1968 Yamaha NS "EAR" Speakers - Open Baffle - Some Questions.


Looking to share and acquire more information on these speakers.
Does anyone have any information on the crossover / electronics in these speakers ? To be honest they sound fine, very open. but wondering if replacements for the electronics are available. The fellow at the place to buy capacitors, thinks the top capacitor in the picture is oil filled and not available.

I don't recall how I acquired mine - NS 15. I do remember with the grills on and not much attention given to their placement, I initially, didn't think much of them as the sound was so-so; and they went to my son for his surround sound back speakers. They returned last week, was told one tweeter was not working and I took the grills off. Much to my surprise.

See the link.

https://photos.app.goo.gl/TSCFtwijM5dcCmid8

The tweeter was fixed with some cleaning of the variable tweeter pot.  I placed them in an open area and they sounded good. Currently tucked in above a record cabinet with the tweeters on bottom.  They will need to be tilted down if left there.   

Japanese, hand made, All good materials Walnut wood. Hand cut outs for the components. Woofer and Tweeter mounted in an aluminum frame. Internet says they were around $250 in 1968.

Research shows their design was meant to be in a very open area. The smaller Japanese audio rooms I have seen, probably helped contribute to their demise domestically. Seen in studios sitting on top of the master control cabinet, a few feet from the recording engineer. When he was done there, the music was moved to full range speakers in same room for final edits. Sound emanates from all directions. This explains the open groove side design of the cabinets and just a mesh in behind.

from the internet

Acoustic system, made in Japan, Issue 1968
Yamaha speaker system in which Yamaha NS JA-5002, a proprietary speaker, is used to reproduce bass frequencies. The NS system reduces vibration caused by the movement of the speaker piston. Aperture of a special shape selected after more than 200 tests.
Yamaha proprietary anisotropic magnet is used to reduce distortion. The device has excellent directivity and surround sound characteristics, a multi-resonance system is used. To reproduce medium frequencies, the cone speaker JA-2053 (cm) is used. To reproduce high frequencies, the speaker horn JA-0505 5 (cm) is used, which is equipped with a level control.
A case with a unique “inward” arrangement of the woofer. Walnut plywood finish. The front housing is closed with a removable mesh.

Very efficient 100 db + I assume.
The electronics has me baffled. The AC and DC capacitors. See the pic. 
JIS 4901
MP Condensor nmp 1135
cap 3.5 uf
w.a.v 100 v.a.c
1968
Nichicon

Please share any info on them.

https://www.gzhifi.com/kt/gallery.php?id=809

Download for users manual

http://www.umlib.com/brand/Yamaha/category/Speaker/model/NS-15

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I own the Yamaha NS-15 speakers and I bring them in and out of my system.  I did a lot of searching on the web for information and there is not much there.  What I learned was that Yamaha did not have a Speaker for the home market in the 60's so as a stop gap, used their electric piano's "ear" speaker in an open baffle format combined with a JA-5505 Aluminium Tweeter.  There were many evolutions of this basic designs.  The NS-15 seems very close to the NS-250, the former having a broader ownership.  

The crossover is extremely simple and some have recommended that the woofer should not be limited and to just replace the tweeter's caps and eliminate the Woofer's caps.

 They are very very efficient at 98 db, so the Yamahas are perfect for triode amps.  I have removed the front and rear covers.  I have them placed well away from the back wall, and I pair them with a set of subs.

They do sound very interesting, piano sounds very realistic and alive.
Being an open baffle design, they create a gorgeous sense of depth.
Eventually, Yamaha dropped the design and developed a speaker
with a more traditional cabinet leading to their power house 
Yamaha NS-1000 speaker with it's beryllium drivers.

One of my caps is leaking, so I intend on implementing a newer modified crossover with a tweeter recap and the woofer bypass.  Due to Yamaha's research in developing the JA-3501 woofer for their musical instruments, this speaker represents a unique value decades later at current used prices.
lowrollinghills
Thank you for the post and the information. I really did not think I was going to get a response as these speakers are so rare and ....well different and unique.
The woofer you can feel vibrating but it doesn't move to the eye.
I have them set up in an office type environment.
I was told the caps were oil filled. I would be interested to know the parts you select for replacing any electronics.
Maybe in the future I will look for a triode amp - never thought I would be going down that route. 8^0  

They are very very efficient at 98 db, so the Yamahas are perfect for triode amps.

Please recommend a SET Triode amp (brands). I am familiar with SS, Push Pull and OTL. 

Without any actual measurements, I estimated 100 db + just based on how they reacted to a few different amps. ......so I came close.8^)