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In Reply to: Re: Tom Danley at AES Chicago posted by tomservo on February 23, 2007 at 10:56:06:
In all fairness, the diaphragm in a horn is not immune to breakup and the additional acoustic load may actually exacerbate the problem. Further, horns provide uneven loading at low frequencies where the horn is less than 1/4 size. This is linear, but still represents rapidly shifting phase. Throat distortion isn't an issue except at very high SPL, but it does introduce non-linear behavior. Magnetic non-linearities from the movement of the voice coil introduce non-linear behavior. All these things prevent a horn from operating with zero phase shift, same as a direct radiator. There is only the advantage of acoustic load, which is significant, but certainly not the only contributor to transient performance.
Follow Ups:
Cripes V, are you becoming a Stalker who shows up in every thread that Tom Danley participates in to spread disease? Please don't drive him away from this and other forums, he has so much to share and is generous with his knowledge.
Benford's law of controversy - Passion is inversely proportional to the amount of real information available.
Wasn't trying to offend, sorry if I put you off. What exactly did I say that was offensive to you?
Hi V
Hey hey, its you again.
I remember you, do you remember this thread where you “suggested” I used Martin Kings work to develop the Tapped horn?http://www.audioasylum.com/forums/hug/messages/118585.html
Did you also happen to catch Martin King, commenting on that same thread and you, “not exactly” backing you up on that ?
http://www.decware.com/cgi-bin/yabb2/YaBB.pl?num=1168762375/15
I don’t know it just stuck me as ironic that you would begin by saying “in all fairness”.
I mean “in all fairness”, with the “fatal problems” you seem to see, how would you explain the fact that the speaker actually does (as in the mic signal viewed on an oscilloscope) reproduce a square wave over a range spanning all three sets of drivers?
You talk nonlinearity as a show stopper, just what effect do you think gobs of headroom has?
These speakers were independently measured and they found they change their response less than 3 dB up to 56Volts shaped pink noise (about 780 Watts average) which has peaks +6 dB (3120 Watts peak) over that average. .
At a little over 100dB 1W 1M, how hard do you think do you need to push them at an AES meeting at a Hotel?
The only thing that reached any significant peak power (where I had set the level just below clip on peaks) was the fire works and there I needed the subs and could have used more power.
Fireworks are not like music however, they are technically very hard to reproduce and they have a huge peak to average power ratio. They also don’t sound right unless all the energy arrives like in real life and so were part of the AES demo.
I would like to think that time part also helps with music and voice reproduction too.
Tom
Regarding the current topic, which is loudspeaker non-linearities, my point is that if one were to be objective, they would find that all the same non-linearities that caused a direct radiator to become non-minimum phase also cause a horn loudspeaker to be non-minimum phase. That doesn't make anything a "show stopper" except of course, marketing blather.About the MLK spreadsheets, the beauty of them is they model standing waves in transmission lines with driver offset. They are able to calculate nodes at 1/4, 3/4, etc and this allows the DIY builder to position the driver some distance down the line to reduce notches from standing wave nodes. The flare is able to be modeled too, although the fold isn't considered, which will matter at higher frequencies if you make a folded horn. Still, the advanced spreadsheet is very close to being able to model exactly the configuration of your tapped horn. I would have thought this would be interesting to the DIY community, and flattering to you.
Martin King said he hadn't made a spreadsheet specifically to model your "tapped horn" but did say he thought his spreadsheet would just need to be modified slightly for that purpose. He went on to say he didn't think he wanted to make a spreadsheet that would model it exactly because he wasn't sure there was any value in doing so.
Quoting MJK from here:
http://www.diyaudio.com/forums/showthread.php?postid=879165#post879165
I thought about the problem yesterday and concluded that a worksheet to model this type of enclosure is possible. It would require some rearranging and extension of the math but I believe it could be done. Unfortunately, it is not on my list of priorities and can only be classified as something interesting to look at if I ever run out of things to work on (there are a few other enclosures on that list also).
So let me ask a couple of questions :
1. What is special about the performance of this design compared to a classic TL?
2. What performance advantages does it offer?
3. Where is this design used and over what frequency range?
If there is some performance advancement possible with this geometry that would be interesting, if this is just an old design cobbled together by a very creative thinking individual that sounded good compared to state of the art at that point in time then I am not sure this is worth pursuing. Is the Jensen Transflex just another Karlson or Hageman style of exotic, outside the norm, or curiousity enclosure that appeals to a small group of enthusiasts or is it truely a high performance design that has fallen through the cracks?
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