Speaker power ratings: a hard line?

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

  1. trxx

    trxx Tele-Afflicted

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    What kind of coffee was that guy drinking? Sounds like a hummingbird flew into a jazz session.
     
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  2. MilwMark

    MilwMark Doctor of Teleocity Ad Free Member

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    Right on.

    Why does this come up like every 6 weeks?

    The simple answer - always the same - is:

    It will be fine . . . Until . . . it isn't.

    How long you get away with it is impossible to predict. Kinda like the first quote in red above . . .

    Making this another perfect analogy:

     
    Last edited: Jan 24, 2020
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  3. BigDaddyLH

    BigDaddyLH Tele Axpert Ad Free Member

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    Nothing against anyone giving advice, but I think when I see these threads, "yeah but it's not your speaker that may blow up..."
     
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  4. BobbyZ

    BobbyZ Doctor of Teleocity

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    That's just it I have no idea how many watts anyone is actually using. Nobody does.
    For me I get a ballpark just from having too many darn amps.
    When I lived in town I had a Vibro Champ that was the smallest amp. That amp cranked way up was really about all the volume I used there in that basement. So I figured I was actually using maybe 5 to 10 watts max, even plugged into my 100 watters. Probably less because the VC had the stock 8".
    Now I live in the sticks I haven't figured out my "baseline wattage" here yet. It's a lot higher !
     
  5. telemnemonics

    telemnemonics Telefied Ad Free Member

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    Oh boy does the discussion of safe gambling get going in threads about the sawstop!

    The sawstop is a table saw that costs three times as much as a comparable saw and has a part that literally implodes and locks the blade if you touch the running blade with something like a hot dog or your finger.

    Folks get really worked up and insist that you need one, while others hold up ten fingers and say they’ve run table saws fifty years with no problems.

    My feeling is that if you’re cool with blowing a speaker at home you might as well find the limits of your luck.
    If OTOH you ask “can I gig my 100w Boogie with a 25w GB?” I’d say “no, buy a suitable speaker”.
     
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  6. telemnemonics

    telemnemonics Telefied Ad Free Member

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    BTW I have too many blown speakers in boxes to even remember but there’s gotta be ten or more.

    Also still have all ten fingers after fifty years running table saws.
    OK so part of my LH pinkie is missing but just the tip...
     
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  7. Frodebro

    Frodebro Doctor of Teleocity Ad Free Member

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    I think this is the area where things get muddy. For most home playing (meaning reasonable volume levels that cannot be heard outside your front door), the chances of blowing a speaker are honestly pretty slim. For band/drummer volume levels, or even loud home playing things shift gears completely. I have no concern about running any of my amps (ranging from 15 to 100 watts) through a single, low wattage speaker at home-I never play loud enough to cause the speaker to break a sweat. If I do feel like pushing the volume up a bit, I don't take chances and make sure that I have enough speaker(s) to handle the power they'll be receiving. If I'm playing with others (especially with drums) I follow the basic guideline of double the speaker rating for the power rating of the amp used.
     
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  8. W.L.Weller

    W.L.Weller Tele-Holic

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    What's the plan? Sculpture piece?
     
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  9. BobbyZ

    BobbyZ Doctor of Teleocity

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    I blew three of the CTS alnicos in my '73 Super Reverb almost 20 years ago. Why not four? One was still in the box from Midwest Speaker, guy I bought it from sent it down for a recone and hadn't put it back yet. That ones still going.
    Honestly I don't think volume got those. I think it was stored in a bad environment that dried the glue out more than anything.
    It's Minnesota, I'll blame it on the road salt. :)
     
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  10. Jammin'John

    Jammin'John Friend of Leo's

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    Telecaster.
     
    Last edited: Jan 24, 2020
  11. telemnemonics

    telemnemonics Telefied Ad Free Member

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    Good question!
    Three or four are Altec 417 alnico like Santana used for years for his sig tone and I’d like to get at least one reconed.
    Santana of course blew those altecs regularly.
    One is a mid ‘60s Celestion “Blue” as we call them now, but in original silver finish and I ran that in low wattage amps at low volume off and on for a few years before it blew.
    Several are vintage Greenbacks I blew or got cheap already blown.
    Then there’s maybe a couple of ‘60s ceramic Jensen’s I used until they blew, and always using the vintage speakers at way way below rated power handling.

    I can’t say I’ve blown new speakers but I’ve certainly run some hard enough for long enough that they lost the ability to produce bass properly.

    I bought a showroom clean 28w Carr Hammerhead with the stock Carr branded Eminence that has to be a 50-60 watt speaker and that speaker is pretty much blown. I’d have to listen again to describe it but it just can’t produce bass without sounding crunchy, even with a clean amp sound.
     
  12. telemnemonics

    telemnemonics Telefied Ad Free Member

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    Well of course if you buy an old super with those speakers they often have replaced cones after being blown in the past.
    I always turn it to ten before buying to see if they are still OK.
     
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  13. BobbyZ

    BobbyZ Doctor of Teleocity

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    The '66 SR I bought last year, on ten wouldn't blow a 3" speaker out of a clock radio. :)
    Most old amps I see are like that. So over due for service they're aren't putting out anywhere close to the power they should be.
    I've found with old speakers some, for what ever reason have dried up glue, I've reglued a bunch like that. (Unfortunately with the 73 SR I just pulled the CTSs, stuck something else in and misplaced them during a move.)
    Then you get some like a P12Q from 1958 pulled out of tone cab. Couldn't blow it plugged into a 5e7 running flat out. It's a smooth cone so I figured I'd blow it and recone it. But it held up to that so I'll just keep it as is. Now I need to build a 5e3 or something for it. First World problems. . . . .
     
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  14. telemnemonics

    telemnemonics Telefied Ad Free Member

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    I’ve been amazed at how much abuse some old Jensen’s dan take to the point where I don’t believe the old power handling charts.
    But then some just fall apart of arrive blown, and I guess I used up one or two.

    I wonder if the glue maybe lasts longer if used regularly and warmed up?
    Like at least where the VC is glued to spider and cone and it might warm up?
    Or maybe like you said storage in certain conditions make the old glue fail.

    But while for example the 20w or so P12N blew eventually in HPTTs but ran a while taking double the rated power.
    Might be simply that back then bar volume was just way lower.
     
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  15. Jupiter

    Jupiter Telefied Silver Supporter

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    Not very loud—prolly... I reckon I’ll have a new cab before this thing gets out of the bedroom, but that G12H30 has never been louder than maybe halfway up on my 15w Tweaker, and that was a cavernous space...

    Of course, it’s always caveat emptor with free advice. ;-)
     
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  16. DougM

    DougM Friend of Leo's

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    Although a speaker with 3 db higher sensitivity will be the same volume with 1/2 as much power, it will NOT be twice as loud with the same power input. 3db will only sound slightly louder. To sound twice as loud requires a 10db increase, so a speaker with 10db higher sensitivity, or 10 times as much power into the same sensitivity. Power levels in db's and sound pressure level in db's are not the same thing.
     
  17. BobbyZ

    BobbyZ Doctor of Teleocity

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    The Eminence FDM speakers are a good example of power and SLP ratings being independent. They're rated at about 75 watts but can go from around 91.5 to 100 db by twisting the dial.
    Honestly think if Eminence put demo cabs in stores so people could mess with them, they'd sell a lot more. Then again most people probably buy that sort of thing online anyway.
     
  18. telemnemonics

    telemnemonics Telefied Ad Free Member

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    Your explanation got me confused! but just to clarify, to sound twice as loud you need ten times the watts, into the same speaker.
    Dbs of sound pressure, dbs of gain, and output in watts, are a confusing bunch of numbers!

    The problem created by this scenario, where turning a vol knob from where the amp puts out ten watts to where the amp puts out 100 watts only making the speaker sound twice as loud when it’s getting driven by ten times the power?

    That means that while supposedly 1w sounds kinda loud, and 5w sounds brutally loud, 50w really doesn’t sound a whole lot louder than 5w, or at least 50w certainly doesn’t sound ten times as loud as 5w.

    Not knowing the science, if someone asked me how much louder a 50w Marshall is than a 5w Champ, I’d certainly not guess correctly at only twice as loud.
     
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  19. BobbyZ

    BobbyZ Doctor of Teleocity

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    It's a HELL OF ALOT LOUDER ! :)
    Especially if the Champ has the OEM speakers. Even if you plug the Champ into a 4 ohm cab and try the 1987 Marshall with the same cab. It's a huge difference. Twice as loud? I'd say it's more than that but I wasn't using a db meter at the time.
    Also not sure what constitutes twice as loud on a db meter? The Champ in that cab had to be over 100 db. Based on the speakers ratings at one watt, one matter, Champs put out over one watt. But I know it wasn't over 200 db with the Marshall. It's a weird scale like the Richter scale, twice as much ain't just a simple times two thing.
    Also did a volume war with Deluxe and Twin Reverbs one day. The DR had a slightly more efficient speaker that day but the TR has two. At any rate at a certain point the only way I knew the DR was still on was by looking at the pilot light.
    Even living out in the woods volumes like that could get me in trouble, so it's pretty rare when I'll do stuff like that and frankly even though I like things loud I have my limits. :)
    Really a 12 watt(ish) 6v6 Reverberocket with a G12H30 Anniversary puts out about all the volume I want to hear. I seldom even have that amp over halfway up. Which could already be over 12 watts for all I know.
    One of these days I gotta start using my scope and see what kind of wattage I'm actually using.
     
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  20. DougM

    DougM Friend of Leo's

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    The 5 watt Champ and the 50 watt Marshall would have to have speakers with the same sensitivity. I may have been inarticulate in my explanation, but it's common knowledge in speaker and power amp design circles, and among hifi enthusiasts and audiologists. This is why power is meaningless without knowing speaker sensitivity.
    https//www.noisehelp.com/decibel-scale.html
     
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