Home>Support>Tech article

How many power of practicing amp need?

Not only professional guitarists, but also hobbyist and advanced learner all need many time practicing their guitar play skill at home or smaller venue. What difference between amp used on the stage and practicing amp used at home? How many power of practicing amp need ?Before we answer these questions , let us start from relationship between power and loudness.

The relationship between power and loudness
The unit of measure loudness most common is the decibel(dB), the dB is a unit of measure for sound intensity or level. It is a logarithmic scale developed to express wide ranging quantities on a simple scale. Because it is logarithmic, it can be a little bit confusing. As an example, a doubling of volume is not equal to twice the number of dB. The chart below will help you to better understand the dB and how it relates to what you hear, and what is happening throughout your system as volume levels change. But first, we need to look at the other end of the equation.
 Power,in this discussion, refers to watts. Power defined is the rate at which energy is converted or dissipated, as in the case of an amplifier driving a loudspeaker. It is important in our discussion in defining the general relationship.

dB Change
























Looking at the chart, and starting at the left, we can see than an increase of 3dB results in a voltage increase 1.4 times the original, a doubling of power, and yields only a subjective increase in loudness only 1.23 times the original. To get a doubling of loudness, it is important to note that an increase of 10dB is necessary. And to reproduce that volume through our loudspeakers, note that we require ten times more power from the amplifier!
The chart below is relationship between power with loud
100 watts is 1.23 as loud as 50 watts.
80 watts is 1.1562 as loud as 50 watts.
60 watts is 1.0578 as loud as 50 watts.
40 watts is 94% as loud as 50 watts.
30 watts is 86% as loud as 50 watts.
25 watts is 81% as loud as 50 watts.
22 watts is 78% as loud as 50 watts.
20 watts is 76% as loud as 50 watts.
18 watts is 74% as loud as 50 watts.
15 watts is 70% as loud as 50 watts.
12 watts is 65% as loud as 50 watts.
10 watts is 62% as loud as 50 watts.
9 watts is 60% as loud as 50 watts.
8 watts is 56% as loud as 50 watts.
7 watts is 55% as loud as 50 watts.
6 watts is 53% as loud as 50 watts.
5 watts is 50% as loud as 50 watts.
4 watts is 47% as loud as 50 watts.
3 watts is 43% as loud as 50 watts.
2 watts is 38% as loud as 50 watts.
1 watt is 31% as loud as 50 watts.
3/4 watt is 28% as loud as 50 watts.
1/2 watt is 25% as loud as 50 watts.
1/4 watt is 20% as loud as 50 watts.
1/10 watt is 15% as loud as 50 watts.
50mW is 13% as loud as 50 watts
20mW is 10% as loud as 50 watts.
10mW is 8% as loud as 50 watts.
5mW is 6% as loud as 50 watts.
So we can know
All other things being equal, a 100-watt amp will be just perceptibly louder than a 50-watt amp.  It takes about a ten-fold increase in power to double perceived volume.  That's means, you'd need a 500-watt amp to be "twice as loud" as your buddy's 50-watt amp.  Even more thought-provoking is the fact that a 50-watt amp will only be perceived as a little bit louder than a 15-watt amp driving the same cabinet!
All other things are almost never equal.  There are so many variables controlling sound pressure level (SPL) and perceived volume that it is quite common for a small amp to sound louder than a much more powerful amp.

  • The initial purchase price of a 100-watt amp will be significantly higher than a 30-watt amp with similar features.
  • It will cost you signficantly more to re-tube a 100-watt amp.
  • If you are driving a 30- or 50-watt amp hard enough to require frequent re-tubing, chances are very good that you will also drive the 100-watt amp hard enough to require frequent re tubing (at significantly higher cost).
  • Does practcing amplifier need 100w amp?
    Below are relationship between hearing and volume:
    50dB-60dB volume of electric guitar without power.
    70dB-80dB the volume of watching TV and wood guitar 
    80-90dB Volume of solid guitar amp, this volume don't noise your neighbor on day. 
    90dB-100dB The volume of ROCK ,you can start feeling cool ,although it still need more headroom. It is only one fifth of full volume of 30w-50w amp damaging your hearing. Not face to speaker.
    100dB-110dB The volume is very cool. half of volume of 50w amp, good headroom, damaged hearing serious .
    110dB-120dB It is limit of amp. Within a few years hearing of player will be permanently damaged.
  • There is absolutely no venue that requires a larger amp and cabinet than one suitable for use as a stage monitor – provided that the members of the band don't get into a juvenile competition to outdo each other. Need more feedback? Fine, move closer to the amp, for crying out loud! Typically, a really good 30-watt rig with a suitable cab is ample! Depending on the composition of your band and the variety of venues you play, an even smaller rig mic'ed to the PA and then pumped to stage monitors may be even better. Note that while a good 30-watt rig has ample volume you may end up having to buy a more powerful rig to get other desired features.
  • At a small venue, a 15 to 30 watt amp can be placed behind the band in a traditional position and used without a mic. In this position the rig serves as a monitor for the guitarist and as the primary amplification for the guitar.
  • At a medium venue, the small rig can be placed in front of and facing the guitarist as a monitor, and be mic'ed and run through the band's PA. The band's PA speakers are placed along the front of the stage and facing out. This arrangement allows the sound to be balanced at the mixer and allows the band to flood a medium to large venue without damaging their hearing.
  • At a large to giant venue, that same small rig can be arranged much as described above but now the band's mixer feeds the house PA. This is the only way to reach the back of the room without dangerous SPLs near the stage at a large venue and would be required no matter how powerful a rig the guitarist has.
  • Smaller equipment takes up less space on cramped stages.
  • The money you save by purchasing a smaller amp can fund a nice power conditioner to protect your equipment and clean up power line noise the conditioner will cost less too since now you don't need one that will handle a billion watts.
  • If the band members will agree not to compete, all of them can recognize significant savings by not having to purchase unnecessary equipment.
  • Your band is far more likely to be called back for a repeat engagement if you provide a well-balanced, easily managed performance than if you are just obnoxiously and uncontrollably loud.
  • Many guitarists already have the monster amp it isn't necessary to get rid of it. You can use an attenuator (see the attenuator myth) and perhaps a smaller cab.
  • How about amp which power is within 10w?

    It depend on whatsound you want. If you like clean sound, No problem, one 5w combo which has smaller speaker is good for you.But if you want distortion sound(many people want it). It is different.
    There are fours components in total guitar amp syetem.
    No.1 preamp tube distortion( sound hard ,more metal).
    No.2 power tube distortion( sound warm ).
    No.3 speaker distortion ( No-Line of speaker)
    No.4 the physical movement of air that your speakers produce at high volumes.
    When the power of amp is smaller such as 5w.It is difficult to obtain more distortion from power tube. At same time, because the capacity of power tube is smaller, the distortion of preamp is limited . The power push coil of speaker is too smaller . The response of speaker will became bad.

    How Many Guitar Amp Watts Do You really need?

    How much power they really need. Bascially, we determine together how much clean headroom is required and select the amp on that basis.
    Headroom is defined as being the volume at which the amp starts to overdrive or distort the incoming signal from your guitar. Fender Twins are known for producing LOUD clean tones – it’s extremely difficult to get that amp to overdrive. Therefore, it has LOTS of clean headroom.
    A one watt amp designed to produce overdriven and distorted tones (basically more of a distortion pedal than an amp!) will overdrive at very low volume. This type of amp has very low clean headroom.
    So, how do we figure out how much clean headroom and output power is required?

  • Determine the syle of music. There are two extremes that relate power to music style to clean headroom. AC/DC cover band? Crunch all night with extra distortion for solos. Country band? Predominantly clean all night. The cleans have to be loud enough to keep up with your band's stage volume.
  • Determine how to get distortion for solos. Are you going to rely on your amp for distortion or are you going to set up your amp for cleans and use pedals?
  • Determine the venues where the amp will be played. Do you only play at home? Do you occasionally jam with another guitarist or two? In a garage/basement band? Gig in small venues only? Large rooms? Stadiums? The jump from playing by yourself or with another guitarist to play  in a band is step that may require more clean headroom regardless of music style and method of generating distortion. The jump from a band setting in a small venue (basement, small bar) to a larger venue (bigger bar, halls, etc.) may require another increase in clean headroom. The key is to determine when/if your amp will be mid’ed and your band's stage volume.
    The louder you need clean tones the more headroom you need and the more power you require.
    Play music that requires lots of clean tones and you have to be loud enough to keep up with the band on stage? You need more headroom.
    Do you rely on pedals for overdrive and distortion and your amp to be clean all the time? You need more headroom.
    Do you want your amp to produce overdrive and distortion and loud cleans are not as important? You don’t need as much headroom – you want the amp to overdrive at lower volumes. You need to drive the amp into its sweet spot at a volume level that won’t make the first 5 rows of the audience look like those guys riding rocket sleds.
    Now, not all amps are designed the same. Some amps of equal power are specifically designed with more or less headroom. It’s rare to get the opportunity to play an amp in your chosen venue before buying – whether you buy online or from a local store – so you need to rely on knowledgeable players and the manufacturer to guide you.

  • What is the best combination of amp for practicing ?
    We have discussed 100w and 5w guitar amp , know disadvantages of two kind of amp.
    What is good choice for practicing amp?
    One amp, which power is within 50w , is good selection
    2009 Kldguitar Electronics. All rights reserved. Terms/Privacy