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Old 23rd July 2010, 06:08 PM   #6791
a.wayne is offline a.wayne  United States
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Quote:
Originally Posted by badman View Post
Ah, so you like low Qms speakers that are dull sounding and soft at low volume, got it

Less power in means less potential flux modulation, less heat to dissipate, and high efficiency usually includes a high Qms so less suspension related artifacts.
Never had one of those and you are generalizing to suit ......

Let me travel the road for you ..

Soft sounding is when you have very quite passages in the recording, the system get 's soft, quite but with detail ( none of that hash usually associated with high eff horns) then on crescendos , it get's big ... Si ! ...

Nothing to do with turning down the volume , the horn systems i have heard do get big , they do not get small and while they will rise to the occasion , there louder DB lacks energy so guess what , no realism .

All Horn speakers i have ever heard exhibited such, not necessarily other high efficiency speakers .....................
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Old 23rd July 2010, 07:54 PM   #6792
Pano is offline Pano  United States
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Back on topic, gentlemen. No more trolling. Yellow cards given.
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Old 23rd July 2010, 08:06 PM   #6793
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Quote:
Originally Posted by badman View Post
Ah, so you like low Qms speakers that are dull sounding and soft at low volume,
If a low Qms loudspeaker is driven with an amplifier with a very low output impedance then it is possible that it becomes heavily overdamped & sound as described. On the other hand if you use a loudspeaker (system) with Qm of 0.7>1.0 you have a system ideal for use with a current amplifier.

Remember that a loudspeaker cannot be considered independent of the amplifier driving it.

dave
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Old 23rd July 2010, 08:43 PM   #6794
badman is online now badman  United States
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Quote:
Originally Posted by planet10 View Post
If a low Qms loudspeaker is driven with an amplifier with a very low output impedance then it is possible that it becomes heavily overdamped & sound as described. On the other hand if you use a loudspeaker (system) with Qm of 0.7>1.0 you have a system ideal for use with a current amplifier.

Remember that a loudspeaker cannot be considered independent of the amplifier driving it.

dave
I think you may be mixing Qm and Qt.
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Old 24th July 2010, 12:19 AM   #6795
gedlee is online now gedlee  United States
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Originally Posted by planet10 View Post
Remember that a loudspeaker cannot be considered independent of the amplifier driving it.

dave
I would say that it can if the output impedance of the amp is very low. But if there is any significant output impedance then what you say is true. Most SS amps these days have very low output impedances.

Regarding the topic of dynamics - consider this. A low eficiency loudspeaker likely has a smaller voice coil - it comes with the territory. Now the smaller voice coil has less copper so its temperature changes much more quickly than the larger VC with more copper for a given amount of current. But not only that, the lessor copper coil requires more current for the same SPL. This situation is a hands down win for High Efficiency because its voice coil temperature changes for a given SPL will be a fraction of that for the low efficiency design. And this is completely independent of the amplifier power OR the speakers power handling capacity, it depends only on efficiency and SPL. These are "dynamic" thermal/resistance changes not to be confused with "power compression" which is another thing altogether.
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Old 24th July 2010, 01:18 AM   #6796
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BOX SPEAKERS. Is there a great non-horn design with high enough efficiency for Lynn's tube amps?

My boxed speaker sketches these days look like a BIG B&W 801. Two Lambda TD15S covering 20-80Hz at 96db/watt after BSC. A 10" midbass covering the 80-1,500Hz "vocal_range", and a dome or RAAL type ribbon tweeter. The main goals are 94-96 db/watt efficiency from large cone areas, and putting the vocal_range on just one speaker. Personally, a cone midrange puts the correct level of energy into my room better than a compression driver on a horn.

Today there are good dome tweeters with 94db@2.83v, and it seems possible that NdFeB motors can increase this to 96db@2.83v before a 25-28mm dome cannot move enough air to provide a 110-115db SPL. The RAAL ribbon provides 95db@2.83V. A 10" vocal_range speaker in a sealed 2 cu ft volume can provide 95db/watt over 80-1,500 before high IMD(dopler) or noticable beaming. Two Lambda TD15S in a 16 ft3 fiberglass filled ported box can provide 25Hz 96db/watt after BSC. Passive radiators cannot increase efficiency like a second woofer motor.
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Old 24th July 2010, 03:22 AM   #6797
a.wayne is offline a.wayne  United States
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Originally Posted by gedlee View Post
I would say that it can if the output impedance of the amp is very low. But if there is any significant output impedance then what you say is true. Most SS amps these days have very low output impedances.

Regarding the topic of dynamics - consider this. A low eficiency loudspeaker likely has a smaller voice coil - it comes with the territory. Now the smaller voice coil has less copper so its temperature changes much more quickly than the larger VC with more copper for a given amount of current. But not only that, the lessor copper coil requires more current for the same SPL. This situation is a hands down win for High Efficiency because its voice coil temperature changes for a given SPL will be a fraction of that for the low efficiency design. And this is completely independent of the amplifier power OR the speakers power handling capacity, it depends only on efficiency and SPL. These are "dynamic" thermal/resistance changes not to be confused with "power compression" which is another thing altogether.
This is true if we are discussing low efficiency drivers vs high efficiency drivers, not a given if we are discussing speaker systems.

In order to continue we all should first define this arbitrary speakers System

What is high efficiency ?
What is low efficiency ?
What is the design purpose or goal ( SPL, domestic environment )

For domestic hi-fi purposes it is very rare you will get into temperature deficiencies in an home environment, unless you are using very crappy drivers to begin with, X-over topology will play a bigger role in defining this efficiency and dynamics as well as the drivers. If one is to build a truly dynamic and balanced multi -driver speaker with full bandwidth you will have to give up some efficiency even with efficient drive units.

While high efficiency and power handling drive units ( mid/high freq) might not suffer from power compression as you describe they can and do suffer from acoustic compression due to their small diaphragms ( relative) and small rear chambers .

A well designed full bandwidth multi-driver system exhibiting low efficiency (84db for eg) will not lack dynamics, because of it's lower efficiency , it will do so because of it's poor design and x-over implementation.
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Old 24th July 2010, 04:52 AM   #6798
gedlee is online now gedlee  United States
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Quote:
Originally Posted by a.wayne View Post
For domestic hi-fi purposes it is very rare you will get into temperature deficiencies in an home environment.
Not necessarily true and I guess that you did not understand my post. At ANY SPL the High Efficiency will have less thermal modulation than the low efficiency.
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Old 24th July 2010, 06:20 AM   #6799
mige0 is offline mige0  Austria
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Originally Posted by gedlee View Post
Not necessarily true and I guess that you did not understand my post. At ANY SPL the High Efficiency will have less thermal modulation than the low efficiency.
Not true

Any thermal distortion - for a given SPL - in speakers relate to

a) efficiency
b) thermal properties of coil / motor design

This already has been discussed in any detail back then...
*If* one is able to improve on motor design more than loosing on efficiency the net result is less thermal distortion for a given SPL.



Lynn was wrong (or at least "not completely right") to connect dynamics with efficiency on a mere technically level (not sure he even really meant it that way !) - though he is certainly right that it may *usually* be the case - hence his surprise ...

Those guys at Dynaudio have had a feeling on this subject a looooong time ago and I'm glad to hear this continues to our times

Michael

Last edited by mige0; 24th July 2010 at 06:43 AM.
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Old 24th July 2010, 06:56 AM   #6800
mige0 is offline mige0  Austria
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Originally Posted by gedlee View Post
These are "dynamic" thermal/resistance changes not to be confused with "power compression" which is another thing altogether.
To be possibly more precise :
Form the outcome = our perception, there are several different "departments of thermal distortion", depending on the time span we look at - but form a mere technical viewpoint its all the same.

For any further reading, I set up a page on the topic and also there is one from John Kreskovsky

Michael

Last edited by mige0; 24th July 2010 at 07:25 AM.
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