Many bassists prefer tube amps for their deeper harmonics than solid-state models.
When entering the preamp stage of an amp, input from a bass guitar passes first into its preamp section to control tone and add harmonic distortion and overdrive effects.
Some bassists consider it a holy grail of tones; they prefer it over the more clinical, digital sound of solid-state amps.
Tubes
Tubes inside of a guitar amp may be its most mysterious components. Working alongside circuits and transformers, these mysterious devices determine how your guitar’s signal is translated to sound waves that are then released by its speaker to play back out to listeners’ ears.
Changes to an amp’s tone can have a substantial effect from switching out power tubes; just swapping in a new power tube may alter its entire personality. Your selection also affects secondary harmonics that give it its signature sound signature – for instance, short plates like those found in 12AX7 power tubes provide less-audible distortion while increasing microphonics susceptibility in some instances.
There are still numerous misperceptions surrounding the sound of various tubes that persist to this day, however. For instance, some may assume that if a tube glows blue inside then it must be defective and should be replaced; actually this occurs because of superior vacuum conditions in its tube and makes it more effective at transmitting sound transmission, meaning it will continue working just fine!
Other myths surrounding tube amps include the notion that they’re unreliable and require warm-up before sounding great. While these issues may be legitimate concerns, many current tube amplifiers use Simul-Class switching so you can run them as Class A amplifiers at lower wattages while changing over to Class AB for higher ones – meaning your amp might actually be more reliable than you initially imagined!
One common misperception about tube amps is their difficulty in transport. While this was once true for many amps, modern models are much more transportable compared to prior generations. At Sweetwater we carry several portable tube amps which can easily be brought along on gigs or practice sessions without fear of broken tubes in transit; just make sure they remain cool in order to prevent heat damage!
EQ
Your bass amp’s Equalization Process, or EQ, is its heart. Your guitar signal reaches the preamp where it is amplified to a higher level and colored by tone tubes to produce that special sound of each amplifier – giving every amp its individual sound and character. From there it goes directly into your power amp for maximum impact across speakers.
The mid knob adjusts the frequency range that sits between lows and highs, altering overall tone. The treble control boosts or cuts high frequencies for an additional sparkling tone or to tone down darker, more mellow sounds. Some bass players enjoy having lots of treble for rock and metal music while other prefer less for blues and folk sounds.
Bass players often tinker with their Equalization settings to find the ideal tone for their songs and genres. A helpful approach for approaching equalization settings is trying each setting in turn and listening for results; then tinker further until you find what suits your bass guitar best and music.
Your bass guitar may also feature a “presence” knob, which adjusts the intensity of high frequencies. This feature can help shape how much high-frequency detail exists within its tone – however it should typically remain at midway for optimal use.
Tube amplifiers remain popular with professional bass guitarists who appreciate their warm, organic ‘holy grail’ tone when pushed into distortion. Solid-state amps can produce similar tones, yet their clipping characteristics tend to be harsh and digital compared with that of tube amps.
Modern amps combine both tube and solid-state technologies in the same cabinet, which offers the best of both worlds. You get both organic response from tube amps as well as reliable workhorses great for gigging. Some even feature built-in effects like reverb, delay and chorus that enhance bass guitar tone.
Gain
Gain is one of the key components that distinguish classic tube amps from each other, playing an essential role in creating their unique tone. While other controls like EQ and volume also play a part, gain is at its core: It controls how much amplification is applied to signals arriving at the preamp stage from your bass guitar, thus influencing how much of this signal gets “overdriven” before reaching the power amplifier section.
Most bass players typically possess at least one input jack, gain control and 3-band equalizer on their amplifier – these basic controls provide a good starting point when dialing in their tone.
A bass guitar tube amp is an amplifier composed of pre and power vacuum tubes for its amplification functions, creating unique tones from their preamplifying effects by mixing in distortion, overdrive and other interesting overtones to the amplified signal from an incoming bass signal. Once amplified, this tone then makes its way through speakers creating a wall of sound bass players love playing through.
Different amps offer various controls that enable players to tailor the tone and play feel. While some amps offer multiple gain stages or just one high-gain gain stage, nearly all offer some form of gain control – often called Gain, Drive or Overdrive depending on its label – which controls how much an amplifier overdrives or distorts its tone.
Some amps, such as larger tweed amps, Vox top boost channel amps and Marshall plexi-style amps feature one main gain stage that produces heavy overdrive; in contrast, Trainwreck amps designed by Ken Fischer and currently built by Komet feature two gain stages after their phase inverters that produce less overdrive while still producing an amazing crunch sound.
Higher gain settings tend to produce more overdrive or distortion, and when turned up too high can overload an amplifier’s signal and distort. Therefore, for optimal results use lower gain settings and use a pedal for extra distortion or overdrive effects.
Distortion
Many bassists appreciate the unique natural distortion of a tube amp. This unique tone and overdrive quality cannot be replicated by solid-state amplifiers. A tube amp utilizes glass vacuum tubes in its preamp and power amp sections, and when struck hard enough an electric current pushes these tubes into overdrive creating harmonic distortion which gives a tube amp its signature tone and overdrive quality.
An amplifier’s equalization (EQ) typically features a high-pass filter to help cut off frequencies below the lowest open string and avoid excessive cone excursion from damaging speakers, especially important when performing slap bass techniques.
Gain increases will usually cause the amp to distort more, which is why some players prefer fixed gain structures. Some amps allow players to drive the amplifier into saturation at lower volumes – for instance Laney Lionheart and Ironheart amps feature this type of vintage-style distortion which can be enjoyed without becoming overwhelming at any volume setting.
Other bassists prefer amps with variable gain structures that enable them to control both their tone and how much distortion will occur based on how the instrument is played, for example when they switch from playing slap bass to power chords or melodic basslines. Some amps even feature master volume switches for switching back into clean sound mode for recording purposes.
Some bassists utilize tube distortion pedals to enhance the solid-state amp’s distortion, particularly useful when wanting a cleaner tone but needing some additional distortion for chorus sections of songs. Also note that distortion on an amplifier differs significantly from that produced by guitar pedals.
Many high-wattage tube amps can produce considerable subsonic distortion. To protect the speakers and prevent damage to them, it’s wise to limit how often you play at this level. If in doubt as to how much power your bass amp can handle, consult either its user manual or manufacturer directly for advice.