• Wish list
  • be
    Choose your store
    All countries
  • 0

Thomann's Cool Online Guides: Guitar Amp Heads

4. Valve Amp Basics

Amplifier circuits can be described in terms of the layout or ‘topology’ of components which plays a crucial part in shaping the sound. Most classic guitar amps employ the ‘Class A’ design, which is characterised by wide dynamic range, penetrating tone and creamy distortion. Early Class A designs without a master volume control could of course only produce their distortion at full volume, and so one of the disadvantages of this design is that the valves are subject to relatively high wear and tear – regular maintenance is therefore essential.

Class B designs are much less subject to wear, and also maintain a cleaner signal through most of the path - they are ultimately more flexible.

Mesa-Boogie valve amps, regarded as among the most advanced modern designs, combine the best of Class A and B circuitry in various ways, which are often user-switchable for maximum flexibility.

Other than their topology, valve amps are also commonly characterised as having either a ‘British’ or ‘American’ sound. The difference applies mainly to the overdriven sound and can be hard to describe in words, but broadly speaking, ‘British’ generally refers to the classic rock sounds of the seventies (Led Zeppelin, Deep Purple, Free, Thin Lizzy etc), whereas the American sound has found favour with bands such as Green Day.

Modern heads and combos generally have a similar array of features. Most have two separate channels – essentially separate preamps – which are optimised for clean and distortion sounds respectively, and selectable via footswitch. Some manufacturers such as Mesa-Boogie have added a third ‘crunch’ channel for overdriven rhythm playing.

Most amps incorporate an effects (‘FX’) loop enabling the connection of external effects such as chorus, delay and phasing. This is usually placed between the preamp and power amp, although some amps include flexible routing options, for example allowing the FX loop to be assigned to one channel but not the other. An FX loop is particularly important if you like the amp’s own distortion, as opposed to using a distortion pedal, but want to add a modulation effect such as chorus, which must be added after distortion – chorus before distortion sounds rather unpleasant! Other effects such as delay and wah-wah can be used in either configuration according to taste.

Amps’ power ratings give only a very rough indication of maximum volume, particularly as much depends on the impedance, configuration and sensitivity of the speaker(s) they’re connected to. As a general indication though, many loud combos are rated at 50 or 60 Watts, and heads rated at 100W have a little more power for comfortably driving four or even eight speakers.

Lastly, guitar speaker connections are usually made with quarter-inch jack leads. Although speaker leads have exactly the same external appearance as ordinary jack leads, they should never be mixed up. Instrument/line level cable is co-axial in design - a single core is surrounded by a braided shield which protects the signal from interference. The thin wire used results in a high impedance, which at best will degrade the signal between amp and speaker, and at worst can overheat to the point of catching fire! On the other hand, speaker cable consists of two cores and no shield - using a lead made from this between guitar and amp, while not dangerous, will usually be very noisy.

Your Contact People
Phone: +49-9546-9223-20
FAX: +49-9546-9223-24
Question! Give the right answer and win 1x Harley Benton Electric Guitar Kit Single Cut worth 98 €.
Which of the following is not a popular video-game?
Conditions of participation
Terms and Conditions for participation
in online competitions

Note: Participation in an online competition runs independently from any purchase at Thomann GmbH. The following Competition Rules apply when participating in any online competition run by Musikhaus Thomann:

  1. Competition

    1. The competitions are organised by Thomann GmbH, CEO: Hans Thomann, Hans-Thomann-Straße 1, 96138 Burgebrach, Germany.
  2. Participation

    1. Competitions are only open to persons of full age.
    2. To take part in the competition you must answer all questions correctly, fill in the registration form and submit your entry to Thomann GmbH by pressing the "send" button.
      By pressing the "send" button the participant accepts the aforementioned terms and conditions.
    3. The participant is responsible for entering their email and/or postal address correctly. Entries to the competition will be logged electronically.
  3. Qualifying Entrants

    1. Staff of Thomann GmbH and any cooperation partners and their dependants are excluded from participation.
    2. Should these conditions of participation be violated, especially by using illegitimate means, Thomann GmbH reserves the right to exclude persons from the competition. In case of such violations prizes can be withdrawn and claimed back subsequently.
  4. Announcing the winner

    1. The winners will be notified by Thomann GmbH by email or in writing and their names may be published on the homepage www.thomann.de. The winner accepts this form of publication explicitly.
      Should for whatever reason the winner not claim their prize, then a new winner will be drawn.
    2. The prize presented to the winner may not be identical to the item description. There can be deviances regarding the model, colour etc.
    3. The merchandise prizes will be sent by Thomann GmbH or by one of its contracting delivery companies, per freight forwarder, courier or postal service to the postal address indicated by the winner.

      The delivery is free of charge. Only extra transport costs and customs/duties must be covered by the winner. In the case that the delivery has to be made through a freight forwarding company the freight forwarding company will contact the winner to arrange delivery timings.
    4. An exchange, cash alternative or replacement prize is not possible.
    5. The claim to the prize or replacement of the prize cannot be assigned to a third party.
  5. Data protection

    1. The participant accepts explicitly that Thomann GmbH saves all necessary data for the duration of the competition and forwards them exclusively for purposes related to the winning process to the respective cooperation partner, who is also permitted to save the personal data only for the duration of the competition. The participant is free to withdraw his entry at any time. Please direct the withdrawal to:

      Thomann GmbH
      to the data protection officer
      Hans-Thomann-Straße 1
      96138 Burgebrach, Germany
    2. Thomann GmbH is obliged to consider the regulations for data protection according to the Federal Data Protection Law (BDSG) valid at the conclusion of the competition. In this context the general data protection regulations under notes regarding data protection should be noted.
  6. Liability

    1. Thomann GmbH will be released from any obligations by handing out the prize.
    2. Thomann GmbH is not liable for the insolvency of a cooperation partner and the resulting consequences for the implementation and processing of the competition.
  7. Other

    1. Legal proceedings are barred.
    2. The law of the Federal Republic of Germany applies exclusively.
One of our Fans
I was kept informed throughout and so I knew wher it was at every step of the way.
jtjoxxxbk@gxxx.com, 05.04.2017

Guitar Amp Heads overview


Found an error or want to give us feedback about this page?

We're looking forward to hearing from you and aim to solve any problems as soon as we can.