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Speaker wattage handling

Discussion in 'Amp Input - Normal or Bright' started by jp66, Sep 16, 2020.

  1. jp66

    jp66 Strat-Talk Member

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    Hey all.

    I'm considering getting a cabinet with an amp head. In high-fi, I know that the more efficient a speaker is, the less powerful your amp needs to be. However, I'm not sure how this translates to guitar amps and speakers.

    My question is how much wattage should the speaker be be able to handle versus the wattage of the head?

    For example, if I get a 5 watt amp head, then should the speaker be less efficient (say a 25 watt speaker) or more efficient (say 50 or 75 watts)?

    How much of a difference would it make in overall loudness, breakup, etc.?

    Thanks,
    JP
     
  2. Cali Dude

    Cali Dude Strat-Talker

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    It really depends upon your taste. I have a 5 watt Clapton vibro champ, and it has an inefficient 8 inch Weber speaker. I also have a Tone King Gremlin, 8 watts, but with a 70watt Celestion. Both sound great.
     
  3. Miotch

    Miotch Senior Stratmaster

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    Topic I researched a lot couple of years ago and will never be an expert on. But when you referred to a 50-watt or 75-watt speaker being more efficient, the wattage rating has no correlation to efficiency, that I know of. To a point, you may be able to ascertain the "efficiency" of a speaker by their SPL ratings. The speakers with the higher power ratings will generally have different coil construction/size and simply be able to handle higher wattage inputs.

    I assumed when I was looking for a speaker for a low-wattage amp, that I would want a speaker with a lower wattage rating, but that isn't necessarily the case. I thought that a speaker rated for 25 watts would be more "efficient" than one rated for 75 watts, thinking the rating indicated it takes less power to drive it. And I was wrong there, too.

    The rule of thumb I kept reading is you want a speaker that can handle at least twice the RMS wattage of your amp. With a typical 5 watt amp, I think any quality speaker rated 15 watts and up would be able to handle it. But I think the voicing of the speaker is where you want to concentrate your focus on, more than the wattage. And, of course, it is always safest to match the impedence with your amp.
     
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  4. jp66

    jp66 Strat-Talk Member

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    Thanks, guys. Yeah - it's easy to figure out when I'm looking at hi-fi speakers how much power the amp has to have to drive them efficiently, but guitar amps appear to be another story. Your input helps clarify things a little more.
     
  5. fezz parka

    fezz parka fezz parka

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    With guitar speaker...wattage ratings = the heat the coil can take.

    A Celestion Blue is a 15 watt speaker. But it's efficiency makes it a loud speaker.

    I've run a 50 watt Red Fang with a five watt Champ. Worked great.
     
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  6. soulman969

    soulman969 Senior Stratmaster

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    True. As you shop speakers check their specs for that speakers sensitivity as measured in decibels, dB. That will allow you to compare the efficiency of one speaker to another.

    A speaker with 102dB rating will be far more efficient and louder with the same amp volume input than a speaker rated 97dB regardless of it's power handling capabilities.

    With a 5w head 15w-20w is sufficient power handling but you can use speakers rated far above that as well and a larger speaker, 12" vs 8", will give you more apparent volume and a "bigger" sound.
     
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  7. Stratomike

    Stratomike Strat-Talker

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    Additionally, there is/can be speaker breakup (or compression) in guitar speakers. This is something you want to avoid at all cost in Hifi of course. But many classic rock tones have very characteristic speaker compression (Greenbacks...). It occurs when you start to push the speaker closer to its max power handling capability. In general guitar speakers are designed to color the tone (they act like a filter). However there are also some very neutral speakers like the EVM12L, which is also more or less immune to speaker breakup due to its 200W power handling rating.

    Premiere guitar has a nice series of article for/from speaker geeks: https://www.premierguitar.com/articles/25831-all-about-speakers
     
  8. BlurgyWurgyWibble

    BlurgyWurgyWibble Strat-O-Master

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    Best sounding amp I own with a strat is a AC4TVH in to a Creamback 65.
    Best sounding amp all round is an AC30 in to two 15w alnico blues.
    Its all to taste. I've even seen people using greenbacks in 100w twin reverbs.
    They just don't turn them up!
    One fellow on youtube just installed 2 15w alnico blues in a blackface twin and swears by them.

    Assuming you understand how speaker power handling works in relation to cones and amps, what you get is roughly as follows.

    1. Higher power handling speakers tend to have tighter bass and will stay clean (in that they will not introduce any dynamic element in to your output in addition to the EQ/frequency response curve of the speaker cone itself and what comes from the amp) even when the signal gets dirty if used with a lower wattage amp. Good for crisp cleans and tight bass. I use 75w Eminence Legends in my 135w Silveface Twin for this reason.

    2. Lower power speakers will introduce speaker distortion as they are pushed to their limit and you get - subjective - speaker "tone" in addition to your amp tone. For me the sound of a severely upset Greenback or Alnico Blue is epic and highly desirable.

    All depends on the application, the amp and what you play. When we think of "vintage" and "classic" tones from records or from great live performances of yester-year, especially with Marshalls and Vox and to a degree Fenders, we are largely hearing a happy mash up of both amp distortion AND speaker distortion. Its like power tube saturation though = unless you dime it you won't hear it. So paying mega bucks for that, but playing at bedroom or modern PA stage volume levels you'll never hear it anyway. Worth bearing in mind..

    Its also worth bearing in mind, in relation to the above, that "Godtone" is very often confused as being the guitar, or the pickups .. when in reality its nearly always the amplifier and the speaker(s) working together in a harmonically pleasing way. And it was always loud as all heck.
     
    Last edited: Sep 25, 2020
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  9. Baelzebub

    Baelzebub Senior Stratmaster

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  10. telepraise

    telepraise Strat-Talker

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    In general, a higher efficiency speaker (say 100db) is going to give you more volume per watt. More clean headroom. You might not be able to get the amp up into the breakup zone without frying your ears if it's a higher wattage amp.

    A lower efficiency speaker (say 93db) will require you to turn the amp up higher to get the same level of sound. More likely to get you up into the amps break up zone.

    It all rests on the wattage rating of your amp head and whether you want to use pedals or the amp's natural break up for overdrive (or stay clean).
     
  11. ptb1

    ptb1 Strat-Talker

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    A HiFi loudspeaker is in general a more complex Construction where the combination of different elements and the filter Constructions makes them more difficult to drive.
    If a loudspeaker is easy or hard to drive has very little to do With the sensivity. That´s just a "standard" expression for how load it can play in db w/1W at a "static" given distance.
    What´s important, and matters here is the resistans curve and the phase angels.

    If Your loudspeaker (nominated 8 ohm) drops as example Down to 2ohm at 80hz you need a very powerful amp to handle the consequence that Your loudspeaker will try to soak the "needed" Power out of Your amp.