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New P Audio 3 inch neo driver

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Andy Kos View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Andy Kos Quote  Post ReplyReply Direct Link To This Post Posted: 06 November 2014 at 12:22am
Originally posted by Timebomb Timebomb wrote:

Id take p audio plots with a bucket of salt.

Although there is some variation with any driver, we have tested several P-Audio components and the results we have got are not far off the published plots.

The test environment will affect the results, so ANY plot from ANY manufacturer does need a certain element of salt with it.


just a guy with a warehouse and a few speakers... www.bluearan.co.uk
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Saturnus View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Saturnus Quote  Post ReplyReply Direct Link To This Post Posted: 06 November 2014 at 12:39pm
Well. There is clearly something wrong with the published plot. Both the frequency response and impedance curve are way off, at least if we are to trust the annotations. However, it would be spot on if the impedance and sensitivity annotations are moved one step up or both curves are moved one notch down.

As it is now the impedance curve indicates a nominal impedance of about 18 ohm. Move that one step up and it becomes the correct 8 ohm as listed in the data sheet. And the average sensitivity is according to the published plot about 96dB/W/m in the listed usable frequency range. Move the annotation one step up and it becomes the correct 86dB/W/m as listed in the  data sheet.

What I think has happened is that someone saw the real response curves and decided to move both one notch up because the impedance curve would be very near the bottom as it happens when you use a linear annotation instead of the normal logarithmic annotation.

Fact is. The published plots and the data on the data sheet cannot both be correct. Somehow I trust the published data set more than the plots.


Edited by Saturnus - 06 November 2014 at 12:45pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Timebomb Quote  Post ReplyReply Direct Link To This Post Posted: 06 November 2014 at 12:47pm
I realize that Andy but im not talking about variance in test method / room, Theres a lot of p audio spec sheets that just dont add up too me,  eg this one

http://www.bluearan.co.uk/index.php?id=PAUSD34SF&browsemode=manufacturer

States 103dB sensitivity, which is very low for such a driver, then shows a measurement plot showing about 110dB average at 1M/1W ,  with peak around 115dB, which is extremely high for such a driver.  So is the spec sensitivity measured without a horn, and measurements taken on a plane wave tube?  It dosent say so i kinda have to guess?  Paper cone drivers have similar irregularities so maybe thats not it?

Then this one (i am literally picking drivers at random from your website, some do make sense, theres plenty that dont though)

http://www.bluearan.co.uk/index.php?id=PAUSN8250CX&browsemode=manufacturer

States 97dB sensitivity, then gives a measurement at about 83dB , stating its 1M/1W.  Its really hard to know whats going on from that, HF sensitivity seems very low considering theres a proper horn on this driver,  im guessing this one is just a mistake and it was measured at a lower voltage, so im left to guess on real world sensitivity.  I might of tried more p audio drivers but i look at them and these things put me off, dosent exactly inspire confidence if there getting things like this wrong again and again.

http://www.bluearan.co.uk/sales/p-audio/E8_150S.pdf
States 93dB, plot shows about 101dB 1M/1W

http://www.paudio.co.uk/pdf/SN8_250N.pdf
States 98dB, plot shows about 105dB 1M/1W 

http://www.bluearan.co.uk/sales/p-audio/E8_200N.pdf
States 92dB, plot shows about 95dB 1M/1W, This driver looking interesting at a good price, if sensitivity is at about 95dB i might give it a try, if its more like 92dB its a bit low really? 

Im not trying to have a go Andy and i realize you have an interest in promoting P audio but i think what ive said is fair criticism, i think you would do yourself a favor by measuring the drivers you deal in (with HF measurements done on a typical 60x40 horn like pretty much every other manufacturer) and publishing the results, i recon it would encourage confidence to more potential customers, me for one.

James   
 
James Secker          facebook.com/soundgearuk
James@soundgear.co.uk               www.soundgear.co.uk
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Saturnus Quote  Post ReplyReply Direct Link To This Post Posted: 06 November 2014 at 12:56pm
Here's the corrected plot for the driver.






Edited by Saturnus - 06 November 2014 at 1:01pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Saturnus Quote  Post ReplyReply Direct Link To This Post Posted: 06 November 2014 at 1:16pm
I feel I have to point out that I actually use and promote the use of p.audio drivers in many of my designs. They are staggeringly good quality for the price. It's just a shame and really a nuisance that the published plots on the new data sheets are pretty much all incorrectly annotated. I can live with it because I can deduct from the data set would they actually should be but an inexperienced designer may look at them and discard a potential candidate driver just on the basis of these incorrect plot annotations.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hemisphere Quote  Post ReplyReply Direct Link To This Post Posted: 06 November 2014 at 1:46pm
*double post*

Edited by Hemisphere - 06 November 2014 at 1:55pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hemisphere Quote  Post ReplyReply Direct Link To This Post Posted: 06 November 2014 at 1:54pm
I'm sure it does more than 80dB per Watt at 200Hz though or the Minirig wouldn't be as loud as it is. If you look at the plot comparison I posted, it seems that the driver has actually been EQ'd down by several DB over much of the frequency range. 

Judging by performance I'd say it's much more likely that the 86db/watt line sits more or less around the 150-400Hz area. It's possible they're using some arcane method of determining average sensitivity, like using a typical music program signal to determine 'average' frequency values.

It's quoted as achieving 100dB SPL on the Minirig specs, and that includes a peak at 225Hz, which matches real world performance. If it's managing 100dB at 225Hz with 15 Watts then it's around 89dB sensitive at that point. P Audio's plot says it's 91dB/watt at 225Hz but that's on an open baffle, not in a <0.4 litre enclosure that you would expect would lose more than a couple of dB in the bass range.

So is it not possible the original plot, and quoted numbers, are more or less accurate?


Edited by Hemisphere - 06 November 2014 at 1:54pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Saturnus Quote  Post ReplyReply Direct Link To This Post Posted: 06 November 2014 at 2:01pm
No. It's a free air measurement so anything below 200hz is first order acoustically filtered. And in fact the whole lower mid range will be boosted in a cabinet. Sadly, it doesn't specify this measurement condition either. The 86dB/W/m line I drew in is correct.

Anyone can verify this by plotting the data set into any (reasonably accurate) speaker simulation software. The data set is correct. The plot is also correct. It's only the annotations on the plot that are incorrect.

Originally posted by Hemisphere Hemisphere wrote:

So is it not possible the original plot, and quoted numbers, are more or less accurate?

No. That is impossible.


Edited by Saturnus - 06 November 2014 at 2:10pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hemisphere Quote  Post ReplyReply Direct Link To This Post Posted: 06 November 2014 at 2:26pm
Oh well.

That'll teach me for believing as many as 6 impossible things before breakfast.


Edited by Hemisphere - 06 November 2014 at 2:27pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Saturnus Quote  Post ReplyReply Direct Link To This Post Posted: 06 November 2014 at 2:34pm
You have to realize that the plots are only to show relative linearity. And even so they are more or less complete garbage anyways.

To have any relevance for a real speaker designer plots should be standardized to having a ohm scale from 0 to 100, logarithmic, and a dB scale from 60 to 120, linear. What lies 20-30-60 dB under average level is completely irrelevant really. And impedance plots should be logarithmic which would reveal small nonlinearities in the suspension.
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Andy Kos View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Andy Kos Quote  Post ReplyReply Direct Link To This Post Posted: 06 November 2014 at 8:39pm
Originally posted by Timebomb Timebomb wrote:



Im not trying to have a go Andy and i realize you have an interest in promoting P audio but i think what ive said is fair criticism, i think you would do yourself a favor by measuring the drivers you deal in (with HF measurements done on a typical 60x40 horn like pretty much every other manufacturer) and publishing the results, i recon it would encourage confidence to more potential customers, me for one.
 

As and when we spot anomalies, we let P-Audio know, and push them to provide corrected information. One of the issues is that they are so busy concentrating on OEM manufacture, some of the branded product doesnt get as much attention as it should.

You are right, there are probably a few plots and spec that have issues, but P-Audio arent the only ones, lots of manufacturers have made mistakes, and happily carried on selling a product that doesnt match the published TS parameters.


just a guy with a warehouse and a few speakers... www.bluearan.co.uk
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Saturnus Quote  Post ReplyReply Direct Link To This Post Posted: 06 November 2014 at 9:46pm
What annoys me most being a long time p.audio user (since 1995-1996) is that they actually used to make plots on their old data sheets that were spot on. A bit heavy on the smoothening but otherwise totally accurate. Eg., http://www.paudiothailand.com/pdf/products/SN-10MB.pdf

Edited by Saturnus - 06 November 2014 at 9:48pm
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