OA 116 Crossover - inductors

[JoelRiehl]

I pulled the bottom off of my e-bay OA 116s. On the crossovers at the bottom of the speaker, there are 2 inductors at right angles to each other. On one of the crossovers, the adhesive had come off and one of the coils detached from the frame. On both crossovers, all four wires from the inductor coils appear to be knotted together - all touching each other. Are they supposed to be? Can anybody tell me the principles behind this crossover, and if this condition is normal - or if somebody just got in there and messed it up?

[Russ]

[JoelRiehl]

These are great Russ! I see that the wires from the outer coil are insulated where they cross over the inner. Mine are not at all. Obviously mine have been modified - both sides. I have a feeling they are not working. The schematic is a huge help for repairing it. Thank you.

[Nick]

Hi Russ,

I see the image of the crossover diagram you posted says "original". Is there an updated crossover diagram? Mine seems to be a bit different from this. I also see mention of an upgrade to the crossovers that Stig suggested, but I can't find any specific reference to what needs to be done. Is there a description available somewhere?

Regards,
Nick

[Russ]

Yes there is a updated crossover diagram by Stig Carlsson from 1979.

You can order the diagram here: http://www.carlssonplanet.com/order.php

At the site: http://www.carlssonkult.se/OA116.aspx you can read more.(you must translate the text)

You can find many different tweeters in OA-116.

From left: MT20, MT225, MT24 och CT62.

http://user.faktiskt.se/phon/telia/disk1.jpg

http://user.faktiskt.se/phon/telia/disk2.jpg

And a new one: Obi T22-oa : http://user.faktiskt.se/Kalejdokom/Obi-T22oa.jpg

It`s not easy to be a Carlsson fan!

[Nick]

Hi Russ,

Thanks for that. I pulled off one of my bass boards and found that I do in fact have the old style mid-range crossovers, and referring to your images, the MT24 tweeters.

The question now is: is it worth doing the upgrade to the midrange crossovers? Have people noticed a worthwhile improvement in sound? I assume that if Stig modified the design, it must have been for the better, but is it a large improvement? I realise this may be a subjective matter, but I would be interested to hear what others think.

Regards,
Nick

[Nick]

Hmmm, seems that even if I do want to change to the later design, I will struggle to get a 4.2mH inductor; Stig didn't compromise his designs by choosing off-the-shelf components, did he?

Does anyone know of a reasonably priced option? The only one I've found so far is a foil-coil from the UK at UKP47 excluding shipping each.

[STDI!]

In the document you order from Carlssonplanet (mentioned above) there are detailed information (only in Swedish though) about how to modify the existing inductors to get the correct values.
I made the total modification last year on my otherwise original OA116 (refoamed woofers and mid range). It costed me 613 SEK in new components to the filters. I can't say that I noticed much difference, if any. But I find it difficult to detect differences unless I compare directly within seconds. Unless it's big differences of course.
But still, now I know that I have the best possible Stig Carlsson original OA116.

[Russ]

Hi Russ,

Thanks for that. I pulled off one of my bass boards and found that I do in fact have the old style mid-range crossovers, and referring to your images, the MT24 tweeters.

The question now is: is it worth doing the upgrade to the midrange crossovers? Have people noticed a worthwhile improvement in sound? I assume that if Stig modified the design, it must have been for the better, but is it a large improvement? I realise this may be a subjective matter, but I would be interested to hear what others think.

Regards,
Nick

In my opinion the original design is good enough.
I had a pair of OA-116 wich I made a total upgrade.( B65-oa II 8 ohm midrange,Silver Flute bass,Obi T22 tweeters and new filters).
Very expensive,but the sound was better.
But the difference was not huge,so I would recomend the original configuration.
Stg Carlsson choosed his drivers with care and drivers in good condition will work even today.