Pairing amp and cabinet of different wattage

Discussion in 'Amps and Cabs [BG]' started by UrthCrimson, Nov 23, 2022 at 3:52 AM.

  1. UrthCrimson


    Sep 21, 2022
    I am planning to buy a Darkglass setup. I need some clarification about the pairing of amp and cabinet

    An online dealer is selling Darkglass bundles pairing a 200 watt amp with a 500 watt cabinet. In fact, I have not found where Darkglass produces a 200 watt cabinet, if they do. I have seen none less than 500.

    So how does it work, pairing a 200 watt amp with the 500 watt cabinet? Will the cabinet only be able to utilize (if that’s a proper term) 200 watts with this kind of setup? Or will it calculate to some other ratio?

    Thanks in advance for any clarifications!
  2. two fingers

    two fingers Opinionated blowhard. But not mad about it. Gold Supporting Member

    Feb 7, 2005
    Eastern NC USA
    You're fine. Watt ratings mean very little, actually.

    Bo matter what tye watt ratings are, always use your ears to determine whether or not you're giving the cab more than it can handle. You can absolutely blow the speakers in that cab with a 200W amp. But the speakers will start to get distorted when things are getting to be too much. So test your volume with a clean tone before stomping on any pedals or dialing in overdrive.
    UrthCrimson likes this.
  3. UrthCrimson


    Sep 21, 2022
    Cool! Good to know, thank you so much! So then, what would be the advantage of using, say, a 500 watt amp head? Would you then be able to boost the volume up with less (unwanted) distortion?
  4. el murdoque

    el murdoque

    Mar 10, 2013
    It's like pairing a car that can go 120mph with a set of tires that is rated for 200mph. Works just fine.

    When you pair the same set of tires with a car that can go 200mph, it's also fine - and makes not much of a difference when you never exceed 70mph. It only makes a difference when you want to go faster than that.
    If you occasionally want to do 115mph, the first combo is okay. If you want to do 120mph for extended periods of time, you will have to redline your car a lot. If you don't mind the noise of the engine at max rpm, you're still fine. But if you want the sound and feel of a car that's riding without effort, pick one that can go faster than 120.
  5. JimChjones


    Aug 6, 2017
    SE England
    There's not nearly as much difference between 200W and 500W as one might expect, but yes a 500W ought to go somewhat louder before it runs into distortion. Remember though watts are not a measure of volume. The whole thing is a mess. Amplifier watts are a measure of the power an amp will put out before distortion gets above a certain level. If you wind it up to horrendous levels of distortion it may produce quite a lot more power.
    Speaker watts are a measure of how much power you can put into a speaker system before it gets damaged, usually from overheating.

    There's a lot of poor information in the world about watts and speaker damage, but traditionally if the speaker power rating was double the amplifier rating you were reckoned to be pretty safe. When it comes to high levels of distortion tweeters are most vulnerable. You may see people and web pages talking about underpowering speakers. This is basically a myth. No speakers are damaged by not having enough power.
  6. gtirard


    Feb 22, 2020
    Paris, France
    Agree with all replies above, with one small detail: Agedhorse previously said that some cabs may burn before giving any sign of suffering, so "use your ears" is not always enough.

    There are a lot of threads on this topic, and I understand why it is so confusing for new users or bassists with little technical knowledge. I think that a lot of the confusion comes from the way marketing teams communicate on the products specifications, it really doesn't help.

    Maybe we need a sticky post on the topic, or a Youtube video like "pairing amp and cabs for the dummies" or "what amp power and can power handling do I need?"

    I'm sure a few of us could do that? Not me, because I'm French, and I'm not a technical expert.

    But if one of you want to try to write the definitive explanation, I'd love to offer my help in order to verify that the explanations are straightforward enough for dummies. :) LOL it would be fun.
    BlueTalon likes this.
  7. abarson


    Nov 6, 2003
    Santa Cruz
    Actually, there already is a healthy sticky on this very subject. But who has time to read stickies?
    AMPS FAQ!! Info on OHMS, Allsize RIGS-OverUnderPowerCabs DIY TechTalk-Links
    gtirard likes this.
  8. You don't need too, and in many cases should not get a cab rated at the same power as the amp.
    The 200 Watts of the amp is usually the RMS rating, but it can take short excursions above that.
    The 500 Watts of the cabinet is usually the maximum power rating.
    A 200 W and 500 W cabinet won't sound any different (all else being equal, if that's possible) and the 200w cab may limit your ability to get all you can from your amp. The 500 W cab will usually have plenty of headroom with that amp.
    When playing bass guitar through your cab, you may also need to significantly derate the power for the lower bass frequencies.
    IMHO a 200 W amp and 500 W cabinet is a very good match.
  9. Wasnex


    Dec 25, 2011
    The only concern in the described scenario (IMHO) is whether the rig will get loud enough for your needs.

    Volume is a result of useable power and the sensitivity rating of the cab. Cabs are typically rated at 1W and measured at 1m. So you might see a sensitivity rating like 97dB 1W/1m.

    The decibel change from raising the power from 1W to 200W is Log(200/1) x 10 = 23dB. Add this to your 1W sensitivity rating and you get the volume the rig can produce at the rated power of the amp. 97 + 23 = 120dB. 120dB is fairly loud, but it may not be enough for some situations.

    I normally prefer a rig that is rated to produce at least 124dB. Even this level is not enough for the loudest situations, but I am not willing to turn up beyond this level.

    If you want/need 124dB, you can either use a more powerful amp, assuming the cab can take more power, or you can use a more efficient cab.

    Let's figure out how much power is required to push the cab rated for 97dB 1W/1m to 124dB. The required decibel change is 124 - 97 = 27dB. Now we need to figure how much power is required to produce a 27dB change, so we need to figure out Log(X) = 2.7.

    I haven't had trig for almost 40 years, so I had to Google how to solve Log(X) = 2.7.
    The answer is X = 10 to the 2.7 power which is 501.2W.

    Now let's figure out the Sensitivity rating we need to achieve 124db with a 200W amp. Remember 1W - 200W produces a 23dB change. So the minimum required sensitivity rating is 124 - 23 = 101dB 1W/1m.

    Attached Files:

    mrperkolator likes this.
  10. Marko 1

    Marko 1 Supporting Member

    Mar 9, 2009
    N.E. Ohio
    Get far more watts than you need,

    Get far more cab than you need,

    Now you get the volume you need and no worries. :)
    Last edited: Nov 23, 2022 at 9:45 PM
    chris_b and gtirard like this.
  11. JeezyMcNuggles

    JeezyMcNuggles Supporting Member

    Feb 23, 2018
    Santa Maria, CA
    I suck, but nobody really notices
    A 200w amp, paired with cabinets that equal the minimum load, will produce 200w into the cabinets.

    A 200w, paired with a cabinet that equals twice the minimum load, will produce about 130w into the cabinets.

    A cabs power rating being greater than the amps power rating, is always a good thing. It means that there is pretty much no way to set the cabinet on fire.
  12. DaveB in VA

    DaveB in VA Gold Supporting Member

    May 27, 2015
    Charlottesville VA
    In the simplest terms, an amp's power rating is the maximum number of watts that the amp can output before bad things (i.e., overheating, etc.) may start to happen to the amp. A speaker's power rating is the amount of power (in watts) that can be applied to the speaker before the voice coil of the speaker will begin to overheat. It is important to understand that other physical damage may occur to the speaker before that amount of power is reached.
  13. Killing Floor

    Killing Floor Supporting Member

    Feb 7, 2020
    Austin, TX
    All the Watts come from the amp. So like all setups plug in and let your ears be the judge.
  14. Killing Floor

    Killing Floor Supporting Member

    Feb 7, 2020
    Austin, TX
    This. Except I don’t really know my top line but I have gone about 140 out in west Texas. Point is get the Y rated tires. Brakes aren’t for stopping. They’re to trim away speed. And your cab will sound great too. And don’t drive like I do.
    el murdoque likes this.
  15. Sharko


    Jun 18, 2009
    Washington, DC
    You’re not ready
  16. el murdoque

    el murdoque

    Mar 10, 2013
    ...or move to Germany ;-)

    I'd like to quote Alex from Barefaced:

    Truth #14 - You can safely use any amp with any cab, regardless of power ratings, but if you hear distortion or farting, turn down the volume or the bass knob.

    rodl2005, Killing Floor and gtirard like this.
  17. gtirard


    Feb 22, 2020
    Paris, France
    True for Barefaced cabs, not for all brands.
    Again, Agedhorse said that some cabs may giving any warning.
    I consider that "if Alex says it, it's true", and "if Agedhorse says it, it's true". So I think it is quite safe with Barefaced cabs, but no so safe with any brand.
  18. JimChjones


    Aug 6, 2017
    SE England
    I have to say I am unconvinced. That makes two assumptions:
    One being that running into those regimes for a time doesn't do any permanent damage to the speakers
    The second, and most dangerous one is that the player can actually hear the sound of potential damage in time to back off. I'm sure Mr Barefaced can tell when gear is running into danger, but he has plenty of experience. Personally I have absolutely no confidence that I could hear the wrong sort of distortion or "farting" (whatever that sounds like) in a live situation in time to take action, and for that matter have the self (and band) discipline to back off the volume sufficiently in the middle of a set.

    Mind you, having said that I pay very little attention to the ratings of either my cab or my amp, because I simply don't play very loud any more!
  19. el murdoque

    el murdoque

    Mar 10, 2013

    The big danger is bringing not enough cab to the gig with a mismatched pair of strong amp/weak cab. You won't hear the death rattles of your speakers as they fart the last of their life into the room when you're struggling to hear yourself on a loud stage.

    You should know roughly where the limits are. If your amp is clearly more powerful than your cabinet, it's not a bad idea to carefully approach the limits of the cab from different angles to get an understanding of where they are - and the whole signal chain plays a role here. With an active 5 string where the bass is boosted, you'll reach the limit much easier than with a passive 4 string.
    Nonetheless, you should always bring enough cabs to the gig, so you never get into the situation where you might endanger your cab but actually have no clue because you can't hear it with all the other noise going on.

    I think I only killed one cabinet until I figured that out.
  20. Al Kraft

    Al Kraft Supporting Member

    May 2, 2016
    Northern Virginia
    I have two concerns with this advice. First, it requires that you pay super close attention to the state of your equipment and are able to listen carefully to it in loud band mix...that is rarely my first priority for what to focus on when playing a gig. There are a number of reasons that we as engineers provide product specifications and ratings. One prime reason is to clearly establish an envelope of safe operation that doesn't unduly degrade the life of the equipment or place the user at risk of a catastrophic failure.

    The Barefaced designs may have a more significant design margin/safety margin than other brands so I would not be comfortable generalizing Alex's advice beyond his brand, especially with extreme rating mismatches. In aviation we allow certain more extreme operational conditions for limited periods of time. However, in these cases that "beyond normal limits" operational condition would be explicitly known and most often deliberately operator selected for emergency/urgent reasons.

    IMO Alex's products are exceptional and he is a highly respected designer for good reason. It's simply that my background and experience would have me taking a more cautious approach than simply listening for when to turn down. In many cases (at least outside of the Barefaced product line) some level of damage may already be done by the time you hear something not sounding right.
    Wasnex and gtirard like this.