Passive sub woofer question - AVS Forum
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Old 12-19-2013, 10:23 AM - Thread Starter
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I was given an old passive sub it originally came from a custom speaker maker JS Audio in NJ. I don't know too much about this but it has a 14" speaker and is in a solid wood cabinet. see attached pictures. My question is should I get an amp and use this or just buy a powered sub. I will use this primarily for home theater not music. I have a Sony STRDH720 receiver. I saw a   Harman/Kardon PM640 vxi amplifier on craigs list for $50... will that work. I'm not sure how to hook up the sub... there are a lot of connectors on the back, any help will be appreciated.

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Old 12-19-2013, 11:09 AM
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Before you buy an amp, try setting your L/R speakers to Large, set all other speakers to Small, run the L/R speaker connections from your Sony receiver to the sub, then run speaker wire from the sub to your L/R speakers.

From the way the connections are configured on the subwoofer's back panel, looks like it was intended to be in-line with the speaker connections rather than powered by an outboard amp.

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Old 12-19-2013, 11:56 AM
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Quote:
Originally Posted by sdurani View Post

Before you buy an amp, try setting your L/R speakers to Large, set all other speakers to Small, run the L/R speaker connections from your Sony receiver to the sub, then run speaker wire from the sub to your L/R speakers.

From the way the connections are configured on the subwoofer's back panel, looks like it was intended to be in-line with the speaker connections rather than powered by an outboard amp.

but which are the inputs, and which are the outputs, haha

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Old 12-19-2013, 12:39 PM
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From the layout I'm going to guess that the bottom ones are the inputs and the top (separated) connections are the outputs (to your speakers).

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Old 12-19-2013, 02:12 PM
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Personally I would remove the driver and see how it is hooked up. However you do not sound versed on the inner workings of loud speaker systems.
if this is true, but you feel you can remove the screws and lift out the driver without punching a hole in it with the screw driver (been there done that) you could possibly take some photos of the wiring and any crossover components that maybe mounted withing.

If you have an ohm meter you could also use to get an idea of how it is wired.
If there is no info on the cabinet giving the drivers impedance, you will need remove the driver to see if it is labeled or measure it with an ohm meter.
If the driver is 4ohms or greater this is a very nice amp that could be mounted into the cabinet assuming sufficient wood working tools and skills.
http://www.mcmelectronics.com/product/50-6272 I do own this amp and have had it for several years, I also have a 200 watt version that looks to be no longer carried by mcm.
Good luck!
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Old 12-23-2013, 10:17 AM - Thread Starter
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I tried to remove the driver. Took out all the screws but it looks like it is glued into place as well, so no luck with that. There is no writing anywhere on the cabinet.

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Old 12-23-2013, 11:49 AM
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Have you called the manufacture?
http://www.jsaudiovideo.com/
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Old 12-23-2013, 01:10 PM - Thread Starter
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They do not make speakers anymore.

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Old 12-24-2013, 08:10 AM
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Are you measuring 14" across the driver's surround? Most likely it is actually considered a 15" driver by current practice. Very few 14" drivers have been marketed during the 20+ years that I've been in this hobby.

The driver probably has a gasket that's sticking to the cabinet. Use a thin screw driver, putty knife, etc. to pry it loose. If it's 10+ years old, most likely, current subwoofers will out perform this unit in both output and extension. For a hybrid approach, you could probably fit a new driver and amp to the existing cabinet. I would need to know the cabinet's net internal volume to generate recommendations. If your DIY skills aren't up to making a replacement baffle, I'll also need to know the existing driver cutout diameter to limit recommendations to drop-in replacements.

Your existing driver probably has a label on the magnet or frame that will identify it's manufacturer and model. If we can find the T/S parameters for the driver, using the internal volume, we can simulate your existing unit to more accurately predict its capabilities versus current solutions.

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