PD186's over excursion and hot of Proline 3000

odc04r wrote: Few things here you might be confusing. If drivers are getting hot it is due to the average sustained power. With kick bass you are not getting as much physical excursion as lower frequencies (depending on music played of course but this is likely as a general rule). If the drivers are better cooled by larger excursion (driving more air through the voice coil) then you can see why they might get hot as you have the worst of a situation. Being hot is not necessarily a problem, but you will hit diminishing returns as your coils warm up due to power compression (the coils get more resistive). If they are too hot to touch without burning skin you may want to back off a little, but they are probably ok. Just let them cool down before you start moving them. Just because your amplifiers are not clipping, does not mean you can't pop a driver due to physical excursion. That depends totally on the driver, the enclosure, the music you play, and the voltage of the signal being applied to the driver.

Power is very complicated, a driver's power rating is determined by following a specific procedure, with a certain bandwidth of signal, in certain circumstances.

Edited by Andy Kos - 26 November 2014 at 11:15pm

tcourtneyvincent wrote: Andy Kos wrote: Slight blackening of enamel can be cumulative over year and years of use. There is no way to detect this when you buy a second hand speaker, it just means the driver has been pushed hard on a regular basis, but not quite hard enough to kill it. All it needs is something to finish the job and it will die..   Ok thanks, i see why people generally try to go for new drivers or recones!

Edited by Andy Kos - 27 November 2014 at 10:05am

Andy Kos wrote: Its quite normal for drivers to get 'hot' to the touch. A modern driver, with fibreglass coil former and high temperature enamel on the copper wire should be able to cope with atleast 150 degrees celsius, probably more. A lot of that heat will get transferred to the magnet and chassis, so easily reach a temperature that you shouldnt be touching with bare skin.

DC on your amp output is not good. Have you checked how much 'a small amount' actually is? And depending on the kind of problem the amp may have, the DC could also vary/increase when being used. Simple to take a multimeter and check that. Any DC will cause a displacement on the speaker and so reduce it´s effective Xlim. That will definitely lead to a shorter life.




Edited by Earplug - 27 November 2014 at 9:36am

tcourtneyvincent wrote: Ok great thanks, that makes sense. Seems like i need to just be less timid. I dont understand your last paragraph though. If the peak the amp can provide is 1k per bin, then how can a driver that "supposedly" rated at 2.8k peak exceed it mechanical limit with only 1k especial only being fed 75hz and up...

What you have to remember is the amount a driver moves in a cabinet at a given frequency depends on how much it is loaded at that frequency. I.e. how much the air contained in the cabinet is acting as a spring pushing it back towards it's rest position.

If you design a reflex with a port tuning frequency of 40Hz, under that frequency the driver becomes unloaded. I.e. as you go under the port frequency then it behaves less like a resonating port and more like a giant air leak. In this case 1W at 20Hz is going to cause more excursion than 1W at 100Hz. But it is the same amount of power (or amplifier voltage swing into a constant load).

So this is why stating that a driver can take 1kW free air relates to only what the voicecoil can take thermally and is nothing more than a rule of thumb when it comes to puttign it in a box. The box changes the game completely. Stating 1kW is also not much help. What you really need to make any useful measurements is a frequency analysis of your source material power. Then you can start making more useful statements about how much power a given box/driver combo can take.

As always the real world is a lot more complex than the numbers marketing people like to put on things.