dB means??...

Polk addict
Polk addict Posts: 558
edited February 2008 in Basic Hookup/Wiring Questions
What compared to watts?

I have computer speakers, but I only know how many dB their output is, but not the max watts like all the other speakers specs...

It was originally being powered by an amp in the sub that was giving out 44 watts per 3 channels...

I have them set up through a receiver giving 100 watts per channel...
How many watts can I power through these without overpowering them??

The speakers are 1 - 3" and 103dB...
And the sub is 1 - 4" ...

Hope someone can help :cool: ...
Chiranth
hoosier21 wrote:
Cobra + SDA's = dead amps laying all around.
Post edited by Polk addict on
· Share on FacebookShare on Twitter

Comments

  • tcrossma
    tcrossma Posts: 1,301
    edited February 2008
    I don't think there's any correlation, although i'm no expert. But I think it depends largely on the sensitivity of the speaker and configuration.
    Speakers: Polk LSi15
    Pre: Adcom GFP-750 with HT Bypass
    Amp: Pass Labs X-150
    CD/DVD Player: Classe CDP-10
    Interconnects: MIT Shortgun S3 Pro XLR
    Speaker cables: MIT MH-750 bi-wire
    TT:Micro Seiki DD-35
    Cartridge:Denon DL-160
    Phono Pre:PS Audio GCPH
    · Share on FacebookShare on Twitter
  • dragon1952
    dragon1952 Posts: 4,907
    edited February 2008
    The 103dB figure is the speakers sensitivity. It has nothing to do with their total power handling capability. It means that at 1 watt of power and at a distance of 1 meter the speakers output will be 103dB. dB meaning decibels which is a measure of loudness.
    2 channel - Willsenton R8 tube integrated, Holo Audio Spring 3 KTE DAC, audio optimized NUC7i5, Windows 10 Pro/JRiver MC29/Fidelizer Plus 8.7 w/LPS and external SSD drive, PS Audio PerfectWave P3 regenerator, KEF R3 speakers, Rythmik F12SE subwoofer, Audioquest Diamond USB cable, Gabriel Gold IC's, Morrow Audio SP5 speaker cables. Computer - Windows 10/JRiver, Schiit Magni 3+/Modi 3+, Fostex PMO.4n monitors, Sennheiser HD600 headphones
    · Share on FacebookShare on Twitter
  • wizzy
    wizzy Posts: 867
    edited February 2008
    dingleBerry?
    · Share on FacebookShare on Twitter
  • mhardy6647
    mhardy6647 Posts: 33,957
    edited February 2008
    dB = deciBel, or one tenth of a Bel, named after Alexander Graham Bell. It is a dimensionless quantity, always the ratio of two things (i.e., always compared to a reference). it is a compressed, specifically logarithmic scale. A difference of, for example, from 80 to 90 dB of sound pressure (referenced to a specific "minimum audible sound pressure level, by the way) takes 10 times as much power, from 80 to 100 dB takes 100 times the power, etc.

    dB can be used to measure anything, the reference should be specified, though. dB (SPL) references the minimum audible sound pressure level (not that I remember what it is). dBW references 1 watt, dBf references one femtowatt (used in RF tuner specifications).
    The 103dB figure is the speakers sensitivity. It has nothing to do with their total power handling capability. It means that at 1 watt of power and at a distance of 1 meter the speakers output will be 103dB. dB meaning decibels which is a measure of loudness.

    We infer the one watt (more typically, 2.83 VAC, which corresponds to 1 watt into an 8 ohm load) at 1 meter. These are standards, but not necessarily universally applied! So, your speaker, fed 2.83 VAC of white noise, should measure 103 dB SPL (VERY loud) at a distance of 1 meter away, on axis. I actually would doubt it's that sensitive, but that's another story!

    The 103 dB sensitive speaker (let's assume it's 8 ohm) will put out 106 dB at 1 meter when fed with 2 watts, 109 dB with 4 watts, etc. If you wanted 123 dB out of it (well past a safe SPL), you'd have to feed it 100 watts of signal.
    · Share on FacebookShare on Twitter
  • McLoki
    McLoki Posts: 5,231
    edited February 2008
    Also - every time you double the distance from the speaker it drops 6db. So if you sit 4 meters from your speakers (about 13 feet) You would have to start your count up of doubling watts at 91db for 1 watt at 4 meters.

    1 watt = 91
    2 watts = 94
    4 watts = 97
    8 watts = 100
    16 watts = 103
    32 watts = 106
    64 watts = 109
    128 watts = 112
    256 watts = 115
    512 watts = 118
    1024 watts = 121

    So sitting 12 feet (ok, actually about 13' since its metric) away from your speaker instead of only 3' away means your 100wpc amp needs to be traded in for a 1,024wpc one to play at the same insane level.

    That is why if you listen loud - large amps (or really efficient speakers) are needed. If you get a speaker with 3db higher efficiency, it is like doubling the power of your amp. (volume wise)

    Michael
    Mains.............Polk LSi15 (Cherry)
    Center............Polk LSiC (Crossover upgraded)
    Surrounds.......Polk LSi7 (Gloss Black - wood sides removed and crossovers upgraded)
    Subwoofers.....SVS 25-31 CS+ and PC+ (both 20hz tune)
    Pre\Pro...........NAD T163 (Modded with LM4562 opamps)
    Amplifier.........Cinepro 3k6 (6-channel, 500wpc@4ohms)
    · Share on FacebookShare on Twitter
  • Polk addict
    Polk addict Posts: 558
    edited February 2008
    Cool!!

    There's a lot that just went straight over my head...

    But that explains a lot about why most speakers by Polk (08') have about 90 dB ...

    As for how many watts... I guess Ima have to figure that out myself... *runs over to receiver remote*
    Chiranth
    hoosier21 wrote:
    Cobra + SDA's = dead amps laying all around.
    · Share on FacebookShare on Twitter
  • mhardy6647
    mhardy6647 Posts: 33,957
    edited February 2008
    McLoki wrote: »
    Also - every time you double the distance from the speaker it drops 6db. So if you sit 4 meters from your speakers (about 13 feet) You would have to start your count up of doubling watts at 91db for 1 watt at 4 meters.

    1 watt = 91
    2 watts = 94
    4 watts = 97
    8 watts = 100
    16 watts = 103
    32 watts = 106
    64 watts = 109
    128 watts = 112
    256 watts = 115
    512 watts = 118
    1024 watts = 121

    So sitting 12 feet (ok, actually about 13' since its metric) away from your speaker instead of only 3' away means your 100wpc amp needs to be traded in for a 1,024wpc one to play at the same insane level.

    That is why if you listen loud - large amps (or really efficient speakers) are needed. If you get a speaker with 3db higher efficiency, it is like doubling the power of your amp. (volume wise)

    Michael

    All true... although it's worth adding (reiterating) that a truly 103 dB sensitive speaker is pretty danged efficient!

    Oh, and a minor semantic quibble. The parameter reported as dB/W/m is accurately called sensitivity. Efficiency measures just that; the efficiency of the speaker's conversion of power in into noise (umm, sound) out. It is said that a symphony orchestra playing at full tilt (ffff maybe?) has an acoustic power output of 1 watt. If it takes a speaker 100 watts in to match that 1 watt acoustic power output, the speaker is 1 percent efficient. Some of the big, horn-loaded speaker systems manage (IIRC) efficiencies of several percent.

    http://www.crutchfieldadvisor.com/ISEO-rgbtcspd/reviews/20030722/match_speakers.html?print=1&page=all
    · Share on FacebookShare on Twitter
  • McLoki
    McLoki Posts: 5,231
    edited February 2008
    mhardy6647 wrote: »
    All true... although it's worth adding (reiterating) that a truly 103 dB sensitive speaker is pretty danged efficient!

    Oh, and a minor semantic quibble. The parameter reported as dB/W/m is accurately called sensitivity. Efficiency measures just that; the efficiency of the speaker's conversion of power in into noise (umm, sound) out. It is said that a symphony orchestra playing at full tilt (ffff maybe?) has an acoustic power output of 1 watt. If it takes a speaker 100 watts in to match that 1 watt acoustic power output, the speaker is 1 percent efficient. Some of the big, horn-loaded speaker systems manage (IIRC) efficiencies of several percent.

    http://www.crutchfieldadvisor.com/ISEO-rgbtcspd/reviews/20030722/match_speakers.html?print=1&page=all

    true enough, and there is additional benefit to having 2 speakers together rather than just one. (just like when running 2 subs) but still, the basic premise is all I was going for....
    Mains.............Polk LSi15 (Cherry)
    Center............Polk LSiC (Crossover upgraded)
    Surrounds.......Polk LSi7 (Gloss Black - wood sides removed and crossovers upgraded)
    Subwoofers.....SVS 25-31 CS+ and PC+ (both 20hz tune)
    Pre\Pro...........NAD T163 (Modded with LM4562 opamps)
    Amplifier.........Cinepro 3k6 (6-channel, 500wpc@4ohms)
    · Share on FacebookShare on Twitter
  • Polk addict
    Polk addict Posts: 558
    edited February 2008
    Ok, I see... I think it's making sense now...
    Chiranth
    hoosier21 wrote:
    Cobra + SDA's = dead amps laying all around.
    · Share on FacebookShare on Twitter
  • mhardy6647
    mhardy6647 Posts: 33,957
    edited February 2008
    oh, and one of my favorite pieces of semi-useless trivia.
    one horsepower = 746 watts

    A 100 watt amplifier, then, can also be described (with a completely straight face) as a (roughly) 0.134 horsepower amp.
    · Share on FacebookShare on Twitter
  • mhardy6647
    mhardy6647 Posts: 33,957
    edited February 2008
    two speakers/two channels vs. one = 3 dB more SPL (all things being equal).
    · Share on FacebookShare on Twitter
  • obieone
    obieone Posts: 5,077
    edited February 2008
    I'm not, 100% sure what went on here, but from my understanding, if you're trying to convert the db measure being displayed on the rcvr and convering it to watts, I've been told it can't be done, because different manufacturers use different reference points?
    I refuse to argue with idiots, because people can't tell the DIFFERENCE!
    · Share on FacebookShare on Twitter
  • Polk addict
    Polk addict Posts: 558
    edited February 2008
    LoL... That's some funny trivia!
    Chiranth
    hoosier21 wrote:
    Cobra + SDA's = dead amps laying all around.
    · Share on FacebookShare on Twitter
  • treitz3
    treitz3 Posts: 19,184
    edited February 2008
    What's funny is the fact that most manufacturers base the data upon 1 watt @ 1 meter. Hell, in an equilateral triangle you could reach out and touch the sons-a behauches! Who listens to the speakers at 3 freakin' feet away? Not many.

    I know it's a measurement, but why not do it 2-3 meters away to where most [I would guess] of the public listens?

    Nevermind. I don't want to know. Just food for thought and what's on my sarcastic mind tonight.
    ~ In search of accurate reproduction of music. Real sound is my reference and while perfection may not be attainable? If I chase it, I might just catch excellence. ~
    · Share on FacebookShare on Twitter
  • mhardy6647
    mhardy6647 Posts: 33,957
    edited February 2008
    What's funny is the fact that most manufacturers base the data upon 1 watt @ 1 meter. Hell, in an equilateral triangle you could reach out and touch the sons-a behauches! Who listens to the speakers at 3 freakin' feet away? Not many.
    It is just a standard. Easily replicated. The old EIA standard for SPL was dB SPL at 40 feet for 1 watt. If you go to the Electrovoice website and look at the specs on their venerable old drivers, you'll see sensitivity levels at the EIA standard. Sort of a PA thing.

    The "1 watt" is probably the most potentially misleading parameter that is sometimes misused deliberately. One watt for an 8 ohm speaker is 2.83 volts of AC. For a 4 ohm speaker, 2.83 VAC is two watts. Boing, instant 3 dB gain in sensitivity -- but not per watt (strictly speaking)!
    · Share on FacebookShare on Twitter
  • Polk addict
    Polk addict Posts: 558
    edited February 2008
    treitz3 wrote: »
    What's funny is the fact that most manufacturers base the data upon 1 watt @ 1 meter. Hell, in an equilateral triangle you could reach out and touch the sons-a behauches! Who listens to the speakers at 3 freakin' feet away? Not many.

    I know it's a measurement, but why not do it 2-3 meters away to where most [I would guess] of the public listens?

    Nevermind. I don't want to know. Just food for thought and what's on my sarcastic mind tonight.

    Well, for Polk's defense these are comp. speakers... I just tore apart the chips in the cabinet a little...
    Chiranth
    hoosier21 wrote:
    Cobra + SDA's = dead amps laying all around.
    · Share on FacebookShare on Twitter
  • mhardy6647
    mhardy6647 Posts: 33,957
    edited February 2008
    I'm not, 100% sure what went on here, but from my understanding, if you're trying to convert the db measure being displayed on the rcvr and convering it to watts, I've been told it can't be done, because different manufacturers use different reference points?

    The OP was asking about speaker sensitivity (EDIT, well, that's the question I tried to answer).

    I don't know what the "zero dB" reference is on these HT receivers (I know nothing about them), but it is quite likely "unity gain" for the preamp section, i.e., that point at which the line-level input signal is neither amplified nor attenuated by the receiver's preamp section. Unity gain is 0 dB by definition if the input signal is the reference point. Basically the (base 10) log of the line level divided by itself is zero. Attenuation would be "-dB" and amplification (gain) would be "+dB" for this reference.
    · Share on FacebookShare on Twitter
  • ward91
    ward91 Posts: 338
    edited February 2008
    my marantz had a "unity gain" at zero db on the readout, kinda helpfull. my cambridge is not like this, i the loudest id listen to it on is -18db with a movie and music on -20 ish, the preamp section only goes to -6 and then reads "max vol".
    ELECTRONICS
    arcam cd93
    linn wakonda
    MC2 MC450
    Teac ud h01 DAC


    SPEAKERS
    Tannoy DC6 t se .
    · Share on FacebookShare on Twitter
  • [Deleted User]
    [Deleted User] Posts: 7,658
    edited February 2008
    Hello,
    Interesting thread. Here's another fact about our friend the "dB", since these are logarithmic values they can't be added or subtracted directly. For example if we wanted to combine 75 dB and 80dB it would be 81.2dB. If we wanted to subtract 81dB from 90dB the result would be 89.4dB.
    Have fun, Ken
    · Share on FacebookShare on Twitter
  • jakelm
    jakelm Posts: 4,081
    edited February 2008
    Is there a way to figure out the sensitivity of a speaker, with a reading of a stadard SPL meter?

    Or how many watts at a certain distance with a certain spl reading?

    Example: (If I can make my self clear enough)

    If I'm standing 10 feet away from a speaker that is 8ohms, and I get a 80dB reading on my spl meter with pink noise. I know the distance and I know the dB's. Can I figure out how many watts my amp is putting out?

    Or would I have to calculate what the 1w/1m reading is first. Then back up to 10 feet , then take another reading, then increase the dB's. Then do the calculation?

    If I have a 92dB eficient speaker and I get 100dB's @ 10 feet. How many watts is my amp putting out?
    Monitor 7b's front
    Monitor 4's surround
    Frankinpolk Center (2 mw6503's with peerless tweeter)
    M10's back surround
    Hafler-200 driving patio Daytons
    Tempest-X 15" DIY sub w/ Rythmik 350A plate amp
    Dayton 12" DVC w/ Rythmik 350a plate amp
    Harman/Kardon AVR-635
    Oppo 981hd
    Denon upconvert DVD player
    Jennings Research (vintage and rare)
    Mit RPTV WS-55513
    Tosh HD-XA1
    B&K AV5000


    Dont BAN me Bro!!!!:eek:
    · Share on FacebookShare on Twitter