# Replacing woofer in loudspeaker?



## hgus

Hello!

 I have a pair of old Bang & Olufsen speakers, and one of the woofers has gone bad, it makes scratchy noices. I consider it dead.

 Well, of course my question is, is there any point in replacing this element? I really don't have much cash right now, so replacing the entire speakers isn't really an option at this point. How adapted to the resonance of the speaker is an average speaker enclosure? In general, will a generic replacement suck, or might it even improve the sound?

 Thanks!

 *edit* The spekers are not one of those modern very special B&O speakers, it looks like most speakers. It's quite old. The model is Beovox s45.


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## Ryan T

well replacing one of the drivers in any speaker system is usually a problem for a few reasons (unless your replacing it with the same driver). First your speakers contain a crossover which separates the highs from the lows. That crossover was designed specifically for the drivers used in the speaker. Also the enclosure is designed with the exact drivers in the speaker in mind. Every speaker has whats called TS parameters. They tell exactly how a driver will act in an enclosure and with a specific crossover and the TS params can vary GREATLY for different drivers. If you stick another woofer in there you will change the sound of the entire system. The best way to go is If you could contact B&O and find out if they offer replacement drivers. 


 Ryan


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## Ryan T

part of the problem with matching the speakers is you have to have a crossover slope among other things. You need to know the TS prams of the tweeter and the FR of the crossover. Then you would have to start modeling crossovers. Like I was saying the crossovers in the B&O speakers are designed with the tweeter and woofer with thier TS params specificaly. If you just get the box size and crossover frequency you still won't know how the woofer acts with the tweeter. The replacement woofer might have a big dip or peak that the original didn't have or it may be less efficient than the original woofer. Unless you have all the TS params and crossover slopes and such. It's very very hard finding a replacement that will work well. Don't get me wrong though you can just buy a regular woofer and stick it in there. It might sound fine it might not. One thing I would suggest if you are going to replace the woofers with just generic ones. Use the same woofer for each speaker. That way even though they won't sound like the original they will at least sound like each other lol. 


 Ryan

 edit:
 didn't realize you said slope in your post


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## BlindTiger

You should try contacting B & O for a replacement if they have one. It would not be that expensive.
 I thought I blew a tweeter and a woofer from my speakers once and called the manufacturer.
 For a sound dynamics tweeter around $60, for a monitor audio woofer, around $45.
 I blew the woofer from the monitor audio and they had the exact replacement for a very old model.
 My Bros's soliliquy woofers were scratched and punctured by his cat and the cost was even less, around $30.


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## insanefred

Hold on! You may not have to spend any money to sort this out. I had a similar problem with one of my B&W DM2 speakers (huge efficient brutes of things); one of the woofers was sounding a bit scratchy. I was going to give it up for gone, with absolutely no chance of finding a replacement, when I happened to mention this to a friend who used to sell the speakers in his shop. Apparently, like a lot of things, drive units can start to 'droop' with age, and turning them round 180 degrees (so that they're still facing outwards!) will correct this. So, I tried this today, and, lo and behold, no scratches! It's worth a try, although it may involve finding clever ways of making the internal wire stretch that bit further.
 HTH
 Andrew


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## hgus

Quote:


 _Originally posted by insanefred _
*Hold on! You may not have to spend any money to sort this out. I had a similar problem with one of my B&W DM2 speakers (huge efficient brutes of things); one of the woofers was sounding a bit scratchy. I was going to give it up for gone, with absolutely no chance of finding a replacement, when I happened to mention this to a friend who used to sell the speakers in his shop. Apparently, like a lot of things, drive units can start to 'droop' with age, and turning them round 180 degrees (so that they're still facing outwards!) will correct this. So, I tried this today, and, lo and behold, no scratches! It's worth a try, although it may involve finding clever ways of making the internal wire stretch that bit further.
 HTH
 Andrew * 
 

Well, I didn't have any trouble with the internal wire, and _it seems like it worked_! I put on the first part of Also spracht Zarathustra, and without diming the volume (it's almost midnight here in Sweden) it sounded fine. I'm amazed. But I'll get back in the morning when I have tried it louder... Still sceptical... 
	

	
	
		
		

		
			





 Thanks for all the ideas, guys! For some reason the email notification didn't work, so I just stopped by to see I had 5 replies, great! Wish they could fix that...


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## insanefred

Oh, good choice! Which recording? Don't crank it up to loud straight off, I don't know what kind of shifting might be going on in the drive unit diaphragm after turning it upside down following 25 years of being the other way round... Hope this works out for you. Let it run for a while, and if it works, great. If not, well, no money wasted!
 Andrew


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## Budgie

Great call, insanefred! I have heard that this can happen, but never seen it myself. Weight of the magnet makes the frame sag and then the voice coil rubs in the gap. I guess you will need to rotate your woofers on the same schedule as your car tires.


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## insanefred

Yeah, Budgie, that sounds about right. Some of those old speakers used big big magnets, I'm not surprised things start to droop! And I'm glad that you don't have to replace drive units as often as you do car tyres, otherwise this would be one expensive hobby; that is, even more expensive than it is now!
	

	
	
		
		

		
		
	


	



 Andrew


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## Budgie

Maybe a tweak for old speakers- A stick to prop up your sagging magnet! Just wedge it in place, tap in to position with a hammer and enjoy that clear sound you've been missing!


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## Sovkiller

Quote:


 _Originally posted by hgus _
*Hello!

 I have a pair of old Bang & Olufsen speakers, and one of the woofers has gone bad, it makes scratchy noices. I consider it dead.

 Well, of course my question is, is there any point in replacing this element? I really don't have much cash right now, so replacing the entire speakers isn't really an option at this point. How adapted to the resonance of the speaker is an average speaker enclosure? In general, will a generic replacement suck, or might it even improve the sound?

 Thanks!

 *edit* The spekers are not one of those modern very special B&O speakers, it looks like most speakers. It's quite old. The model is Beovox s45. * 
 

I would contact the company first to find out the parameters of the drivers, in case they do not suggest any other, this should be at least known parameters for them, later on visit, partexpress or madisound for a replacement, but have to be both woofers, not just one, BTW they have a forum there, and there are lots of people who may give you hand with the finding...just visit www.partsexpress.com go to the technical forum, and try to contact someone there......post your question, model etc..., the other thing is getting any pair of woofers and modify the crossover, but for this you may need also the parameters of the rest of the drivers


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## Sovkiller

Other suggestion, send both to be fixed, there are a lot of people who do that proffesionally for a modest fee, and they will be both like new later...if is just a blown coil, they will replace the voice coil, and as the cone is still good, they will be as new....just do a search, maybe for a lot less of what you expect you can fix both....


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## hgus

Thanks for all help guys!

 The tweak helped alot, but it didn't eliminate the problem. It's still there but only at significantly louder volumes or more bass, so I'll live with it for now. I am shopping around for new speakers anyhow, but this way there is no fire on the roof, I have time to look into it.

 Still, if I end up with a pair of good 'phones instead of speakers, I might go ahead and change the woofers...


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## Budgie

It may get better with time, if the magnet continues to shift position.


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## Music Fanatic

Quote:


 _Originally posted by insanefred _
*Hold on! You may not have to spend any money to sort this out. I had a similar problem with one of my B&W DM2 speakers (huge efficient brutes of things); one of the woofers was sounding a bit scratchy. I was going to give it up for gone, with absolutely no chance of finding a replacement, when I happened to mention this to a friend who used to sell the speakers in his shop. Apparently, like a lot of things, drive units can start to 'droop' with age, and turning them round 180 degrees (so that they're still facing outwards!) will correct this. So, I tried this today, and, lo and behold, no scratches! It's worth a try, although it may involve finding clever ways of making the internal wire stretch that bit further.
 HTH
 Andrew * 
 

 Impressive!


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## Orpheus

hgus...

 all you probably need to do is get it "reconed." call around to see if there are speaker repair shops around. or call professional recording studios and ask where they get their speakers done. it's a normal thing.

 there's a place near here that seems very reasonable... you can even disconnect the woofer from the cabinet and just bring it in... they'll recone just the speaker itself. however, i see you're in sweden..... but i'm sure there's a place that will do it for you too.

 anyway, again, you don't need a complete replacement. just ask for "reconing service."

 but of course, that's assuming your speakers are worth something to you. it'll probably cost you around $50 to recone that one speaker..... and i'm not big on b&o speakers. they remind me too much of bose.


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