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pd1850 aes or rms
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norty303 View Drop Down
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Joined: 18 August 2004
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Points: 8800 		Post Options Post Options   Thanks (0) Thanks(0)   Quote norty303 Quote  Post ReplyReply Direct Link To This Post Posted: 17 November 2009 at 6:04pm
I'm not sure I understand where/why the efficiency stuff has come into this. The AES rating doesn't say 'but obviously stuff will change like when they're in a horn'.

Its about a common set of parameters by which to compare drivers. So if a driver will do 800w under AES conditions then it can do 800w. If it happens to gain different parameters under horn loading then so what? It's different paramters to how other drivers are being measured. I'd guess that the horn isn't a magic horn for just 1850's, therefore you could say that about any of the other drivers too (assuming they're meant for horns)
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Timebomb View Drop Down
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Points: 2763 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Timebomb Quote  Post ReplyReply Direct Link To This Post Posted: 17 November 2009 at 7:25pm
Exactly, the efficiency of the cab dos not directly affect the thermal power handling.  if you put 150V across a 1850 your going to blow it whatever cab its in.  You may gain better mechanical power handling due to decreased excursion but that depends on the designs your comparing.

If your horn is 6dB more efficient than the reflex, so you put in 1/4 the power to get the same output, then the driver wont get as hot, but that's only because you putting less power in, it hasn't magically been transformed into a driver that can take twice the power. 


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Timebomb View Drop Down
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Points: 2763 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Timebomb Quote  Post ReplyReply Direct Link To This Post Posted: 17 November 2009 at 7:34pm
Originally posted by levyte357 levyte357 wrote:

Originally posted by Timebomb Timebomb wrote:


Older Turbo and FK1 stuff is the same, the new FK1 21" has a 6" coil but is only rated at 750W.  ive seen 4" coil drivers rated at twice that.
 
Thought length and guage of VC primarily dictate power handling, not the diameter.
 
Would be possibe to make 3" VC that handles 2Kw, but sensivity would be about as good as deaf man wearing cheap hearing aid, with no batteries.


Just looked it up and its the area of the coil that primarily dictates power handling, so the circumference multiplied by the winding height.  A 2" coil with 20mm depth would have the same power handling as a 4" coil with 10mm depth, assuming everything elce was the same, thermal transfer to the pole peice etc.

I think i read the FK1 6" coil driver i mentiond has 2 coils and 2 magnets and 2 top plates, im not sure how that changes the power handleing compaird to 1 longer coil, id assume its similar though the thermal transfer to the top plates would change.

  
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pfly View Drop Down
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Points: 2827 		Post Options Post Options   Thanks (0) Thanks(0)   Quote pfly Quote  Post ReplyReply Direct Link To This Post Posted: 17 November 2009 at 9:06pm
Timebomb but you understand my logic behind the question, if the horn/driver -combo transforms more of that power it receives into sound, then there should be less power transforming into heat...
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Points: 3471 		Post Options Post Options   Thanks (0) Thanks(0)   Quote RUS Quote  Post ReplyReply Direct Link To This Post Posted: 17 November 2009 at 10:19pm
Originally posted by pfly pfly wrote:

Timebomb but you understand my logic behind the question, if the horn/driver -combo transforms more of that power it receives into sound, then there should be less power transforming into heat...
 
 
no i wouldnt say so
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Points: 1513 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Meat Quote  Post ReplyReply Direct Link To This Post Posted: 17 November 2009 at 10:32pm
I assume theres something peer reviewed that'd settle it. If anyone knows the paper or has a reference that looks like it could I'll download it.

I'm not an engineer. All I know is that thing about free lunches and that the energy input = useful output - losses. If I'm wrong I'd like someone to explain why. I've heard about more horn drivers being consistently overdriven than just the 1850. I love being wrong because then I can learn and move on however I'm going to bark up the wrong kettle of fish until I find out otherwise.

Is it possible that PD have actually underrated their driver on purpose because a blown driver is a bad advert for that driver and they'd rather have the reputation of dependability, being built like a tank than just have a bigger number for the marketing department willy waving competition that is spec sheets?

Maybe the mark 3 will be like the 'new' fane XB ie. exactly the same but with the less conservative number on it?
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norty303 View Drop Down
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Points: 8800 		Post Options Post Options   Thanks (0) Thanks(0)   Quote norty303 Quote  Post ReplyReply Direct Link To This Post Posted: 17 November 2009 at 10:41pm
I think what you're referring to is not a function of the horn allowing them to be overdriven so hard thermally, but the fact (as someone commented on previously in the thread) that other factors DO NOT prevent such heavy use, most usually Xmech.

In a vented box there will be less resistance to the cone movement so it'll bottom out probably long before the VC burns. In fact, you may well expect the vented box to take more power (if you could control the other factors) as it'll be cooling better with the increased cone movement.
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Points: 3471 		Post Options Post Options   Thanks (0) Thanks(0)   Quote RUS Quote  Post ReplyReply Direct Link To This Post Posted: 17 November 2009 at 10:54pm
i personally dont think pd would under spec there drivers even tho some amp companys do
its not like they've ever made it know
 
 
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Points: 10932 		Post Options Post Options   Thanks (0) Thanks(0)   Quote toastyghost Quote  Post ReplyReply Direct Link To This Post Posted: 17 November 2009 at 11:10pm
How many of the people saying that the PD1850 can take more than it's AES spec are actually putting all that extra power in as a continuous sine wave?
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Timebomb View Drop Down
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Points: 2763 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Timebomb Quote  Post ReplyReply Direct Link To This Post Posted: 17 November 2009 at 11:19pm
To do a proper power test you want to use bandwidth limited pink noise,  if you used a sine wave it will depend on what frequency.

EG it could well be 50 ohms at 40 Hz so that will throw things way off.

I bet 5 internets it would take 1000W
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Points: 1513 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Meat Quote  Post ReplyReply Direct Link To This Post Posted: 18 November 2009 at 2:02am
I see your 5 internets and raise you a jelly snake.
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