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Bringing a pair of Beovox 5702 back to life...

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MrRoast
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MrRoast Posted: Sun, Jan 17 2016 10:33 AM

Hello all,

After a long while keeping my eyes open for some I've just acquired a pair of Beovox 5702. I've been using my Beovox 3800s (which I love!) with my Beomaster 7000 and thought a nice progression would be the 5702. 

They've come from a nice lady who was left them by her late father and are in generally nice condition.

As seems to be the case the KEF passive radiator surround has disintegrated as have the dust caps on the bass drivers.

Fortunately I've managed to source a donor pair of the KEF B139-SP1037 units with the rubber surrounds in very good condition apparently (they are yet to arrive!). I've done a bit of searching but haven't found anywhere that can repair the original radiators, has anyone had any success with this?

As you can see the front grills have had an incident or two (with fetching repair work!) but are structurally solid. I'm going to recover these but would like to source a fabric that is as near as identical to the original as possible. Can anyone suggest any material matches?

I removed the drivers as I'm going to replace the caps in the crossover and was surprised to see a very fine dusty layer of oxidation on the aluminium cage of the bass unit. A good careful bit of brushing and vacuuming removed that swiftly!

The Celestion drivers look to be in good condition so I'm hopeful that these will eventually sound great.

Cosmetically everything is there and will brush up nicely with a bit of TLC and Danish oil - the only slight flaw it that on one speaker the corner aluminium trim and cabinet is a tiny bit bashed! Given the bulkiness and weight of these I'm not surprised that It made contact with a hard floor at some point in the last 40+ years!

I'm looking forward to bringing these back to life and will probably pair them up with my Beolab 5000 which should be coming back from Frede in not too long!

MrRoast
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MrRoast replied on Sun, Jan 17 2016 6:23 PM

A few more pictures...

Does anyone know what this label would relate to?

MrRoast
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MrRoast replied on Sun, Jan 17 2016 8:42 PM

Fresh capacitors ordered - need to sort speaker cloth next!

MrRoast
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MrRoast replied on Sun, Jan 17 2016 9:01 PM

Does anyone know where I can get replacement dust caps from in the UK? I'm pretty sure that 70mm / 2.75" will do the trick. I've found a store in the U.S. but the shipping is £20!!

MrRoast
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MrRoast replied on Tue, Jan 19 2016 8:58 PM

Well today has been a good day - I've ordered dust caps from speakerrepairshop.com and the capacitors have arrived today from www.hificollective.co.uk (formerly Audiocap).

The donor bass radiators are in with he courier and I've had an interesting lead about possibly getting the original ones restored!

Sadly it doesn't look like I'll be able to get hold of original spec fabric for the frets so will go with another variety - I'm getting a sample of the Jantzen Audio material sent to see what I think.

I'm getting excited about hearing them when they're done!

 

Dillen
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Dillen replied on Tue, Jan 19 2016 9:13 PM

The label inside is the woodworkers checklist; Sanding, polishing etc....

Martin

MrRoast
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MrRoast replied on Wed, Jan 20 2016 7:30 AM

Ahh - thanks Martin! I like to find these bits that connect with the building of the speaker - it's rewarding to think that the hard work in the factory in Struer hasn't gone unnoticed!

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MrRoast replied on Sat, Jan 23 2016 1:05 PM

The KEF passive radiators arrived - and as described they're in great condition (eBay plays nice for once!)

As the original fabric is a non-starter I've decided to go with Jantzen Audio fabric in black, a sample arrived yesterday and looks good so the order has been placed!

Very prompt shipping of the dust caps means I've cleaned up the disintegrated muck off the cones and have glued them in place - with a little help from some kitchen items to hold them in place!

I'll aim to get the crossovers done this weekend if I can.

MrRoast
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MrRoast replied on Sat, Jan 23 2016 4:57 PM

Out with the old sweeties...

...and in with the new

Dillen
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Dillen replied on Sat, Jan 23 2016 5:44 PM

Are you replacing the polyester film capacitors with electrolytics? - Why ??

Martin

MrRoast
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MrRoast replied on Sat, Jan 23 2016 7:49 PM

@ Martin – probably because I didn't think there was any difference and so no reason not to Laughing.  Should I put the film caps back? Is replacing them with electrolytic ones a no-no?

Dillen
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Dillen replied on Sat, Jan 23 2016 8:59 PM

It will work as-is, I'm sure, but those "tropical fish" polyester caps are some of the most
reliable components on this planet (and not cheap!).
They will practically last forever because they contain no fluids so can't dry out.
I would've left them in.

Martin

MrRoast
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MrRoast replied on Sat, Jan 23 2016 9:06 PM

Ahh I see - I'll replace them with the originals (which I kept). Thanks for your advice Martin - this is an enjoyable hobby for me and I'm keen to learn. Sometimes that comes through making mistakes though!

chartz
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chartz replied on Sat, Jan 23 2016 11:05 PM

Martin is right, by all means don't replace those with electolytics!

I have never seen one fail in 35 years, and I've seen a lot. Every manufacturer used those in the old days. I think they were made by Philips. They were replaced with the orange ones still available today.

Jacques

Dillen
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Dillen replied on Sun, Jan 24 2016 7:50 AM

chartz:

I think they were made by Philips.

Mullard, - but that's actually almost the same as Philips. :-)

Martin

MrRoast
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MrRoast replied on Sun, Jan 24 2016 10:15 AM

Tropical fish back in the fishtank!

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MrRoast replied on Sun, Jan 24 2016 5:01 PM

A good afternoon sanding and wire-wooling the cabinets. Frets given a dust coat of black in advance of re-clothing.

Everything ready for putting back together, just waiting for some gasket tape for the passive radiators!

MrRoast
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MrRoast replied on Sun, Jan 24 2016 5:12 PM

double post

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MrRoast replied on Tue, Jan 26 2016 11:18 PM

Almost finished...

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MrRoast replied on Sun, Jan 31 2016 12:12 PM

Got time this weekend to put all the bits back together...

Replaced the gasket tape on all the drivers, gave the cabinets an oiling (Frede kindly recommended beeswax to match with my Beolab 5000 but I went with Danish oil to match my 3800's 3702s and 2702s) and then mounted all the drivers and radiators back in.

Recovered the frets and replaced the B&O badges...

And finally all done! They've replaced my 3800s which were paired with the 7000 system - only a few inches bigger on paper but noticeably larger in real life!

And the sound.... they sound amazing! Had a quick test with them hooked up to my Beomaster 1200 and they sounded underwhelming (not surprising given it's modest output) but with the 7000 very impressive Big Smile

I was interested in how they compared to the 3800s given the larger 12" Goodmans driver in those (and the similar frequency range on paper) - but the 5702s are noticeably more punchy bass wise, the passive radiator is something I've never experienced before but it definitely seems to enhance the lower end. The midrange and treble is a total revelation compared to the 3800s - listening to my 'reference' tracks they're effortlessly cleaner and more defined through the volume range.

Overall I'm really happy with them and would certainly recommend anyone who's considering them to try and track down a pair!

 

Ben_S
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Ben_S replied on Sun, Jan 31 2016 3:21 PM

Great thread and really good work! 

I fancy a pair myself but they are not at all common from what I have seen.

Also, notice your Beolit 500 there. Did you manage to find a wall bracket for it in the end? 

Ben

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MrRoast replied on Sun, Jan 31 2016 6:45 PM

Cheers Ben! 

With hindsight I was really lucky to find a pair of the KEF passive radiators in great condition as donors (which was after I'd bought the 5702s!) else I could have been scuppered. From the scouting around I've done it doesn't look as if getting replacement surrounds for those is possible and they seem to be the thing that disintegrates. With that in mind the 5700s may be a safer option? I've kept the original slaves though and will get them restored if the chance arises.

The 5702s are big old things and weight a ton but I love the look of them with the flat front and slim aluminium edging - the later S speakers don't look as good to me personally!

As for the 500 I didn't find a bracket so decided to fabricate one using measurements from the actual Beolit. I sketched up a rudimentary technical drawing and made a card template and over a few evolutions had a pretty solid design.

I used a 30cm aluminium ruler as a base starting point and it all went pretty well until attempting the final 90 degree bend at which point the aluminium fractured. Angry At that point I left it in the shed for another day! One day I'll attempt another one but it would be much easier if someone could laser cut one and machine bend it out of 1mm steel! Big Smile

Astonmartin
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I’ve just picked up a pair of 5702’s in exactly the same condition. I’m glad that there are fixes for them.

MrRoast
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MrRoast replied on Thu, Feb 8 2018 6:54 PM
Are your passive radiators in ok condition astonmartin? I was fortunate to find a pair of the correct 1037 ABRs to replace mine but never found anywhere to get replacement surrounds for the old ones I took out.
Astonmartin
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They look pretty battered, I’ll upload some pics over the weekend.

How much did it cost you overall?

MrRoast
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MrRoast replied on Thu, Feb 8 2018 7:16 PM

I can't remember what I spent exactly but I've used them every day since and so whatever it was I'd say it was worth it!

Craig
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Craig replied on Thu, Feb 8 2018 7:54 PM

Cracking job Dave.......it's good to see your putting your free time to good use ;~)

Craig

MrRoast
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MrRoast replied on Fri, Feb 9 2018 7:39 PM
Thanks Craig - I’ve been trying to keep myself away from eBay Big Smile
Beo_Jean
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Beo_Jean replied on Sat, Feb 10 2018 11:11 PM

Congrats on your restoration!  You certainly got in these 5702 some of the best B&O made.  You put great attention to details and I'm sure they will be your best friends for a long time.  I know what you went thru, I just finished the restoration of M70's...

Astonmartin
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Sorry to hijack again, but these are mine.

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