Tone is abstract and difficult to describe precisely with words. Not only do we lack a common vocabulary, we all have personal taste and preferences which complicates things even more. The best way to describe tone is using concrete and specific examples that we all can refer to, like a specific song on an album, a specific guitar, specific pickups, specific amps or speakers. Tone is always best described as “compared to what”. The more guitars, pickups, pedals, amps and speakers you have played, the bigger bank of concrete reference tones. Experimenting with lots of gear is also an essential part of learning how to pair the right guitar with the right pedals and amp and finding your tone.  

Attack

Attack is the opposite of Sag but also involves treble / sparkle. If you have a mellow guitar with warm, hot pickups its tone will have less attack than a clean guitar due to the lack of sparkle.

Speaker efficiency

Also known as “sensitivity”. Efficiency is how much bang for the buck you get in terms of output volume based on input energy. You measure the volume from the speaker in decibels (dB) and the input signal in watts (W). If you feed a speaker with a 440Hz (A tone) sinus signal at 1w, you can measure the loudness using a decibel meter at a specific distance. With modern, new speakers the values are fairly comparable between different manufacturer brands.

Speaker power 

The power rating of a speaker indicates how much electrical power (in watts) it can handle without getting physically damaged, mostly a burned coil wire or torn paper cone. Power and Efficiency is not the same. A very powerful speaker is usually not very efficient. The stiff cone and heavy and large coil require a significant amount of power to start vibrating. Back in the early amp days only a few speaker brands and models like JBL and EVM could deal with high power above 50w. They were both expensive and heavy. Since the late 90s lots of powerful speakers became available from manufacturers.

Speaker impedance

Impedance means resistance and is technically measured across a wide frequency range. A guitar amp operates ideally when it drives speakers with a specific impedance. In Fender amps it is generally safe to stay in the range between half and double amp impedance. This means that a 4ohm amp, like the Pro Reverb, can take speakers between 2 and 8 ohms. An impedance mismatch will result in less clean headroom, distortion and shorter tube life.  

American vs British speakers

Vintage Fender amps were loaded with typically Jensen, CTS, Oxford, Utah, JBL and Rola. These speakers were transparent and bright. The term American-style speakers is used to describe these speakers that can deliver a bright, clear and sparkling Fender tone. On the other hand, British speakers are traditionally more mid-focused with less sparkle, typically (British) Marshall amps with (British) Celestion speakers.

Sweet spot

An amp’s sweet spot is the breakup point where clean tone meets distortion. The sweet spot is more a range rather than a specific volume setting. Be aware of that people have different understanding of “clean tone”. For me personally, Robert Cray’s strat tone with big Fender amps like Super Reverb and Vibro-King is the definition of “sweet spot”.  

Sag

The effect “sag” happens when an amp is dialed in it’s sweet spot or beyond. It is also known. See Tube amp tone for detailed explanation. The Pro Reverb, Vibrolux Reverb and Vibroverb are famous for this. At the other end of the scale, the Twin Reverb’s huge transformers and diode rectifier has minimal sag.

Headroom

Headroom refers to the power amplification of an amp and is measured in watts. The amp’s power indicates how loud it can play without distorting NOT considering the speakers. An 85w Twin Reverb has more clean headroom than a 40W Pro Reverb. Whether an amp sounds loud and clean depends also on other factors:

• Speaker efficiency and power rating.
• Design of the power amp circuitry. Amps without negative feedback in the power amp circuitry (like Vox amps, the Fender Vibro-King ++) distort more than amps with negative feedback. Also, the bias design will determine amount of sag. Cathode bias (Fender Tweed era) has more sag than fixed bias (Blackface era).
• Preamp circuit design. If the preamp section is designed to distort on purpose, like Fender Bassman and Marshall amps with several tube gain stages in the preamp circuit, you will have less clean headroom even if the power amp section has lots of headroom.
• The phase inverter design will also affect the clean headroom. The Princeton Reverb is known to have an inefficient phase inverter and will create a distorted signal already before it enters the power tubes.

Hot and cold bias

A tube is basically an amplifier. Depending on the function in the guitar amp, its job is either to amplify the voltage or the current, or both. All tubes require bias, meaning they must be provided certain voltages and current in order to operate. Preamp tubes have a circuitry around them of resistors and caps which provides the right bias voltages and currents. The power tubes do have bias adjustment possibilities and depending on preferences and tube type, the bias can be adjusted cold, neutral or hot. Hot bias will lead to more distortion and earlier breakup while cold bias is the opposite. Hot bias therefore sounds best, huh? Be aware of that hot biasing will shorten tube life. We therefore recommend neutral/hot.  

Cranked  

Cranking an amp means turning up the volume beyond its sweet spot.  

Spread 

An amp with good spread can be heard easily in a room or a stage without being loud. The opposite is a directional amp. 10″ speakers are known to be directional while 12″ and 15″ speakers have more spread. Closed cabinets have no spread backwards while open cabinets have decent spread in the front and back. Directional amps are more difficult to use on stage and requires micing and monitors. 

Scooped

A tone with reduced mids. If you study a signal in an oscilloscope the bass and treble are the dominating frequencies. A stratocaster is a typical example of a scooped guitar tone, particularly with weak/clean sounding pickups.  

Natural sounding

The word Natural means a flat frequency response.  

Sparkle

To me, sparkle is the upper treble frequencies of guitar and amp tone. The best example I can think of is the effect of the bright switch on Fender blackface/silverface amps. It will either let through or stop the sparkle of your tone. These are higher frequencies than the treble control will handle. Single coil guitars have more sparkle than humbuckers. A guitar’s neck wood and construction also play a role, same does pickups where hotter pickups with more coil winds will have stronger signal with less sparkle. One can use the guitar or amp tone controls to alter the treble, but if the speakers and guitar both are bright you may find it difficult to tame the sparkle. One example is a Fender Mustang with thin strings played through a clean Deluxe Reverb reissue loaded with a new, bright and efficient Jensen C12n speaker. It is very bright with tons of sparkle, sometimes tending towards “harsh” if you push the amp into distortion.  

Quacky

The best example of a quacky tone is the stratocaster’s in-between pickup positions, position 2 and 4. The two pickups, wither neck+mid or bridge+mid, are used in parallel and lots of frequencies are cancelled, particularly the upper mids. There is lots of sparkle and funky, firm bass in a quacky tone, and it is easy to get drowned on stage or get too muddy. If you master the difficult technique of pairing up with the right pedals, amp and speakers, you will experience Hendrix tone heaven and play Wind cries Mary dreamfully and beautifully. Be careful to not only play with a quacky sound. You should vary with single pickup positions to keep the audience interested. Dynamics and change of tone along the song are key requirements to all guitarists.  

Fullness

You cannot have fullness without strong bass and lower mids together with good spread, often related to larger amp and speaker cabinets and/or more speaker areal. A 2×12” cabinet sounds fuller than a 1×12”. A large 1×12” cabinet also sounds fuller than a small 1×12” cabinet, for example a Deluxe Reverb with 1×12” vs a Princeton Reverb where a replacement 12” speaker is squeezed into the small cabinet. A certain amount of power is also required to achieve fullness, otherwise the amp won’t be able to feed the large speakers with bass notes at medium/higher volumes. Bass requires a lot of energy and power. Treble does not. 

Vintage tone

Hah! The most hyped word in this business. Vintage tone is simply explained as the tone of a vintage amp in an original condition. To achieve a vintage tone, you first need a vintage-style amp with vintage-style speakers or close replicas. You can of course achieve a vintage tone with modern amps as well as long as the amp is based on vintage specs. Vintage-style speakers are key to vintage tone. First of all, they are not powerful or very efficient. The original CTS, Jensen, Oxford, Utah, JBLs were typically 25-50w for 12″ speakers or 10-20w for 10″ speakers. Vintage style speakers are low-powered, natural sounding with medium/low efficiency. They do not have an impressive punch in the lower bass compared to typical modern speakers who have become very popular. Loud and punchy is always popular with beginners. Vintage speakers have strong treble, particularly the ceramic ones. Alnicos tend to be a bit smoother. Finally, a nice thing with low-powered speakers is their fingerspitzenefühl, aka touch-sensitivity. Given the light construction it requires very little energy/current to get the speaker vibrating. 

Tube amp tone

You may have heard that transistor amps are distorting differently and harder than tube amps caused by a distinct and sudden signal clipping when max effect level is reached in the transistors.  Still, it’s not just the tubes that provide the desired distortion in tube amps. Other components such as the ower and output transformers and large caps in the power supply cifcuit also contribute to sag and compression. In general, transistor amps don’t have this because they don’t need a big power transformer and the corresponding high voltage DC caps to function. They are built light, small and efficient and need only to provide the transistors with a tenth of the voltage compared to tube amps.Figure showing large transformers and caps in a Super ReverbWhile transistor can operate with a typical 40 V DC voltage supply, 6L6 tube amps require ~500 V This requires a big iron power transformer, a rectifier (tube or diode) and big capacitors to store the 500V DC. When striking a chord on your guitar, the whole value chain of electrical components must quickly transport a large amount of energy (current) to the preamp and power tubes. At high volumes the power supply struggles to deliver fast enough. The result of this struggle is sweet compression, also known as “sag”. You’ll notice that your amp adds sustain to your notes. A hard string attack will jump sweet, warm and soft out of your speakers, and your note will hold longer.