SPL trace question

[nigelb63]

I am trying to generate an FRD using spl trace. looking at the image the trace is cut off at the lower of the scale. What would be the best approach to achieve a workable trace?

 

[TBTL]

It does not matter too much because it is already down by 20 dB and it is likely to be even further suppressed by an electrical low pass filter. I would trace the lower scale limit or an estimate of the curve.


By the way, there appear to be more versions of this Volt BM220 woofer with for example a significant difference around the 2 kHz peak:
https://voltloudspeakers.co.uk/wp-content/uploads/2014/03/BM220.1.pdf
https://voltloudspeakers.co.uk/wp-content/uploads/2014/12/BM220.8.pdf

 

[AllenB]

I would also guess the dip. However, I wouldn't be trusting a single measurement in this chaotic region, I would be cutting it to be sure.

 

[nigelb63]

It does not matter too much because it is already down by 20 dB and it is likely to be even further suppressed by an electrical low pass filter. I would trace the lower scale limit or an estimate of the curve.


By the way, there appear to be more versions of this Volt BM220 woofer with for example a significant difference around the 2 kHz peak:
https://voltloudspeakers.co.uk/wp-content/uploads/2014/03/BM220.1.pdf
https://voltloudspeakers.co.uk/wp-content/uploads/2014/12/BM220.8.pdf

Thanks for your response. I have contacted Volt to clarify this difference. As I understand it, the BM220.8 and the BM228.8 are the same but the part number designation is all that has changed.