Restoring OA-12

Ställ frågor, diskutera och prata om Sonab och deras produkter.
Ask questions, discuss and talk about Sonab and their products.
JoelRiehl
(50+ posts)
(50+ posts)
Posts: 67
Joined: Sat 02 Feb 2013, 08:13
Location: Seattle
Contact:

Restoring OA-12

Post by JoelRiehl »

Sorry for the double post - copying this over from the OA-12 Clone thread. New Topic:

I bought a pair of OA-12s on e-bay. The bass elements in them are shot - and were themselves earlier replacements of unknown provenance. I looked up the Carlsson B 65 oa at hifikit.se. $123.43 US each if I'm reading correctly ("799 SEK / ST" - that's "each", right?). The discussion on carlssonkult.se seems to indicate that even this speaker has compromises (e.g. peakiness at around 1,000 hz) compared to the original. Since the Silver Flute is $29.80 US each, and since I am not made of solid gold, please remark if you don't mind Momus, on what sorts of compromises you would expect from the Silver Flute. Meantime I'll start looking for a restored or restorable pair of Peerless CT 62 or somebody parting out an old pair of speakers. Thank you as always for sage advice.
momus
(515+ posts)
(515+ posts)
Posts: 572
Joined: Wed 15 Oct 2008, 16:53
Location: Anders Gjöres, Enskede

Re: Restoring OA-12

Post by momus »

Again, take a look at http://www.carlssonkult.se and let google translate. As you can see there, the Silverflute is made for much smaller enclosures than the OA 12. You will get sound and bass, but it is not a speaker that fits the OA 12 perfectly. ( I have not tried it myself, just been reading about it). I´m not made of gold either, but I saved and saved and bought the B 65 OA II.
Last edited by momus on Tue 25 Aug 2015, 12:16, edited 2 times in total.
JoelRiehl
(50+ posts)
(50+ posts)
Posts: 67
Joined: Sat 02 Feb 2013, 08:13
Location: Seattle
Contact:

Re: Restoring OA-12

Post by JoelRiehl »

Momus,
Now that you put it that way - I have been waiting for a pair of OA-12s for 38 years, and I should do the best job possible of restoring them. Thanks for your input.
momus
(515+ posts)
(515+ posts)
Posts: 572
Joined: Wed 15 Oct 2008, 16:53
Location: Anders Gjöres, Enskede

Re: Restoring OA-12

Post by momus »

Then you should also consider the T 22 OA tweeter. A bit more expensive than the now defunct Peerless tweeter, but much easier to find (you can get them from hifikit). You have to make some changes to the filter though. Not a breathtaking difference soundwise, but very efficient and sturdy. I have two OA 12 with B 65 OA II, and T 22 OA. With new filters. (I fixed the filters myself and it was quite easy)
Although I love the sight of them (and the sound), the OA 50.3, which I use daily is much, much better.
Last edited by momus on Tue 25 Aug 2015, 12:17, edited 1 time in total.
JoelRiehl
(50+ posts)
(50+ posts)
Posts: 67
Joined: Sat 02 Feb 2013, 08:13
Location: Seattle
Contact:

Re: Restoring OA-12

Post by JoelRiehl »

Hi Momus,

I'll start saving my pennies.

What parts did you replace on the filter? I think on Carlssonkult.se I saw a notice that "[email protected]" was providing plug-and-play upgraded crossovers. Do you know anything about this?

I did not see any Carlsson speakers here on the US West Coast market after the 70s models. Now I am intrigued to hear the OA 50.3. "Much much better" than the OA-12 - at least if my memory is not playing tricks on me - must be very good indeed.
momus
(515+ posts)
(515+ posts)
Posts: 572
Joined: Wed 15 Oct 2008, 16:53
Location: Anders Gjöres, Enskede

Re: Restoring OA-12

Post by momus »

Well the OA 50 was never popular abroad. I think they did distribute them in England in the late nineties, but never in the states. The English press were not so keen on the "omnidirectional" speakers from Sonab. I think Noel Keywood (now HiFi World) called Stig the swedish "tweeter fetishist". But the OA 50.2 got some good press all the same. HiFi World was rather impressed of the OA 50.2, but thought that they could hear some unpleasant sounds from the metallic dome tweeter (made by Vifa). The OA 50.3 use a silk dome instead.

I am a lazy guy.Here is a instruction how to rebuild the filter in the OA 12, but it is in swedish. Maybe you could find a way to translate the text on the net.


Delningsfilter till OA 12 med nya diskanterna.

Jag har gjort motsvarande på OD11-kort, det går ganska bra. Det är samma kort.

1. Ta ytterligare en tur till HiFiKit. Köp två motstånd 5,6 ohm och två 8,2 ohm.
2. Skär loss den lilla spolen från kretskortet .
3. Skär loss 5,6uF kondensatorn och löd loss den.
4. Skär loss motstånden 1,8 ohm och 2,2 ohm och löd loss dem..
5. Löd loss de två svarta trådarna som går till diskanterna, och de två bruna. Löd fast de två svarta där de bruna satt.
6. Sätt 5,6 ohm där det satt 1,8. Sätt 8,2 ohm där det satt 2,2.
7. Sätt 4,8uF där det satt 5,6.
8. Löd nya spolens centrumtråd där gamla satt. Spolen ska man limma.
9. Sätt ena änden av 2,2 ohm där gamla spolens andra tråd satt och limma fast motståndet ovanpå spolen. Löd samman spolens och motståndets fria trådar rakt i luften.
10. Löd ena änden av 8,2uF i ett av hålen där svarta trådarna till diskanterna satt. Böj den över stora spolen och limma fast den.
11. Limma också fast 1,5 ohm motståndet på stora spolen, bredvid 8,2uF och löd ihop ena änden med kondensatorns fria ände - rakt i luften.
12. Löd båda bruna trådarna till diskanterna direkt på motståndets fria ände.


När du monterar nya diskanterna är det viktigt att allt blir tätt. Täta de gamla skruvhålen, och täta genomföringarna för trådarna. Små läckor ger direkt hörbart pustande vid kraftig bas.

Nu ger tonbyglarna dämpning på -3dB respektive -6dB. Standardläget kan kallas Öhman-läge och det tycker jag ger alldeles för mycket diskant. Dämpningen på 6dB låter mest likt mina OA50, och då låter det fakiskt väldigt bra tycker jag. Man kan inte låta bli att undra över poängen med att kosta på dessa diskanter dyra och kraftiga magneter så att de får hög verkningsgrad, för att sedan tvingas dämpa dem med motstånd.


The OA 12 is a very good speaker. But the OA 50 (OA 50.3) sound more coherent, has more detail and less distorsion. Which is strange because the woofer is the same. I will use the OA 12 in my new summerhouse with a NAD D 3020 . But for now, one of my daughters use them.
momus
(515+ posts)
(515+ posts)
Posts: 572
Joined: Wed 15 Oct 2008, 16:53
Location: Anders Gjöres, Enskede

Re: Restoring OA-12

Post by momus »

Sorry, I forgot.Yes Grafpro builds filters for OA 12 and Obi T 22 oa. They cost 1500 SEK for a pair. Just plug and play.
momus
(515+ posts)
(515+ posts)
Posts: 572
Joined: Wed 15 Oct 2008, 16:53
Location: Anders Gjöres, Enskede

Re: Restoring OA-12

Post by momus »

Sorry again. Here is a link to what you have to buy to modify the filters on OA 12 with the T 22:
http://www.hifikit.se/images/5309/carlsson_1.pdf
Schmutziger
(40+ posts)
(40+ posts)
Posts: 42
Joined: Wed 12 Jan 2005, 16:29

Re: Restoring OA-12

Post by Schmutziger »

Important, don't know if momus have informed you of this:
remember to add ~4.7-5uF for a total of 15uF for the bass filter if you are going to use B65oa-II or it will be to bright.
Image
Schmutziger
(40+ posts)
(40+ posts)
Posts: 42
Joined: Wed 12 Jan 2005, 16:29

Re: Restoring OA-12

Post by Schmutziger »

Post Reply

Who is online

Users browsing this forum: No registered users and 73 guests