主题：Power handling and heat dissipation

modifed: For transducer driver mechanisms, talking about "Power handling and heat dissipation",thanks a lot! i want to learn this from your help

好题目,然而这儿偏好中文哪.欢迎.

Good topic, but it prefers Chinese here

as there are Chinese engineers here. Most of them could not handel English very well,

I am afraid.

Any way, welcome.

Maybe I can say there are two major points from.

One is from JBL web,another from Rane web.

There are good points there indeed.

A lot of Chinese audio engineers got strong influences from JBL points.

Also some did serious tests in their companies or their projects,

but I wonder if they have freedom or willings to talk here.

A lot of transducer engineers have done a lot for that.

For instance, there are engineers in below companies, who did a lot about.

http://www.dongyuan.net/

http://www.evervictory.com

How to define the Rated power and 1/2 retaed power of sound enclosure?

i could not find out related data for ref.

In any inefficient device,the wasted power almost always showw up as heat and the lodspeaker is no exception.Most of energy loss appears as heat in the coil.Most manufactures rate their loudspeakers by the amount of power they can eurvive,measured in Watt,under certain conditions,without sustaining damage. This is known as power holding figure and is absolutely meaningless.

The power-handling figure is not the power actually dissipated. In fact it is the power taht would be dissipated by a resistor having the same resistance as the normal impedance of the speaker.As a driver unit is a comples or recative load as well as being temperature dependent,the actual power delivered by the amplifier will be substantially less than the power delivered to an ideal resistor.

Good points indeed.

Thanks.

As far as I know, the chief engineer Mr.Dong of DongYuan company went to AES conferences  a fewtimes,

once I read his article about ways to deal heat trasfering. I guess they did a lot in their car drivers. Mr. Dong handle English very well. Maybe you can take time to meet him as he is in Shenzhen now.

The evervictory company is in Dongguan. They made a lot of drivers. If you visit their company you shall find some interesting stuff. Engineers there are very hardworking, maybe they need more indtructions more even they have done a lot. The company is not small with some sales persons who can speak English.

Of course, there are other companies, you shall be interested too.

I can offer some information if you need.

Reading with thanks!

In driver units which offer high power-handling,the designer is backed into a corner by the survival requirement.The cone will have to be heavier to survive the mechanical ordeal,and so the speaker will be less efficient.This means that more heat will be developed,which in turn means that the coil temperaure will rise and the coil will expand in diameter by 0.4 mm. This requires a greater clearance in the outer pole piece, raising the reluctance of the gap and reducing the BL product,further reducing efficiency. Consequently high-power handling speakers are seldom very efficient and therefore need to consume that hight power and suffer more from thermal compression.

Thank you very much for your good comments about some designs.

I agree with you.

I guess you are an expert from one of west countries.

You can see a lot of designs which are not wise I think at least.

In most cases, we Chinese engineers could not change the stupid trends

because some sales guys said you engineers do just what we demand.

So, I appreciate your comments very much.

This place is to improve our skil and to share our comment,only for this.hope some comment from you in this world.

For quality reasons, moving-coil drivers must be designed with effective cooling measures so that the coil temperature excursion is minimized. The coil can shed heat by radiation and by conduction. Conduction is limited because the coil former is attached only to the cone and the spider. Most spiders are thermal insulators, as are most cone materials, with the notable exception of aluminium cones,which can contribute significantly to coil colling if the attachment of the coil former to the cone is designed as a thermal path.

 

Yes,this place is a good site to communicate each other.

Thank you again for your concepts about the design.

We would love to exchange ideas with foreign engineers and experts too.

Personely, I will say for a lot of Chinese engineers there are only ways to follow or copy, I am sorry to say that.

One big reason is the demand from marketing even some professors and experts including me to worry about trends.

But no way right now.

I prefer to discuss the issue with foreign experts in the same occupation. But it is not easy.

Before we say more, one thing is clear, that is there are all most same points of view in a lot of design questions.

For reasons of the enviroment protection and fully useage of material, I came here to do some knowledge sharing

among Chinese engineers. I guess it does work, even it is a little progress.

Power handling and heat dissipation 这是主帖的内容.

请注意

楼主已把hest更正为 heat了.

To:hzhan1974

Hello.

From your talking,can i say your point @ the way increasing power handling is improving the efficiency of speakers or something else?

In my personal opinion,the best way to improve the power handling,by using magnet-liquid in the woofer speaker,as there still some tech-problems to using it ,and the cost may be a little higher.Can u pls tell us how is going in your country?thank you very mach!

The ultimate cooling method is ferrofluid, a magnetic liquid is retained in the magnet gap by the magnetic field itself and conducts heats to the pole pieces. Ferrofluid became available around 1974, and consists of a colloid of magnetic particles (Fe₃O₄) of about 0.01 mm in diameter suspended in a low vapour pressure diester based on ethylexyl-azelate. The use of ferrofluid does result in some viscous damping due to shearing in the fluid.

Ferrofluid is generally designed to saturate at flux levels considerably below those present in the gap so that the reluctance of the gap is not affected. It is compatible with most coil, adhesive and former materials, except for paper and rubber-based materials. Capton absorbs some of the carrier but without ill effect. The cooling effect is typical in the tweeter.

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GOOD