The Carlsson OA-52 was the real top-of-the-line model in the Stig Carlsson 1980 series.
The Sonab name had disappeared and the new twoway speaker series was named Carlsson OA-52 after Stig Carlsson himself and his Ortho Acoustical principles. This was the largest model in the OA-50 series, designed by the art professor Lars Lallerstedt and built by the newly established Carlsson factory in Skillingaryd.
OA-52 didn't look like any other existing speaker. A floor standing quadratic box in reversed pairs, where the rear outer corners were designed with a pyramid shaped baffle where the elements were mounted, all protected by a triangular shaped metallic net. On top of the base box heavy sound damping absorbents covered by textile was attached and against the back wall absorbing panels were attached surrounded by a wooden frame. The absorbing material was damping the early reflexes in the recordings and caused the OA-52 to become the most disappearing speaker, acoustically speaking, that the Hi-Fi world ever had heard. The design of OA-52 with its strange child sized armchair shape is still unique in the speaker world.
The speakers were built out of heavy MDF board and the cabinets were massively braced inside. The filters were made of high-class components: air core inductors and thoroughly selected Rifa metallized plastic film capacitors. The elements were a Scan Speak 7 inch bass with a heavy magnet, a wide coil and very small cone area sharing the pyramid shaped baffle with a omni directional dome tweeter from Peerless.
Stig Carlsson meant that his earlier designs were out of date and that he finally had built the world’s best speaker adapted for ordinary rooms.
The OA-52 partly got excellent critics the speakers were called “Helt fantastiska!” (“Amazing!”) by the Swedish magazine “Teknik för Alla” and soon became a reference speaker among hundreds of sound technicians, producers, musicians and other music related people.
The whole 1980 series OA-50/51/52 had a somewhat less successful textile dome tweeter, the Peerless 115DT26. An element often blamed for the 50 series models unfairly negative critics during the eighties; this also caused an economic catastrophe for Stig Carlsson and gave him a life close to starvation for the next 20 years.
However the tweeter was chosen with extreme care for its low distortion and as it was at that time the most omni directional existing tweeter, with a high current tolerance.
The OA-52 Scan Speak (18W/8542) was at that time a completely new speaker element and probably the best available at the time. The bass element is still being produced today, but sounds a bit distorted in the midrange and diffuse in the bass register. It is probably not worth the cost today (new element price 1300 SEK).
More than 900 Carlsson OA-52 was sold during 1984-1989.
In 1996 the successor OA-52.2 was presented.
In 2002 the latest and best version OA-52.3 was presented.
UPGRADING:
All speakers in the 50 series could be upgraded to the .3-version, with an even better silk dome tweeter the Carlsson T-11oa and new filters, something CarlssonPlanet definitely recommend.
There were three upgrade kits:
1. Upgrading from OA-52 with new Scan Speak bass 18W/8545, new tweeter T-11oa and new filter with expensive paper-oil cap
acitors, Jensen copper foil coil and Teflon isolated solid cable. Also included are special calibrated SD-feet, wooden- and aluminium details and damping rug. Price: 8700 SEK.
2. Upgrading from OA-52 with the same elements as above, but with simpler filter components. Price: 5500 SEK.
3. Upgrading from OA-52.2. Price: 2500 SEK.
CarlssonPlanet means that the last upgrade”.3” gives the OA-52 series the best sound ever. Even the simpler filter based on SCR/MKP capacitors also gives an excellent sound, capable of outperforming most of the speaker market today!
The production of OA-52.3 ended in 2007.
TECHNICAL DATA Carlsson OA-52
Principle: 2-way omni-directional bass reflex with absorbent panel
Positioning: On the floor against a wall with damped floor and reflecting ceiling
Impedance: 8 ohm
Sensitivity: 89 dB
Cabinet: 19 and 22 mm chipboard/MDF. Six inner supporting walls
Inner volume: 20 litres
Total volume: 32 litres
Bass tuning: 30 Hz
Bass element: Special manufactured version by Scan Speak 7 inch 18W/8542 with
paper cone, aluminium chassis, aluminium wired coil.
Tweeter: Peerless 25 mm textile dome 115DT26 (K10DT according to some articles)
Crossover frequency: 2.600 Hz
Frequency range: 27-20.000Hz
Frequency response: 30-17.000Hz within 2 dB
Weight: 17,5 kg per pc
Measures B x H x D: 41 x 37 x 53 cm
Finish: Walnut, white and black lacquer. Other finishes on request
Price 1984: 8000:- SKR
Second hand price today: 3.000-6.000 SEK depending on condition, prices rising since production ended -07.
Upgraded to OA-52.2 in good condition should cost at least 6.000 SEK
Upgraded to OA-52.3 in good condition should cost at least 11.000 SEK and has during -08 been reported sold close to the price of a new pair (18.000:-)
Bo Sehlberg - Translator
This page was last edited 2008-07-13 23:48:28 by Per