digital circuitry built into it. Inspite of all this advancement, Line 6 has it’s heart built upon the traditional tubes. Settings such as gain, bass, treble, etc are all controlled using digital controls. The front panel controls are in fact, rotary encoders which rotate very smoothly and do not degrade with time. The gain knob has colourful LEDs around it which glow in different colours when you change the gain. It starts with amber colour indicating Clean channel, then becomes Blue which is 60s style clean, and so on up to the maximum setting called Insane. The clean channel is extremely clean and warm with no grit. The crunchiness begins to grow after the “Twang” channel and it becomes extremely gritty at “insane” channel. I would say that the insane channel should not be used by any normal person, because only a death metal person can bare it. You can make Line 6 produce any kind of tone with the help of the vast number of settings at your disposal. You might actually need to go through the user manual to make full use of all the features it comes with. Inside this beast are two 12AX7 pre amplifier tubes and four 6L6 tubes in the power stage. Line 6 Spider Valve HD100 head is something meant for the pros, but it does not mean that you cannot buy it. It comes at a modest price of £ 500 and it is worth every penny. There are hundreds of amp heads out there. Some specialise in one thing, while others come loaded with features. Try to find a balance between features and tone qualities before you make a purchasing decision, because amps do not come cheap and a wrong decision can be depressing.