Yamaha NS 1000M

johsti

johsti

Active Member
I posted this in a thread on the speaker forum but thought I might get more views and input here. I just picked up a pair of NS-1000M locally for what seemed like a fair price. The cabinets were pretty beat up, but can be refinished at some point. I noticed that one of the domes on the tweeter was red and the other was green, other than that they looked identical. At first I thought someone swapped out one of the tweeters, but after inspection, both tweeters were labeled JA-0513 and both midrange were labeled JA-0801. I didn't bother checking the woofers since they had cloth surrounds and metal grills, I figured they were the right ones.

Also, one of the tweeters was missing two screws to fasten it to the cabinet. Anyone know where to get replacement fasteners?

I hooked them up last night and they sounded great just sitting on the floor in front of my current speakers. I need to build some stands and set them up properly to see what they can do.

Any input on why the tweeter dome is red and where to get a couple of fasteners for the tweeter would be appreciated. Thanks.
 
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Hmm, if the body of the tweeter (front and back) and model number on back look and are the same then perhaps the dome is a replacement or somehow has oxidized to a different patina. Definitely worth a look, but don't touch the dome (beryllium coated!).

Note: There is a slight reddish hue to the midrange on my NS1000Ms (see photos). The tweeters and midrange should both have a black metal screen on them if they are original. Photos below: tweeter on the left and midrange on the right.

You could probably find matching screws/washers at a good hardware store.
 

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Here are a couple of photos. All part numbers match on the tweeter and midrange (ja0513 and ja0801). The serial numbers on the cabinets are matched. Being that these speakers are 30+ years I would be surprised if all the drivers are original. I put a little bluetak over the tweeter holes with the missing screws to seal the cabinet. It seems the t-nut inside the cabinet is stripped. Not sure if the t-nut can be replaced or if I need to go with a nut and bolt.
 

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They look pretty original from here. Just check to make sure that you are getting sound out of all drivers (tweet, mid, woof). Sometimes the tweeters are shot, but don't assume that they are blown if you get no sound. Often the tweet and mid level adjustments just need some Deoxit in them or (as I found out) there is a loose wire in the crossover or at the speaker itself.

I chased, what I thought was a wonky midrange for a LONG time before I isolated it to a loose wire connection on the crossover board (speaker worked fine when isolated, but sound dropped out). Once I found the problem, I resoldered the connections and now they sound as good as new.

Your speakers look to be in pretty good shape from what I can see in the photos!

For the missing screws/washers, you can take a good one out and go to a hardware store to find a match. I suspect at some point a tweeter was replaced and screws were lost (not uncommon). EDIT: Just saw your note on the T-nut.
 
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I don't have a multimeter but from what I can tell the tweeters are working. I don't hear any distortion when adjusting the tone controls so the prior owner must have maintained and cleaned them recently. The tone controls work as they should and attenuate and increase the tweeter and mid levels. There is a loose solder connection on one tweeter that needs to be addressed. If the tweeters weren't working I would assume I would hear a change in tone when adjusting the tone control, right? When I put my ear near the tweeter it is definitely producing sound. The tweeters are crossed pretty high around 5khz from the specs I read.

The front and back look pretty good but the top, sides and bottom have scratches and one corner is chipped but glued back on. They can definitely be refinished to look presentable.
 
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I just borrowed a multimeter and tested the tweeter terminals while still attached to the crossover. Both tweeters measured 2.2 ohm. This measurement is with the tweeters connected and not removed from the crossover/speaker.
 
Easy, the one with the red tweeter goes on the left (port) channel and the one with the green tweeter goes on the right (starboard) channel :D :D
 
johsti said:
I posted this in a thread on the speaker forum but thought I might get more views and input here. I just picked up a pair of NS-1000M locally for what seemed like a fair price. The cabinets were pretty beat up, but can be refinished at some point. I noticed that one of the domes on the tweeter was red and the other was green, other than that they looked identical. At first I thought someone swapped out one of the tweeters, but after inspection, both tweeters were labeled JA-0513 and both midrange were labeled JA-0801. I didn't bother checking the woofers since they had cloth surrounds and metal grills, I figured they were the right ones.

Also, one of the tweeters was missing two screws to fasten it to the cabinet. Anyone know where to get replacement fasteners?

I hooked them up last night and they sounded great just sitting on the floor in front of my current speakers. I need to build some stands and set them up properly to see what they can do.

Any input on why the tweeter dome is red and where to get a couple of fasteners for the tweeter would be appreciated. Thanks.
Click to expand...
Beryllium has a variance of colors. Chances are one of the original tweeters has been replace with a new replacement.
I have 7 or 8 of the same tweeters, in 6-7 different flavors. From dark metallic-yellowish metallic green -dark purple/red metallic etc.
 
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Yes, the beryllium tweets on my 500m's have a greenish pupil with a reddish pink iris...quite pretty actually:scratch2:
 
Has anyone replaced the t-nuts on the cabinet that secure the drivers? I am missing two screws that fasten the tweeter to the cabinet, and it appears that the t-nuts are stripped. I want to remove them and install new t-nuts. Not sure if the original t-nuts are barbed, threaded, or if replacement is possible.
 
Just had the same issue with a pair of NS-1000M's that I picked up. Someone reinstalled one of the midranges with drywall screws and trashed out the threaded inserts. The original inserts have barbs, see attached photo, item on left. I determined that the threads are M4-.70 and was successful finding some tee-nuts that matched (item on right). Also found the screws, washers, and lock washers, see labels. Good luck.
 

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Easy to replace T nut.

Drive out the stripped one with an appropriately sized punch. Then place with the new one. Try to line up the barbs with the existing holes.
 
miklemke said:
Easy to replace T nut.

Drive out the stripped one with an appropriately sized punch. Then place with the new one. Try to line up the barbs with the existing holes.
Click to expand...

Thanks. Where did you source barbed t-nuts similar to the originals?
 
I was unsuccessful in locating threaded inserts with barbs that matched the originals. Did see some, but none with the correct threads. I found the tee-nuts shown in my previous post at Home Depot.
 
voodoocanoe said:
Easy, the one with the red tweeter goes on the left (port) channel and the one with the green tweeter goes on the right (starboard) channel :D :D
Click to expand...

Hahahahahahaha! You mutht be a thailer. POWER BOATER HERE! Great speakers! I agree the dome was probably exposed to some element and patina'd reddish like a raddish.
 
So I found some t-nuts and hardware, but noticed another issue. It looks like the previous owner wired the tweeters "in phase". From what I understand the tweeter was wired out of phase intentionally from the factory. The purple wire is currently attached to the + terminal and black to - but it should be the other way around.

Is it worth swapping the wires? It sounds good as is, but will they sound better wired out of phase?
 

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