Nola tweeter impedance readings troubleshoot

[Werd]

Hello

I've got a Nola tweeter that stopped working. Measuring the impedance it reads at about 4ohms. The other working tweeter is less than an ohm. What is wrong with the tweeter that isn't working?

Thanks,

[Werd]

Ok nvm they both are at about 5 ohms.  The tweeter doesn't work and it's not in the xover because they are external xovers for the hi freq and midrange.  It's easy to move xovers to the other speaker and check.

[tmazz]

Doyou have a record or CD with test tones on it? if so play a tone with a frequency that is above the tweeter xovr point and then with your voltmeter measure the voltage at the xovr inout and the HF output. This should tell you  if the xovr is passing a signal to the tweeter. If it is then measure the voltage at the teeeter terminals of the Nola. If you get signal there, pull out the tweeter and measure the voltage at the terninals on the tweeter tiself. If you have a good voltage at all theese points it wouls indicate t me that the driver itself is somehow broken. (If the tweeter cone itself has pulled away from the piston the drive may not produce sound even though you canelectrically see the impedance across the voice coil.) If you need help troubleshooting give Carl Marchisotto a call. I have found him to be very helpful and approachable. (Nola's phone number is 631-738-2540, plus whatever country codes you need to get a call from Canada to the US).

[Werd]

Tom they use outboard xovers. I took the xover from the working tweeter and used it. The tweeter still doesn't work. The working tweeter still works trying both xovers.

And thanks 

[Werd]

It is not blown and it hasn't opened up anywhere. It just doesn't go on.

[richidoo]

Pisser

Sounds like a rare broken tweeter. If you have 5 ohms across the tweeter terminals with crossover disconnected then the VC is OK, at least enough to move. Double check the easy stuff, like hookup wire connections in back of tweeter and in back of binding posts.

Last resort, do click test on the bare tweeter with a dry cell battery. A short click will not hurt it at all = 1/2Watt. You can use the speaker hookups and binding posts to make it easier. Reverse polarity, it should make two clicks on and off for each polarity. If not, it's an internal mechanical failure. Nola should replace it for free. You should ask about matching tweeters, either get 2 new matched tweeters, or mail in your other good tweeter to be matched with a new one.

Over the phone they will not want to believe that it is not a blown voice coil, as that is 99% of tweeter failures. Take a pic of your meter showing DCR 5ohms across the uninstalled tweeter.

[Werd]

Pisser

Sounds like a rare broken tweeter. If you have 5 ohms across the tweeter terminals with crossover disconnected then the VC is OK, at least enough to move. Double check the easy stuff, like hookup wire connections in back of tweeter and in back of binding posts.

Last resort, do click test on the bare tweeter with a dry cell battery. A short click will not hurt it at all = 1/2Watt. You can use the speaker hookups and binding posts to make it easier. Reverse polarity, it should make two clicks on and off for each polarity. If not, it's an internal mechanical failure. Nola should replace it for free. You should ask about matching tweeters, either get 2 new matched tweeters, or mail in your other good tweeter to be matched with a new one.

Over the phone they will not want to believe that it is not a blown voice coil, as that is 99% of tweeter failures. Take a pic of your meter showing DCR 5ohms across the uninstalled tweeter.

That is interesting, I guess it doesn't matter what size dead battery it is?

[richidoo]

Dry cells make 1.25V. It will say it on the label. A new cell is OK, a "dead" cell is usually around .9V so it still has enough to make a click. Of course the lower the voltage, the safer for the tweeter VC.

If you leave the DC applied for a long time the voice coil would overheat and short, so just do a short click, not sustained DC. It's <1/2w so safe for quick clicks.

This will only work for normal voice coil speakers. I don't think that ribbons with input transformer would work, nor would it be wise to apply a big step transient to a delicate ribbon.

Probably just as easy to call Nola for replacement driver. If you burn the VC while testing you'll have to pay for the replacement.

[Werd]

Ok apparently there is a foam thing that was detached from the magnet to the VC. Took the magnet off and reattached and voila. Works! I am all that is man!     got lucky actually.

[tmazz]

Sometimes it's better to be lucky than to be good. 

Glad to hear that you are up and running again.