Is this how to compare speaker sensitivities?
 User Name Stay logged in? Password
 Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read Search

 Multi-Way Conventional loudspeakers with crossovers

 Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
 22nd August 2004, 06:43 PM #1 Datoyminaytah   diyAudio Member   Join Date: Mar 2004 Location: Connecticut, USA Is this how to compare speaker sensitivities? A speaker's sensitivity, or SPL, equals the decibel level of 1 watt measured at 1 meter. Right? Now...from googling around, I've found (I think) that multiplying watts times about 1.29 should increase the volume by 1 decibel. That fits pretty well with the general rule I've read that doubling watts increases dB by 3, and that watts x 10 equals double the volume, and that "double the volume" is subjectively measured at between a 6 to 10 dB increase. So, that should mean that a speaker with a sensitivity of 92 dB, supplied with 100 watts, and a speaker with a sensitivity of 88 dB, supplied with 277 watts, should produce about the same perceived volume. The math I used: 92dB - 88dB = 4 decibel difference Multiply 100w @ 88dB times 1.29, 4 times 100w x 1.29 x 1.29 x 1.29 x 1.29 = 276.9w Is that right? If not, please enlighten me.
 22nd August 2004, 07:03 PM #2 Svante   diyAudio Member     Join Date: Feb 2004 Location: Stockholm It seems right to me, even though I get the factor 1.26. Also, the more general power gain formula is 10^(dB/10), so 1 dB is 10^(1/10)=1.26, 3 dB is 10^(3/10)=2.00. But you get the same result (if you use 1.26), so your method is OK too. __________________ Simulate loudspeakers: Basta! Simulate the baffle step: The Edge
 22nd August 2004, 09:51 PM #3 BillFitzmaurice   Banned   Join Date: May 2004 Location: New Hampshire Watts up? Keep in mind impedance also. 2.83 volts into 8 ohms is one watt, but so is 2.0 volts into 4 ohms, and 4.0 volts into 16 ohms. You cannot compare the relative SPLs of different drivers without taking impedance into consideration.
 23rd August 2004, 02:20 AM #4 Datoyminaytah   diyAudio Member   Join Date: Mar 2004 Location: Connecticut, USA Yes, but almost all automotive drivers are 4 ohm, and I wasn't thinking about other impedances. But, could you explain what you mean? Isn't a watt a watt regardless of the volts and impedance used to get it? In your example of 2.83 volts into 8 ohms vs. 2 volts into 4 ohms, if both drivers have the same sensitivity rating, won't they be equally loud? If not, why?
SY
On Hiatus

Join Date: Oct 2002
Location: Chicagoland
Quote:
 A speaker's sensitivity, or SPL, equals the decibel level of 1 watt measured at 1 meter. Right?
Not right. Sensitivity is the SPL at a reference distance (usually 1 m) at a constant reference voltage (usually 2.83 v). That way, under likely drive conditions (most amplifiers are voltage sources), you can know how loud the speaker will be independent of what the impedance is at the reference frequency.
__________________
"You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is."

 23rd August 2004, 04:16 AM #6 wunhuanglo   diyAudio Member   Join Date: Jun 2004 Location: New Orleans, LA Aren't speaker sensitivities quoted as dB/w/m? At least all the ones I've seen are. If so, then 2.83V only applies to 8 ohm impedence speakers.
SY
On Hiatus

Join Date: Oct 2002
Location: Chicagoland
Quote:
 Aren't speaker sensitivities quoted as dB/w/m?
No, they're not, and specifically because impedance is complex and not constant with frequency. I've seen efficiency spec'ed as dB/W/m, but that's a different kettle of fish. And not nearly as useful in design as sensitivity specs.
__________________
"You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is."

BillFitzmaurice
Banned

Join Date: May 2004
Location: New Hampshire
Quote:
 A speaker's sensitivity, or SPL, equals the decibel level of 1 watt measured at 1 meter. Right?
Yes and no. You can quote SPL with 1 watt input, but it's not the only way to compare relative SPLs. They are often stated with a voltage input, which is to some extent a better indication of how loud a speaker will actually be with a given amplifier. That is because an amp will have different wattage output capabilities with different load impedances but it's maximum voltage output never changes.

For an 8 ohm speaker and a 4 ohm speaker with the same wattage sensitivity and the same voltage input the 4 ohm speaker will be 3dB louder, because with the same voltage input the 4 ohm speaker will be receiving twice the wattage as the 8 ohm speaker. If the two speakers are rated for SPL/2.83 volts the 4 ohm speaker will be 3dB higher than the 8 ohm speaker even though the SPL/watt is the same. Therefore the 2.83 v sensitivity rating gives a more accurate representation of how loud different speakers may be with the same voltage input.

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is Off Forum Rules
 Forum Jump User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home Site     Site Announcements     Forum Problems Amplifiers     Solid State     Pass Labs     Tubes / Valves     Chip Amps     Class D     Power Supplies     Headphone Systems Source & Line     Analogue Source     Analog Line Level     Digital Source     Digital Line Level     PC Based Loudspeakers     Multi-Way     Full Range     Subwoofers     Planars & Exotics Live Sound     PA Systems     Instruments and Amps Design & Build     Parts     Equipment & Tools     Construction Tips     Software Tools General Interest     Car Audio     diyAudio.com Articles     Music     Everything Else Member Areas     Introductions     The Lounge     Clubs & Events     In Memoriam The Moving Image Commercial Sector     Swap Meet     Group Buys     The diyAudio Store     Vendor Forums         Vendor's Bazaar         Sonic Craft         Apex Jr         Audio Sector         Acoustic Fun         Chipamp         DIY HiFi Supply         Elekit         Elektor         Mains Cables R Us         Parts Connexion         Planet 10 hifi         Quanghao Audio Design         Siliconray Online Electronics Store         Tubelab     Manufacturers         AKSA         Audio Poutine         Musicaltech         Aussie Amplifiers         CSS         exaDevices         Feastrex         GedLee         Head 'n' HiFi - Walter         Heatsink USA         miniDSP         SITO Audio         Twin Audio         Twisted Pear         Wild Burro Audio

 Similar Threads Thread Thread Starter Forum Replies Last Post Khron Multi-Way 9 2nd August 2005 12:56 PM murat Solid State 4 10th March 2005 05:12 PM murat Everything Else 0 8th March 2005 05:23 PM metebalci Tubes / Valves 8 24th December 2004 12:36 PM Grahamt Multi-Way 2 20th September 2004 06:42 PM

 New To Site? Need Help?

All times are GMT. The time now is 02:45 AM.