Cab limits

Discussion in 'Amps and Cabs [BG]' started by Colin Boonstra, Jan 10, 2019.

  1. Colin Boonstra

    Colin Boonstra

    Jul 8, 2018
    Hi everyone
    I have a question that is about tube amps, solid states and cabinets. If a solid state runs lets say 250watts and i plug it into a 350watt cabinet i should be fine but how does it work with tube amplifiers? If i would run a 250 watt tube amp into a 350 watt rated cabinet would it blow the speakers because the tubes go way louder?

    Thanks in advance

  2. Al Kraft

    Al Kraft Supporting Member

    May 2, 2016
    Northern Virginia
    The simple answer is that a notional 250 Watt head plugged into a 350 Watt rated cab should be fine regardless of what (tubes or SS components) is producing the 250 Watts - and this assumes that the head is producing that Wattage or less at the same impedance the cab is rated for. Do be aware that even a 100 Watt amp can be pushed hard enough to potentially do damage to a 350 Watt speaker, so common sense and listening is always recommended when cabinet safety is concerned.
    eriky4003 likes this.
  3. Safety is way over rated. Note also that a tube amp usually outputs its maximum into a selection of impedance loads while a Solid State produces somewhat less at 8 ohms than 4.
    Al Kraft likes this.
  4. Wasnex


    Dec 25, 2011
    Often the power rating of a speaker is related to the thermal rating of its voice coil. The mechanical power handling is determined by both driver characteristics and the tuning of the cab it is used in. The mechanical power handling under 100hz can be significantly lower than the driver's thermal rating.

    Take a look at the attached cabinet tuning document and note some designs are thermally limited and some are mechanically limited. Take a look at the cone displacement graph to see what happens to cone excursion at the port tuning frequency (labeled Fb), and also what happens to excursion as the frequency dips significantly below Fb. This will give you a good idea why high pass filters (HPF) have become popular. @Stumbo has a thread on HPFs if you are interested.

    You really can't give a generic answer that applies to all tube and solid amps. Each amp is different and the way amps are rated varies from one manufacturer to the next. Some 250W amps can make a lot more power than 250W, and some don't make their rated power.

    Attached Files:

    Last edited: Jan 10, 2019
    Wisebass likes this.
  5. JimmyM


    Apr 11, 2005
    Apopka, FL
    Endorsing: Yamaha, Ampeg, Line 6, EMG
    Forget numbers and use your ears and good judgment .
    Wisebass, MrLenny1 and Wasnex like this.
  6. Wisebass


    Jan 12, 2017
    Lost in Space
    Hi Colin :)

    This!!!!! :thumbsup: :D

    Ears and common sense will help you more than numbers!


    may the bass be with you

    Mingo Sanders, Stumbo and JimmyM like this.
  7. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

    Sep 22, 2021

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