Originally published on dolphinmusic.co.uk on Thu October 29, 2009
Whether it's a small portable amp, large 4x12 or a simply a valve head. The choices are seemingly endless. So we decided to put together a guide covering the many options available and try highlight some of the features which make each unique.
In real simple terms amplifiers come in several forms valve amps, transistor amps otherwise known as solid state amps & modeling amps. These in turn can be a head and cab, a combo ( or combination of head and cab) amp. There is even acoustic amps and even mini amps to consider!
Major companies such as Orange cater for all different needs: from Valve amps ideal for professional gigging players to solid state practice amps, and even mini amps. View Orange Amps here
There's no "right" or "wrong" amp, actually, because it always depends on your personal tastes, on your ear. But here's a few pointers that will help you look in the right direction anyway!
Beginner / Just playing at home? If you're just a beginner, a mini amp might be enough for you. For playing at home, either beginners or even experienced players don't need anything bigger, better or more expensive than a sub-£100 guitar practice amp.
Busker? If you're a busker, you're better off with an amp that does not require a power supply. The Roland Micro Cube is a great little amp, very popular with buskers who require amplification due to its portability, cheap price and the fact it can be powered by batteries! It's pretty loud, too! Here's a great blog on some of the best amps for busking.
Recording? The best amps for recording WON'T be big, 100-watts Marshalls, for instance! On the contrary, small amps are the best choice. We're talking about small valve amps, here. That's because, unlike with bigger, louder amps, you can crank up small valve amps, pushing them to tone heaven. If you did the same with bigger amps, it wouldn't work - you'd sound so loud you wouldn't be able to make a good recording! This technique has been used by many, many top artists. Despite using big & loud marshall amps onstage, Jimmy Page used a small Supro valve amp on the early Led Zeppelin albums. Likewise, the Arctic Monkeys used an old Fender Champ on most of their debut album.
Playing Small Gigs? If you play small gigs, such as at pubs, clubs etc, small places with capacity of 200 persons or less, you won't need a massively loud amp. A 15-Watt Valve amp will be more than loud enough, such as the Fender Blues Junior or Vox AC-15. You can use louder valve amps, such as a Vox AC30 or Fender Hot Rod DeVille, but in most cases you won't need to set the volume more than halfway up (or less!) Valve amps sound louder than solid state amps, so even though a 15-watt valve amp is loud enough fro gigs, a 15-watt solid state amp will be only recommended for home practice. Good solid state amps include the Orange Crush 20 RT and Blackstar ID:30TVP 30W. Both are loud enough for mid-sized venues and sound superb.
If you're in a small, unsigned band, it's very important to choose an amp that's loud enough - as not every venue will mic your amp. Ironically, bigger artists don't need to worry about this, since they are safe in the knowledge they'll always have a good sound and their amps will always be mic'ed. That's why Seasick Steve plays a small Roland Cube amp, but it's not necessarily a great choice if you're in a band who plays live.
Valve Amp or Solid State Amp? There's no right or wrong here, but, for tone alone, valve amps are way better. If you can afford a valve amp, just go ahead and buy one! They're the amps all the great bands ever used - from Beatles and Rolling Stones to Arctic Monkeys and Radiohead, 99% of all professional musicians simply prefer valve amps, like the Vox AC30 or Fender Hot Rod Deluxe III. But there's nothing wrong with solid state amps - the audience at a gig wouldn't be able to tell the difference.
Solid state amps have many advantages: they are cheaper, lighter, and require less care than a valve amps (which eventually will need new valves, for instance!). Vox, Line 6 and Hiwatt make really good solid state amps that you can gig with without worries. They are not necessarily "worse" amps. The Rolling Stones, Status Quo and many other big acts have used solid-state amps at some point. They're also quite popular with jazz guitarists.
FX or no FX? Again, it's almost a question of valve or solid state, here. Most valve amps don't come with any effects other than tremolo and reverb, at most. Solid State amps often come with a wide range of features such as digital FX and amp modelling. If you're an have lots of fx pedals, you don't really need a modelling unit, but if you're new to guitar playing, buying an amp with modeling FX might be a good way to get familiar with all those sounds.
Combo or Head + Cab? Again, this is a personal choice. It's easier to have a combo, but a head + cab combination might be easier (& lighter) to carry, as you can carry both parts separately. Of course, if you're in a metal band, you simply MUST use a really loud head amp (no matter how small the venue is) and a 4x 12" speaker cabinet. That's just how it is...it's in the rock bible, somewhere! We've put together a complete guitar amp buyer's guide to help you figure out what you need.
Here's our top picks...
Our Top 5 Guitar Head Amps
Fender Bassbreaker 15 Amplifier Head
The Fender Bassbreaker 15 Amplifier Head presents a budget friendly option for those in need of great tone. You have 15 watts of pure power to channel here as well as a studio friendly Power Amp Mute so you can record straight into a desk - a great feature for those in need of a powerful stage and studio amplifier. This is a professional grade amplifier head that features 3 very unique tonal options and overdrive levels to provide you with a whole host of lush fender tones that range from glass like cleans to vintage overdrive. Perfectly paired with the Fender Bassbreaker 212 Guitar Cab.
Boss Katana KTN-HEAD Amp Head
The Boss Katana KTN-HEAD Amp Head has become one of the most talked about amplifiers as it features the coveted Waza technology found in the beautiful BOSS Waza Craft Pedals. The same care and attention that goes into these pedals has gone into the BOSS Katana head to produce a versatile and highly aerticulate amplifier. Packed with Five unique amp characters: Clean, Crunch, Lead, Brown (derived from the Waza amp), and Acoustic (for acoustic-electric guitars), the Katana head ensures you have enough sonic diversity for all genres. You can choose from 55 BOSS effects and load 15 on to the amp via BOSS Tone Studio editor software and you can actually use it without a cab thanks to the monitor speaker - making it a great practice amp that you can use to get your sound and hook up to a cab later on at your gigs.
Marshall 2525H Mini Silver Jubilee Head
The original run of Marshall Silver Jubilee amps were designed to celebrate Jim Marshall's 50th anniversary in music as well as 25 years of Marshall amps. These beautiful sounding (and highly sought after) amps have been brought back from extinction with the Marshall 2525H Mini Silver Jubilee Head, matching cab and combo and have been constructed using the original 2525 diagrams. This means you have all that vintage sounding goodness with modern reliability. You can even switch it from 20 Watt to 5 Watt power so you can go from live sound to home practice easily without ever losing your tone. A great amp for stage, home and studio recording.
Vox AC30CH Guitar Amplifier
The Vox AC30CH Guitar Amplifier head contains all that gorgeous AC30 tone thanks to the classic 12AX7 tubes in the preamp and EL84 tubes in the power amp,. However, you have the option of hooking upo your own cabinet to mix and match the sound, or complete your set up with Vox V212C Speaker Cabinet or even the limited edition VOX V212C Extension Guitar Speaker Cabinet, White Bronco.
Orange Micro Terror Guitar Amplifier Head
They say good things come in small packages. Well, "they" weren't wrong! The Orange Micro Terror Guitar Amplifier Head is no bigger than a lunchbox, but packs enough power to stand up to some of the bigger amplifiers out there, especially when you connect it to a 2x12 or even a 4x12 cab. It features a combination of solid state and valve technology and throws out 20w of pure power thanks to the 1 x 12AX7/ECC83 pre amp valve. Easy to use, affordable and even easier to carry around, you can easily gig with this or use it as a practice amp at home when coupled with the custom built Orange PPC108 1x8 Closed Back Speaker Cabinet.
Want more? View Guitar Amp Heads at PMT Online
Our Top 5 Guitar Speaker Cabs
Fender Bassbreaker 212 Guitar Cab
Vintage styling, high quality speakers and that classic Fender cabinet warmth - there's a lot to love about the Fender Bassbreaker 212 Guitar Cab. Perfectly matched with the Fender Bassbreaker 15 & Fender Bassbreaker 45 guitar amp heads. There's 2 x 12 inch, 8 Ohm Celestion V-Type speakers inside and the semi-closed back ensure those rich, low end frequencies are captured. A great addition that can act as an extension cabinet to the Fender Bassbreaker 45 combo/head and the Bassbreaker 18/30 combo. if you want to add that signature fender warmth to your sound, this head is a perfect match to your own amplifier head with a total impedance of 16 Ohms.
Orange PPC212 Guitar Speaker Cabinet - 2x12
Orange make great amplifier cabinets that work with a wide variety of heads. In fact, there are many artists out there who like to mix and match their amp+head combinations to get the specific sound out of their head combined with the classic sound of an Orange speaker cab. The Orange PPC212 Guitar Speaker Cabinet - 2x12 has been designed to bring the best out in your Orange amp head by utilising 13 ply, high density 18mm Baltic Birch plywood in a closed back construction partnered with 2 x celestion vintage 30 speakers. This Power Projection Cabinet (PPC) has been designed to last the test of time thanks to the rugged construction.
Marshall 1936V 2x12 Silver Jubilee Guitar Speaker Cab
This extremely limited Marshall 1936V 2x12 Silver Jubilee Guitar Speaker Cabinet has been created to get the best sound out of your Silver Jubilee heads, most notably the 2555X and 2525H Mini Silver Jubilee tube amp heads. The Silver Jubilee styling looks great on stage and the 2 x 12” Celestion G12 Vintage 30 speakers provide you with all that gorgeous amp tone – perfect for 1980s/1990s hard rock.
Marshall CODE412 - 4x12 Speaker Cabinet
The Marshall CODE412 - 4x12 Speaker Cabinet is a powerful monster designed as a companion to your CODE 100 head. A classic angled cabinet that is packed with four 12” speakers, each with a 30-watt output. This extremely affordable 4x12 amplifier cab is perfect for those in need of a high-quality option for their set up, whether you have a CODE or not. A single input makes it easy to plug and play and the 24kg weight ensures you won’t break your back carrying it to practice. It’s also Marshall’s most affordable friendly speaker cabinet, making it a great choice for those on a budget.
Boss Waza 212 Guitar Amplifier Cabinet
The Boss Waza 212 Guitar Amplifier Cabinet has been specially designed as a partner to the awesome Waza Amp head. Packed with 2 custom made 12 inch speakers and ready to roar! You can even select whether you want the back to be open or closed, allowing you to make whatever sound you want! If you want extra speakers, there's also the Boss Waza 4x12 Guitar Amplifier Cabinet with 2 x 12" speakers to pump out your riffs with.
Want more? View Guitar Cabs at PMT Online
Our Top 5 Guitar Combos
Fender Bassbreaker 15 Combo Guitar Amp
The Fender Bassbreaker 15 Combo Guitar Amp is a great amp for the stage as well as studio recording. You have a single 12” 8-ohm Celestion V-Type speaker pumping out all that glorious Fender tone. The Gain Structure can be adjusted so you have a choice of three different lush overdrive tones – perfect for players of all styles.
Vox AC30C2 Custom Series Guitar Valve Amp
The Vox AC-30 is quite possibly the most legendary guitar amp ever made, used by everyone from The Beatles and Rolling Stones to U2 and The Libertines. The AC30C2 Custom Series updates the legendary amp with new and improved features - a guitarist's dream amp, no less! The new VOX AC30 Custom Classic…
Orange Rocker 32 2x10" Valve Combo Amp
The Orange Rocker 32 2x10" Valve Combo Amp is a great amp for those who want a serious amount of power on stage. This all valve stereo amplifier allows you to channel into that signature Orange crunch and utilise the stereo effects loop to really make use of any stereo pedals you may have (Strymon Timeline etc.) Enjoy massive panning delays, previously only possible by using two amps at once and knock the power down using the "Half Power Mode” for home playing.
Marshall 2525C Mini Silver Jubilee Combo
The Marshall Mini Jubilee 2525C Combo amp is closely based on the highly-coveted Marshall Jubilee series of amps. The powerful preamp has been designed to the specifications of the original 2525 Silver Jubilee diagrams, making this an authentic reproduction of these now out-of-production monsters of rock. Don’t let this little beast fool you though, the ECC83 & EL34 valve set produces some seriously loud sounds through the single 12” Celestion G12M–25 Greenback speaker. Perfect for lead and rhythm, this great combo amp is ideal for both stage and studio!
Fender Blues Junior III 15w Valve Combo with Reverb
The Fender Blues Junior III has quickly become an industry standard amplifier for those chasing that coveted creamy Fender Blues tone. You have 15 watts of pure tube warmth in an easily transportable package and gorgeous sounds emanating from the 3 x 12AX7 preamp tubes and 2 x EL84 Power tubes. A perfect amplifier for small gigs and practice rooms as well as those in need of a quality amp to record with.
Want more? View Guitar combo amps at PMT Online
Our Top 5 Modelling Amps
Line 6 Spider V 120 Modeling Guitar Amp
Packed with over 200 amps, cabs and effects, the Line 6 Spider V 120 is a perfect amp for those who want a wide variety of sounds to choose from. Especially handy for those in cover bands as you can actually dial in famous amp and pedal combinations. It’s also wireless ready via the Line 6 Relay G10 wireless guitar system. No more guitar leads tripping you over while you're rocking out on (or off) stage!
Roland CUBE-10GX Guitar Amplifier Combo
For practice, tone, playback and recording the Cube series is hard to beat. Integrates with iDevices for playing along with music and gives you all the effects and amp sounds you need in one place. The Roland CUBE-10GX Guitar Amplifier Combo is super lightweight and compact making it a great practice amp for home or studio use. If you're in need of a bass amp, the Roland Cube 20XL Bass Guitar Amplifier is a great solution too.
Fender Mustang II V2 40w Guitar Amplifier Combo
The Fender Mustang II V2 40w Guitar Amplifier Combo is an extremely versatile modelling amplifier that comes complete with 8 amp models, 37 effects, and 24 onboard factory and user presets. So, you’ve got a huge amount of different sounds to play with! It’s like having 18 amplifiers in one easy to carry box all pumping out through a powerful 1 x 12” fender Special Design speaker – great for gigs and studio use!
Vox Valvetronix VT40X Modeling Guitar Amp
The people at VOX know a thing or two about creating great sounding amps, after all the AC30 is probably one of the most famous amps of all time. The VOX Valvetronix VT40X modelling guitar amp actually recreates the sound of these great amplifiers and so many more. In fact, you have 11 famous amps to choose from which can expand to 20 when using the included Tone Room Editor as well as 13 effects built in. The hybrid digital/analog power amp provides you with all the warmth of a tube amp but with digital stability! If you want more power, you have the VOX VT100x or the smaller version – the VOX VT20X.
Blackstar ID:30TVP 30w Guitar Amplifier Combo
The new ID series from Blackstar is turning a few heads, using the valve power rating system so 30watts is plenty for gigging. With the Blackstar ID:30TVP 30w Guitar Amplifier Combo you can enjoy true valve power and tone but without the upkeep, hassle or bulk.
Want more? View Guitar modelling amps & pedals at PMT Online.
Historical Background of guitar amps
Rock music evolved from Blues, the music of the streets. Most musos’ of the 50s and 60s were poor and guitar amps made to a budget. Some but not all technical principles of amp designs were well thought out. Fender and Marshall were the dominant and most copied brands. The powerful amps had 4 output valves in parallel push-pull and gave approx 60 - 100Watts.
The Myth: Most amp manufacturers were conservative from a previous generation with a background of country, jazz and religious music. They were horrified by the anti-religious, drug driven, sex crazed rock musos of the 60s’ diving their amps at full power into hard distortion for sustain. When these amps were first designed in the 50s, it was inconceivable they would be used in this way.
The Reaction Many manufacturers reacted by making warranties void if amps were driven at full power, some threatened to cut off retailers who sold their amps to bands that played ‘music of the devil’. The parody of this historical contradiction has been rewritten, to fit mythical beliefs that brilliant designers created these amps for what ‘rock musos’ wanted.
Myths and Legends: Valve technology is intrinsically the most elegant means by which a speaker is able to reproduce music. This is not because valves have magical qualities but because the technology by which they function is not achievable by other means. In ten thousand years from now Valve amplifiers will possible be the only remaining technology from the 20th century that will be still be being used and loved with as much passion as when first invented. As much as there is no proof that Valve amplifiers can sound superior to solid state I for one if given the choice will only listen to music through Valve amplification.
History: Before solid-state technology, Valve amps were manually assembled by large teams of women in conditions that would not be accepted today. For domestic application the majority were not well made. Before manufacture, designs were scrutinised and modified to reduce production cost. Valve count kept to minimum, cheapest components used at voltage rating limits, safety standards almost non-existent.
The heart of a valve amplifier is the output transformer and accounts for most of the bulk and weight, it is also the most difficult and highest cost item to make. Size and therefore performance was reduced to minimum, especially when used for musical instruments. Only a few brands were made with technical excellence.
The arrival of the Solid State Amps By the mid 1960s, valve amp technology started to leap forward, but too late. As solid-state arrived, manufacturers competed to be first to make the change. This new technology reduced size and costs. It enabled production to be mechanised and staff reduced.
The first solid-state amps used germanium transistors, which performed poorly, until silicon arrived. The intense marketing of solid-state amps caused valve amps to be perceived as worthless, except for musicians. Virtually mountains of them ended up in the landfills of our expanding cities.
The Basic Principles: A Valve is an extension of the light bulb. Theoretically inside the valve is a vacuum. The hot filament is called ‘Cathode’ (Let’s not forget a T.V. is a’ Cathode ray tube’ ). Around the outside of the Cathode is a cylindrical metal tube called ‘Anode’. When a +Voltage is placed on the Anode and a -Voltage placed on the Cathode, a large current can flow between them, but not the other way around.
This is called a ‘Rectifier’ or diode. Grid: A fine helix (spiral) wire called ‘Grid’ is placed between the Cathode and Anode. A small variable voltage (music signal) on the Grid varies the large current between the Anode and Cathode. The small varying input signal is now amplified to a large varying current. The result is very linear. Why this happens is a mystery. The fact that it works and the universe exists is a miracle. It pays to be humble. Transistors: (emitter base collector) are complementary to valves (cathode grid anode).
Transistors are related to crystals. Their individual function is non linear and have to be arranged in compound groups to behave as a linear circuit. Solid-state amps operate at low voltages (10 - 100V). Valves amps operate at high voltages (200 - 600V). Speakers operate at approx (0 - 40V). The Output Transformer converts the high operating voltages of valves to the lower operating voltage of speakers. A transformer has 2 separate coils of wire (primary and secondary) wound around an iron core. Electricity flowing through wire causes a magnetic field around the wire and visa versa, a changing magnetic field causes electricity to flow through wire.
The varying amplified current of the valve is connected through the first coil of wire (primary) and creates a varying magnetic field. The varying magnetic field created by the primary coil, causes electricity to be generated in the second coil of wire, which is wound tightly around the first. Electricity is transferred to the second coil only when the magnetic field is changing, not stationary. The iron core of the transformer keeps the magnetic field contained so little is lost. The transfer is very efficient. The secondary coil is connected directly to the speaker. The reduced secondary voltage is adjusted by the ratio of turns between the 2 coils. Eg 1,000 turns on the primary and 100 turns on the secondary would change the voltage 10:1. Most output transformers have a turn’s ratio of approx 20:1.
Why do Valve Amplifiers sound different?
When technology changed from valve to solid-state, it was noticed that solid-state amplifiers lacked warmth and bass performance, and had to be twice as powerful as valve amplifiers, to sound as loud. Current Drive: Solid-state amplifiers behave in ‘Voltage Drive’. This acts as a short circuit (zero output impedance, or 100% damping factor) across the speakers, causing excessive damping, which reduces efficiency, limiting responsiveness. Valve amplifiers behave in ‘Current Drive’. This represents an open circuit across the speaker without over damping, allowing maximum response and efficiency.
Sensitivity: Valve amplifiers (current drive) are sensitive to crossover resonances and speaker impedance variations. Quality speaker systems often used passive crossovers that were second-order, constant impedance, and critically aligned to avoid resonant effects. Some quality speakers had copper caped pole pieces, which helped damp impedance variations. Note:- With solid-state amps in voltage drive, power decreases as the speaker impedance rises. With valve amps in current drive, power increases as the speaker impedance rises. Therefore a flat speaker impedance is synonymous with a flat frequency response.
Modulating Offset: The output of solid-state amplifiers is directly connected to 2 DC power supplies through the output transistors. The instantaneous non-symmetry within the music waveform (particularly from the bass notes) is averaged as a modulating DC offset. This modulating offset is small, but it varies the efficiency of the speaker, introducing inter-modulation distortion, amplitude modulating the music. This problem is mostly eliminated by the trend to use an active sub-bass. In valve amplifiers the output transformer isolates the speaker from the amplifier electronics. No modulating offset can be produced.
Open Loop Gain: Feedback Solid-state amplifiers are inherently nonlinear. They have a very large ‘open loop gain’ approx 20,000. The amplifier output is (feedback) to the comparator input to reduce the gain to approx 50. Therefore 99.9% of this feedback corrects all instability and non-non-linearity of the amplifier, as explained in amplifiers. The speaker also acts as a large microphone. All non-linear movements and vibrations within the speaker cone, (caused by reflected nodes, chaotic resonances etc) of which there are many, are regenerated back into electricity by the voice coil. This re-generated signal from the voice coil is inadvertanetly fed-back to the solid-state amps comparator input, and re-amplified back to the speaker as recycled distortion.
Re-amplified Distortion: This re-amplified distortion is audible by comparison, when switching between a solid-state and valve amplifier in real time. By paying close attention, it is heard as a fine spurious inter-cluttering within the music. This is clearly noticeable with efficient speakers but not with inefficient speakers. Valve amplifiers are inherently linear. Their natural gain is small and therefore require minimal or no negative feedback.
Their designs do not require them to have comparator inputs as with solid-state amps. The small amount of negative feedback in valve amps is only required to provide damping to the speaker. Valve Amplifier Design From physics we know certain things must be a particular order and size to be efficient and this is acutely so with valve amps. 60Watts is the minimum power capacity for an amplifier to bring quality speakers to life with full fidelity.
The reason: The dynamic range of music can exceed 60db (power ratio 1:1,000,000). Transients within the music can exceed 20db (power ratio 1:100). Therefore amps under 60Watts and ‘Single Ended Class A’ will not be discussed in this text. Valve amplifiers are used for applications such as guitar amplifiers, satellite transponders such as DirecTV and GPS systems, audiophile stereo amplifiers, military applications (such as target acquisition and radar) and very high power radio and UHF television transmitters
- Tubeopedia - Wiki of electronic tubes and related topics
- The Vacuum Tube FAQ - Henry Pasternack’s FAQ from rec.audio
- The Audio Circuit - An almost complete list of manufacturers, DIY kits, materials and parts and ‘how they work’ sections on valve amplifiers
- Conversion calculator - distortion factor to distortion attenuation and THD
- AX84.com - Although oriented towards valve guitar amplifiers, AX84’s free schematics and theory document apply well to any tube/valve project