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Old 30th July 2013, 04:18 PM   #101
freddi is offline freddi  United States
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of course, the nominal Re of that blue cone driver was the give-away would a 12pe32L with its low qts be too lean and bumpy in a similar bulk Karlsonator? http://www.parts-express.com/pdf/294-660.pdf
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Old 30th July 2013, 04:59 PM   #102
xrk971 is offline xrk971  United States
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Default 12PE32 sim

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Originally Posted by freddi View Post
of course, the nominal Re of that blue cone driver was the give-away would a 12pe32L with its low qts be too lean and bumpy in a similar bulk Karlsonator? http://www.parts-express.com/pdf/294-660.pdf
Freddi,
This is a very nice driver and it does quite well in a stock Karlsonator (first plot). Second plot is impedance, third is cone displacement (hardly moves), and last is impulse function. I think reducing Vb can improve response since the Qts is very low.
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File Type: png Knator-12PE32-Displ.png (14.5 KB, 241 views)
File Type: png Knator-12PE32-Impulse.png (13.3 KB, 240 views)
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Old 31st July 2013, 01:55 PM   #103
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Originally Posted by xrk971 View Post
Get me some T/S params for your 5 in drivers and I will simulate and optimize a Karlsonator for you. A Karlsonator is a hybrid mass loaded tapered quarter wave transmission-line (ML-TQWT) with an Karlson-coupler on the output "horn".
Sorry, I can't do that. The speakers I'll use are recycled from trash and repaired by a friend whose work is just it: repair speakers, and uses what he find in the market.

I want a design for a generic speaker, I had done some calculus scaling down the original Karlson enclosure.
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Old 31st July 2013, 04:05 PM   #104
xrk971 is offline xrk971  United States
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Do you have a way to measure the TS params? Without it, any design will be just guessing and hoping for something that sounds good. There is a way to measure using downloaded software and pc soundcard and a resistor. There is no such thing as a generic design (except maybe open baffle or sealed box with stuffing) especially with a Karlson that is scaled down. You can try a mini Karlsonator scaled to 0.5x scale and see how it works. If it is a very high Qts driver it may not work well. If it came from car audio, probably high Qts.
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Old 2nd August 2013, 04:27 AM   #105
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Originally Posted by Osvaldo de Banfield View Post
Sorry, I can't do that. .
Rod Elliot has a useful guide to measuing T/S parameters

A PC can be used to generate known frequencies - or use a test tone CD (I have Stryke's at home). Then you only need an A/C multimeter( and some resistors)
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Old 2nd August 2013, 04:33 AM   #106
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That is a great explanation of diy TS params measurement in a nutshell. Thanks, I have been looking for something like this.
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Old 2nd August 2013, 06:24 AM   #107
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and with inaccurate meters, a 10 ohm resistor can be switched in and the test tone adjusted to get a "10" reading - this was in David Weems' book. The little Polk DB525 must have had qts ~1 or so - might have one laying around as an example.
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Old 2nd August 2013, 12:22 PM   #108
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What is the Karlson or Karlsonator being modeled as?

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Old 2nd August 2013, 01:14 PM   #109
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What is the Karlson or Karlsonator being modeled as?

Ben
It is modeled as a series of waveguides with cross sectional areas matching the K15, the K aperture is modeled ( and approximated) as a series of 9 ports with areas prescribed by the K aperture function and spatial locations on the front matching the K15. The effect of the K aperture was tested for convergence by increasing number of ports to 14 with no substantial difference. The effect of the K aperture on spatial directivity was tested by turning it on and off. The post describing the modeling approach is here KARLSON
The general shape of the freq response, the impedance curve, the directionality all seem to be confirmed with either owners' measurements or experience so far. I think I got pretty close to what a Karlson is with the current model. One of the biggest tells was the fact that the K15 exhibits very poor scalability below a factor of 12/15, consistent with observations.

The Karlsonator is modeled using the exact same technique with connected series of waveguides and port array for the K aperture. The difference being the waveguides form a folded tapered quarter wave transmission line that is mass loaded and exits into a Karlson coupler.

So in effect, the models are as close as you can get using 1 dimensional lumped nodes methodology. The next step in modeling would be to do a fully 3 dimensional model using the ABEC software.
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Old 2nd August 2013, 01:32 PM   #110
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Thanks for the explanation, some of whose sophistication is wasted on me, but doing my best to understand.

You are right to recognize the need to "defend" the model since the output of lots of models kind of look kind of like other models, kind of. Since this thread is heading into a discussion of models, maybe you could provide a bit more justification besides suggesting the model output feels about right to some owners.

Funny, all these years I've been quite sure that the "signature feature" of the Karlson, those curved wings, serve no core purpose besides decoration and maybe some useful bit of shaping and dispersion. Help me see the error of my thinking. Although that is my starting point, I am agnostic about the truth of your model; I honestly want to know if your wave-guide model is true or not.

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Last edited by bentoronto; 2nd August 2013 at 01:49 PM.
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