CIGARBUM Posted December 11, 2009 Share Posted December 11, 2009 Is there a performance difference between a 8-ohm and a 16-ohm driver??? cb Quote Link to comment Share on other sites More sharing options...
kouack Posted December 11, 2009 Share Posted December 11, 2009 Driver itself not really, you will need twice the power to achieve same level of SPL. Quote Link to comment Share on other sites More sharing options...
Don Richard Posted December 12, 2009 Share Posted December 12, 2009 The voice coil inductance will be higher for the 16 ohm driver, as well as the resistance. The Qes will be higher also. Quote Link to comment Share on other sites More sharing options...
CIGARBUM Posted December 12, 2009 Author Share Posted December 12, 2009 What is the preferred type, or is there a perferred type? cb Quote Link to comment Share on other sites More sharing options...
JohnA Posted December 12, 2009 Share Posted December 12, 2009 What is the preferred type, or is there a perferred type? cb There are sometimes small differences in sensitivity between 8 and 16 ohm versions of the same driver. The preference is for a uniform impedance across the frequency response of the system, as much as possible. Transistor amps usually tolerate wide impedance variations better than tube amps. The reason is the amp designmore than the properties of tubes or transistors. Quote Link to comment Share on other sites More sharing options...
kevinmi Posted December 12, 2009 Share Posted December 12, 2009 I use ALK universal crossover clones built by Gothover which are wired to have a 8 ohm load present to the amp no matter what impedance drivers you use. This way I can use my K-55V 16 ohm or my SelenuimD405 8 ohm drivers without changing anything, (except big ole horns and drivers). -kev Quote Link to comment Share on other sites More sharing options...
djk Posted December 13, 2009 Share Posted December 13, 2009 "The voice coil inductance will be higher for the 16 ohm driver, as well as the resistance. " The one negates the other. "The Qes will be higher also." No, it won't. See JBL 2226 G/H/J parameter for a good example. http://www.jblpro.com/catalog/support/getfile.aspx?docid=1075&doctype=3 The only thing that really changes is the Bl product (and the Re), but (Bl^2)/Re is constant, and that is what matters. ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- What about Bl? What about it? It is frequently asserted (without proof) that a 'high Bl is better'. Is it? As we saw above, if we want a high Bl all we need do is specify a 16 ohm driver. Of course it is the same exact driver as the 4 ohm driver and performs no different when fed the same power (adjusted for impedance). Comparing the same impedance speakers though, increasing Bl dramatically increases the driver's true efficiency at all frequencies but radically decreases nominal power efficiency in the bass range. http://www.xlrtechs.com/dbkeele.com/PDF/Keele%20(2003-10%20AES%20Preprint)%20-%20Nom%20vs%20True%20Eff%20High%20BL.pdf A real word example of three 15" woofers with a Bl of 19.7, 21.3 and 27.5: Note how the lowest efficiency woofer with the lowest Bl has the higest output in the 50hz~80hz range (dance music application) for a constant 80V input? ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Compression drivers are a bit different. The maximum nominal efficiency occurs when the reflected acoustic load resistance equals the driver 's voice-coil resistance and the maximum true efficiency occurs when the reflected acoustic load resistance is much higher that the driver’s voice-coil resistance. In other words, the lower the resistance the higher the efficency ends up. Or does it? With a finite mouth size, a smalled sized horn will have wide ranging peaks in its resistance. The lower the resistance of the driver, the higher the acousic output of these peaks will be. The trend to building ultra low impedance drivers (Re=3R2 on drivers advertised as being 8R) may make them loud, but they are also peaky. http://www.xlrtechs.com/dbkeele.com/PDF/Keele%20(2004-10%20AES%20Preprint)%20-%20Maximum%20Efficiency%20of%20Compression%20Drivers.pdf Why do big horns sound better? Quote Link to comment Share on other sites More sharing options...
Don Richard Posted December 13, 2009 Share Posted December 13, 2009 "The voice coil inductance will be higher for the 16 ohm driver, as well as the resistance. " The one negates the other. How does inductance negate resistance? The vector sum of inductive reactance, capacitive reactance, and DCR determine impedance, with DCR @90 deg. Thus any added resistance will increase impedance. "The Qes will be higher also." No, it won't. Yes, it may. Every Eminence driver I examined has a higher Qes with the higher impedance driver. Quote Link to comment Share on other sites More sharing options...
djk Posted December 13, 2009 Share Posted December 13, 2009 "How does inductance negate resistance? The vector sum of inductive reactance, capacitive reactance, and DCR determine impedance, with DCR @90 deg. Thus any added resistance will increase impedance." As a high frequency pole it works out the same. "Yes, it may. Every Eminence driver I examined has a higher Qes with the higher impedance driver. " Eminence? It's not the same driver as their 8 ohm model. JBL uses edgewound wire so they can truely make identical drivers in 4/8/16 ohms. On Eminence I have found the Qts to be a bit lower on 16R, and a lot lower on 4R (compared to the 8R) drivers. This is of course due to the round wire, so they really can't be the 'same' in different impedances. Eminence can do edgewound if requested. Quote Link to comment Share on other sites More sharing options...
Don Richard Posted December 14, 2009 Share Posted December 14, 2009 "How does inductance negate resistance? The vector sum of inductive reactance, capacitive reactance, and DCR determine impedance, with DCR @90 deg. Thus any added resistance will increase impedance." As a high frequency pole it works out the same. Please explain. Quote Link to comment Share on other sites More sharing options...
mark1101 Posted December 14, 2009 Share Posted December 14, 2009 Kevinmi said: "I use ALK universal crossover clones built by Gothover which are wired to have a 8 ohm load present to the amp no matter what impedance drivers you use. This way I can use my K-55V 16 ohm or my SelenuimD405 8 ohm drivers without changing anything, (except big ole horns and drivers). -kev " We need to be careful here. This is not really true. You should recalculate and change at least the value of the swamping resistor if you change the impedance of the driver. It is usually not a significant change of value required between 8 and 16 ohm drivers in ALK designs..........but it is not correct to say or assume you can change driver impedances without changing anything else and the design remains the same. It does not. Also, do you actually have 8 ohm networks? I bet you don't if they are ALKs. If your woofers are K33 then you have something like 6.3 ohm networks. Quote Link to comment Share on other sites More sharing options...
artto Posted December 14, 2009 Share Posted December 14, 2009 NO The only reason drivers are available in multiple impedence is for use in multiple driver arrays where one may want to keep the overall impedence load the same by wiring the drivers in series (add the impedence together) or parallel (divide the impedence in half) Quote Link to comment Share on other sites More sharing options...
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