"TRUE" 18" Driver Reference Efficiency Calculator |
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levyte357
The 10,000 Points Club Joined: 10 May 2004 Location: UK, London Status: Offline Points: 11743 |
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Posted: 18 May 2012 at 3:01pm |
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For those sick of dubious manufacturer sensitivity figures.
http://www.mh-audio.nl/Reference.asp Edited by levyte357 - 18 May 2012 at 6:27pm |
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"Who am I? I'm the guy who does his job.. You must be the other guy".
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levyte357
The 10,000 Points Club Joined: 10 May 2004 Location: UK, London Status: Offline Points: 11743 |
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Figures so far,
(Excel spreadsheet image) Edited by levyte357 - 14 June 2012 at 12:04pm |
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"Who am I? I'm the guy who does his job.. You must be the other guy".
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PauliePaul
Young Croc Joined: 14 August 2009 Location: Birmingham Status: Offline Points: 1485 |
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Do the Fane Colossus 18B and 18B600 too..... it may a few!!
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Tony Wilkes
Old Croc Joined: 02 August 2004 Location: West Midlands Status: Offline Points: 4840 |
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Ray, what is the bottom BMS drive unit?
If you want to stick a BMS driver up that is more representative of the rest on the list then you should have chosen the 18S430v2 Tony Edited by Tony Wilkes - 19 May 2012 at 10:47am |
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www.forteaudio.eu - BMS - db-Mark Processors - Lexon (SAE)
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SBC
Registered User Joined: 25 November 2010 Status: Offline Points: 1266 |
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that goes for many drivers... this calculator basically just take this thread (which has been up for ages) one step further by putting it into a dB figure. http://forum.speakerplans.com/calculating-real-subwoofer-efficiency_topic36294.html
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F.T.S.S.
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IanD
Registered User Joined: 17 January 2009 Location: London Status: Offline Points: 400 |
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If you want a formula that relies on physical parameters rather than calculated ones, you can use:
dBref=20*LOG10(BL*Sd/(Mms*SQRT(Re)))+59.4 -- the reason should be obvious, it's proportional to (BL/sqrt(Re) and Sd, inversely to Mms. V18-1000 97.6 Turbomax 1800i 97.4 etc etc I've found that the physical parameters often seem more realistic than the derived ones like Vas and Qes, but this may not always be true... Edited by IanD - 19 May 2012 at 11:24am |
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_djk_
Old Croc Joined: 23 November 2004 Location: United States Status: Offline Points: 6002 |
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The driver No=% is for the octave between the EBP and the Mass Corner, and as we can see is not a good indicator of how the driver will produce bass (we need a speaker program for that). From the above example, the least efficient driver produces the most bass below 100hz. The most efficient driver is 3.39dB more efficient, but requires about 3dB more power to play as loud as the least efficient driver (in the bass), and even then will probably not be able to play as loud due to power compression. |
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djk
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SBC
Registered User Joined: 25 November 2010 Status: Offline Points: 1266 |
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from real world listening however, i will say, and i think a few will agree, the chart at the beginning of the thread is very realistic compared to results of the above calculation.
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F.T.S.S.
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IanD
Registered User Joined: 17 January 2009 Location: London Status: Offline Points: 400 |
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Of course reference efficiency doesn't tell you how a driver will perform in a cabinet especially at the bass end, this totally depends on the cabinet (reflex, bandpass, horn, tapped horn, hybrid...) -- drivers with high efficiency have bass rolloff because of low Qes unless you use a cabinet suited for such drivers, which tends to mean a big horn.
But it is one of the basic "how efficient is the driver" parameters, and is the one that manufacturers should use to describe efficiency -- not the response at 500Hz for a sub driver like some do... If you want to compare the "derived" (first post) vs. "physical" numbers (my equation): Driver Derived Physical Difference V18-1000 97.5 97.6 0.1 V18-1200 95.4 94.7 0.7 18NLW9600 94.8 95.0 0.2 Tmax 1500 94.8 97.9 3.1 18SW115 94.6 94.7 0.1 Tmax 1800 94.6 97.4 2.8 BMS 18N860 92.5 92.6 0.1 It should be obvious which manufacturers have consistent parameters and which don't (Turbomax)... Edited by IanD - 19 May 2012 at 12:13pm |
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levyte357
The 10,000 Points Club Joined: 10 May 2004 Location: UK, London Status: Offline Points: 11743 |
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+1 Is very easy to get lost in equations/graphs, without a realistic point of reference, i.e., having heard most of the above drivers in the chart. Ask anyone who has, and they will tell you, Turbomax/Celestion CF18JVD require huge amounts of power to do anything useful, where as V18-1000 sounds louder than mighty 1850 with same amount of power. The initial calculator/chart mirrors the actual driver performances/comparisons in reality (have personally heard/compared all of them except the Neos), therefore I won't be considering any other theorem in this thread.
http://www.lautsprechershop.de/pdf/bms/bms-18n830.pdf I just put up BMS drivers I've seen mentioned on SP, or drivers members say they have bought. Edited by levyte357 - 19 May 2012 at 1:14pm |
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"Who am I? I'm the guy who does his job.. You must be the other guy".
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levyte357
The 10,000 Points Club Joined: 10 May 2004 Location: UK, London Status: Offline Points: 11743 |
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Driver added. Would expect this driver to have a "very" warm sound, and drop very deeply indeed. Even though "honest" Xmax of 8mm is detailed, by other manufacturers "fudge factor", the Xmax would be approx 10mm. If BL was higher, would be such a serious contender for the big boys, especially at the price. Edited by levyte357 - 19 May 2012 at 1:09pm |
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"Who am I? I'm the guy who does his job.. You must be the other guy".
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levyte357
The 10,000 Points Club Joined: 10 May 2004 Location: UK, London Status: Offline Points: 11743 |
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Just updated table, to include FAITAL PRO 18HP1020.
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"Who am I? I'm the guy who does his job.. You must be the other guy".
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