Beomaster 900RG. - UK Vintage Radio Repair and Restoration Discussion Forum

anthony lawrenc · 17th Aug 2010, 5:12 pm

hi everyone this Bang +olufsen gram has a faulty right hand speaker when playing at low vol theres distortion its one of those speakers with a kind of paper trumpet tweeter in the middle [im sure its got a proper name ] if i pull gently on the trumpet the distortion disapears is it possible to do a repair or maybe replace both speakers its a six and a half inch speaker 5 ohms the amp is rated at 5 watts per channel i have looked at replacements but the only ones i can find with the trumpet affair are car speakers the b and o speaker is quite a heavy thing with a huge magnet on the backa replacement would have to be the same size because of the limited cabinet dimensions i have used the gram with other speakers [from a 70s music centre ] but there not a patch on its own when working properly it sounds fantastic as good if not better than some of todays offerings it was built in 1970 but the design is so modern it looks as though it was made yesterday look forward to your expert advice cheers ANthony

percival007 · 17th Aug 2010, 7:08 pm

It is possible that there is some (-ve?) D.C at the speaker output from that channel.

Is the distortion there when you use the other speakers instead? If so, then this D.C. component may be pulling the cone in towards the rear of the speaker, you pulling it out are overcoming this D.C. and it sounds ok. If not pulled out there is not as much rear going movement and this will make it sound distorted.

If it sounds ok on those other speakers then disregard the above and indeed it sounds like the cone is damaged on that speaker.

I have no idea from where a replacement can be obtained other than B&O. They are surprisingly good at keeping old parts and you may be lucky if you ring them.

James.

roffe · 17th Aug 2010, 9:53 pm

Might be a faulty loudspeaker,since you can correct it with your hands.What puzzles me somewhat is that I've read that these BO's have two 6x4 inch oval units.Which is correct?
And isn't there something stamped or written on the units?Please try to describe them or even better a picture.

anthony lawrenc · 18th Aug 2010, 3:36 pm

thanks for the input guys its definatly the speaker as for them being oval [or eliptical]the older model 611 delux had oval speakers my radiogram is the later 900 compact model i think the tuneramp is the same but the cabinet is much more modern and compact i was thinking of sending the speaker off for repair [will investigate the cost first]of course it may be cheaper to just replace both speakers with something else the problem is finding somthing with the built in tweeter anyone know if this kind of speaker is still made i have also been looking at videos on how to do repairs im not sure im up to that having said that the speaker no use as it is so i may have a go meanwhile if there are any more ideas out there im all ears thanks again guys Anthony

roffe · 19th Aug 2010, 10:30 am

Ah,it's the 900 RG Compact.
http://beocentral.com/beomaster900rgcompact
Very nice looking.
From your description it sounds as if the speakers are of the double cone variety(also called twin-cone or whizzer cone in America).
As B&O almost always used Philips,SEAS or Peerless loudspeakers,it's often possible to identify them from a number stamped on them or a picture.

anthony lawrenc · 19th Aug 2010, 6:05 pm

hi Roffe yes thats the one the only symbols on the speaker are printed on the back of the paper cone they are the 5 ohms sign and then fm however the owners manual tells me they are 17 TV 2 x D35 _40 im having trouble taking pictures at the moment but as soon as i get it right i will post some i have seen some pioneer speakers that would fit the cabinet but they are designed for a car do you think they might be ok for the job in the b and o manual it says they are special speakers what could be special about them ? any idea Anthony

roffe · 19th Aug 2010, 9:25 pm

The first with the 5ohm sign might be a Peerless,and the second is definitely a SEAS twin cone.

anthony lawrenc · 2nd Sep 2010, 11:47 pm

im pleased to say the Beomaster now has two new speakers fitted and it sounds better than ever maybe the new speakers are better quality there again i supose speaker tecnology has moved on in 40 years and to say it only has 6 watts per channel it sound much louder i have fitted a cd player in the taperecorder compartment as for the styling it could have been made yesterday hanks again everyone for the expert advice Anthony

17th Aug 2010, 5:12 pm	#1
anthony lawrenc Retired Dormant Member Join Date: Dec 2008 Location: Leeds, West Yorkshire, UK. Posts: 88	Beomaster 900RG. hi everyone this Bang +olufsen gram has a faulty right hand speaker when playing at low vol theres distortion its one of those speakers with a kind of paper trumpet tweeter in the middle [im sure its got a proper name ] if i pull gently on the trumpet the distortion disapears is it possible to do a repair or maybe replace both speakers its a six and a half inch speaker 5 ohms the amp is rated at 5 watts per channel i have looked at replacements but the only ones i can find with the trumpet affair are car speakers the b and o speaker is quite a heavy thing with a huge magnet on the backa replacement would have to be the same size because of the limited cabinet dimensions i have used the gram with other speakers [from a 70s music centre ] but there not a patch on its own when working properly it sounds fantastic as good if not better than some of todays offerings it was built in 1970 but the design is so modern it looks as though it was made yesterday look forward to your expert advice cheers ANthony

17th Aug 2010, 7:08 pm	#2
percival007 Heptode Join Date: May 2005 Location: Oxfordshire, UK. Posts: 852	Re: beomaster 900 rg It is possible that there is some (-ve?) D.C at the speaker output from that channel. Is the distortion there when you use the other speakers instead? If so, then this D.C. component may be pulling the cone in towards the rear of the speaker, you pulling it out are overcoming this D.C. and it sounds ok. If not pulled out there is not as much rear going movement and this will make it sound distorted. If it sounds ok on those other speakers then disregard the above and indeed it sounds like the cone is damaged on that speaker. I have no idea from where a replacement can be obtained other than B&O. They are surprisingly good at keeping old parts and you may be lucky if you ring them. James.

17th Aug 2010, 9:53 pm	#3
roffe Hexode Join Date: Nov 2003 Location: Linkoping, Sweden Posts: 493	Re: beomaster 900 rg Might be a faulty loudspeaker,since you can correct it with your hands.What puzzles me somewhat is that I've read that these BO's have two 6x4 inch oval units.Which is correct? And isn't there something stamped or written on the units?Please try to describe them or even better a picture.

18th Aug 2010, 3:36 pm	#4
anthony lawrenc Retired Dormant Member Join Date: Dec 2008 Location: Leeds, West Yorkshire, UK. Posts: 88	Re: beomaster 900 rg thanks for the input guys its definatly the speaker as for them being oval [or eliptical]the older model 611 delux had oval speakers my radiogram is the later 900 compact model i think the tuneramp is the same but the cabinet is much more modern and compact i was thinking of sending the speaker off for repair [will investigate the cost first]of course it may be cheaper to just replace both speakers with something else the problem is finding somthing with the built in tweeter anyone know if this kind of speaker is still made i have also been looking at videos on how to do repairs im not sure im up to that having said that the speaker no use as it is so i may have a go meanwhile if there are any more ideas out there im all ears thanks again guys Anthony

19th Aug 2010, 10:30 am	#5
roffe Hexode Join Date: Nov 2003 Location: Linkoping, Sweden Posts: 493	Re: beomaster 900 rg Ah,it's the 900 RG Compact. http://beocentral.com/beomaster900rgcompact Very nice looking. From your description it sounds as if the speakers are of the double cone variety(also called twin-cone or whizzer cone in America). As B&O almost always used Philips,SEAS or Peerless loudspeakers,it's often possible to identify them from a number stamped on them or a picture.

19th Aug 2010, 6:05 pm	#6
anthony lawrenc Retired Dormant Member Join Date: Dec 2008 Location: Leeds, West Yorkshire, UK. Posts: 88	Re: beomaster 900 rg hi Roffe yes thats the one the only symbols on the speaker are printed on the back of the paper cone they are the 5 ohms sign and then fm however the owners manual tells me they are 17 TV 2 x D35 _40 im having trouble taking pictures at the moment but as soon as i get it right i will post some i have seen some pioneer speakers that would fit the cabinet but they are designed for a car do you think they might be ok for the job in the b and o manual it says they are special speakers what could be special about them ? any idea Anthony

19th Aug 2010, 9:25 pm	#7
roffe Hexode Join Date: Nov 2003 Location: Linkoping, Sweden Posts: 493	Re: beomaster 900 rg The first with the 5ohm sign might be a Peerless,and the second is definitely a SEAS twin cone.

2nd Sep 2010, 11:47 pm	#8
anthony lawrenc Retired Dormant Member Join Date: Dec 2008 Location: Leeds, West Yorkshire, UK. Posts: 88	Re: beomaster 900 rg im pleased to say the Beomaster now has two new speakers fitted and it sounds better than ever maybe the new speakers are better quality there again i supose speaker tecnology has moved on in 40 years and to say it only has 6 watts per channel it sound much louder i have fitted a cd player in the taperecorder compartment as for the styling it could have been made yesterday hanks again everyone for the expert advice Anthony