Sonab OA-4 Type 2: questions renovation

För er som vill modda och renovera på egen hand.
For those of you who whish to mod and renovate by yourself.
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schdrag
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Sonab OA-4 Type 2: questions renovation

Post by schdrag »

Hi there

Thanks a lot for the great renovation guide
http://www.carlssonplanet.com/en/renova ... /#bredband

Last week I have bought 2 Sonab OA-4 Type 2 /1/]see,
now I have some questions regarding the refurbishment (expected a bit warmer sound and I wounder what's wrong and how I can fix it):
Just unscrew the four screws going through the rubber suspension into the speaker perimeter. Hold the screwdriver tightly so that you don’t slip and perforate the speaker thus destroying it. Cut or de-solder the cables away after marking plus and minus (red or blue cable is plus). Untie the knots on the cloth around the speaker, remove the cloth and wash it.
according carlsonplanet
Do I have to remove the 4 screws of the big speaker, unsolder the cable, remove the speaker, unknot the know of the tie of the cloth (the cloth has got a bit of wax, which I have removed roughly with the help of my nails...) and to wash the cloth (probably I have to remove the little rest of wax using an iron) , like on the photo here.

Which screws are meant by that?
DO NOT touch the screws outside the speaker-rim, these are fixing the acoustic-damping device behind the mid-bass woofers.
The important thing with 1960’s models V-1, OA-4 and OA-5 both Type 1 and 2 is to avoid touching the screws holding the damp basket behind the wide range element.
Has the capacitor to be replaced? I guess that the exact value was measured once and a capacitor with the proper value was selected. The "black/red SCR/MKP capacitor" is recommended, so do I have to buy simply one with the proper value (which one?) this one? Where is the position of the capacitor exactly?


Carlsson also recommends ”SD-Feet”, I would simply use self adhesive felt or soft rubber feet. Or is the difference really big (according to the guide it is)?
The speakers look ok by the way, no visible damage (ok, the cloth is still on).
Martin Dellstig
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Re: Sonab OA-4 Type 2: questions renovation

Post by Martin Dellstig »

Hello
The three screws are jus outside the speaker, Do not touch these unless you can Rune them in again with correct equipment.
Best regards
Martin
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schdrag
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Re: Sonab OA-4 Type 2: questions renovation

Post by schdrag »

Hi Martin
Sorry I did not realize your answer. In the meantime I decided to do a total change: Visaton W200S + 4 OT-57-148, an active cross-over + class d tpa3118 modules for trebles and basses (closed, not bass-reflex).
A friendly visaton forum collegue offered me to calculate the cross-over and he would like to use the existing coil:
I'm not sure about the value of the coils: is this the same value like the coils from OA5 http://www.troelsgravesen.dk/sonab_file ... over_1.GIF: 0,2 Ohm and 0,510mH?
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