Power
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.
Number of speakers
The number of speakers provided in the design of the device.
This parameter is indicated in cases where there is more than one speaker. Its meaning may vary. Thus, in some models several speakers are provided to be divided into frequency bands (see “Number of bands”); in this case, a small high-frequency emitter can be installed directly in front of the low-frequency one (the so-called coaxial circuit). In other devices, several speakers of the same type are used to provide the necessary sound power - for a number of reasons this is preferable to installing a single powerful speaker.
Number of bands
The number of bands provided in the combo amplifier. Indicated in cases where there is more than one lane.
The frequency band is called a certain part of the total frequency range, for which its speaker (or several speakers of the same type) is responsible. The division into bands makes sense from those considerations that for different frequencies (low, medium, high) the requirements for speakers will also be different: in particular, the lower the frequencies, the larger the radiator should be. Accordingly, the use of specialized speakers improves the overall sound quality of the combo.
In modern combo amplifiers, which are divided into bands, there are most often two bands — HF and LF / MF. This is considered sufficient for most cases. It is extremely rare among advanced models to meet three-band devices (HF, MF, LF), and more are considered technically unjustified.
Woofer size (LF/MF)
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.
Effects
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.
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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.
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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.
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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”).
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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.Footswitch
The number of connectors for
connecting pedals (footswitch), provided in the design of the amplifier.
The pedal is the most convenient way to quickly change amp settings and can be used while playing the guitar. The specific functions "tied" to the pedal connectors can be different: in particular, various effects can be turned on and off in this way (see above). Also, in different models, the number of connectors for pedals may vary: in most “amps” there is only one such connector, however, there are devices that allow connection of several “foot switches” at once.
Line input
The type of line input provided in the amplifier.
The line input is used to supply sound from an external source to a guitar amplifier (“amplifier” or “head”). In this case, the incoming audio signal is sent to the input of the power amplifier and through it to the built-in speaker or external cabinet. In any case, this function allows you to combine the “live” sound of the instrument with additional accompaniment: for example, you can connect a player with a recorded drum and bass part to the line input and learn the guitar part with accompaniment - or perform in a “one-man orchestra” format.
Different types of connectors can be used for line input:
— Mini-Jack (3.5 mm). A socket for a standard 3.5 mm mini-Jack plug. This interface is used mainly in portable audio equipment; Jack 6.35 mm and RCA are more popular in stationary devices.
— Jack (6.35 mm). A connector similar in design to the 3.5 mm mini-Jack and differing only in size. Actually, due to its size, this type of plug is practically never found in portable audio equipment, but is quite popular in stationary ones. Theoretically, a Jack type connector can be used for a balanced connection (see below), but in guitar combo amps a regular unbalanced input is more common.
- RCA. Connector for coaxial cable with tulip type plug. It is used exclusively in stationary audio equipment. A standard RCA input consists of two jacks (for
...stereo sound, left and right channel), but in guitar combo amplifiers there is only one connector, since there is no point in using stereo in this case - one channel is enough.
— Balanced XLR. The characteristic connector is round in shape with three contacts and is quite large in size. The term “balanced” describes the specifics of signal transmission: it is carried out not through two, as with a standard connection, but through three wires, two of which operate in antiphase. Due to this, most of the interference induced on the wire is extinguished by itself, without the use of any special filters, which allows the use of long cables without compromising signal quality. Balanced connections are found mainly in professional audio equipment. As with the RCA described above, the standard XLR input includes two jacks (stereo left and right), but guitar amps use a simplified, single jack version.
Some combo amplifiers are equipped with several types of line inputs at once - for example, Jack and RCA. This usually means having separate connectors for each type. Theoretically, multiple inputs allow you to simultaneously connect several signal sources, but in practice this possibility should be clarified separately.Headphones
The type
of headphone output provided in the design of the amplifier.
Headphones will be useful especially in a situation where you can not make noise — for example, when practicing the guitar at a late time. And the options for their connection can be as follows:
— Mini-Jack (3.5 mm). Output for a standard 3.5 mm mini-Jack plug. This plug is equipped with most modern headphones, especially entry-level and mid-range. However, in terms of the quality and reliability of the connection, it is noticeably inferior to the larger Jack 6.35 mm (see below), so it is relatively rare in combo amplifiers.
— Jack (6.35 mm). The connector is quite large, designed mainly for stationary audio equipment. As the main connection method, it is rarely found among headphones, these are mainly professional models. At the same time, you can connect headphones with a 3.5 mm mini-Jack connector to such a jack using a simple adapter (in many “ears” such adapters are even included in the standard package); and the connection itself is tight, reliable and with a minimum of interference from the point of contact. Due to this, most "amps" use this type of connector.
Built-in looper
The presence
of a built-in looper in the amplifier.
Looper is a module that allows you to record and loop a specific piece of music. Using this function, you can, for example, record a rhythm guitar part directly into the “amp”, turn it on for playback and work out the solo part to the accompaniment played through the looper.