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Hello everyone. This is Yagi writing from Hi-Fi Do Kyoto Repair Department. Here in Kyoto, the climate is very mild and comfortable. Looks like autumn is finally here. I hope you are doing well wherever you are reading this. What I have been excited these days is this TV drama called "Sanadamaru". It is based on the story of one of very famous samurai warriors Yukimura Sanada who lived the age of Japanese civil wars. It is now coming to the climax: Siege of Osaka. I just can't help talking to somebody about it. Another thing that makes me excited is a movie just released called "Sanada Ten Braves". I guess I fell prey of the movie people's strategy.

Okay, let's move on to audio thing. Today's theme is NS-1000M, whose successor is now audiophile's favorite topic like the samurai drama is to Japanese people. I know you might be thinking it is such an out-of-date topic but don't judge yet. This time, I am not gonna list bunch of cliches and blah blah like they used to be monitors at Swedish and Finish national broadcasting stations. I am going to research and speculate whatever I find interesting.

The first thing I wonder was this. NS-1000M was sold 200,000 units for 23 years from 1974 to 1997. Were there any changes during the long history? Out of that curiosity, I dug into the Hi-Fi Do's sales/repair history and found some of slight differences.

First thing I realized was the appearances. It is hard to notice at the first glance but units with younger serials had concavities on the woofer frames (right next to screws). They didn't have +/– signs on the back either. These can be seen until serial 342XX according to Hi-Fi Do database. After, concavities are gone and +/– can be seen. There are some exceptions like early units without concavities and vice versa. Those must have been replaced at some point.


Okay, let's look at the back. Early serials from 1XXXX to 175XX looks like stamped. From 21XXX to 246XX, L/R of them looks stamped. Everything after are the ones we are all familiar to. Another thing was caution sticker (bottom right picture). It cannot be found until 246XX. Since it says not to exceed speaker wattage, I wonder there were some troubles on that.


Another feature of early units are stickers to show that they passed checks. The stickers had two kinds: one is with seal and "goukaku" meaning passed on it (left) and the other say "passed". The former is of number 516XX and the latter is after that. However, these disappear after 795XX and even one cannot be found. It seems they just quit putting them on.

Seeing individual components, the first thing came to my mind were ATT plates. You might not be able to tell the differences of the two images below but the ones on the left (can be seen on very early units until 100XX) are made of metal and somewhat thinner compared to everything produced after which are made of resin (right picture). Holes on the enclosures were shallower on the former to match the plates as well.


The next is networks. Obvious differences are bigger fonts and use of strings instead of vinyl on the earlier units. When I saw it closely, I found 4 digit numbers such as 1979 on the wires, which I assume are years of production. It is not still sure but all the units I checked had corresponding years to their production years. The oldest of them had serial 140XX and the wires said 1974 and the newest (3103XX) said 1993 so my theory seems right. This part could be a key to know approximate production year of the speakers. (Serial of NS-1000M lies 100XX–11XXXX and 30XXXX–31XXXX probably.) (The network below is serial number 489XX and the wires are from 1979.)

Below is the summery of all the serials and years of the wires. 140XX...1974 155XX...1975 246XX...1976 328XX...1977 453XX – 470XX...1978 489XX – 540XX...1979 611XX – 736XX...1980 795XX – 814XX...1981 921XX – 1059XX...1983 1074XX...1984 3073XX...1989 3103XX...1993 By the way, serial 814XX came with a proof of purchase and it was from showa 57 (Japanese calendar, 1982) which was also helpful to detect the production year.
That's it! I hope you enjoyed the blog. There were some difficulties on judgement such as remodeled units and peeled off stickers on the way. So the result is not completely sure but I hope this information helps your audio life somewhat. Please let me know if there are something I missed. Until next time!

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