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.
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.
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”).Equalizer
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.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.
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).