Type
The type of device is determined by the element base — the main type of parts on which the power amplifier circuits are built. Accordingly, this parameter is relevant only for equipment with such amplifiers; for cabinets (see "Type") it is not indicated.
The most popular nowadays continue to use traditional types of amplifiers —
transistor and
tube.
Digital models are noticeably less popular, and
hybrid solutions are rare at all. Here is a detailed description of each of these options:
— Transistor. Amplifiers of this type are relatively simple and inexpensive, while being able to provide quite acceptable sound quality (although, of course, everything depends on the class). It is the “transitor” that is recommended for beginner guitarists as the first “combo”, although there are quite advanced models among such devices. Of the unequivocal advantages of transistor circuits, one can name the durability of the components and the ability to easily transfer frequent carrying from place to place. As for the sound, in such devices it turns out to be more “dry”, “flat” and “cold” than in tube models, which many consider to be a clear disadvantage. At the same time, in the case of electric guitars, even this is quite enough for initial training, rehearsals and not very “fancy” performances; in addition, some transistor ampl
...ifiers use specific signal processing to give the sound a tube-like sound. And combo amplifiers for acoustic guitars are overwhelmingly made with transistors.
— Lamp. Historically, the first type of amplifier, which, nevertheless, is still considered almost the standard when it comes to electric guitar (tube circuits are practically not used for acoustic guitars). The main advantage of such devices is the notorious “warm tube sound”, a characteristic soft, warm and at the same time rich coloring of the sound. At the same time, we note that the level of distortion in tube circuits is higher than in transistor circuits, however, these distortions are more pleasant to the ear, in many respects they provide the mentioned coloring. The widespread use of tube amplifiers is hindered primarily by their high cost — several times higher than that of transistor amplifiers with similar characteristics. In addition, among the disadvantages of such devices, it is worth noting the delicacy (the lamps do not tolerate shocks and shocks), the rapid wear of the lamps and the need for their regular replacement, as well as the need for warming up after switching on. However, professional musicians prefer to use mainly tube devices.
— Digital. Chip-based amplifiers using digital audio processing. The main advantage of such devices is the extensive possibilities for modeling sound and providing various effects. In particular, there are many models that copy tube amplifiers: the imitation is very reliable, and sometimes almost indistinguishable from the original. At the same time, digital models are devoid of many of the shortcomings of lamp technology: they are simpler, cheaper, more durable and more resistant to shock and shock. At the same time, digital processing is considered to take away personality from the sound, and many high-end audio enthusiasts are suspicious of digital solutions.
— Hybrid. Hybrid devices are devices that combine transistor and lamp circuits; usually a preamplifier is made with a tube, and a power amplifier is made with a transistor. In fact, this is a compromise between purely tube and purely transistor models, which allows you to combine the advantages and partially compensate for the shortcomings. Thus, hybrid solutions are noticeably cheaper than lamp solutions, they are lighter, more compact, less delicate and have fewer lamps that require regular replacement. And the sound at the same time turns out to be softer, cleaner and “warmer” than that of transistor analogs. At the same time, not many musicians choose such a compromise: those who strive for the highest quality and reliable sound prefer to spend money on tube equipment, and undemanding users (such as amateurs and beginner guitarists) are quite satisfied with transistor models. Therefore, there are relatively few hybrid models on the market.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.
Impedance
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.
Number of channels
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”).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.
—
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.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.Break (send/return)
The type of insert (send/return) provided in the combo amp.
In this case, a gap means
a set of connectors for connecting an effects unit between the preamplifier and the combo's power amplifier. One of these connectors (preamp output) is usually labeled “Send”, the second (power amplifier input) is labeled “Return”. With such an interface, you can connect various "gadgets" to the combo amplifier, supplementing it with effects that were not originally provided for in the design (see "Effects"). And the type of gap determines the connection format of the "gadget". The options might be:
— Consistent. The simplest connection option: the “gadget” is connected directly between the preamplifier and the power amplifier, and the entire audio signal passes through it.
— Parallel. With this type of connection, the signal at the output of the preamplifier is divided: one part goes through the "gadget", the second — bypassing it. Both streams enter the mini-mixer, where they are again combined into one signal. Such a connection scheme is more complicated and somewhat more expensive than a serial one, but it gives more opportunities: the mixer allows you to change the ratio between the original and processed signal, thus adjusting the final sound. At the same time, in many models it is possible to completely turn off the original signal and feed only the processed stream to the power amplifier, as with the series amplificatio
...n described above.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.
Cabinet output
Type of
output (outputs) to the cabinet provided in the design of the device.
Let us remember that cabinets are specialized passive acoustics for guitar amplifiers; See "Type" for details. Accordingly, outputs to such acoustics, by definition, are available in almost all “heads” (see ibid.); The only exceptions are a few models that were originally intended for use with headphones and do not have full-fledged power amplifiers. In addition, this type of output is found in many full-fledged “combinations”, as well as some active cabinets. At the same time, the format of its use can be different: in some models, the external cabinet can work in parallel with the built-in speaker, in others you have to choose one thing. Be that as it may, this feature expands the capabilities of the combo amplifier, allowing it to be used not only with built-in acoustics, but also with other cabinets that have suitable characteristics.
In any case, the type of this output must match the type of input on the cabinet itself - otherwise the connection, at best, will require the use of an adapter, and at worst, it will be completely impossible. But here are the main options for such connectors that are relevant today:
— Jack (6.35 mm). One of the most popular connectors in modern audio equipment and the most common type of cabinet output in guitar amplifiers. This is due, in particular, to the fact that this connector is relativel
...y small in size, and the cables for it are relatively inexpensive and are available everywhere. True, in a number of characteristics this interface is inferior to other standards described below. Thus, it does not provide a lock for additional fixation of the plug in the socket and is not suitable for high powers and currents (unlike Speakon). And a balanced connection (such as in XLR), although technically possible for Jack, is used extremely rarely in practice - guitar amplifiers and cabinets usually use two-pin connectors with a classic (unbalanced) connection. However, the need for more advanced connection options arises mainly in situations involving increased requirements for quality, power and/or noise immunity - in recording studios, large concert venues, etc. For other cases, the capabilities of this interface are usually more than enough.
- Speakon. A specialized professional connector for connecting passive acoustics, widely used in concert equipment. Provides very high-quality and tight contact, has a lock to prevent accidental disconnections, and is designed for higher currents (and, accordingly, powers) than XLR and especially Jack. In addition, Speakon sockets and plugs are also distinguished by high-quality insulation, which reliably protects live parts from moisture and human touch.
Note that such a connection can use a different number of contacts - 2, 4 or 8 (respectively, for one, two or four audio channels); however, the latter option is practically never found in guitar amplifiers. The connector itself has a round shape, with contacts located around the circumference; however, a 2-pin plug can work with a 4-pin socket, but not vice versa. It wouldn’t hurt to clarify the specific configuration of this output separately. However, in any case, the presence of Speakon is usually a sign of a powerful and advanced amplifier, designed primarily for concert use.
— XLR. A characteristic round connector with 3 contacts and a metal shell around them on the plug; such a shell is often supplemented with a lock, which additionally secures the plug in the socket. However, the main advantage of this interface is that XLR cables and connectors usually operate in the so-called balanced format. This connection format provides not two, but three wires - relatively speaking, two signal and one common “zero”; and the input signal is processed in such a way that noise induced on each wire from external sources is “out of phase” and cancels out each other. Thanks to this, a balanced connection allows you to transmit high-quality and pure analog audio signals even over long cable lengths. On the other hand, the connector itself is quite large in size, its presence inevitably affects the cost, and the real need for a balanced output to the cabinet does not arise very often. Therefore, this connector is not particularly popular.
— Jack/XLR. A combination of the two types of outputs described above in one amplifier. See above for details on each type; Let us note here that most often these are separate connectors, although another option is technically possible - a combined socket that allows the connection of both Jack and XLR. These nuances should be clarified separately. In any case, this combination makes the amplifier more versatile and means it has a balanced output (see “XLR” above); however, such versatility, as well as a balanced connection, are required in practice relatively rarely, which is why this combination has not become widespread.
— Speakon/Jack. Another combined option, which assumes the presence of the two types of outputs described above. It is slightly more popular than the Jack and XLR combination; We also note two more specific points. Firstly, in this case, different types of connectors are made exclusively in the form of separate sockets. Secondly, by the number of Jack outputs, you can determine the type of “speakon”: in this case, each 6.35 mm connector is responsible for one audio channel - accordingly, if there are two such outputs, then the only Speakon will also be two-channel (that is, four-pin).