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Old 23rd January 2012, 09:45 PM   #1441
Mark Kravchenko --- www.kravchenko-audio.com
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@ AndrewT

Most of the time I set power sensitivity using 1 watt into the nominal impedance . Signal is pink noise.

That tends to give the most honest results. Some manufacturers use this method. But unfortunately not to many.
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Old 24th January 2012, 01:05 AM   #1442
Djim is offline Djim  Netherlands
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Hi david,

I have been thinking about it and maybe I have a more simple solution that is still user friendly I think and hopefully more easy to imply :-)

Make for Zmin a separate box in the "Input Parameters" page (see figure 1). This way the user is responsible for manually searching for the Zmin in the "Electrical Impedance" chart.

After the Zmin is filled in the box the corresponding Watts appear in the "P" box beneath it. By changing the Voltage in "Eg" the power will automatically change (based on Zmin). When you change the power in the "P" box, the Voltage in "Eg" will change with it. If Zmin is not used there is also no value in "P".

This way the user can have full control over Power and Voltage.

In figure 4, I made a suggestion for a new screen page that shows the "POWER response" with all valuable information. If Zmin is not used this page is not available.

What do you think?

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Old 24th January 2012, 01:35 AM   #1443
Djim is offline Djim  Netherlands
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To make it more user friendly you can add an "Export to Zmin" button in the "Electrical Impedance" page that uses the value of the cursor.

Click the image to open in full size.
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Old 24th January 2012, 06:30 AM   #1444
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Quote:
Originally Posted by Djim View Post
What do you think?
Hi Djim,

I thought that you wanted a chart showing SPL response calculated using the value of Eg that delivers 1 watt into Zmin. Your suggested power response chart has the same general form as the electrical impedance chart, only inverted - Iím not sure how much value it would really add in practice.

If you are prepared to manually search for Zmin, then why not just use the Calculate Parameter tool to find the value of Eg required to deliver 1 watt (or any other desired power level) into the chosen Zmin value, and to then calculate the standard SPL response chart using that value of Eg, giving you the sensitivity result you want.

The Calculate Parameter tool can be selected by double-clicking on the Eg input box in Edit mode - see attachment.

As a general comment - this whole process of measuring sensitivity seems to be very subjective :-). It all depends on the value of Zmin within a passband that appears to be arbitrarily chosen. If the passband is not arbitrary, then what are the rules (applicable to any speaker) that can be used to determine the upper and lower frequencies. Comparing the performances of different speakers in this way seems to be rather questionable...

Kind regards,

David
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Last edited by David McBean; 24th January 2012 at 06:33 AM.
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Old 24th January 2012, 09:41 AM   #1445
AndrewT is offline AndrewT  Scotland
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David, you are correct to question the method of determining sensitivity.

That is why I asked the question.

I don't know, but I do know that the method proposed for power sensitivity modelling is not right.
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Old 24th January 2012, 11:23 AM   #1446
Mark Kravchenko --- www.kravchenko-audio.com
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Quote:
I don't know, but I do know that the method proposed for power sensitivity modelling is not right.
Quote:
As a general comment - this whole process of measuring sensitivity seems to be very subjective :-). It all depends on the value of Zmin within a passband that appears to be arbitrarily chosen. If the passband is not arbitrary, then what are the rules (applicable to any speaker) that can be used to determine the upper and lower frequencies. Comparing the performances of different speakers in this way seems to be rather questionable...
For what it is worth I whole heartedly agree with these two quotes. Not much is to be gained. And secondly the means and methods are not different enough from what is already being done in Hornresp. The ambiguity in the industry is the main culprit. And trying to tailor a program for a very narrow interest group is not what seems to make the most sense.

As Andrew pointed out not one of us has demonstrated a universally accepted method of calculating sensitivity. Not because the methods are wrong. But because the wide acceptance is the problem.


I think David has given a very balanced means to do this. And some tools to delve deeper like the Calculate Parameter tool.


There is a saying in english. No use beating a dead horse.

Lets let David work on other improvements. He has some up his sleeve for sure!



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Old 24th January 2012, 02:54 PM   #1447
jbell is offline jbell  United States
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Thanks to david, and all for the discussion. I've enjoyed reading and watching.
It's been a very valuable discussion for me, and I'm honored that it was associated with this thread.

The SS15 would never exist without Hornresp.... what a wonderful tool.
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Old 24th January 2012, 05:53 PM   #1448
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+1!!!
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Old 25th January 2012, 05:41 AM   #1449
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Hi jbell,

Quote:
Originally Posted by jbell View Post
Thanks to david, and all for the discussion. I've enjoyed reading and watching.
I also, would like to acknowledge those who have contributed to the loudspeaker sensitivity discussion - it has been a most interesting collaboration. Thanks to Djim in particular, for raising the issue in the first place. If nothing else, we have established that there is no universally-accepted single method for measuring loudspeaker sensitivity. Hopefully an agreed standard can be developed sometime in the future.

Meanwhile, some "food for thought":

The SPL response measured using the voltage that delivers 1 watt into Zmin is simply the SPL response obtained using any value for Eg plus an offset of 20 x Log10((Zmin ^ 0.5) / Eg).

For example, if the SPL at 100 hertz is 105 dB when Eg equals 2.83 volts, then the SPL at 100 hertz using the voltage that delivers 1 watt into Zmin = 7 ohms will be:

105 + 20 x Log10((7 ^ 0.5) / 2.83) = 105 - 0.58 = 104.42 dB

Quote:
Originally Posted by jbell View Post
It's been a very valuable discussion for me, and I'm honored that it was associated with this thread.
And here's me thinking that you would be upset because we had hijacked your thread... :-).

Kind regards,

David
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Old 25th January 2012, 11:07 PM   #1450
Djim is offline Djim  Netherlands
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Quote:
Originally Posted by jbell View Post
I'm honored that it was associated with this thread
Hi Jbell,

Your single sheet thread seems to have become a standard on its own! Anyway, sorry for the "occupy movement" around here Jim :-)

Maybe it didn’t lead to something concrete but it was an interesting read with quiet some useful info from everybody. To be honest I didn’t realise there were that many different interpretations besides the sensitivity based on Zmin and an average sensitivity figure. Thanks everybody and especially for you David, for your patients and willingness.
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