D-130 cone

[Wayne914]

I have and old JBL D130 with the ID tag missing. The only number on the speaker is 21057 stamped on the back side of the cone. How do I check the impedance of the speaker and what does 21057 represent? How old is the speaker?
Thanks, Wayne

[Harvey Gerst]

Measure the DC resistance across the speaker terminals. Actual impedance is a little higher than the DC resistance.

For example: 5 or 6 ohms DC resistance means it's an 8 ohm speaker, 11 or 12 ohms would be a 16 ohm speaker.

The 21057 (if it's original) would be the JBL part number from Hawley cones.

[Wayne914]

Thanks Harvey, very helpful! I'm installing the D-130 in a guitar amp that can go 8 or 16 ohms imped. This D-130 measures 7.4 ohms DC so I'll set the amp up for 8 ohms.
Thanks again,
Wayne