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Beovox p45 Replacement Mid-Drivers

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roblongdesign
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roblongdesign Posted: Thu, Aug 7 2014 3:18 PM

Hello All, 

I've a pair of Beovox p45's one of which isn't now working properly as the two mid-units have succumbed to frozen-cone syndrome. I was wondering, as replacement ones are quite difficult to come across, are there any other more readily available drivers that can replace these? 

I have no idea the specs of the original drivers as i've no plans =/

Also has anyone replaced any of the capacitors? I wouldn't mind upgrading them? 

Any help would be appreciated guys! 

Robb 

Rich
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Rich replied on Thu, Aug 7 2014 6:09 PM

Read this thread and do a search in this forum on P45.

The woofers can be fixed, and it's easy to replace the capacitors.


Søren Mexico
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Rich:

Read this thread and do a search in this forum on P45.

The woofers can be fixed, and it's easy to replace the capacitors.

Rich did it, DIY is the man, just follow the instructions, and if you have questions, come back here.

 

Collecting Vintage B&O is not a hobby, its a lifestyle.

roblongdesign
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Nice one guys. I've already the magnets off the back. Just need to go to the hardware store today to get some epoxy! 

I'll let you know how i get along! 

Rich
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Rich replied on Fri, Aug 8 2014 6:13 PM

Good luck!

Remember Forum Rule #3:  Pictures, or it didn't happen!


roblongdesign
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Haha Noted. i'll upload a recent pic showing progress asap! What have people used to remove the old glue? I saw that you used goo gone. Anyone got anything else they've tried and had luck? Goo-gone isn't available in the UK.

Also, found another thread giving advice on how to prevent working ones freezing (putting additional epoxy placed round the interface between the magnet and basket: http://archivedarchivedforum2.beoworld.org/forums/t/35543.aspx). Fingers crossed they're ok for another 30-odd years. 

roblongdesign
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Rich
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Rich replied on Sat, Aug 9 2014 3:07 AM
Just scrape with a putty knife and/or hobby knife as best you can. Then use isopropyl alcohol soaked into a rag. That should work just fine. They don't have to be spotless for you to get good results.


roblongdesign
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There we go - picture finally! Got a little further today. Just playing getting the correct sized shims so i can glue the magnet back on. Will post a pic asap.

What diameter cable did you use to do this? Any ideas? 

Cheers 

roblongdesign
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Does this look ok for a gap between the magnet & basket in peoples opinion?

Søren Mexico
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IMO the gap is bigger on the right side, shim the same all around.

Collecting Vintage B&O is not a hobby, its a lifestyle.

roblongdesign
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ok guys having trouble getting the magnet centred. What thickness of wire did people use? 

Cheers, 

Rob 

Rich
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Rich replied on Mon, Aug 11 2014 1:04 PM

roblongdesign:

What thickness of wire did people use? 

To be honest, I don't know what thickness it was.  It was snipped from a bulk roll of craft wire, probably marketed as picture hanging wire.

I used 4 pieces equally spaced.  (0 degrees, 90 degrees, 180 degrees, and 270 degrees.  Or, if you prefer, 12 o'clock, 3 o'clock, 6 o'clock, and 9 o'clock.) 

I take it you're doing a dry run, and once the magnet and basket are attached, you can't center it.  Well, when you have epoxy in there, you will be able to slide it a bit to center.  I believe I noted that in my thread.


Orava
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Orava replied on Mon, Aug 11 2014 1:57 PM

If I remember right, this had very small gap. I did use few mm wide cuts from plastic sheet, for example plastic copysheet or something you can buy from diy shop..

Starting here

 blah-blah and photographs as needed

roblongdesign
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Thanks guys,

I used some strips of an old drivers license i had lying around and both seem to have a fairly consistent gap (knock on wood!).

How did you guys prise the dust cap off? Just with a hobby knife? Next step is to look for something to shim the inside of the coil with... Maybe an old laminated business card will do it. 

p.s. thanks for all the advice. It's essential & appreciated!

roblongdesign
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Stage that i'm at. Going to Croatia tomorrow so will be taking a slight break from these! =)

roblongdesign
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Back from vacation so back to these!

i was wondering has anyone done this without using the inside shims? I've not removed the dust cap off either of these yet and was wondering if this was totally necessary? I have to say; my gut feeling is that you need inside and outside shims but i thought i'd ask.

Thanks again.

 

Rich
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Rich replied on Sun, Aug 17 2014 5:08 PM

To borrow from Hamlet:  "To Shim or Not To Shim" - that is the question.  The issue is debated endlessly.

With my P45 woofers, I was able to pry up the dust cap with an X-Acto knife, making shimming and reattachment of the dust cap easy.  It's a relatively painless operation that virtually guarantees success.  I vote "To Shim."


Leslie
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Leslie replied on Sun, Aug 17 2014 7:06 PM

Unless you have steady hands and a good sense of feeling you not necessaraly need to shim.

An endless discussion, indeed.

Brengen & Ophalen

Orava
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Orava replied on Mon, Aug 18 2014 7:29 AM

In these, gap is really narrow between pole and coil, I did shim. Some CX I did not, but they have much more to play...

 blah-blah and photographs as needed

roblongdesign
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Ok, My first go at gluing. Now just wait till the Aleene 7800 sets (thanks rich for recommending!!). I shimmed both inside & outside in the end. Fingers crossed its ok!!! Hopefully 6 clamps is enough too!

What did people use to re-glue the spider by the way? Again, getting hold of adhesives at shops in the UK is rubbish! I was thinking of using superglue as it's easily available however if people don't think it's any good i'll get some wet look. 

 

Dillen
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Dillen replied on Fri, Aug 22 2014 5:29 PM

Superglue hardens and will eventually break. No good for anything that moves.
I am currently testing "Pattex 100%" and so far results were good but I'm not quite done yet. It will have
to prove a long-term stability before I will use it for serious speakerwork.

Martin

Rich
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Rich replied on Fri, Aug 22 2014 5:59 PM

roblongdesign:

I was thinking of using superglue

No way!

Diluted PVA (white, "Elmer's") glue applied with a brush in multiple thin coats, allowing to dry between coats.  (Diluted with tap water, that is.)

My repaired P45s, used at least 5 hours per week now for over a year, are still working fine.


roblongdesign
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ONE WORKING SPEAKER!!!!! I just have to glue the spider on the 2nd one now and that's the divers working! =) Looks good! 

Upload a picture ASAP. 

My 2nd question was about capacitors. I don't know whether to replace these or not given i've the speakers in bits. Did anyone who did this notice a large improvement in sound?

Rob

 

Leslie
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Leslie replied on Wed, Aug 27 2014 8:39 PM

My compliments to you...

Brengen & Ophalen

Rich
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Rich replied on Wed, Aug 27 2014 8:39 PM

roblongdesign:

ONE WORKING SPEAKER!!!!! I just have to glue the spider on the 2nd one now and that's the divers working! =) Looks good! 

Upload a picture ASAP. 

My 2nd question was about capacitors. I don't know whether to replace these or not given i've the speakers in bits. Did anyone who did this notice a large improvement in sound?

Rob

Congratulations!

I can't speak to a difference in sound as I never heard mine before the change in caps.


Søren Mexico
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Rich:
My 2nd question was about capacitors.

If both drivers turn out good, change the caps too, they are old and will need changing in a couple of years anyway if still good. Nothing special, something like this will do

Collecting Vintage B&O is not a hobby, its a lifestyle.

roblongdesign
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Ok, First test. All seems to be going well. 

Thanks for all the help guys. Really pleased they're up and running again!

Cheers!  

roblongdesign
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Snap of glueing the spider using pva. worked really well.

Rich
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Congratulations!

But you have to stain that IVAR!  Devil


roblongdesign
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roblongdesign
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They do look very good. I'm tempted. 

Actually i've been a little disappointed from my Ivar. I've only 1/2 filled one of the shelves with records from my collection and it's started to sag! They do look very good however. Plus, they're ideal for a hi-fi until i can afford some of these:

https://d2lsod3xpjaepj.cloudfront.net/files/assets/1000/221/sizes/650_2x.jpg

I'm always impressed with these little p45's. Great sound. particularly considering the comparatively small volume!

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