The BMS 4547nd distortion at 10W is marked +20 dB compared to 4550 / 4552nd which is +10 dB at the same power. Anyone know if it is true or typo? Makes quite some difference in THD...
Thanks
Petter
Thanks
Petter
+20 or +10 dB is to make everything fit on the same graph. Is it reasonable that a different value has been chosen for this reason?
Yes, I hope so. What made me doubt was that if so, the 4547nd outperforms every other driver in BMS' product range distortion-wise. All other drivers have fairly consistent distortion values.
Post the distortion plots and we'll see what's up. I'm not sure if you are following what tbtl is saying, Displaying them +10 or +20 does not mean that the values are higher or lower, it just let's them display them on a smaller graph so the distortion isn't so far down. Hope that makes sense.
Petter,
After looking at BMS old and new formats for displaying the same information, my vote is for a typo, there is nothing about the 4547 that should give it an even 10dB reduction in distortion at 10 watts over their previous drivers, considering the 1 watt distortion levels are nearly the same between them.
They also stop the 4547 distortion chart just above 10kHz so we don't see those upper lines meeting each other up around 19 kHz ;^).
If they used the same horn, the 4547 appears to have a few dB less top end than the 4550/4552nd.
Art
Petter Persson was writing about the 10 watt distortion figures, which are raised only +10 dB in the 4550 and 4552, but are claimed to be raised +20 in the 4547, as can be seen below.
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Thanks Art for your interpretation. I agree, another thing to note is that if the +20 would be true, the distortion would not increase between 1 and 10 W, which is unlikely.
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