Mundorf aluminum oil mcap for b&w

[Deepinton]

"You have 802D?" Those are working great. It's the 800D3 that is giving me headaches. The cap probably shorted and blew out the mid range voicecoil as well. So much for super premium caps. But yes, I am with you on going the cheap cap measuring route. All things considered (mainly my time) I'll just replace the crossover board and be done with it

 

[MAB]

"You have 802D?" Those are working great. It's the 800D3 that is giving me headaches. The cap probably shorted and blew out the mid range voicecoil as well. So much for super premium caps. But yes, I am with you on going the cheap cap measuring route. All things considered (mainly my time) I'll just replace the crossover board and be done with it

Have you confirmed the midrange is toast?
The midrange is able to handle a bit of power, even if the cap was completely shorted.

 

[Deepinton]

Yes, open circuit across the voice coil

 

[MAB]

Yes, open circuit across the voice coil

Oh. I see. Do they get played at high power? Or are you thinking this was a chain of events starting with a defective cap? Or not sure?
In any case, I think you have a path to fixing them.

 

[Deepinton]

Oh. I see. Do they get played at high power? Or are you thinking this was a chain of events starting with a defective cap? Or not sure?
In any case, I think you have a path to fixing them.

I don't play them very loud but there has/have been other owner(s) before me. Probably a chain of events that included very loud play that cooked the Caps over time and then some incident that broke the camel's back

 

[DatSpeakerTho]

800v cap in a hifi speaker?! Why lol? No need for that here.

You're really overthinking it, you can put pretty much any 22uf film cap in there and get identical performance to the stock one. The first response in the thread should be enough info to support that claim.

 

[Maxim-ICOM]

Yes, open circuit across the voice coil

I suppose that driver failed due to internal reasons or overpowering.
Very often it happens in joint point - terminal to leadwire or whhere lead wire soldered to coil wires - that point on back of cone under the glue.
Your crossover components looks fine and capacitor look like it is Classic Supreme, and now big values over 10uF discontinued.

I've never seen failed Supreme, but if you suspect that they got damaged, you can get last pair here: Mundorf Supreme Classic 22uF

If you still think that the problem may be caused by crossover, check there resistors - blue ones screwed to radiator sink.

 

[Roland68]

The speakers were built in 2019. I would expect the much ballyhoo'ed premium mundorf to last way more than say 4 hrs a day times 1800 days

That is what strikes me as odd.
The industrial-grade capacitors I recommended—the very same ones I use myself—have an MTBF of 100,000 hours under higher loads, a figure that is typically exceeded in practice.
I would suggest contacting both B&W and Mundorf simultaneously (ideally by CC'ing each other on the email) to inquire whether the capacitors can be replaced as a goodwill gesture; after all, it simply shouldn't be the case that such high-quality capacitors fail after less than 8,000 hours of operation under such low load conditions.

 

[Ruediger]

No, but now that I have seen them, I can't unsee!

The inner monk seizes control!

 

[Deepinton]

I suppose that driver failed due to internal reasons or overpowering.
Very often it happens in joint point - terminal to leadwire or whhere lead wire soldered to coil wires - that point on back of cone under the glue.
Your crossover components looks fine and capacitor look like it is Classic Supreme, and now big values over 10uF discontinued.

I've never seen failed Supreme, but if you suspect that they got damaged, you can get last pair here: Mundorf Supreme Classic 22uF

If you still think that the problem may be caused by crossover, check there resistors - blue ones screwed to radiator sink.

Well the cap measures OL on my fluke 115. Thanks for that link. I just ordered a new board and will fix this and keep it ready for when the other one blows.

 

[LTig]

Well the cap measures OL on my fluke 115.

The Fluke 115 cannot measure capacitance. If you measure the resistance of any cap it will always be infinite, as resistance is measured with a DC current and caps block DC. If however the cap shows a low resistance it is broken.

Edit: I was wrong, it can measure capacitance.

 

[Deepinton]

The Fluke 115 cannot measure capacitance. If you measure the resistance of any cap it will always be infinite, as resistance is measured with a DC current and caps block DC. If however the cap shows a low resistance it is broken.

The 115 has capacitance measurement mode.

 

[voodooless]

it simply shouldn't be the case that such high-quality capacitors fail after less than 8,000 hours of operation under such low load conditions.

Yeah, but it's like complaining to Ferrari that your transmission failed after 10000 km... it's all part of the deal, I guess

The fact is, these Oil caps are prone to leaking. It's not super common, but it can happen. The industrial counterparts are just way more reliable.

 

[sq225917]

800v caps are pointless for a speaker xo, 200v is more than enough. Smaller and cheaper

 

[Deepinton]

That is what strikes me as odd.
The industrial-grade capacitors I recommended—the very same ones I use myself—have an MTBF of 100,000 hours under higher loads, a figure that is typically exceeded in practice.
I would suggest contacting both B&W and Mundorf simultaneously (ideally by CC'ing each other on the email) to inquire whether the capacitors can be replaced as a goodwill gesture; after all, it simply shouldn't be the case that such high-quality capacitors fail after less than 8,000 hours of operation under such low load conditions.

B&W insists I take the 210 lb speaker to a local service shop for evaluation. The shops have a wait list 3 weeks long. I have neither the time, strength or the patience. I'll try contacting mundorf. Maybe shame them into helping out.

 

[DatSpeakerTho]

800v caps are pointless for a speaker xo, 200v is more than enough. Smaller and cheaper

Bigger number go brrrrr and customers eat that shit up.

 

[Roland68]

The Fluke 115 cannot measure capacitance. If you measure the resistance of any cap it will always be infinite, as resistance is measured with a DC current and caps block DC. If however the cap shows a low resistance it is broken.

Actually, yes, 1nF - 9999uF.

 

[Maxim-ICOM]

Well the cap measures OL on my fluke 115. Thanks for that link. I just ordered a new board and will fix this and keep it ready for when the other one blows.

This image shows it it a kind special to B&W version of Supreme - hardly available to buy except only as complete assembled crossover board from B&W.
If capacitor is really failed, you may go with Mundorf Supreme EVO Oil 22uF - they will be "same or better" then your Supreme Oil and Supreme Classic.

 

[Deepinton]

If you still think that the problem may be caused by crossover, check there resistors - blue ones screwed to radiator sink.

Well, just to be sure, I checked the resistors and they both show open. I measured them while they were still mounted and yes I ensured that conformal coating was not getting in the way. Now I am very confused. Any ideas on what's going on here?

 

[Maxim-ICOM]

Well, just to be sure, I checked the resistors and they both show open. I measured them while they were still mounted and yes I ensured that conformal coating was not getting in the way. Now I am very confused. Any ideas on what's going on here?

If resistor is "open" and it is serial to driver it may be the problem. If it is parallel, it will cause the problem when it short.

Would be good if you can draw schematics, then it will be easier to understand which elements may cause the problem and how to diagnose.

The first what comes in mind - disconnect driver and check if driver is working, then you can go one by one in a signal path in crossover.
Switch your multimeter to resistance and measure driver. Typical multimeter measure resistance with 1kHz, you will hear it from driver and you will see some ohms on display.