renewing yamaha ns 20 speakers [Archive]

dequincey

03-12-2018, 23:43

hi

i started in this NS (natural sound) world just 2 months ago with a pair of a ns230, just choose them because my grado headphones are sort of open box (is this the correct definition ?) and i love them so i thought what about an open box speakers ?

bought the ns230, they were afordable and happen to be good but with some troubles that i could solve easily by cleaning, fixing some loose screws, and adding a new strap adhesive perimetral sponge band, did not replaced capacitors and resistors, but will look on this later

24819

in the mean time a pair of huge ns20 popped up in the radar and simply i have to had them.

if the profound bass is what makes the ns great just imagine a 800x600 mm sized bass driver in the ns20

see the 230 in black grille cloth compared to the ns20 in light brown

24820

dequincey

04-12-2018, 08:35

When recived, i checked tha sound was good but found some differences between them. So i wanted to take a look at the interior,

started the dissasembly,...

BTW, i have seen that even being ns20 there are slight differences between these speakers (seen the photos in the internet) some have two coils, mine, only one, some have a fixed panel for the medium and tweeter, mines have those dirvers hanging with the front cover grille

dequincey

04-12-2018, 08:43

this is a picture of my setup
24821

first i removed the front to find no absorbent material in the walls and moreover no sign of staples or eny fixing glue, my guess is that these came with no absorbent, is this possible ?

24822

ok, front panel with drivers medium and high

24823

removed the woofer, it is really huge, it has its own suspension with rubbers, separators and washers

24824

the empty shell with new absorbent installed

24825

Macca

04-12-2018, 08:59

New one to me. Open baffle, but bass fires backwards and tweeter fires forward?

walpurgis

04-12-2018, 09:04

I remember the old NS range with the big expanded polystyrene diaphragms. I saw and heard them at audio shows in the early seventies and thought they sounded pretty good. I still see the occasional set for sale and it's interesting that they have survived this long in decent condition, they must have been very well made.

I think the lack of damping material was because they were a doublet design and relied on front and rear output.

dequincey

04-12-2018, 18:01

actually i need some help

as one of my medium drivers is not original and it sounds not perfect i am considering going the route of swapping both medium and tweeters (both 8 Ohm rated) with a 5 Ohm rated Saba Greencones (greencones are known for working well in open box configuration)

here is my question:

can I directly replace a 8 Ohm rated driver with a 5 Ohm rated driver ? or should i add a resistor to this 5 Ohm rated to make the equivalent of the 8 Ohm previous driver ?

if that is the case which kind of resistor should i use ?

forgive me for this question if you feel is too obvious, but i have no idea what to do

regards

Macca

04-12-2018, 18:03

Should be fine, no driver is exactly one resistance anyway. Try without the resistor first.

walpurgis

04-12-2018, 18:13

I think your proposed mid driver change may not be a great idea. A 5 ohm driver with series resistor will give unpredictable results with the existing crossover.

The Saba green cone units may be favoured by some, but are not necessarily ideal

Although marked Yamaha, I suspect the original mid units may actually have been sourced from a reputable Japanese maker of the time, like Coral, Foster or Crysler. It may be best to look for something similar. Many used drivers of this sort appear on ebay US listings, it could be worth keeping an eye on those.

dequincey

04-12-2018, 21:31

Should be fine, no driver is exactly one resistance anyway. Try without the resistor first.

I think your proposed mid driver change may not be a great idea. A 5 ohm driver with series resistor will give unpredictable results with the existing crossover.

The Saba green cone units may be favoured by some, but are not necessarily ideal

Although marked Yamaha, I suspect the original mid units may actually have been sourced from a reputable Japanese maker of the time, like Coral, Foster or Crysler. It may be best to look for something similar. Many used drivers of this sort appear on ebay US listings, it could be worth keeping an eye on those.

thank you for responding, both approaches might be sound

i have tried to source the mid drivers, very rare in europe, might have a chance in US and AUS, and of course JPN but that market is almost impossible to access,

first thing will be to refresh crossovers,

meanwhile will check different approaches and will report here

regards

dequincey

10-12-2018, 10:56

started the process:

https://i.postimg.cc/RFP9RnJq/20181125-125138.jpg (https://postimg.cc/G8sZ3tQ1)

https://i.postimg.cc/jdnKH2xd/20181125-130423.jpg (https://postimg.cc/ppvgx25g)

https://i.postimg.cc/brWPXcTh/20181125-174622.jpg (https://postimg.cc/fScpXPp2)

first big surprise (but i had heard the difference before) was to find two different circuits for the crossovers

https://i.postimg.cc/L4b2gLMb/20181125-182207.jpg (https://postimg.cc/YjYJJ406)

dequincey

10-12-2018, 10:59

i will replicate the A circuit as it is the one found in the specs drawing

https://i.postimg.cc/tgWNWhft/20181209-191455.jpg (https://postimg.cc/bGYnj2qs)

i will have to recreate the two bridges

https://i.postimg.cc/50Jq3XWc/20181209-194239.jpg (https://postimg.cc/GBMy3hpz)

https://i.postimg.cc/PJrWg0q2/20181209-203211.jpg (https://postimg.cc/ygt39QcZ)

adding resistors from Kiwame, Japanese brand that offers exact resistance values

https://i.postimg.cc/gJKyBGGx/20181209-203522.jpg (https://postimg.cc/MMvjn2Mw)

https://i.postimg.cc/Pf2zWf6c/20181209-205026.jpg (https://postimg.cc/Hj8yHm14)

https://i.postimg.cc/C5PGSJBY/20181209-205034.jpg (https://postimg.cc/9w9RBdYN)

dequincey

10-12-2018, 11:02

and using the mundorf capacitors, one 1+1,5 uf in series, and one 100uf directly

https://i.postimg.cc/RVmhZwQx/20181209-210210.jpg (https://postimg.cc/F1PNPdBT)

due to their size i have to place them in the other side of the circuit

https://i.postimg.cc/FKws5Ssq/20181209-211957.jpg (https://postimg.cc/GBJ1vHDJ)

https://i.postimg.cc/Hx5WpLrL/20181209-211959.jpg (https://postimg.cc/PpXnyTzG)

please, comment anything that you consider odd or that can be done other way

dequincey

10-12-2018, 14:22

list of materials

100uF 50V Mundorf ECap AC PLAIN electrolytic capacitor
1uF 600V Mundorf MCap Supreme Capacitor
1.5uF 600V Mundorf MCap Supreme Capacitor
3R9 5W Kiwame Resistor
8R2 5W Kiwame Resistor
16R 5W Kiwame Resistor
24R 5W Kiwame Resistor

dequincey

11-12-2018, 21:04

finished the renewal of these crossovers

https://i.postimg.cc/R0t51QqX/086-E58-BB-5011-47-E2-AA83-15-A966-FF5-AA6.jpg (https://postimg.cc/cKdb03Rn)

https://i.postimg.cc/wT4SSbmw/19459128-E89-D-47-BC-BDDE-9747-C3942-B53.jpg (https://postimg.cc/KRLqTfQT)

silver solder and new cables OFC

https://i.postimg.cc/85G3h22z/782-EB42-E-A70-B-41-B7-B342-E2-AD8-EF13820.jpg (https://postimg.cc/PL62HRfg)

https://i.postimg.cc/pVCNBdXb/9-A1510-C3-4-C05-444-C-A8-E8-74-E858-F7-F8-E4.jpg (https://postimg.cc/WtdfNTkX)

https://i.postimg.cc/3wmV08bq/CB9-F2064-E397-4992-A192-50-C4-E87-A0270.jpg (https://postimg.cc/Lq4NrpSk)

https://i.postimg.cc/cLKVZM70/D2-A43685-8-AAD-4241-BBD4-1679547-FCE8-A.jpg (https://postimg.cc/xX2s3mF4)

https://i.postimg.cc/BndRvLND/FB292839-4-C72-474-F-BD4-D-81-C87-AB3-E97-C.jpg (https://postimg.cc/QFJf4M2x)

JohnJo

11-12-2018, 21:12

Looks great. Those Mundorfs take time to run in. Give them a few days use before making any judgements. They will sound dull and flat for a while, at least mine did. Love the speakers :)

Wakefield Turntables

11-12-2018, 21:34

Looks great. Those Mundorfs take time to run in. Give them a few days use before making any judgements. They will sound dull and flat for a while, at least mine did. Love the speakers :)

+1 with everything John says, I remember thinking I'd made a massive mistake when I had my Tannoy's upgraded. Fantastic thread arsenico.

Edward

11-12-2018, 22:34

Really interesting!

I'm intrigued by this type of speaker (back facing bass driver) so did a bit of googling. Came across this blog entry from Japan (https://aspect.blog.so-net.ne.jp/2014-11-11) which goes into a lot of interesting detail.

Here is a translation (https://translate.google.com/translate?sl=ja&tl=en&u=https%3A%2F%2Faspect.blog.so-net.ne.jp%2F2014-11-11).

dequincey

13-12-2018, 06:30

Looks great. Those Mundorfs take time to run in. Give them a few days use before making any judgements. They will sound dull and flat for a while, at least mine did. Love the speakers :)

thank you, will delay any judgement, ...but i must say they sound fantastic even now

dequincey

13-12-2018, 06:36

+1 with everything John says, I remember thinking I'd made a massive mistake when I had my Tannoy's upgraded. Fantastic thread arsenico.

thanks

Really interesting!

I'm intrigued by this type of speaker (back facing bass driver) so did a bit of googling. Came across this blog entry from Japan (https://aspect.blog.so-net.ne.jp/2014-11-11) which goes into a lot of interesting detail.

Here is a translation (https://translate.google.com/translate?sl=ja&tl=en&u=https%3A%2F%2Faspect.blog.so-net.ne.jp%2F2014-11-11).

yes, my thought was exactly that, i was intrigued so i wanted to try them, not easy as there are not many available for sale in europe, and shipping such a huge and heavy speakers is indeed expensive

i started with a pair of ns230 just to try the open-back faced bass, i was very positively surprised by them, so the big brothers were the nxt target

thank you very much for the japanese blog, there is not much information on these speakers

dequincey

17-12-2018, 22:38

sound test,

dequincey

18-12-2018, 08:22

i know that a youtube video is not the best way to share a test, but here you are

IMHO a chet baker piece with drums, piano, bass and trumpet is one of the most difficult tests for speakers, IMHO again they sound great, pristine clear high tones and smooth silky bass

https://youtu.be/b6Y1WXesKFg

happy with them, but,....more to come soon :-)

Edward

18-12-2018, 08:40

videos are both totally overexposed, can't see much. Sounds good, but of course limited by the speakers I'm using here and no doubt by the mic you are using.

dequincey

18-12-2018, 20:13

videos are both totally overexposed, can't see much. Sounds good, but of course limited by the speakers I'm using here and no doubt by the mic you are using.

yep, overexposed to focus on sound, house bad and dirty
i understand the limitations,
apologies

Edward

18-12-2018, 20:55

yep, overexposed to focus on sound, house bad and dirty
i understand the limitations,
apologies

No need to apologise. :) As mentioned I'm fascinated by these speakers and its pretty unique driver arrangement.

dequincey

28-12-2018, 21:39

and things can be improved substantially,...

here they are,...

https://i.postimg.cc/kgYKjVQh/34123134-EE73-4-BFF-AE4-C-FA1-B8-B28-EBF2.jpg (https://postimg.cc/Wdrdz1fM)

https://i.postimg.cc/Bnn2c5KK/B5-B43669-339-E-4337-A4-D8-AD7-DFC370-A6-A.jpg (https://postimg.cc/SJHXmMVS)

dequincey

01-01-2019, 10:27

so as you can see i bought these tweeters JA 0506

my plan is to use them as supertweeters with my ns20 speakers

https://i.postimg.cc/fWq3SKr1/20181228-115308.jpg (https://postimg.cc/rzWyvSc9)

https://i.postimg.cc/NfW5p0Y4/20181228-120010.jpg (https://postimg.cc/gnHz0mxX)

https://i.postimg.cc/mgChqGgG/20181231-174543.jpg (https://postimg.cc/4Y4J7qc8)

https://i.postimg.cc/wBz3Yb1R/20181231-174557.jpg (https://postimg.cc/QF6jpmkj)

i will prepare some base material and put the electronic components on it

https://i.postimg.cc/X7Zrf5Mq/20181231-181714.jpg (https://postimg.cc/KR2cFR8h)

i would like to have you opinion on this, please

dequincey

01-01-2019, 10:41

OPINION PLEASE:

to use them as supertweeters i will need to prepare a couple of things, a high cut pass filter + an L-Pad for attenuation

the characteristics of the Ns20 could be assimilated to the bass JA5002

This is the data about JA-5002
Voice coil 66mm dia alminium edge wound voice coil
Alnico magnet
impeadance 8 ohm
f0 : 35Hz
efficiensy : 92dB/w/m
f-range : 35Hz～6kHz
size : W500×H680×D110(mm)

and on the other hand the tweeter is:

https://i.postimg.cc/7LQ6JPB0/compara-db-dios-tweets.jpg (https://postimages.org/)

the performance curve
https://i.postimg.cc/T1bp68Jm/curva-optima-tweeter.jpg (https://postimages.org/)

as a summary from specs:

- the bass is 92dB and frec range up to 6000Hz

- the tweeter is 115 dB and nice response frec range from 5000Hz

here is my thinking:

1- I will cut high pass the tweeter from 5000Hz using a second order filter (a capacitor and a coil); there is a doubt here, to cut at 5000Hz or at 8000Hz ??

2- I will attenuate around half of the sensitivity gap = the difference (115-92= 23) / 2 = 12dB using a L-Pad filter

3- this will be the setup: (C and L values are for 8000Hz) where it says CrossOver is the NS20 internal one

https://i.postimg.cc/PJC1vFzr/montaje-bueno-en-supertweet.jpg (https://postimg.cc/CnVRW7QW)

your thoughts ?

THANK YOU

walpurgis

01-01-2019, 10:47

Can you not plot the natural roll-off of the main tweeter and mirror (reverse) this for the roll-in curve of the supertweeter? Might need a tweak here and there, but it should give a nice result.

Macca

01-01-2019, 12:26

dequincey

02-01-2019, 14:04

Can you not plot the natural roll-off of the main tweeter and mirror (reverse) this for the roll-in curve of the supertweeter? Might need a tweak here and there, but it should give a nice result.

thank you, seems a possibility, but unfortunately i do not know how to do this

dequincey

02-01-2019, 14:14

The speakers already have a tweeter so I don't know what gains you are hoping to make by adding another. From the response you show it doesn't extend much higher than 20Khz anyway. Usually you would look to roll in a supertweeter where the existing tweeter gives out. Do you know the upper FR of the existing tweeter? I guess if it is quite low(15Khz) say then it might be worth trying the supertweeter. Otherwise you are just doubling up on what is there already, you'll get cancellation, reinforcement, comb filter effects. All a bit random it seems to me.

i agree with you,

my first idea was simply to replace the actual tweeter, that is not an original yamaha JA0505 as it should be, you know these 50 year old things, the present tweeter is a Phillips AD0160/T8, for which i found an experimental curve like this:

https://i.postimg.cc/Fz51N0CF/curva-tweeter-phillips-AD0160-T8.jpg (https://postimg.cc/mzjTS1GK)

so this means that this phillips tweeter gives up at 18.000Hz, and the sensitivity is aorund 92dB, and not very flat neither

once this is said my alternatives would be:

1- to use the yamaha JA0506 it as a supertweeter keeping the phillips, and then where to cut the supertweeter frec. 8000Hz. ? more ?

2- or get rid of the phillips and put this yamaha JA0506 tweeter in its place, in this case i will be using the existing crossover with its high pass filter at 6000Hz and adding an L-Pad attenuator to attenuate from the 115dB given by the tweeter and accomodate to the rest of the speaker´s setup (woofer and squawker)

should this be better ?

thank you

Macca

02-01-2019, 15:27

walpurgis

02-01-2019, 15:41

I hadn't recognised the Philips tweeter and should have done, because I experimented with a couple of pairs of these years ago. They are the same model that Goodmans employed in their SL series speakers. Unfortunately, I found them rather brash sounding and moved to using lovely smooth sounding Audax silk dome units instead. Possibly worth considering here.

dequincey

03-01-2019, 08:50

If I were you I would go for option 2 - I didn't realise the existing tweeters were not original.

You might find you don't need the attenuator at all, I'd try it without first as it makes things a lot simpler.

ok, so i went option 2 yesterday,

first i prepared an L-pad attenuator of 8dB as the sensitivity gap is 115-92 = 23dB and i should attenuate around half that value, with the available resistors i could make for 8dB,...

https://i.postimg.cc/tJNzftDx/9-BF6-E0-C0-40-CF-4-E66-925-C-C2-F99-F30-ED32.jpg (https://postimg.cc/0KrmKSTk)

https://i.postimg.cc/B6Dp5GKN/468-B3014-D670-4-E2-B-8675-86-E9-AF6-EAB64.jpg (https://postimg.cc/VrfX1p4b)

https://i.postimg.cc/RhBRXb1m/7-EB97161-C71-F-4-C98-B3-A5-680-B19-ECA8-E7.jpg (https://postimg.cc/62MnQc1b)

so armed with that i made the connection, first without L-pad

https://i.postimg.cc/h4LMfcgt/99-F31-B3-B-827-C-47-AD-99-D9-11-F27-E8785-A8.jpg (https://postimg.cc/3Ww2qMds)

must say that the difference is mindblowing, exceptional tweeter, pristine clean rich high tones,...but toooooo loud !

so i should install the L-pad

will report later...

thanks

dequincey

04-01-2019, 23:09

today, waiting for the L-pad to arrive
i have prepared the base to seat the tweeters

https://i.postimg.cc/wBD3MyHj/026-F86-B6-0481-480-B-B8-D0-C1162562-CBDE.jpg (https://postimg.cc/R3Vvb0Nk)

https://i.postimg.cc/brwvmmnZ/0-EA32875-5842-458-D-BAC1-917-AD435-CB3-C.jpg (https://postimg.cc/bD48JH3P)

https://i.postimg.cc/25d8msFq/1-AB64-A8-D-C9-B1-4-F96-8-E21-8-EC987131022.jpg (https://postimg.cc/3yRHFbq7)

https://i.postimg.cc/Jnqn3fsw/215040-A7-D632-4-C9-A-ABCD-4138-F4850-CA3.jpg (https://postimg.cc/Kk1xxs7Q)

https://i.postimg.cc/sD0MNCws/26710-FDA-A796-45-EF-BD63-1-DB7675523-B4.jpg (https://postimg.cc/w7Lx1PCG)

https://i.postimg.cc/P5w5VpCQ/383547-E4-4694-49-A2-8735-883-A824-D952-C.jpg (https://postimg.cc/5XfJ6tqX)

https://i.postimg.cc/MTxHQ6Kb/3-C832533-777-D-42-C7-B091-40-D2289-B6081.jpg (https://postimg.cc/Ty7T8Xbp)

https://i.postimg.cc/zX3BWP5M/5-ACA1-A11-74-FA-4-E6-E-82-C9-366-DD4-D0154-C.jpg (https://postimg.cc/PPsTnyCz)

https://i.postimg.cc/3NfxV2jn/61-F2-A2-FB-BAC2-49-E6-9527-F76-B3-C141-BFB.jpg (https://postimg.cc/vx9y6gNV)

https://i.postimg.cc/FHM7hbM6/62492-C3-E-D33-E-4-F2-C-B0-BF-5-EFA33-B4-D593.jpg (https://postimg.cc/MnYWDBK0)

https://i.postimg.cc/FsKfpHbT/6544-E556-E2-CC-40-BC-BDDB-7-EC901-C2-DCC2.jpg (https://postimg.cc/YjJqqksF)

https://i.postimg.cc/Gm840g5Y/78-F6-BB81-D008-4-E95-B2-E0-230-CED1-C9771.jpg (https://postimg.cc/jDTxPcKd)

https://i.postimg.cc/kMTG2drK/831-A44-BE-0-AC2-4-BAF-B021-65-C6262-A6860.jpg (https://postimg.cc/F1JN68HH)

https://i.postimg.cc/HsKLt4kL/9-A90-FAAC-1208-46-E1-A4-E2-7-FD33-EC16-AA0.jpg (https://postimg.cc/QHQs875L)

https://i.postimg.cc/W3XNq0yT/D13-A255-A-9-A3-B-48-E3-BC0-C-AAC7-B3-A1-ACCB.jpg (https://postimg.cc/2bLRPLmK)

https://i.postimg.cc/QMZx285G/FABC4984-8-C45-4-A19-AB3-D-20-F0027-D99-E5.jpg (https://postimg.cc/mPVsMG88)

https://i.postimg.cc/pT2Vdsqs/FDF11700-6-E7-A-464-B-9-DF0-601460-F5012-B.jpg (https://postimg.cc/GB5n7x0D)

dequincey

13-01-2019, 21:37

well

attenuators have not arrived yet, so tweeters are being managed through the amplifier,

but i am still making some tuning

the construction of this speakers is apparently odd when compared to the ones that you can see in the catalogues, drivers in this pair are installed in the covers, nevertheless they seem to be absolutely originals

so two goals:

1- check the squawkers, in my case one is a yamaha original, and the other is a phillips, it is clear that they sound different, right now i prefer the yamaha over the phillips, but i have a pair of saba greencones to check, and i do not have a second yamaha

2- build a support for the squawkers and an idependent cover

dequincey

13-01-2019, 21:50

first step is to build a support, same style as the one present in the yamaha speakers

https://i.postimg.cc/qvXwfv8D/20190109-185830.jpg (https://postimg.cc/w1MLLH4D)

https://i.postimg.cc/Xvj8n6Lj/20190109-185834.jpg (https://postimg.cc/LJWfV7Gw)

https://i.postimg.cc/NMLkr8ZZ/20190109-190335.jpg (https://postimg.cc/WFLkBZN7)

https://i.postimg.cc/6QMh3bbd/20190109-190804.jpg (https://postimg.cc/LqZPQDpX)

https://i.postimg.cc/nz5YKjJr/20190109-192114.jpg (https://postimg.cc/WFGkT4tc)

https://i.postimg.cc/ZK6F35DY/20190109-192126.jpg (https://postimg.cc/7fY2rwkj)

https://i.postimg.cc/qBPxz3wZ/20190109-192133.jpg (https://postimg.cc/c6cnz6VQ)

https://i.postimg.cc/h4z0DrLd/20190109-210428.jpg (https://postimg.cc/4nGcwpFf)

https://i.postimg.cc/L51kx99T/20190111-182616.jpg (https://postimg.cc/SYmzspz2)

once prepared and painted in black, we start replacing the squawkers, the yamaha goes from the cover to the support, and the phillips is replaced by the saba, strong fixing, and absorbent adhesive tape

https://i.postimg.cc/dVvR9cz2/20190112-160209.jpg (https://postimg.cc/vcq6Qk8T)

dequincey

13-01-2019, 21:57

installed firmly and arranged the cables

was able to check the two speakers carefully

woofer the big ear shaped yamaha, squeaker one yamaha other saba, tweeters as yamaha

https://i.postimg.cc/W41MQ6pt/20190112-165427.jpg (https://postimg.cc/pm3hjjFt)

https://i.postimg.cc/x1RvxF2W/20190112-175035.jpg (https://postimg.cc/9DDwzbzp)

https://i.postimg.cc/KYpnFk4f/20190112-200856.jpg (https://postimg.cc/McRcmG7f)

https://i.postimg.cc/rsxWSfjZ/20190112-200904.jpg (https://postimg.cc/1VRfScLD)

pour some jazz music over them, and asked other people about the black or the green cone

answer was clear: the green saba was clearer, brighter, and nicer

dequincey

13-01-2019, 22:01

love how they look without a cover, you can see them there and they are beautiful enough to fill the room

...but i bought a piece of nice fabrik,....and i wanted to see how they will look dressed with it

dequincey

13-01-2019, 22:04

first the frame

https://i.postimg.cc/XJZ9vjCb/20190113-165502.jpg (https://postimg.cc/LYpJCMDC)

https://i.postimg.cc/tCGFXHRK/20190113-172134.jpg (https://postimg.cc/qgQNLS3w)

https://i.postimg.cc/VL9nvHdd/20190113-175623.jpg (https://postimg.cc/w7v7b25p)

https://i.postimg.cc/pVFDbdvQ/20190113-180814.jpg (https://postimg.cc/kD7VWqBD)

even placed the yamaha plate, that by the way is made of brass

https://i.postimg.cc/2SzvZFZT/20190113-184510.jpg (https://postimg.cc/tYMY06DV)

and here they are, splendid in my opinion

https://i.postimg.cc/6pYZL2VK/20190113-191243.jpg (https://postimg.cc/MnfXzGr3)