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120W head into 500W speaker?

Discussion in 'Amps, Mics & Pickups [DB]' started by Jaromir, Dec 30, 2005.

  1. Recently I came back to my old SWR Electric Blue head (with Fishman Blender preamp - sounds really very nice together) and I'm looking for a speaker cabinet to match this head. I would prefer 1x12 configuration and my question is: since most of the cabinets are capable of handling 300 or more watts - will they work good with 120W head (into 8 Ohms)? I mean if the speaker "expects" a lot more power (300 or 500W), will it work optimally at much lower power? Or should I find speaker rated around 100W instead?
    Thanks in advance for your advice / experience!!!
  2. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    The rig will work fine. You can't underpower a speaker. The power rating is simply what the voice coil can tolerate on a continuous basis without catching fire. Consider the extra power rating "room to grow" in case you ever decide to buy a more powerful head. But 100W into a 1x12 may be all you ever need.
  3. AxtoOx


    Nov 12, 2005
    Duncan, Okla.
    Just don't clip it and you'll be fine. Constantly clipping it will blow even a much lager watt cab. Other than that no problem.
  4. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    The good news about clipping is that it mainly destroys tweeters, thus a full-range speaker without a tweeter might be a better choice for your use in this case. If you want a lot of tweet, consider an EA Wizzy cab.
  5. James Hart

    James Hart

    Feb 1, 2002
    Endorsing Artist: see profile
    solid state power amp clipping kills drivers (not just tweeters)

    overdrive / distortion has been rumoured to kill tweeters, but I've seen plenty of Keys and guitar through PA speakers with raging distortion and no issue at all.

    120 watts into a speaker rated @ 500 watts is fine as long as you don't try to make it go louder than it can go.

    I've done a 60 watt head into an 850 watt cab with no problem... I've also done 1100 watts into a 500 watt cab. You play within the limits of your gear and there is no issue

    IMO/E & YMMV
  6. Kevinlee


    May 15, 2001
    Phx, AZ..USA
    This actually happend to me once. I was doing a bass guitar gig, playing through an swr head of some kind into a single 15" cab. I heard the amp cut out and when I turned around there were flames & smoke coming through the speaker grill.

    The opening band lent me a combo amp to finish the set.

    The best part is when I got off stage and people were telling me what a great effect/trick that was and wondered if I did it at all the shows. Entertaining folks by playing music sometimes has very little to do with playing music.
    Sad but true.

  7. seamonkey


    Aug 6, 2004
    If you can get the specs - Compare the sensitivity sound pressure level (SPL DB 1w/1m) of the cabinets you're looking at. You'll more than likely want an efficient speaker.
  8. for your responses - this forum is really amazing!
    So far I've played few gigs with a Flite 112 (no tweeter) cab (rated 500W) and sounded pretty nice. The only issue was that in some rooms I've experienced somehow thinner upper register than I would love to. To be more specific - the higher notes on G string, let's say from c and higher, started to be a little thin, not enough meat.
    Two times I tried out my old Hartke 2x10 (rated 150W) and the upper register on G string was thicker - more in line with the bottom. On the other hand, the bottom itself wasn't as deep and warm as with the Flite... I was wondering if the thinner upper register has something to do with the size of the 12 speaker or with the ported design of the cabinet (the Hartke cab has no port). Or it's just the Flite...
  9. AxtoOx


    Nov 12, 2005
    Duncan, Okla.
    As a rule the 10's will give you more highs than the 12. Ported cabs have more bottom. I haven't played those cabs so I think that's the best I can do. Sorry.
  10. Aleph5


    Feb 24, 2004
    To be more direct about it, a power rating of a speaker has nothing to do with how much power the speaker "expects," but, as stated by others, is just the safe handling limit (in general, without clipping). As seamonkey stated, it's the sensitivity (or sometimes stated in the marketing as efficiency) rating that tells how loud the speaker will be for a given input level.

    Even with a higher amplifier output rating than the speaker's, the average power delivered (which determines voice coil heat stress) will likely be far less than the momentary power reached on musical peaks, and thus would likely fall safely within the speaker's rating. In other words, a 300W speaker would have to receive 300W average power to be damaged, and a 300W head wouldn't be able to put out 300 average watts using normal music waveforms (that is key!) without a LOT of audible distortion (and while such heavy distortion--the clipping--may kill the speaker BEFORE the amp's 300W average output level is reached).
  11. TroyK

    TroyK Moderator Staff Member

    Mar 14, 2003
    Seattle, WA

    Now THAT'S Rock and Roll!