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Ile
Joined: 09 Mar 2006
Posts: 1491
Location: Jyväskylä, Finland
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| Posted: Tue Oct 19, 2010 6:13 pm Post subject: Sonab OA-12 vintage speakers |
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Got similar Sonab OA-12 -73 pair from friend and going to restore those.
Always wanted to hear how these omnidirectional speakers sounds, pretty interesting design.
Here's lot of info about Sonab and Carlsson speakers.
http://www.carlssonplanet.com/oa12.php
Original Peerless 6.5" bass drivers was swapped to some universal crap drivers at some point and two tweeters was missing and two was broken.
So I just ordered new substitute drivers and filter parts from Sweden.
http://www.hifikit.se/index.php?id=947
http://www.hifikit.se/index.php?id=2725
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jask
Joined: 17 Mar 2006
Posts: 10187
Location: kamloops BC
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| Posted: Wed Oct 27, 2010 4:54 am Post subject: |
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Very cool, pretty rare over here though. I would like to know more about the crossover ( everything else was pretty advanced for the time these were built) when you open them up can you take a few pics?
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Ile
Joined: 09 Mar 2006
Posts: 1491
Location: Jyväskylä, Finland
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| Posted: Wed Oct 27, 2010 9:30 am Post subject: |
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| jask wrote: | | Very cool, pretty rare over here though. I would like to know more about the crossover ( everything else was pretty advanced for the time these were built) when you open them up can you take a few pics? |
These are also pretty rare here in Finland, but in Sweden these seem to be still quite common.
I can't take picture of original crossover, because I already disassembled old tweeter filters.
I need to make different filter for new 8 ohm Obi tweeters.
http://www.hifikit.se/files/carlsson_1.pdf
Crossovers are second order and made from premium parts, polyester caps and air core inductors glued and soldered to professionally made circuit board. There is also jumpers in speakers top panel for tweeter level +2, 0, -2 db. Inductors was only 0.7 mm (21 AWG) wire, so power handling was not so high.
This guy built new crossovers for Obi modded Sonab/Carlsson speakers. Lot of measurements of different elements used in these speakers.
http://www.grafpro.se/carlsson.html
I measured bass filter components and found out that bass inductor in other crossover was only 0.6 mH, so it have internal short somewhere in wounds. So I will swap those to new 1.0 mm (18 AWG) inductors. Tweeters are going to have 1.2 mm (16 AWG) inductors, because it will have now 4 ohm load (2x8ohm) instead of old 8 ohm (2x16 ohm).
Today I got rest of the parts, so I might get these ready sometime soon. 
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Ile
Joined: 09 Mar 2006
Posts: 1491
Location: Jyväskylä, Finland
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| Posted: Mon Nov 01, 2010 12:39 pm Post subject: |
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Got crossovers ready yesterday. Boards needed few new holes and one trace was needed to cut to get new circuit made to old board. I'm going to solder all cables to board, so I also removed cable connectors.
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Ile
Joined: 09 Mar 2006
Posts: 1491
Location: Jyväskylä, Finland
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| Posted: Sun Nov 28, 2010 2:51 pm Post subject: |
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Installed rubber c-strip to top grilles and now there is room for new tweeters under grille.
Been listening speakers now some time and these sounds just great for livingroom use. Mostly I use these for radio and tv, but also sometimes for movies and music since my theater/music room is still under construction.
Yesterday I measured room response and all was fine. Tweeter level is ok with modifiet crossover. Bass extension is not that great, but considering speaker size it's ok.
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