{"id":1454,"date":"2015-07-18T11:26:50","date_gmt":"2015-07-18T11:26:50","guid":{"rendered":"http:\/\/2016.carlssonplanet.com\/en\/speakers\/sonab-oa-4-type-1\/"},"modified":"2015-10-04T15:33:28","modified_gmt":"2015-10-04T13:33:28","slug":"sonab-oa-4-type-1","status":"publish","type":"page","link":"https:\/\/carlssonplanet.com\/en\/speakers\/produced\/sonab-oa-4-type-1\/","title":{"rendered":"Sonab OA-4 Type 1"},"content":{"rendered":"

\"Click<\/a> Sonab OA-4 was the low budget version of the 1960\u2019s great success OA-5. The difference is primarily a smaller cabinet and one tweeter less, giving a slightly degraded frequency range compared to OA-5. It also had a somewhat less robust electronic solution.
\nThe model lived very much on the success of the OA-5 and was an alternative for all who couldn\u2019t afford the larger model. OA-4 looked just like the OA-5 but was smaller and the Swedish loudspeaker guru had made the design! OA-4 Mk I was equipped with one of the cheap but very good sounding 8 inch wideband element Philips 9710 in 8 ohms version, together with three tweeters, positioned in a inbound\/omni polar direction. The tweeters were identical to the tweeters in the \u201cCoalbox\u201d and OA-6 Mk I, the Peerless 2-inch MT 20 HFC. The filters where based on air winded coils and age resistant plastic film capacitor.
\nHowever the OA-4 Type 1 suffer as the OA-5 Type 1 do from the same kind of unnecessary problem: the top baffle with all the elements is countersunk around 6 cm from the top edge of the loudspeaker walls. This will of course prevent the high range and mid range sound to spread freely in the room. This and the lack of a real bass reflex port, was a failed effort to save costs.
\nThis positioning of the speakers only caused unnecessary and unacceptable sound problems in the mid range and high range. The bass sound is not in level with the real bass reflex solutions.
\nRestoring the OA-4 Type 1 but keeping the original solution with countersunk baffle is not really worth the effort. The speakers with this design fail to provide the normal Carlsson quality level, which should be possible with the used elements and indeed is shown to be possible with the OA-4 Type 2 and OA-5 Type 2!<\/p>\n

RESTORATION<\/strong>
\nThe important thing with 1960\u2019s 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. This damp basket has been impedance adjusted at the Sonab factory in order to give each individual speaker a correct bass reproduction and the correct transient response. It should therefore NOT be changed.
\nYou should however dismount the wide range element and make the modifications according to RESTORATION AND UPGRADING. The only solution to get an acceptable sound reproduction from the Mk I models is to raise the baffle to the right level. This allows the tweeters to freely spread their sound, all according to the basic idea with the design. It also clears up the mid range.
\nHowever this restoration work is rather extensive and tricky and may cause many problems. The original baffle is glued to the cabinet (sometimes screwed), and the inside bracing with limited space, makes it very difficult to remove without the mediocre chipboard to crack.
\nShould the baffles brake, making new baffles is a possible solution to this problem. Another problem is how to mount gold plated terminals in a good way in the glued cabinet with vertical braces on the inside of the cabinet walls. I have brutally used the circular cutter and used a recess plate connector. This also decreases the braces stabilising effect in the rear part of the speaker, but I think this is something you can live with.
\nAnother problem is how to reach the coils and the cabling for replacement purpose. Since the cabinets are glued, there are only two alternatives and both are bad:
\nOne is to dismount the damp basket below the wide range speaker and go that way. However this will also destroy the factory adjusted bass calibration, which isn\u2019t possible to restore without measuring equipment. The other alternative is to use a saw to remove the whole baffle with a great risk of destroying too much of the cabinet and also cause great problems to restore the cabinet to original look. However if you decide to raise the baffle then it is an opportunity to change the cabling a.s.o.
\nIt is much easier to replace the high frequency dividing capacitor usually standing on top of the baffle between the two front tweeters.
\nThe alternatives are:
\n\u2022 A giant restoration and upgrading as described above on a low performance loudspeaker from the 1960\u2019s series.
\n\u2022 Simple restorations according to RESTORATION AND UPGRADING whereby the original less well sounding attributes are restored.
\nOn the other hand you will be the proud owner of a pair of original Carlsson speakers.<\/p>\n

TECHNICAL DATA Sonab OA-4 Type 1<\/strong><\/h3>\n

According to the Sonab instructions manual and\/or HiFiHandboken<\/p>\n

Volume:<\/strong> 36 litres
\nMeasure B x H x D:<\/strong> 24 x 46 x 43cm
\nWeight:<\/strong> 9 Kg
\nPrinciple:<\/strong> Omni-directional. Bass reflex. (Editors comment: Well. The model lacks a real bass reflex tunnel. There are only two round holes in the bottom with glass wool inside, almost a variant of Dynaudio\u2019s bass vented systems. Due to production technical reasons, was Sonab\u2019s excuse. Or greediness? Stig Carlsson never used this solution in any of the following models.)
\nImpedance:<\/strong> approx. 7 ohm
\nFrequency range:<\/strong> 44-18.000 Hz
\nFrequency range:<\/strong> 48-15.000 Hz +\/- 5 dB on the floor against a wall
\nCross over frequency:<\/strong> 3500 Hz
\nBass\/mid range element:<\/strong> 1 pc 22 cm 8 ohms Philips 9710 fullrange element.
\nTweeter:<\/strong> 2 pc 5 cm 8 ohms och 1 pc 16 ohms Peerless MT 20 HFC
\nFinishes:<\/strong> Rosewood, walnut, teak, oak and white laquer.
\nPrice 1973:<\/strong> 630:- SKR per pair
\nSecond hand price today:<\/strong> 100:- up to 1500:- SKR
\nFully restored pair in good condition may cost up to 2.400:- SKR, if the tweeters are replaced with the Peerless CT62 up to 4.500:- SKR.
\nHowever it is doubtful if it is economically justified to replace the tweeters if the baffle isn\u2019t lifted up at the same time.<\/p>\n

Bo Sehlberg – Translator<\/b><\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

Sonab OA-4 was the low budget version of the 1960\u2019s great success OA-5. The difference is primarily a smaller cabinet and one tweeter less, giving a slightly degraded frequency range compared to OA-5. It also had a somewhat less robust electronic solution. The model lived very much on the success of the OA-5 and was […]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":603,"menu_order":7,"comment_status":"open","ping_status":"open","template":"","meta":{"footnotes":""},"class_list":["post-1454","page","type-page","status-publish","hentry"],"yoast_head":"\nSonab OA-4 Type 1 - CarlssonPlanet<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/carlssonplanet.com\/en\/speakers\/produced\/sonab-oa-4-type-1\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Sonab OA-4 Type 1 - CarlssonPlanet\" \/>\n<meta property=\"og:description\" content=\"Sonab OA-4 was the low budget version of the 1960\u2019s great success OA-5. 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