Replacing Yamaha NS-4 Woofer/suitable alternative?

[boonefrog]

Hi all,

So one of my Yamaha NS-4 woofers went out. My assumption is that something happened to the voice coil as the bass got instantly muddy/distorted/nonexistent low-end, though there doesn't seem to be too much rubbing. Switched channels, took it out and tested, etc. So it's looking like I'll have to replace it.

My question is this: I have not been able to find an original replacement NS-4 woofer anywhere. Any leads on where to find one? Assuming I can't track one down, can anyone help me identify what's in there/a suitable replacement?

Here's what I've got in terms of identifying info:
-- 8" woofer, rubber surrounds
-- on backside of cone is printed 128-1003
-- stamped and centered on the metal part of the back of the magnet is 421-1002D

I've heard elsewhere on AK that these might be hard to find a suitable replacement for, but was wondering if anyone might have found something since. Thanks!

BTW, in case any confusion, these are the NS-4's I'm talking about: http://cdn1.ioffer.com/img/item/755/729/96/dded_1.JPG

 

[cablephil212]

Let's start with the basics.

Have you tried the driver directly to the speaker wires from the amp? Does it have the same problem?

What does "not too much rubbing" mean? Is there a VC rub when you press down equally on the inside of the cone?

This might be a x-over problem. Have you looked to see if anything looks burnt or swelled caps on the tops?

Have you tried removing the "good woofer" and installing it into the other cabinet?

 

[boonefrog]

Let's start with the basics.
Have you tried the driver directly to the speaker wires from the amp? Does it have the same problem?

Yes, on 2 different amps.

What does "not too much rubbing" mean? Is there a VC rub when you press down equally on the inside of the cone?

When I've had speakers blow out in the past, the rubbing's been much more substantial. And I've had a similar amount of rubbing (maybe from a previous poorly done refoam?) on speakers that don't appear to have any performance problems. Hope that clears it up...

This might be a x-over problem. Have you looked to see if anything looks burnt or swelled caps on the tops? Have you tried removing the "good woofer" and installing it into the other cabinet?

No I didn't get down below the insulation material, but like I said above, the same problem appeared with speaker wires going straight from amp to a single woofer. And it's still there doing that and the full speaker on different amps. I think this eliminates those possibilities, but I'm a novice so let me know if that's not the case

 

[cablephil212]

One question I didn't ask. Is the other box OK? Does it sound right?

OK. You most likely have a bad driver.

I would still check out the x-over. That could have caused the problem.

Tell me the dimensions of the box, from the inside. If you can, post a pic of the woofer. While you're at it, if you can, take a pic of the x-over.

Trust me, they'll be more questions if you want to get those back into shape.

post back when you can.

 

[Sal Tuna]

Same here

I picked up a pair of NS-4's recently at a Goodwill for $25. Of course a cone is blown, but at least it's only one. Woofer, as well, so I'm interested what people might recommend, too. My needs probably aren't nearly as picky as people who've developed an ear toward them, though. Listening to the "good," working one, I can see what people mean by using these to focus on mids in a less-than-stellar (more "mass-production"-style) overall speaker.

Mine measures 3.4 ohms DC on both the working and non-working coil. Weird, as it still passes signal but just barely audible. No easily discernible rubbing of the voice coil, either. Connecting this woofer directly to a couple of different amps, it truly seems to be the culprit though. I also put an 8-ohm composite cone I had lying around in the "bad" box, just to test functionality, and rest seems OK, messed up level and crossover points aside.

 

[Gumbee]

Same here

I picked up a pair of NS-4's recently at a Goodwill for $25. Of course a cone is blown, but at least it's only one. Woofer, as well, so I'm interested what people might recommend, too. My needs probably aren't nearly as picky as people who've developed an ear toward them, though. Listening to the "good," working one, I can see what people mean by using these to focus on mids in a less-than-stellar (more "mass-production"-style) overall speaker.

Mine measures 3.4 ohms DC on both the working and non-working coil. Weird, as it still passes signal but just barely audible. No easily discernible rubbing of the voice coil, either. Connecting this woofer directly to a couple of different amps, it truly seems to be the culprit though. I also put an 8-ohm composite cone I had lying around in the "bad" box, just to test functionality, and rest seems OK, messed up level and crossover points aside.

Resurrecting an old thread but I have one speaker where the woofer isn't working. I tested it with a multimeter and it reads around 3 ohms. The tweets play. Took a picture of the insides. Any idea guys? I'm new to diagnosing and fixing speakers so any help would be awesome.