Beovox 5700

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Lomax (archived2)
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Posted August 24, 2014 at 21:22 GMT
#2200744

So, this is my first post here after lurking for a few months! I have enjoyed reading about all the different adventures and amazing repair stories from other users - I am in awe of the skills on display! In fact knowing this forum exists was one of the reasons I felt I dared to jump into the B&O pond myself :) After much reading and geeking out on tech details I decided that the target system for my first ever B&O set-up should be the Beovox 5700 speakers, paired with either a Beomaster 6000 or (budget permitting!) 8000, with other bits added later on (the remote being one thing, a Beogram another). I've always wanted a pair of 70s monster speakers and having fallen in love with the design of the 6/8000 systems I felt it had to be B&O all the way. Can't beat matching wooden trim, and the 5700s are about as "monster" as anything they've done!

I'm happy to be able to say that after a couple of missed opportunities and failed eBay bids I have finally secured a pair, in decent-ish condition, and at a price that while on the high side is juuuust within the reasonable :) I should be getting my hands on them sometime next week! 

Now the thing is, these speakers have been around and are pretty grubby. The dust caps have (of course) vanished, and there's a fair amount of dust and dirt on the cones and surrounds. So they will need some restoration work before I can start using them! Now if I'm going to strip the elements out of the boxes for cleaning and dust-cap replacement, I might as well take the opportunity to replace the original wiring and the caps on the cross-overs. I have read enough stories about the improvement a re-cap on these particular speakers can offer to know it's something I'll want to do!

My question to the forum is simple: what capacitors will I need for a full re-cap of the 5700 crossovers? I have the circuit diagram, and a couple of high-res photos, but I'm not able to identify the types from either. Are some of these caps bi-polar? What are the chunky rectangular things with colour coding stripes - film caps? What about voltage tolerances, these are not noted on the diagram? Ideally I'd like to order the cap sets and the dust-caps so I get them in time for next weekend, so I can do the work then - your help is much appreciated!

Many thanks,

Lomax

 

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Lomax (archived2)
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Posted August 24, 2014 at 21:37 GMT
#2200745

Some photos:

 

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Lomax (archived2)
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Posted August 24, 2014 at 23:31 GMT
#2200746

Some pictures of the 5700 cross-over (not mine):

mexking
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mexking
Bronze
Posted August 25, 2014 at 00:14 GMT
#2200747

The crossover diagram shows 2-3.3-5-12-100 uF, the part list in the manual says 3,3-10-50 all 25V, one 4.7 uF 50V all bipolar, and one 1uF 250V so wait until you have your speakers and can check them in the flesh.

The missing dust caps makes me wonder, why would someone take off the dustcaps ??

The wood works are an easy fix, but dont buy anything before you have checked all drivers, and which caps and more you will need for the crossovers. Also the 5700 should have some connection for tweeter cubes, + potentiometers for sound adjustment (not sure about this).

As for the crossovers, B&O sometimes made changes, during production, these changes did not always show in the manual.

Location: Mexico city

Retired
Printing machine technician
Restored various 1960-70 items
Rock and Roll music
Collecting Vinyl
Restored Jukebox Wurlitzer 1050
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Lomax (archived2)
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Posted August 25, 2014 at 01:08 GMT
#2200748

Hi Søren!

Many thanks for your reply! I guess you're right about checking my actual crossovers before ordering anything - just eager to get them working! Thanks for sharing the service manual data - so all the caps are bipolar electrolytes? The rectangular ones look like (old) film caps to me, though I'm not sure.

The 5700s almost always have missing dust caps, something to do with the material they were made of. It's probably nothing ominous, though I am a little concerned that junk may have ended up in the coil gap. The seller assures me that all drivers are fully functioning, so if there is a problem I expect I can ask for some form of refund. Otherwise I wouldn't have jumped!

Re. the wood, I'm not terribly worried about the water stains etc, like you say this can probably be fixed with relative ease, should I want to. More important is that the boxes are structurally intact, with no crushed corners etc. The 5700 doesn't have the external tweeter connection, or the level adjustment, that you mention - you're most likely thinking about the (older but still awesome) Beovox 5000!

Many thanks again for your input - I'll hold off on ordering those caps!

mexking
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mexking
Bronze
Posted August 25, 2014 at 03:47 GMT
#2200749

Right, I got it mixed up with the 5000s, I have here the 3700 speakers, same family, they plays every day.

The rectangular caps are film caps and normally OK, if bad, the color code will tell you the size, and that would be the 1uF 250V that is listed in the part list.

Location: Mexico city

Retired
Printing machine technician
Restored various 1960-70 items
Rock and Roll music
Collecting Vinyl
Restored Jukebox Wurlitzer 1050
DI
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Dillen
BronzeModeratorFounder
Posted August 25, 2014 at 06:41 GMT
#2200750

Worth noting that there are two different versions of Beovox 5700!

Martin

Peter
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Peter
Gold
Posted August 25, 2014 at 09:51 GMT
#2200751

I would be a little cautious using 5700s with a Beomaster 8000 - the 5700 was deigned for use with the Beomaster 4000. The 8000 is more powerful and it was designed for use with the MS150. Most music you play will actually be at about 1W so no problems but the 8000 does have a damped volume control which can lose its damping and an inquisitive child could inadvertently give it a good twirl! The 5700s take 60W and peaks of 100W so are ideally suited to the 4000. The 4400 or 6000 (stereo) are unlikely to give issues either.

These are not common speakers so it is good to see a pair about to be put back into service.

My B&O Icons:

BeoCenter-9500.png BeoCenter-9500.png
Beoremote-Beo4.png Beoremote-Beo4.png
Beovox.png Beovox.png
Beovision-11.png Beovision-11.png
Beotime.png Beotime.png
Beosound-Stage.png Beosound-Stage.png
Beosound-Moment.png Beosound-Moment.png
Beosound-5.png Beosound-5.png
Beosound-2.png Beosound-2.png
Beoremote-One.png Beoremote-One.png
Beoplay-Portal.png Beoplay-Portal.png
Beoplay-Earset.png Beoplay-Earset.png
Beomaster.png Beomaster.png
Beolit.png Beolit.png
Beogram-400x.png Beogram-400x.png
Beocenter-2.png Beocenter-2.png
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Lomax (archived2)
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Posted August 25, 2014 at 14:13 GMT
#2200752

Dillen wrote:
Worth noting that there are two different versions of Beovox 5700!

Do you mean the 5702? IIRC, these are easily identified by the 5702 having an oval shaped passive slave (made by KEF?), as opposed to the circular one in the 5700, and a different arrangement of the drivers. Or did you mean something else? Here's a photo of a pair of BV 5702 (not mine). It's worth noting the disintegrated surrounds on the slaves; this appears to be a common problem with these:

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Lomax (archived2)
Bronze
Posted August 25, 2014 at 14:51 GMT
#2200753

Peter wrote:
the 8000 does have a damped volume control which can lose its damping and an inquisitive child could inadvertently give it a good twirl!

That is a very good point, and I fully recognise that the BM  8000 is a little over the top - not only in terms of power,  but also size, complexity, rarity and cost! It also easily has the capacity to fry the speakers if something malfunctions. The fact that you can tell the MCU to jump directly to a (very loud) pre-set level (8.0?) also makes me a little wary, should it decide to do so on its own accord... :o The more I think about it the more sensible a (stereo) BM 6000 seems - I'm just so totally in LOVE with the design of the 8000, with the large displays and volume/tuning wheels; the 6000 is damn sexy as well but not quite as drop-dead gorgeous ;) Another important thing to note is that the design of the amplifier section in the 8000 is much more advanced and high-end, the 6000 is a pretty basic amp in comparison (from what I've seen of the innards). I'm also very interested in the remote control possibilities of these machines; I understand they used a very early version of MCL (called DataLink?), and that the BM 8000 implementation is more advanced than the 6000 - though I do not know the details! Perhaps someone here knows more about this? Also, and I know this is a crazy idea, maybe it would be possible to limit the max volume on the 8000 somehow?

Peter wrote:
These are not common speakers so it is good to see a pair about to be put back into service.

Thank you! We'll see how it goes; looking at the photos again today I'm starting to get a little worried - particularly the MF 500 drivers look like they're in really bad shape, they're moldy and the domes appear to have begun to separate from the spiders (enlarge pictures 5 & 7 above). I've seen people restore these, so I know it can be done - if the coils are still fine - but it's not for the faint of heart. I'm kicking myself because I had a pair of 5700s in mint condition (even one of the dust caps was still intact) that I could have bought for just a little bit more money, but I hesitated and lost out :( They are indeed quite rare; in the two/three months I've been looking I've only seen three pairs in the UK that were in "working" order. Hopefully, with time and patience - and the help of the knowledgeable people here on BeoWorld - I'll be able to get them back in good enough shape that having missed out on a mint pair won't feel so terrible :)

Thanks to everyone for your valuable input!

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