speaker resistance and load

[Smolder]

I just picked up a pair of very good condition JBL D123's that appear to have the original cones (stamped 123504). They are marked on the foil label as 16 ohm, but they read 4.6 and 3.9 resistance. Should I assume these are 8 ohm and treat them as such?

[BMWCCA]

Lots of discussion on this topic. Here's a good place to start: http://www.audioheritage.org/vbullet...055#post119055

[Smolder]

Lots of discussion on this topic. Here's a good place to start: http://www.audioheritage.org/vbullet...055#post119055

thanks very much for the link.

I understand the 8 ohm marked as 16 as a non truth, and the difference between resistance and load. my concern was the reading below 4. Typically an 8 ohm speaker will read a resistance of 60% plus or minus. In the case of a reading of 3.6-3.9 my question is, is this a 4 ohm or 8 ohm speaker.

[Mr. Widget]

DCR and impedance are not linear... the DCR is typically quite a bit below the rated impedance, however an "8 ohm" driver may have a DCR of 3.8 ohms or 6.5 ohms or ???

Below is the impedance plot of a JBL 1200Fe-8. It is an 8 ohm woofer with a DCR of 5.6 ohms. More importantly, as you can see it is only ~8 ohms over a fairly narrow range. The actual impedance at a specific frequency region is more important than the rated impedance.


Widget

[Smolder]

thanks guys. Very helpful. And the chart is really interesting. I'd forgotten that load is an aggregate state. I'll consider them 8 ohm and move forward.