Help with reading frequency/impedance chart

[retroman]

Hi all,

I am planning on using some Vifa P21WO-20-08 woofers in a future design but the frequency/impedance chart on the spec sheet (see link below) is confusing me. The SPL scale on the left that I am used to seeing with 0 in the middle and the +/- range usually going up and down is all out of whack. I'm not sure how to read it.


http://www.madisound.com/catalog/PDF/p21wo20-08.pdf

Also, I would like to use this the Dayton RS52AN dome midrange with this woofer and was think about crossing over at 700Hz. Would that be too high for this woofer?

As always your advice and opinions are appreciated.

[Inductor]

Originally posted by retroman
...the +/- range usually going up and down is all out of whack. I'm not sure how to read it.

If you read in the bottom of the page 0=60dB, so you start with 60dB and go from there (add ten each time). The woofer works good for that frequency. It all depends of the x. order you are going to use. 700 is not a nice xover frequency though. Try to cross at arround 200/300 or 2K/3KHz. Not with a dome mid, if you gonna use one. It should work.