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Amp to cab power recommendations ?

Discussion in 'Amps and Cabs [BG]' started by luknfur, Feb 3, 2004.

  1. luknfur


    Jan 14, 2004
    Replied to a post and saw some interesting posts thereafter and was wondering what kind of kind of response to a post I'd get regarding power players suggest using for amp and cab(s). One guy suggested double amp to cab power. Speakers are built to take more than their power rating but that seems a bit much. I recall in the past reading a "pro" recommendation of amp power to be 75% of cab(s). So what say you?
  2. I think a perfect match (power and cab being equal) is a good starting point. Anything more then about 2x's the power though and you're running into a bit of over-kill (IMO). My cabinet is rated at 750 watts RMS and I run 1400 watts into it. This gives me all of the headroom I would ever likely need, allowing me to utilize the full volume potential of the cabinet (if I ever needed to) without distorting the amplified signal from my pre-amp. It's really about taste, preference, needs, etc... Some amps actually sound better when diven really hard. That just isn't the sound I'm looking for!
  3. My thought - worth less than a cup of coffee is this:

    If you have a SS amp that clips - you'll soon blow the speakers. Digital amps sound horrible when they clip.

    If you have a tube amp that you run into a small amount of clip - you may eventually blow the speakers, but you'll probably love the sound. It take a lot of experimentation to get the right combination, but it can be magical. Because it's also heavy and a difficult to achieve balance in the ever changing gig situation, it's not very practical.

    The standard recommendation seems to 2x (amp 2x the speakers) so speakers distort before the amp clips, saving blown speakers, but I think it really depends having enough speaker for your playing situation - if you are not driving them too hard, e.g., using an actual 200 watts of a 600 watt speaker rating, you can get away with a lower power amp.

    Interestingly for guitar amps, it's generally opposite - folks love tube distortion so they often choose speakers rated 2x the amp. My choice for guitar is a tube amp run into a small amount of clip, and speakers with a small distortion too - My home rig is a 15 watt Princeton into a 30 watt Jensen.
  4. Richard Lindsey

    Richard Lindsey

    Mar 25, 2000
    Metro NYC
    Not to be blunt, but you should do a search in this. It's been discussed here a lot.

    Briefly, i'd say that focusing on the amp-to-cab ratio is really kinda missing the point. What's more important is ratio of the power your amp can put out to the power you need to get the volume and tone you want for your playing situation. Once you have enough power--or better yet, more than enough--it doesn't matter whether the cab is rated at less than the amp, the same as the amp, or more than the amp, *provided that it can take at least the amount of power you dish out when you play*, which as many have noted is often considerably less than the full rated power of your amp. Having an amp rated higher than your cab, in itself, isn't what gives you headroom: having an amp with more power than you need to get the volume and tone you want is what gives you headroom.
  5. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    You'll blow the speakers if the amp puts too much power into them, not necessarily by clipping.

    There are very, very, very, very few digital amps on the market. Their clipping characteristics will largely depend on whether the output section clips (in which case the amp will behave in a manner consistent with that kind of output section and power supply) or the digital data stream "clips"—i.e., tries to exceed full scale. Depending on how bad the "clipping" is, it may sound horrible—nevertheless, many commercially released CDs have peaks that digitally "clip," and they still sound good.
  6. natrab


    Dec 9, 2003
    Bay Area, CA
    I think he was just meaning that when SS amps clip they can do damage as well as sound horrible.

    I'm a big fan of overkill. My PLX 3402 can run my bass rig as well as the PA (in mono) if required. I just like having the resources.

    A good rule is twice the power of the cabs. That gives you headroom as well as the ability to add another cab later.
  7. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    I meant that it doesn't take clipping to do damage. ;)

    If you severely clip a 100-watt amp driving a 500-watt (continuous) speaker, you won't damage the speaker. However, do the same thing into a 100-watt speaker, and trouble is on its way, for the magic smoke will soon be released from the speaker's voice coil.

    The hidden danger in clipping is that the amp's output then exceeds its power rating.
  8. luknfur


    Jan 14, 2004
    Appreciate the responses. Hadn't really thought about it but the recommendation I recalled I'm sure was in reference to guitar, not bass. And actually, I hadn't realized there was a search option for this site. Also, in posting I was thinking along the lines of potential situations for damaging equipment. But a general phrasing generates a broader spectrum of potentially useful information.