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AR 3a need of changing the capacitors ?


FluAR
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Hello to everyone here,

I'm new to this great forum.

I was on the way to recap my late 74 3a but after some reading in the forum, I think I´d prefer to

let the original capacitors in it. A technician measured the value and told me " you must change all"

I prefer to ask You to be sure before going on

here the measurement of both Speakers

150 uf cap (Callins) = 1x 88 uf,  1x 90 uf

the 50 uf cap from Industriac =2x  44 uf

and the 6 uf (no name on it) = 1x 5,7 uf 1x 5,6 uf

If I change some of them I would stay with the original NPE not because the money, only to respect the design and beware the sound signature

they were created. I already tried on one with new PP Dayton, sound has changed a little but not for the better, maybe they need break in ?

The system they were in is a Marantz 7c 8b 

Thanks a lot for some suggestion and your Idea on it, and sorry for asking something that maybe already was discussed before in the forum.

Sincerely

FluAR

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1 hour ago, FluAR said:

If I change some of them I would stay with the original NPE not because the money, only to respect the design and beware the sound signature

they were created. I already tried on one with new PP Dayton, sound has changed a little but not for the better, maybe they need break in ?

I agree with you regarding using NPEs, but I have found that even some new NPE caps can present problems.  Case in point:  I proactively changed out the gray Unicon NPE caps in a pair of Boston Acoustics A70 speakers with Parts Express NPE's.   The results were not good..."honky" sound.  I had to add 1/2 ohm in-line resistance and then subsequently a 0.01 F&F bypass capacitor across the the NPE to achieve something I perceived as close to the original A70 sound signature.

Regardless, FluAR, I assure you that you will have a fun and educational experience recapping your AR3a's.

 

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First of all thank you very much for your answer and ideas how to go on with it.

Sorry for my English, not used to write in it very often, only training reading English with stereophile.

I started today clean the L pads as a beginning. They looked very good, only very few signs of corrosion,

the filament looked like new.

will work on one speaker first  and let You know.

Greetings from Europe

FluAR

PS. yes, I love the Marantz combo, not as transparent or quick as new gear, but a lot of soul and sound

 

IMG_8230.HEIC IMG_8234.HEIC IMG_8235.HEIC

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6 hours ago, FluAR said:

way to recap my late 74 3a

I reread the first post, among my ARs, I also have a late couple from the first half of '74 taken in pitiful conditions, without a woofer and a KO tweeter, after having found the speakers I also recapitulated the crossover: in this pair i capacitors were all Sprague and the measure were perfectly in tolerance all, I however replaced the 50uF and 6uF capacitors (the used ones, of excellent quality I think they will have infinite life, so I did not use non-polarized electrolytics) leaving the original Sprague for the woofers , the deoxidized pans, adjusted as per original specification, new foam to the woofers, for about 2 years these AR3a have been with me every day in a satisfactory way!

Before recapping

1976475533_ARinc33.thumb.jpg.3101609b1a4807ecc316be784214103d.jpg

A new crossover

410631275_ARinc34.png.05798a871fad48424f16e63a12d3db34.png

At work completed: AR3a European cabinet '74

1488835989_20181008_1128412.jpg.78b04e9d45a87f7ff18df5276dc550b6.jpg

In this photo, if you look closely, half of the screws of the woofers are missing, purchased and mounted later!

 

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52 minutes ago, giovanni56 said:

The Sprague are the best conditioners, however in the many deliveries I have done, I found several out of specification, they are not eternal and after 45/50 years once you open the case for maintenance I think it is useful to replace them and not have problems for other decades

Dear Giovanni, I am attaching the photos of the AR3 capacitors to me above: old Sprague and substitute, among the thousands of photos now I do not find those of the 150 uF capacitors, but in percentage they measured better than this 50uF one that I am attaching in the picture ... I have sometimes found Sprague out of specification, but most of them are still in tolerance (among other things I have saved for this pair of ARs about 100 euros per pair of 150uF Jantzen!
You see it used for a pair of my AR3a improved in the last photo.

wall73.jpg.6f25f263688567d81025ce79219ab38f.jpgwall74.jpg.1271eca8dff7c5ffa697aec8e0bc2bf0.jpg

wall75.jpg.260819626bd2403a050bc641df6399d7.jpg

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14 minutes ago, Giorgio AR said:

Caro Giovanni, allego a me sopra le foto dei condensatori AR3: vecchio Sprague e sostituto, tra le migliaia di foto adesso non trovo quelle dei condensatori da 150 uF, ma in percentuale misuravano meglio di questo 50 uF che ho allego in foto...a volte ho trovato Sprague fuori specifica, ma la maggior parte di esse sono ancora in tolleranza (tra l'altro ho risparmiato per questa coppia di AR circa 100 euro per coppia di 150uF Jantzen!
Lo vedete usato per un paio del mio AR3a migliorato nell'ultima foto.

wall73.jpg.6f25f263688567d81025ce79219ab38f.jpgwall74.jpg.1271eca8dff7c5ffa697aec8e0bc2bf0.jpg

wall75.jpg.260819626bd2403a050bc641df6399d7.jpg

Hi Giorgio, I have always preferred to replace components with others with identical dielectric, and above all, I do not think it is useful to use plastic capacitors among other very expensive that are not in series with the signal, it might make sense for 50nF and 6nF but not for 150nF.

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Giovanni, the next recaps when I will be able to do them will be for the pair of early Ar3a and AR10TT MK2:
ARra early for the first sections medium-high will be in paper / oil, perhaps also for the woofer, instead for the AR10s I have already purchased NPE Mundorf ECap for the woofer (many recommend the use of NPE capacitors) and in the case of the AR10s and others I will follow this path. ..

last work today, I photograph the blister for cutting the woofer I attach it and then ... to sleep ...

wall76.jpg.cfd7df8782b7011daf1faa7a3e8eeef0.jpg
Thanks Giovanni

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10 hours ago, giovanni56 said:

Grazie a te, Giorgio, apprezzo molto i tuoi restauri e la tua competenza, un mio parere sono veramente ottimi lavori che esprimono la tua passione per il marchio Ar. 

Buonanotte!! 

Translation:

Thanks to you, Giorgio, I really appreciate your restorations and your expertise, in my opinion they are really excellent works that express your passion for the Ar brand.

Good night!!

Giovanni, I am a passionate self-taught collector and I like to restore the "good things" of yesteryear to their original splendor and functionality or as close as possible!
I do not have your technical skills, nor knowledge of electronics, too old to learn and without a good teacher it is even more difficult ...

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On 12/11/2021 at 5:04 PM, Giorgio AR said:

Giovanni, the next recaps when I will be able to do them will be for the pair of early Ar3a and AR10TT MK2:
ARra early for the first sections medium-high will be in paper / oil, perhaps also for the woofer, instead for the AR10s I have already purchased NPE Mundorf ECap for the woofer (many recommend the use of NPE capacitors) and in the case of the AR10s and others I will follow this path. ..

last work today, I photograph the blister for cutting the woofer I attach it and then ... to sleep ...

wall76.jpg.cfd7df8782b7011daf1faa7a3e8eeef0.jpg
Thanks Giovanni

I used Mundorf Ecaps for the series caps of the UMR on my AR9's and AR90's.   I am very happy with the results.   I suspect they will perform very well in the earlier series of AR speakers also.

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  • 2 weeks later...

An Update on the Projekt,

in England i found a Company, they sell  Ecap from Mundorf in the required values, 150 uf, 50uf and 6 uF all NPE

the 50 and the 6 uF are custom made.

i will start with this configuration and hear wathˋ s happen. For the 6 uf i also ordered two sonicaps

just to try if it makes a difference.

wath i did  not know before  is that the old 150 uf capacitors where polarised one with + and -

in one speaker the orange cable connection was at the + in the other the yellow one. ???

they used polarised NPE ˋs but obviously it did not make a difference how they where connected.
So i assumed that for the 150 uf it should be possible also to use polarised NOS Capacitors.

any Suggestion about that ?

will update wen the parts arrived and one loudspeaker got the new parts installed.

with the best wishes for christmas 

and a better new 2022

FluAR

PS. per gli amici italiani : Auguri di buon Natale a tutti e grazie  per  i Vostri consigli.

 

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1 hour ago, FluAR said:

per gli amici italiani : Auguri di buon Natale a tutti e grazie  per  i Vostri consigli.

Danke! Thanks and best wishes to you and ... good listening ... you have to revive your AR3a if you can before Christmas, they will give warmth to the party and the house,
sincerely

Giorgio.

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  • 1 month later...

I am working on recapping my AR 3a's, my first recap so first time working with caps, so newbie alert, but have soldered wiring forever.  I have wired the black wire into the 150 uF and the green wire into the 50 uF with the common wires out for both caps going to the blue wire. I think this is how the AR 3a restoration guide diagrams it, but want to make sure I am right. Is the blue the ground?  I think I am confused because black is usually ground.  See pic. 

C18BF061-8C0B-4E18-B3DC-7F9DEAB267D4.jpeg

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On 12/21/2021 at 4:30 PM, FluAR said:

OK,

but why did the capacitors have a + sign ?

 

FBBF18CE-FC13-4611-93B5-AAF494E32FB7.jpeg

Crossover caps need to be non-polar as the current has to be able to pass in both directions. The reason for the (+) is it probably indicates the inner foil and should connect to the destination (driver). All of the 2500uF caps in my 9s and 10pi have the (+) and they are all connected to the driver/red wire marked + on the driver.

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