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Old 26th November 2013, 07:28 AM   #3781
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Quote:
Originally Posted by David_Web View Post
Do both total and (net) within brackets.
Hi David_Web,

Because system efficiency is also given, I would prefer to show just one value for acoustical output power to avoid any confusion as to how efficiency is calculated - I don't want to include two separate efficiency figures.

Unless anyone can see a good reason not to, I think I will probably just change the acoustical output power to show the net or 'combined system' value rather than the total or 'sum of the components' value.

If a user still wants to know the total acoustical power, then they can readily manually add the two known individual power outputs together.

Kind regards,

David
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Old 26th November 2013, 12:17 PM   #3782
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I guess that makes sense.

Does that mean that the efficiency figure or graph was incorrect for BR or other two source designs?
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Old 26th November 2013, 12:56 PM   #3783
Mark Kravchenko
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Quote:
Does that mean that the efficiency figure or graph was incorrect for BR or other two source designs?
Back Loaded Horns?

In practice and using measurements I don't find it to far different.

But I'm not working on the math end. I'm working on the end of the line...

Had to do it.

Just to much temptation.
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Old 27th November 2013, 06:50 AM   #3784
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Quote:
Originally Posted by David_Web View Post
Does that mean that the efficiency figure or graph was incorrect for BR or other two source designs?
Hi David_Web,

An interesting philosophical question. It depends on how system efficiency is defined. The existing figure is calculated as [total acoustical output power] / [total electrical input power] * 100. The proposed new figure will be calculated as [net acoustical output power] / [total electrical input power] * 100.

Both values are correct, it's just that the proposed new figure will probably be more useful in that it gives the net efficiency of the practical system, rather than the total efficiency of the two separate sources.

Kind regards,

David
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Old 27th November 2013, 06:56 AM   #3785
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Originally Posted by mwmkravchenko View Post
Back Loaded Horns?
Hi Mark,

Yes, those also.

Kind regards,

David
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Old 28th November 2013, 05:02 PM   #3786
Kolbrek is offline Kolbrek  Norway
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Quote:
Originally Posted by David McBean View Post
An interesting philosophical question. It depends on how system efficiency is defined. The existing figure is calculated as [total acoustical output power] / [total electrical input power] * 100. The proposed new figure will be calculated as [net acoustical output power] / [total electrical input power] * 100.
Strictly speaking, the total acoustical power should be calculated by integrating over the solid angle into which the loudspeaker radiates. The power may be different in different directions, but the total, integrated power should be the same as the power dissipated in the radiation resistance(s), unless there are losses in the medium. There may be large dips in the response at certain angles due to phase cancellations, but these will be compensated by reinforcements in other directions.

Regards,
Bjørn
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Old 29th November 2013, 06:47 AM   #3787
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Originally Posted by Kolbrek View Post
Strictly speaking, the total acoustical power should be calculated by integrating over the solid angle into which the loudspeaker radiates. The power may be different in different directions, but the total, integrated power should be the same as the power dissipated in the radiation resistance(s), unless there are losses in the medium. There may be large dips in the response at certain angles due to phase cancellations, but these will be compensated by reinforcements in other directions.
Hi Bjørn,

Many thanks for your insight. It seems that the Hornresp acoustical output power shouldn't be changed after all :-).

Kind regards,

David
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Old 29th November 2013, 04:29 PM   #3788
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Yes it should, as now the acoustical power between TH and BR for example can't be compared. Which would mean that the efficiency graph is incorrect for BR. Right?
I thought the SPL graph was already the power response thus already "integrated"?

Directivity is not available when choosing combined result anyway.

I guess it's a question of being correct at the simple lever or never be correct. You have to sum the port and driver part of a BR if it's in the same room, with it's cancellations. Otherwise it would be radiating into two different rooms, which you could already check without the combined response tool.

Adding the two figures together is easy, getting the net output without generating it inside the software would be hard. So changing it would be more user friendly.
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Old 30th November 2013, 06:51 AM   #3789
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Originally Posted by David_Web View Post
Adding the two figures together is easy, getting the net output without generating it inside the software would be hard. So changing it would be more user friendly.
Hi David_Web,

A compelling argument :-). I will make the change.

Kind regards,

David
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Old 30th November 2013, 07:37 AM   #3790
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Default Hornresp Update 3300-131130

Hi Everyone,

CHANGE 1

The Loudspeaker Wizard tool can now simulate transmission line loudspeakers containing absorbent filling material. See the Hornresp Help file for details (search for references to transmission line using the Find tool).

CHANGE 2

The airflow resistivity parameter Fr is now specified in units of mks rayls/m rather than cgs rayls/cm, where 1 cgs rayl/cm equals 1000 mks rayls/m. Existing Fr values will be automatically updated the first time that the new version is run.

CHANGE 3

Charts are now provided showing front and rear horn throat, horn mouth, port inlet and port outlet velocities and pressures as appropriate, for the specified loudspeaker system. Charts showing the direct pressure on each side of the driver diaphragm are also provided. My thanks to James (jwmbro) for suggesting this enhancement.

CHANGE 4

The Sample tool now shows the net value for combined response acoustical output power, rather than the summed outputs of the two sources. This means that the combined response system efficiency figures will also change. My thanks to James again, for initially raising this issue.

CHANGE 5

Setting the D3 slider to zero in the Driver Front Volume tool generated a fatal Overflow error. This bug has now been fixed.

Kind regards,

David
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