Quote:
Ilkka wrote:
 How can you say that? Have you done any testing at different temperatures?
When I said that lower temperature means slightly better results, I meant regular long sine sweep tests. They put a lot of heat into VC and ambient temperature plays some role on how the VC dissipates this heat. But the short burst of the CEA-2010 is vastly different. Because it's only 6.5 cycles long, it doesn't create much heat at all. Therefore ambient temperature doesn't matter that much. 10 C or 20 C will give very close to identical results. That is one more reason why I started to use it: accuracy and especially consistency.
And in any case, the ambient temperature for rounds 4 and 5 was within 2-3 C. Quote: jakeman wrote:
The CEA guideline (22C-/+5C) is a fairly uniform standard for outdoor measurement which is why it was explicitly stated for purposes of the standard. Its not just the VC but to mention a few more, also driver surround, amplifier performance, microphone, suspension linearity, enclosure resonance as well as other measuring equipment that is also impacted. Copper resistive properties decrease with lower temperatures and while any one item may give slight change, if you add it all up experimental error does increase significantly as temperature falls. How much of an effect it will have on compression, FR, transient response, distortion patterns etc will not be the same in each sub. Anyway I'm not trying to detract from your efforts here. Its your methodolgy so good luck with it. | |
This is interesting. I didn't think about the voice coil heating at all, but like jakeman said, the first thing that came to my mind was the driver surrounds. How does that affect to the results? Especially with LMS drivers wich have rubber surrounds. Maybe the noise at high output was partially from the surround, because of the coldness? Higher distortion levels or something like that?
