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Beovox P45 Crossover Help Needed

dragon

dragon

can't take me anywhere
Hey all,
I rescued a pair B&O Beovox P45 wall speakers from a dumpster
a few days ago, along with a pair of Bose 601 series III. Both sets need some TLC.
The drivers on the P45’s are all good but they sounded lifeless.
When I opened one up I discovered that the x-overs were in really bad shape.
Check out the pics.
My only experience with crossovers is replacing 3 caps on both of my Altec Model Fourteen’s. They were easy but these are old West German caps with different codes.
Some of the other stuff I don’t know about. Like that white thing that’s burnt up and those long gray things (resistors?).
The printing on the caps are – ADE (type?), glatt (company?), EBAZ – 40 and 25/35V.
The other 2 caps are both 8/35. Does the 8 represent mfd and the 25 volts? The coils seem OK.
That white thing is – UTM 214—1, 9w, 6RB 10%.

Could I get some help identifying the components?
I really like to hear how these sound with some upgrades.
 

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Yes, those caps are 25uF@35V and 8uF @35V Use non polar electrolytics, or mylars if there's room for them. The long skinny things are resistors. The white one is a resistor. sounds like a 6ohm/9 watt

I'd sketch out a schematic before replacing anything and make sure it makes sense. ..... polarity and everything. B&O liked to use a "phase link" driver that was wired out of phase at the crossover frequency.

For in-wall speakers, it's normal for them to sound "lifeless" if they aren't mounted in the wall. The wall is their baffle and low frequencies will just cancel if they aren't in their extended baffle.
 
That helps alot. Good info and good advise. Why is that one resistor so different than the rest?
 
OK, I need to pick out some caps. Any suggestions on what brand of resistors to look for?
 
hahahahahahaha I'm the wrong guy for that.

I'd pick a material and not a brand name. I'd choose mylar caps. If you can't find the specific value, you can just parallel them. Their values will sum. For the resistors, choose the same or higher wattage ratings. The skinny ones look like 2~3 watt, the rectangular one is 9W, but 10W is a typical 'normal' wattage size. Try to find non inductive type resistors if you can. Resistors are rarely designed into crossovers with their inductance designed in.

Mylars are good because they have very low series resistance and generally don't drift or fail over time. Changing these will make it so you don't have to worry about ever having to rebuild the crossover again. Resistors? eh, get the right values. Check with Parts Express

Put it this way, if there are measurable differences between brands, these differences would be vanishingly small compared to the error (distortion) the speakers will be responsible for.
 
I rebuilt the crossovers on a pair of Beovox S75 as one caught on fire. It was a horrible job. The schematics were wrong on some parts, and rebuilding it on that particle board was a nightmare. If I was to do it again, and I never will, I would redo the entire thing on a project board or anything other than the linear way they did it.

The S75 had about 10 times more parts though. Read up on the S75 horrible crossovers on Oaktree. Its a hilariously funny read. Did I mention how horrible the crossovers were?

I ended up parting out the good speaker as it never sounded right after the rebuild (I think a driver was toasted in the fire).
 
I was thinking the same thing about using a project board. Thanks, I'll check out that link.
 
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