The Workbench

Re: Bang & Olufsen Red Line Authentic DIY ABR (Auxiliary Bass Radiators) Successful Repair

mfishmike — Sun, 01 Nov 2009 21:41:44 GMT

I have come up with a great ABR repair/modification and many folks in several countries have used my advice and love their finished speakers. Many are original owners and didn't want to loose them after enjoying them for so many years.

I use twin 5.25 passive radiators with an Fs of 23 hz in place of the ABR plates. The bass is outstanding. I don't have any testing software but my ears have worked well for me for years. I do have a track history of building some fine speakers. My B & O Redline modification can be found at: http://www.speakerhobby.com/bangolufsen.htm

I have provided a fully detailed photo of the modification for your convenience. I also rebuilt the crossovers to get rid of the 63 volt electrolyte caps.

Unfortunantly, Tymphany has discontinued the passive radiator, so I've ordered 1,000 of them specially built for me by Tymphany to have them available to those who want to rebuild their Redlines using my method. I'll also be using them in some other projects and will be selling them retail. The build completion date is November 30th, and I expect to have them by December 15th.

These resonant free B & O cabinets are so well built and sound so good, I would hate to see them go to the dump because of the failed ABRs. I've bought several pairs of attempted repairs with various rubbers, carpet underlayments, and unusual foams, all which didn't work at all. I have a nice inventory of drivers available.

Mike

Re: Bang & Olufsen Red Line Authentic DIY ABR (Auxiliary Bass Radiators) Successful Repair

abdank — Sat, 01 Aug 2009 14:43:00 GMT

Thank You for help!

Everything is OK now!

Wladek.

Re: Bang & Olufsen Red Line Authentic DIY ABR (Auxiliary Bass Radiators) Successful Repair

tournedos — Sat, 01 Aug 2009 13:18:43 GMT

abdank:

I'm from Sandvika, Norway. I have a pair of Redline 45. I'm having the same trouble as everyone else with the rottening foam in the bassport of the 45's. I have problem to open the case. I removed 10 screws at the rear of the cabinets, but I have problem with opening and will not damage frontplate. Please help me!

Did you get the two screws under the strap holders as well as the one in the bottom of the connector bay?

If yes, it might just be tight (there's a foam gasket in there), or you're trying to pull at the wrong place. The "red line" will stay with the front plate, you have to pry between that and the rear part of the case.

Re: Bang & Olufsen Red Line Authentic DIY ABR (Auxiliary Bass Radiators) Successful Repair

BeoMatt — Sat, 01 Aug 2009 13:13:51 GMT

Hi Wladek,

I hope I can be of help, if my memory serves me correct it does require a little confidence to prise the rear section away, I think I removed the central part aswell with the screws that hold the rear stand on. Matt

Re: Bang & Olufsen Red Line Authentic DIY ABR (Auxiliary Bass Radiators) Successful Repair

abdank — Sat, 01 Aug 2009 12:50:44 GMT

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Hi BeoMatt!

I'm from Sandvika, Norway. I have a pair of Redline 45. I'm having the same trouble as everyone else with the rottening foam in the bassport of the 45's. I have problem to open the case. I removed 10 screws at the rear of the cabinets, but I have problem with opening and will not damage frontplate. Please help me!

Wladek.

Re: Bang & Olufsen Red Line Authentic DIY ABR (Auxiliary Bass Radiators) Successful Repair

Dillen — Mon, 20 Apr 2009 15:09:00 GMT

Mikael,

Welcome to Beoworld !

You have a PM (in danish) - check your inbox in the upper right corner of this page.

Martin

Re: Bang & Olufsen Red Line Authentic DIY ABR (Auxiliary Bass Radiators) Successful Repair

shwaya — Mon, 20 Apr 2009 12:55:00 GMT

Hi... or could I say "Hej"? Er du dansker?

I'm from Denmark, Humlebæk north of Copenhagen. I've just had a pair of Redline 45 for free together with a Beocenter 7700 and a Beogram CD 3500.

I'm having the same trouble as everyone else with the rottening foam in the bassport of the 45's. I'm not a wizzard with electronics, but I've managed to remove all the smuldered foam without damaging the speakers.

Now I wonder can you help me with a good solution for replacing/rebuilding the 'woofers'? Or can you offer any good advice if I have to do it myself?

Hvis du fx taler dansk og kan hjælpe mig med at oversætte/forklare noget af det tekniske lingo, som BeoMatt bruger i sin forklaring af 'how to do it', ville det være en kæmpe-hjælp!!

Glæder mig til at høre fra dig...

Mvh Mikael

Re: Bang & Olufsen Red Line Authentic DIY ABR (Auxiliary Bass Radiators) Successful Repair

Craig — Sun, 15 Mar 2009 16:50:25 GMT

For a while I had some RL60's in my garage/workshop. These had the ABR's removed, have to admit they still sounded good. Although I was not able to compare them to a pair with the ABR's.

Craig

Re: Bang & Olufsen Red Line Authentic DIY ABR (Auxiliary Bass Radiators) Successful Repair

Dillen — Sun, 15 Mar 2009 15:25:01 GMT

Brilliant answer from B&O.

In other words; They don't know and/or they don't care.

Martin

Re: Bang & Olufsen Red Line Authentic DIY ABR (Auxiliary Bass Radiators) Successful Repair

BeoMatt — Sun, 15 Mar 2009 12:51:34 GMT

Hi Dillen, I took shots before and after the repair, using a mic, laptop and Adobe software. I don't think it was very conclusive. The shot on the left is without an ABR, and the other after my repair.

I have since written to B&O asking them for advice on the material to use. Their reply was that any appropriate material can be used

Re: Bang & Olufsen Red Line Authentic DIY ABR (Auxiliary Bass Radiators) Successful Repair

Dillen — Sun, 15 Mar 2009 06:05:27 GMT

Certainly, Puncher.

It seems Matt did exactly that if you look higher up in this thread.
Though I must admit not being able to see much in those little pics.
However, it does seem to me that, if the "after" shot is the one to the right,
the repair seems to have introduced some kind of hump in the lower midrange
if you look at the light blue curve, or maybe I'm reading it wrong, I never
used Adobe Audition.
He doesn't tell us where he got the "before" shot from. Safe to say that he
didn't have access to an original and yet complete RL60 ABR, I haven't seen one
myself for many years (and I've seen many RL's) and won't ever see one again I'm sure,
so maybe it was merely a shot of the speaker with no ABR installed
though obviously, that would be useless for comparison.

Matt, you will have to tell us a little more about your measurements if possible.

Martin

Re: Bang & Olufsen Red Line Authentic DIY ABR (Auxiliary Bass Radiators) Successful Repair

Puncher — Sun, 15 Mar 2009 05:48:41 GMT

Obviously refoaming them with anything is better than having no ABR's but the originals have a particular resonant frequency, I would like the material used to match the original's compliance. Without an original to compare I guess this is all but impossible.

Re: Bang & Olufsen Red Line Authentic DIY ABR (Auxiliary Bass Radiators) Successful Repair

Dillen — Sun, 15 Mar 2009 05:41:06 GMT

Puncher,

Yes, I still refoam many ABR's (not using neoprene).
Still, it's nice to know that there are a stabile and guaranteed ABR refoam
service available in the UK.

Martin

Re: Bang & Olufsen Red Line Authentic DIY ABR (Auxiliary Bass Radiators) Successful Repair

BeoMatt — Sat, 14 Mar 2009 12:32:51 GMT

Superb link Puncher, cheers.

I think i'll offer my services as an ABR repair man ! Satisfaction guaranteed, just send your faulty ABR's by post email me here mattybrillo@hotmail.com

Re: Bang & Olufsen Red Line Authentic DIY ABR (Auxiliary Bass Radiators) Successful Repair

BeoMatt — Sat, 14 Mar 2009 12:28:30 GMT

Yes you are correct, my mistake sorry never mind, I could sell them on ebay as memory foam for small pets !