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LaScalla Base Driver not working suggestions ?


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I picked up a nice set of Birch LaScallas for a great price but the owner said the one bass was not working.

Can anyone suggest what I should look at to repair this one speaker? Maybe use a meter on something?

I've attach a photo of the crossover should 

anyone have a suggestion maybe to replace anything on it?

Much Appreciated

58F72DB7-BC7E-4E5D-8675-DF2A62EAEFFC.jpeg

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First, put a voltmeter set to AC Volts across the two screw terminals for the woofer.

 

The number you read should bounce around in conjunction with the music that has some bass. Any rock or Jazz is fine; string quartets, not so much. As you raise the volume, so should the numbers on your meter.

If the numbers don't rise and reflect the music, you have a problem with the crossover. Crossovers don't usually go bad.

 

Next, access the woofer through the bottom door, I believe. Make sure the wires are connected to the woofer terminals. One connection could be detached or broken, or the wire could be cut.

 

Last, unplug the wires at the speaker. Set your voltmeter to ohms/resistance and place one lead on each terminal. On the back of the woofer you should

see it listed what the speaker's resistance is; usually 8 ohms. You should read 8 ohms +/- a couple ohms. If you read a very high number say, over 100 ohms, the woofer is bad.

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1 hour ago, postman56 said:

Does the speaker need to have a audio source being supplied in order to take a reading as suggested above to check for the ohms?

NEVER check for resistance with power or a signal applied. You can damage your voltmeter.

You must however, disconnect at least one woofer wire from the crossover

to "open" the circuit, which will ensure you're measuring just the woofer.

 

Please report back to the forum with what you find.

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On 5/14/2022 at 9:05 PM, postman56 said:

Does the speaker need to have a audio source being supplied in order to take a reading as suggested above to check for the ohms?

 

Start by verifying the internal  wiring of the woofer  -the connectors  might  be unhooked .  take the  bottom panel out-

-are the  positive/negative connectors  on the woofer terminals  hooked up properly ? , if yes .......

-place the prongs of the Ohmmeter on the terminals of the woofer by selecting Ohms . if the reading is  lower  than 3 Ohms  , you'll need a new woofer .

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AT THIS POINT, THERE IS ABSOLUTELY NO NEED TO REMOVE THE WOOFER HATCH DOOR TO TAKE A READING DIRECTLY FROM THE WOOFER TERMINALS.

 

Once again, the EASIEST way to verify whether the woofer is good or not is to remove the wires on the crossover marked "Woofer".  Place your meter leads on each of the wire ends and take a reading.   You can then further investigate if this reading is zero or is intermittent.  Why some here are making this more difficult is ridiculous.

 

@postman56You are welcome to PM me, I am happy to assist.

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Sorry, edit, I confused „open“ and „short“. if your measurement is correct without any other influences than just the wiring to the woofer it seems to be a „shorted“ voice oil. Perhaps I nevertheless would measure directly at the woofer‘s solder points. Here was talk about disconnected wiring but theoretically a short could happen also on the way to the woofer re the wiring.

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4 hours ago, jimjimbo said:

AT THIS POINT, THERE IS ABSOLUTELY NO NEED TO REMOVE THE WOOFER HATCH DOOR TO TAKE A READING DIRECTLY FROM THE WOOFER TERMINALS.

 

Once again, the EASIEST way to verify whether the woofer is good or not is to remove the wires on the crossover marked "Woofer".  Place your meter leads on each of the wire ends and take a reading.   You can then further investigate if this reading is zero or is intermittent.  Why some here are making this more difficult is ridiculous.

 

@postman56You are welcome to PM me, I am happy to assist.

It is neither difficult nor ridiculous. Checking the woofer directly at the terminals will tell you whether that connection is broken. There are many ways to troubleshoot electronics. You can start from the beginning of the circuit and work toward the end; you can work backward from the woofer, or you can break the circuit up into segments and test each segment individually. None of the three are better or worse than the others; at least that's what I was taught in school.

 

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If you should need a new K33, Michael Crites could be the first address. Others here will know exactly what the model is called and also if you need two new woofers or if the Crites woofer could meet the criteria of the remaining K33 (after all these years).

I have heard that there are two Crites models. One is sheet metal stamped and the other has a rigid cast basket. The original K33 is sheet metal stamped. And the other cast basket may be too large in diameter in the Lascala. I personally would take the sheet metal stamped woofer.

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20 minutes ago, KT88 said:

Sorry, edit, I confused „open“ and „short“. if your measurement is correct without any other influences than just the wiring to the woofer it seems to be a „shorted“ voice oil. Perhaps I nevertheless would measure directly at the woofer‘s solder points. Here was talk about disconnected wiring but theoretically a short could happen also on the way to the woofer re the wiring.

That would be exactly my argument if any, for doing the connection via amp, wire first to network before proceeding onto going into the speaker directly. If philosophy were to apply, do the simplest first troubleshooting.

Or KISS...

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