Speaker power ratings: a hard line?

Discussion in 'Amp Tech Center' started by Jupiter, Jan 23, 2020.

  1. Jupiter

    Jupiter Telefied Silver Supporter

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    Yeah, my speaker does happen to be 16ohm. I have inferred from a few other sources that watts go down as ohms go up with these SS amps, but it's not clear how much...

    The one I got has this too, though it's not clear how accurate it is, or what happens if you boost the signal on the front end, etc. That said, my other amps are a 6-watter (that does tend to get cranked) and a 15-watter (that has NEVER really sweated), so I feel pretty confident that I can keep the knob on the safe side of the 25w mark for as long as it takes to get another cab together.

    Hmm, that's not very much of a fudge...I'll be careful.

    That sounds wise!

    Yeah, I agree that is an important consideration. The speaker I have was partly chosen for its efficiency. But for the situation I'm in right now, I'm not so concerned about how loud it can get with the amp (I got plenty of watts now) as I am with how careful I have to be to avoid ruining the speaker before I get a new cab.

    That's interesting. I understand that there are plenty of folks who even enjoy speaker distortion, but it seems like you'd also want to know at what point is the thing going to BREAK...

    I generally play pretty clean, but sometimes mess with fuzz and stuff just for goofing around, so I'll bear that in mind.

    I understand the power/volume thing. I even read an explanation of it once, but it didn't stick. :oops: The Master knob on the amp also shows the relationship pretty clearly:
    quilter master knob.JPG

    That's always been my understanding with tube amps, but I kinda wonder about the Quilter, since it's marked as you can see above...

    Well, as you can see above, I do have an actual number, but yeah, still seems nebulous! ¯\_(ツ)_/¯
     
  2. Ricky D.

    Ricky D. Doctor of Teleocity

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    So, it's a gamble. A smart gambler knows how many chips are on the table and can afford to lose them if the hand goes bad. That's what it boils down to.

    So can you afford to blow the speaker? If not, stick to quiet home play only until you have an adequate speaker.
     
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  3. trxx

    trxx Tele-Afflicted

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    I have blown a few speakers over the years. It has always been a single 12", of 50 watts and higher power ratings, using both solid state and tube amps.

    Me: Sounds fine / sound great. I think it'll be ok.
    Speaker: *fizzle* *scratch* *buzz*

    Too bad no one makes speakers that always sound like they are just on the edge of blowing, without actually blowing.
     
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  4. telemnemonics

    telemnemonics Telefied Ad Free Member

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    Can you show a source of this claim?

    AFAIK that is just not true.
    Speakers blow if run for long at or above their rated power handling.
    We hear tales of getting away with using under rated speakers but there we don’t know what volume the lucky owners ran the amps at.
    An AC30 will blow a pair of 15w Celestion Blues though of course that was a common use back when 15w was the highest power handling speaker available.
    The blew and got replaced.
    Same with Marshall’s into 100w or 120w 4x12s, a 100w amp would blow four 30w speakers.
    Modern speakers are pretty much the same aside from handling more power and being used in smaller numbers.
    Power handling is power handling.
     
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  5. Jupiter

    Jupiter Telefied Silver Supporter

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    Yeah, I'd rather avoid that. :lol:

    I'm not gonna be ruined if that speaker dies, but G12H30s ain't cheap, and I'd rather sell it than trash it! I just wanna be able to mess with this amp when it arrives, and it's gonna take a few weeks or more before I have a new cab (either gotta build it or save up for it), so...
     
  6. trxx

    trxx Tele-Afflicted

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    I should clarify here. In every case, I pushed those speakers. I didn't plan to push them, but one thing leads to another, and you have a spanking new baby in the oven.
     
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  7. Old Deaf Roadie

    Old Deaf Roadie Tele-Afflicted Silver Supporter

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    Funny thing about speakers is that you can have a 30 watt rms driver and run considerably more power than those 30w if you can keep the signal crystal clean. Likewise, run a bunch of square waves down the line at 20 watts into that same speaker and you can almost see the life draining from the driver. Of course, telling a guitarist not to use distortion is simply a theoretical excercise, at best. All that being said, a good general rule is to match up with speakers that can handle all the amp's continuous rated power plus about another 30-40% while keeping your impedance within limits. This has served me well for 40 years of tinkering.
     
  8. W.L.Weller

    W.L.Weller Tele-Holic

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    If you set the Quilter to 2w, use all the fuzz/bit-crush/blue box you want.

    If you set the Quilter to 50, you'll still probably be ok (Quilter is 50w at 4 ohms, yr Celestion is 16ohm, higher impedance=less SS output) but I'd stick to Tal Farlow tones at that setting.
     
    Last edited: Jan 24, 2020
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  9. kbold

    kbold Tele-Afflicted Silver Supporter

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    Yes, so long as the input signal is squiggly, the speaker converts it into noise.
    Once the signal flat-lines the energy is being converted into heat (in the voice coil) rather than noise.
     
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  10. W.L.Weller

    W.L.Weller Tele-Holic

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    And it's heat that kills speakers. If you ever blow one up and perform the autopsy yourself, you'll see that you literally melted the thin wire the voice coil is made of.
     
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  11. trxx

    trxx Tele-Afflicted

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    In other words, those (more or less) sine waves become more like square waves (clipped sine waves), where the speaker is seeing significantly more current in the same amount of time, which cooks the windings and insulation of the voice coil.

    Note for the adventurous: When a G12H30 type speaker starts to sound much more like a loud greenback (loses it's pronounced lows and highs and goes all mids), you're probably pushing it too hard. And when you start hearing some nice grit that wasn't there at lower volumes, you're well on your way.
     
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  12. trxx

    trxx Tele-Afflicted

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    Also, for what it's worth, Weber recommends twice the power rating for speakers of the amp's power rating. So if the amp is rated for 50 watts, speakers with a combined power rating of 100 watts would be considered safe with the amp at full tilt.
     
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  13. kbold

    kbold Tele-Afflicted Silver Supporter

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    The speaker is not necessarily seeing more current: the sine wave (squiggly line) moves the cone back and forward (sound), while the square wave (flat-line) does not move the cone anywhere for that moment (equivalent to a DC voltage applied), so the coil absorbs all the energy = heat.
     
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  14. trxx

    trxx Tele-Afflicted

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    I suppose I should have said that the speaker expends more power in the same given time frame (V x A). And I'm just imagining here that the increased heat along with the more sudden square'ish wave swings between the cone moving out and in (hard vibration) is what does the damage.
     
  15. BobbyZ

    BobbyZ Doctor of Teleocity

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    How loud are you really going to play ?
    A G12H30, (I've got the Anniversary) is very sensitive like 100 db you start hitting it with much wattage at all and it's really loud. Really think you're going to even get close to 30 watts?

    The wattage of the amp really doesn't mean anything. It's the wattage the speaker(s) actually get that matters.
    Some guy playing a 100 watt Marshall in his apartment with an attenuator really doesn't have to have 200 watts worth of speakers.
    Of course he thinks he does and so do most people on forums. The fact is one 30 watt G12H30 would do the trick just fine. He sends that speaker even 10 watts and he'll be looking for a new place to live real soon. (volume) As long as he stays in the apartment that speaker is real safe. (although these days that'd probably handle most gigs too)
    You see you get more volume out of a speaker by sending it more wattage. A 100 watt amp is only louder than a 5 watt amp when you turn it up so it's putting out over 5 watts. There's people that have never gone much over 5 watts with their 100 watt amps in this world.
    And they have no clue. It's sad really. And funny when they plug into a Princeton Reverb and ask where the MV is.
    Actually that's sad too.

    Now if you are one of those lucky people with no worries about cops, wifes, killing birds, your ears and you can crank the snot out of a Hiwatt stack, then you better follow that old etched in stone rule of double the wattage. And don't expect to never blow a speaker.
    The trick is knowing what you're actually using. I certainly don't know what other people's actually wattage is so I'll probably fall in line with the twice the amp rule.
    Sounds like you've used that speaker cab before so you can make that call.
     
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  16. Si G X

    Si G X Tele-Holic

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    Then I am mistaken but it's what I was told by my father who is no longer with us and what I always thought was the case. But he wasn't a guitarist, but a hi-fi nut... so maybe different types of speaker are rated in different ways? because obviously distortion is not something you would want from a hi-fi speaker.
     
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  17. Frodebro

    Frodebro Doctor of Teleocity Ad Free Member

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    This is the most accurate response so far. A fifty watt amp isn't putting out fifty watts all the time, only when the volume knob is up around six or seven (typically). For normal, conversation level or slightly louder playing, you're only hitting the speaker(s) with around one half a watt. A speaker with a sensitivity of 96dB (which is about average for most modern speakers), driven by just one watt, is going to be about as loud as firing up a lawnmower in your living room.

    I run my powered Kemper (600W @ eight ohms) into a single 1x12 with a Greenback (25W rating) all the time at home, but I never crank it loud enough to fry it.
     
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  18. trxx

    trxx Tele-Afflicted

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    That is about what I told myself for a DSL50 at around 6 on the master and nearly half-attenuated through a Weber G12H30 50 watter, which definitely has a rubbing voice coil now. How much power you recon I was sending into that speaker? Mid-gain on the classic channel, slightly hotter than vintage PAF style humbucker, still had some good dynamics with softer pick attack, no big bass dialed in, about bar gig level loud.
     
    Last edited: Jan 24, 2020
  19. Ricky D.

    Ricky D. Doctor of Teleocity

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    Hifi signals are a whole different world from guitar signals. Hifi speakers have a crossover that divides frequency ranges among multiple driver, so no one driver gets all the power. Guitar into a hifi speaker, all the power slams one driver, you can forget what the speaker system was rated at.
     
  20. BigDaddyLH

    BigDaddyLH Tele Axpert Ad Free Member

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    Tal could blow speakers not by volume, but by velocity!

     
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