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JBL 075 function

C

cassette

AK Subscriber
Subscriber
Greetings!

I have a long term project where I bought some 4505wx that were in great working order and along with that came some 075 bullet tweeters. The cabinets have knockouts for them so adding them would be easy and I was told that I could get some N8000 or n7000 crossovers and add them to the cabinets. The cabinets also have a space for a second crossover ( I have no idea how that works but that is a future question :)

My questions is simple: How can I test the 075 to make sure they work before going through the expense and trouble? I did check them on the multimeter and they have continuity and crackle.. but does that mean they are good to go? Thanks for any help and suggestions!

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cassette said:
I did check them on the multimeter and they have continuity and crackle.. but does that mean they are good to go?
Click to expand...

When you used the multi-meter, what did you measure exactly? Measure the resistance in ohms and see if they are the same between the two. Note that this is the DC resistance (DCR), not the impedance (which is AC and cannot be measured via a multimeter), but it is usually possible to find out what the DCR is supposed to be. Even without knowing, if one measures significantly different than the other, that would be a big red flag.
 
The continuity and crackle is a good sign, but as Chris said you can measure resistance and you should see similar resistance between the two, if they are 8 Ohm expect DCR around 6. There are other things you can do, use the output from a smart phone with maybe a 8kHz tone at a low level (can get tone apps) and you should hear the tone.
 
cassette said:
Greetings!

The cabinets also have a space for a second crossover ( I have no idea how that works but that is a future question :)

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Click to expand...

JBL would have a crossover (e.g., LX5) between the woofer and the horn and this would fill one of the two holes. The output for the horn would then go to a second crossover (N7000/N8000) that separates the horn and tweeter.
 
Ok, thanks for the replies! I was measuring resistance and they both were hovering about 7- 8 ohms but I think the hovering was more a function of my hardly used multimeter. Thanks also for letting me know how to use the second crossover! It sounds like things are looking good for me to start looking for the second pair of crossovers. I wiill keep you posted and thanks again!

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