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7th December 2012, 08:32 AM  #1871  
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Join Date: Jun 2007

Quote:
Thanks for your kind words  they are much appreciated :). I am a bit surprised that doubling the value of Le would make a worthwhile difference to the predicted response across the desired subwoofer passband. For example, in the attached screenprint the gray trace shows a typical tapped horn with a driver voice coil inductance Le of 1.2 millihenrys, and the black trace shows the same horn with 2 x Le. With this example, it is only above about 400 hertz that the difference in response becomes meaningful. Kind regards, David
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7th December 2012, 08:42 AM  #1872 
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Join Date: Jun 2007

Hi Djim,
Just to clarify  Hornresp calculates the reactive impedance (or reactance) of the inductance at each frequency. The value of the inductance itself (Le) does not change with frequency. Kind regards, David
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7th December 2012, 12:18 PM  #1873 
diyAudio Member
Join Date: May 2011
Location: Arizona

David ,
The link i pasted in this message was an example i found of what seems to often happen when people compare their simulated graphs with their measured responses ... I know it doesn't always work out exactly this way but it does seem to frequently show this pattern as far as i can tell ... In this example the Sim shows a slight dip, like a "saddle" between two peaks..Im talking about the first peak at just under 30hz and the other just above 70hz with the dip being centered around 40hz ..... However in the measured response the dip is diminished and the peak at around 30 is gone completely .... The results are moreso flat than the model ... People will say that this is due to various "losses" and maybe this is true but i have also noticed that i can create the same effect in simulation by simply increasing Hornresponse's LE/inductance value ..... It may be purely coincidental but it seems to work ... Sorry to "preach to the choir" because i know many people have already noticed this pattern ... A similar thing also seems to sometimes happen when a TH simulation has a perfectly flat graph in HR but once built and measured it shows a realworld rise somewhere in the middle (maybe around 5070 hz depending on where the TH is tuned) and a slight sagging on the lower end of the usable response falling short by a few decibels compared to the sim around the fundamental ..... This is also a scenario that can be emulated by added some LE in the simulation ... I know it may be improper to add LE to sims but in some cases it does seem to help get you closerish to real world results. http://lh3.ggpht.com/_WXjTASetbPo/S6...chy%201w1m.JPG Last edited by Matthew Morgan J; 7th December 2012 at 12:25 PM. 
7th December 2012, 01:46 PM  #1874  
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Join Date: Apr 2010
Location: amsterdam

Quote:
the black trace looks a bit flatter. al the th i have seen so far al have a flatter responce in realety then the sim ,under 100hz. when you double le value in that sim ,its much closer to the real thing. i know pannelflex could play a part also. id like to see some th comparisons between 1 watt and 100 watts,to see if amplitude plays a role here to.
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one good thing about music ,when it hit you feel no pain. so hit me with music. hr driver db 

7th December 2012, 04:05 PM  #1875  
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Join Date: Jun 2003
Location: Chamblee, Ga.

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GM
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Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents. 

7th December 2012, 09:05 PM  #1876  
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Join Date: Dec 2009
Location: Les PaysBas

Quote:
Sorry, time was up to change my post. Correct me if I am wrong but as far I know is the electrical resistance of an inductor in an AC circuit called an 'inductive reactance' and in a DC circuit a 'reactance'. 

8th December 2012, 06:54 AM  #1877  
diyAudio Member
Join Date: Jun 2007

Quote:
The electrical reactance (not resistance) of an inductor in an AC circuit is called an 'inductive reactance' or reactive impedance. The electrical resistance of an inductor in a DC circuit (or in an AC circuit) is called a resistance or resistive impedance (not 'reactance'). Reactance is a measure of the opposition of an inductor to a change in electrical current. The magnetic field generated in the inductor coil by the changing current acts to resist the change. Reactance does not apply in a DC circuit. The impedance of an inductor coil at frequency f hertz is given by: Z = R + j * X where: Z = complex impedance in electrical ohms R = resistance in electrical ohms j = imaginary operator sqrt(1) X = reactance in electrical ohms and: X = w * L where: w = 2 * pi * f in radians L = coil inductance in henrys R is the resistive or real component of the inductor’s complex impedance, and w * L is the reactive or imaginary component. In Hornresp, R = Re and L = Le. Kind regards, David
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8th December 2012, 07:08 AM  #1878  
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Join Date: May 2011
Location: Arizona

Quote:
I suppose yes, That is possibility .... Its a sim/measure graph comparison for a small TH based on the the miniature Anarchy sub driver ..... I didnt make it, it was someone else's project ........ 

8th December 2012, 07:14 AM  #1879  
diyAudio Member
Join Date: May 2011
Location: Arizona

Quote:
For Epa , and David and folks who are following, I have thrown together a few of my own simulated examples of smoothing due to increased LE ..... Some examples use 2x LE , and some use more like 3x or 4x the driver's LE .... Its a few compact compact TH cabinets (ss15 with 15tbx100 and small TH with dual 8" mcm 552421s) , and also for fun i included a tapped pipe (transflex) type design ...... The smoother response in these examples is accomplished with the raised LE in the simulation but if built and measured the real world results can often be just as smooth with less series inductance added, or in some cases none at all when the "saddle" dip and peaks in hornresponse are mild to begin with..... I assume some of the more extreme cases of ripple and dips would still require some amount of added LE to smooth them out just as Mr Danley does with some of his boxes by adding inductors in series with some of his drivers.. 

8th December 2012, 07:31 AM  #1880 
diyAudio Member
Join Date: Apr 2010
Location: amsterdam

hi matthew
if one would ad a coil to the system ,one also need to include the resistance of the coil. that resistance wil have effect on it aswel for pa you wil need a verry heavy (expencive ) coil
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one good thing about music ,when it hit you feel no pain. so hit me with music. hr driver db Last edited by epa; 8th December 2012 at 07:42 AM. 
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