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  Complete Instruments      Instrument Bodies

       Generators           Switching Power Supply



        Synthesizers         Synthesizer Controls




          Amplifiers     Loudspeakers   Resonances        Horns


Favorite speakers on partexpress.com, 2016_02

Full range 4-inchers













Most Efficient Speakers

Speaker Model


Speaker Model at DIYDSP.com



Most efficient speakers available at PartsExpress.com:


     At Exertion Instrument headquarters, we're researching ways to produce the loudest, most efficient portable electronic musical instruments.  Here we present two useful spreadsheets so may also take part in this process.   The first spreadsheet "Efficiency Bass Speakers" lists the predicted efficiencies for about 52 different speakers when used in the exponential Bass Horn configuration.  The second spreadsheet, written and verified against another piece of Windows software by Michael Harradon, will help all of you instrument designers and builders to construct efficient bass horns.  Seriously efficient bass horns.  You may have read that horns can increase efficiency from the 1-3% of a typical loudspeaker, to "up to 50%."  That seems to be the claim I keep running into.  Our spreadsheet has predicted efficiencies of greater than 50%!  Using parameters from real speakers, we have been able to design for 53 and 55%!  Michael was able to show one easy way to predict the range of efficiency of the speaker when used in a bass horn configuration.  Compute this coefficient:   1000 * Qes / Fs.  That is, one thousand times the quality factor of the electrical system of the speaker divided by the speaker's Thiele/Small resonance.  If that value is between 4.67 and 6.67, then the efficiency in a bass horn configuration will be about 50% or greater!  



Efficiency Bass Speakers.xls



4-inch speakers at Parts Express on gdrive



Favorite speakers




     Ever more Interestingly, we found that it's easier to find speakers in the 4 inch range with these characteristics than in the larger range, e.g. 8 inches and greater.  This seems to be because the Fs of smaller speakers is naturally higher.  In fact, Michael produced the "optimum" set of parameters for efficiency:  Fs =  Hz, Qes = . (hold on, retrieving numbers).  Nevertheless, we were still able to find one speaker able to produce 40% efficiency at 8 inches.  And guess what?  It's not unfairly priced either!  Speaking of cost, we found almost no correlation between the factor (1000*Qes/Fs) and the price of the speaker.  This may due because most speaker designers are not concerned with efficiency of bass horns.  Also, it was very difificult to find an appropriate 6" speaker with these specs.  No 7" speakers were found which met the criteria of 4.6 < 1000*Qes/Fs < 6.6.  Anyone who finds a reasonably-priced (<$50) 10" or greater speaker will get a small prize from the people who run this website.  It remains to be examined why some speakers have a lower Qes per Fs and why some do not, but for now, let's buy some speakers.  Here are our favorites so far:


  • "Peerless 850102 4"" SDS Woofer  ($18)
  • "Dayton RS125T-8 5"" Reference Woofer Truncated Frame  ($30)
  •  JAMO 20422 6" Treated Paper Cone Woofer 6 Ohm    ($12) 
  • "Peerless 835004 SDS 6-1/2"" Woofer 4 Ohm      ($10) 
  • "Pioneer B20GR30-51F 8"" Butyl Surround Woofer  ($43)






JVC Speaker from Parts Express


In this section, we analyze some speakers we bought from Parts Express using the Dayton WT3 Woofer analyzer.  



Thiele Small Parameters (as measured by Dayton WooferTester3)


Spreadsheets for determining Instrument Resonator Volume

Jameco Loudspeaker from Parts Express

Speaker Selection Guidelines


Exertion Instruments use common loudspeakers.  For best results, choose speakers with:


  • Higher power rating in Watts (e.g. 5W-100W)
  • Heavier magnets, as they are more efficient than smaller speakers.  (e.g. at least 5-15 oz.)
  • Wider cone, so that smaller, more efficient excursions move a larger amount of air.  (e.g. at least 4-6 inches)
  • Lower internal resistance in Ohms, so that more power is dissipated in the speaker, rather than in the amplifier's transistors.  (e.g. 4 Ohms - 8 Ohms)
  • Softer surround, so that their resonant band is narrower and thus more efficient. 





Good places to buy speakers at surplus prices: 


Speaker Physics Links



Browsing speakers














  Amplifiers  Resonances






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