Comparison VOX VX15GT vs VOX VT20X

Rated power of the device.

Let us recall that in acoustics the rated power is the highest average (root mean square) power of a sound or signal that a device can produce for an indefinitely long time. Individual volume jumps can be several times higher than this indicator, but the key characteristic is the average value. But the specific meaning of this parameter depends on the type of equipment (see above). So, for combo amplifiers, this paragraph usually gives the power of the built-in speakers; The capabilities of your own amplifier, by definition, correspond to this figure, so for such equipment the rated power determines solely the overall sound volume. The power of the acoustics is also indicated for cabinets, but here another point becomes relevant - compatibility with an external amplifier (primarily the “head”). The output power of this amplifier should not be higher than the rated power of the cabinet to avoid overloads; and ideally, these characteristics should match - this will allow you to use the speaker at full power without sound distortion.

For the head, accordingly, this paragraph provides the rated output power, which determines the ability of the amplifier to operate with a specific cabinet or other speakers. However, it is worth noting that the maximum possible power value is indicated as the nominal value for heads, which is not always achieved. Thus, many models provide several sound outputs - for passive acoustics with different...impedances (remember, standard impedance values are 2, 4, 8 and 16 Ohms); and the higher the impedance of the connected speaker, the lower the actual power will be. Other heads have the ability to limit the maximum power - for example, so that at the maximum level the device produces not 100 W, but 50 W or even 25 W. Sometimes these features are combined in one device.

In any case, when choosing according to this indicator, it is worth taking into account the features of the planned use of the equipment. For example, it hardly makes sense to purchase even a 40-watt “combination” for practicing at home - for these purposes 15 watts, or even less, will be quite enough. And if we are talking about a tube device, then in our example the maximum recommended power will be only 5 W - the specificity of tube circuits is such that with the same rated power they are more effective than transistor ones in terms of audibility. For rehearsals in a group without a drum kit (for example, two guitars plus a bass), a higher power is desirable, about 40 “transistor” watts, and if there are drums, at least 60 watts. Transistor devices with a power of up to 150 W and tube devices with a power of up to 40 - 50 W are suitable for specialized rep bases and concerts in relatively small rooms, and higher figures are found mainly in equipment for large-scale events. Detailed recommendations regarding optimal power for certain conditions can be found in special sources.

It is worth mentioning bass amplifiers separately: it is believed that for normal coordination with each other, the power of a bass “combination” should be twice as high as the power of a guitar one.

The impedance of the speaker(s) installed in the amplifier.

Impedance is the resistance to alternating current — that is, the current flowing when an audio signal is applied. This impedance affects the compatibility of the speaker with the power amplifier: if the impedance is too low, sound distortion occurs, if the impedance is too high, the volume is reduced. However, in combo amplifiers, this parameter is most often given as a purely reference: such devices have their own power amplifier, which, by definition, is designed for the impedance of the “native” speaker, and separately, with extraneous components, the speaker and amplifier are not used.

The diameter of the woofer or woofer installed in the combo amplifier. The specific value of this parameter may be different, depending on the number of lanes (see above). In three-way systems we are talking about bass dynamics, in two-way systems — about the dynamics responsible for low and medium frequencies; and if the amplifier does not have band separation, this paragraph indicates the diameter of the main radiator.

In general, the larger the radiator, the louder it can sound and the richer the bass from such a speaker is. At the same time, we note that the speaker diameter is selected by the manufacturer based on the power of the built-in amplifier and the expected sound volume. So the main indicator when choosing is still the rated power, and the size of the speaker is more of a reference value.

The number of channels provided in a combo amplifier or a separate “head” (see “Type”).

This parameter is specified only if the device has more than one channel. The channel in this case can be described as a kind of “path” for the audio signal, which has its own specific set of settings. If there are several such “paths,” then each of them can be configured at your discretion and you can switch between sound options with just one click of a button (in extreme cases, by switching the instrument to another input). The most typical example of using this function looks like this: one channel is used for clean sound, and the second is used for “overdrive” using the built-in distortion or overdrive (see “Effects”). Without channel separation, the sound would have to be changed either by reconfiguring the amplifier (setting the parameters again each time, which is simply inconvenient), or by using external “gadgets” (and this is not always the best option for a number of other reasons).

As for the number of channels, in multi-channel models there are most often just two of them - this gives the mentioned additional capabilities and at the same time does not particularly affect the cost of the device. This option is optimal for beginning musicians, but is also found in professional equipment. Increasing the number of channels makes it possible to provide more advanced options for preset settings (for example, “clean ringing”..., “clean warm”, “Crunch” and “Overdrive”), but it significantly complicates and increases the cost of the design. Therefore, the higher this number, the fewer models with such characteristics are presented on the market. The maximum value found in modern guitar amplifiers is 6; a similar amount can be found in individual professional models, mainly with a digital element base (see “Type”).

Type of equalizer provided in the device design

An equalizer allows you to change the volume of a separate part of the sound range (frequency band), thus changing the color of the entire sound. This is one of the most important functions related to audio settings; therefore, it can be provided directly in the guitar amplifiers themselves. And the type of equalizer is indicated by the number of bands available for adjustment.

The more of these bands, the more accurately you can adjust the sound, but the more complex and expensive the equipment becomes. In light of this, the simplest option involves only 2 bands - low and high frequencies; Often such an equalizer looks like two separate knobs for adjusting the bass and treble levels. At the same time, we note that similar functionality can be found in both budget and high-end guitar amplifiers: in the second case, it is assumed that if finer adjustments are needed, you can use external equipment. However, three-band solutions (low, mid and high frequencies) are the most popular these days: such an equalizer provides quite extensive possibilities for adjusting the sound and is relatively inexpensive (and if finer adjustments are required, you can use external equipment). 4-band equalizers are noticeably less common, but are also quite popular (including in inexpensive devices); and some models provide...5 or more (up to 12) adjustment bands.

The presence in the amplifier of the regulator "Gain".

This control is responsible for adjusting the intensity of overdrive when using effects such as distortion or overdrive. Thanks to him, you can change the severity of these effects — from almost complete absence to pronounced distortion, which has little to do with a clean guitar sound.

Built-in effects provided in the combo amplifier. You can also achieve various effects with the help of external “gadgets”, however, such gadgets need to be searched for and connected separately, while built-in effects are available immediately and without unnecessary settings.

— Overdrive. Distortion in the form of a characteristic electric guitar "buzz" at low frequencies and "howl" at high frequencies, a little softer than distortion. Popular, in particular, in hard rock.

— Distortion. Sufficiently hard and sharp distortion, similar in sound to overdrive, but more intense and brighter. It is widely used in various styles of metal, and is also found in rock.

— Reverb. An effect based on simulating multiple decaying echoes from each sound. Depending on the duration and intensity of repetitions, it can give the sound a different colour. Used as an artistic device; among other things, it can create the effect that the guitar sounds in a certain room (concert hall, room with stone walls, an open area in the mountains, etc.). Note that the reverberation can be adjusted both by individual parameters (intensity, echo duration, etc.), and by selecting a preset set of parameters (for example, “sharp sound in the room” or “soft sound in the hall”).

— Tremolo. Tremolo is basically a trembling effect that res...ults from small and quick fluctuations in the volume of each note. Sometimes this term means vibrato (see below) — to the point that the manufacturers of guitar amplifiers themselves mean the effect of vibrato by the tremolo effect, and vice versa. So the specifics of this effect in each case should be clarified separately. Anyway, the tremolo can be "fixed" or adjustable in depth (range of volume change) and speed (jitter frequency).

— Vibrato. Another effect of "jerking" sound, which is often confused with tremolo (see above) — to the point that both these terms are used as identical. However, this is not true; the difference lies in the fact that vibrato is carried out due to the rapid fluctuations of the note not in volume, but in frequency. A similar effect can be achieved on the guitar itself by "pulsating" the strings, but using the amplifier's built-in instrument is much more convenient in most cases.

— Chorus. An effect designed to simulate the choral sound of an instrument. To do this, the amplifier copies the sound of the guitar and plays several copies simultaneously with the original signal, slightly shifting them in time (about 20 – 30 ms with a constant change) and frequency. However it is impossible to achieve a full-fledged choral sound in this way, but the effect is quite original in itself.

— Delay. A specific type of reverb (see "Reverb") that has become widespread as a separate effect. Delay simulates a clear single echo from the sound being played; for this, the original signal is copied and reproduced with a certain time delay (at least 50 ms).

In addition to those described above, other effects can be found in modern guitar combo amplifiers, in particular:

— Flanger. The effect is reminiscent of the whistle of a jet engine; it is often compared to a plane taking off. It is created similarly to the Chorus described above, differs from it in a shorter delay time and the presence of feedback.

— echo. Another kind of reverb, similar to delay (see “Delay”). It differs in that in this case the echo is reproduced repeatedly.

— Octaver. An effect in which a copy of it is added to the signal, shifted by an octave or two.

— Wah wah. An effect that produces a characteristic "croak" sound.