Hi, I have recently bought a pair of B&W DM14 speakers.
As they are from 1982 I want to replace the main caps in the circuit and have been reading around the net.
I have 3 Caps to replace
HF
10uf 50v - Blue ALCAPS electrolytic
LF
5uf 50v - Blue ALCAPS electrolytic
500uf 100v (this is a grey reversible cap with UK 82-37 stamped on it.
See Picture below
Some questions I have are
1. Should I stick with the blue ALCAPS electrolytic which are cheap to buy
or go for a polypropylenes one like
Ansar Supersound Audio Polypropylene Capacitors Audiophile HiFi Crossover Caps
5uF 450V ±5% 25x44mm
10uF 450V ±5% 30x43mm
Or
ClarityCap 5.5uF and 10uF 630VDC SA Range Polypropylene Caps
2. The 500uf 100v I am not sure what to replace with and should I bypass it with something as well
Thanks
Lee
As they are from 1982 I want to replace the main caps in the circuit and have been reading around the net.
I have 3 Caps to replace
HF
10uf 50v - Blue ALCAPS electrolytic
LF
5uf 50v - Blue ALCAPS electrolytic
500uf 100v (this is a grey reversible cap with UK 82-37 stamped on it.
See Picture below
An externally hosted image should be here but it was not working when we last tested it.
Some questions I have are
1. Should I stick with the blue ALCAPS electrolytic which are cheap to buy
or go for a polypropylenes one like
Ansar Supersound Audio Polypropylene Capacitors Audiophile HiFi Crossover Caps
5uF 450V ±5% 25x44mm
10uF 450V ±5% 30x43mm
Or
ClarityCap 5.5uF and 10uF 630VDC SA Range Polypropylene Caps
2. The 500uf 100v I am not sure what to replace with and should I bypass it with something as well
Thanks
Lee
On another forum
Markus111 in another thread Recapping B&W DM14 crossovers | Page 2 | Audiokarma Home Audio Stereo Discussion Forums
said
2.) Tweeter circuit.
The biggest bang for the buck here are the resistors that are in series with the tweeter. These are the .22uF, 2.9uF, and 10uF. Using good caps in these positions is recommended.
The other cap (.68uF) is part of the zobel correction network. It is important to for the network to operate correctly, but won't get you a lot of sonic impact unless the old one is way out of spec. If you can replace it easily, you may as well go ahead and do it. But don't spend the big bucks on the zobel cap.
3.) Woofer circuit.
The 5uF is a shunt cap, and falls under the same category as the zobel cap above. You may as well replace it when you're in there, but don't spend the big bucks on it. The 500uF is a very low frequency high pass filter. This was most likely to shape the very bottom end. I would use a cheaper bipolar 500uF or so, and bypass it with a smaller film cap as mentioned previously. Incidentally, with a cap this size it is common to be as much as 20% off in value due to tolerance. So don't sweat it if you can't get the value to be exactly 500uF.
Should I just replace the blue electrolytics and grey cap or should I be replacing the square caps as well?
Markus111 in another thread Recapping B&W DM14 crossovers | Page 2 | Audiokarma Home Audio Stereo Discussion Forums
said
2.) Tweeter circuit.
The biggest bang for the buck here are the resistors that are in series with the tweeter. These are the .22uF, 2.9uF, and 10uF. Using good caps in these positions is recommended.
The other cap (.68uF) is part of the zobel correction network. It is important to for the network to operate correctly, but won't get you a lot of sonic impact unless the old one is way out of spec. If you can replace it easily, you may as well go ahead and do it. But don't spend the big bucks on the zobel cap.
3.) Woofer circuit.
The 5uF is a shunt cap, and falls under the same category as the zobel cap above. You may as well replace it when you're in there, but don't spend the big bucks on it. The 500uF is a very low frequency high pass filter. This was most likely to shape the very bottom end. I would use a cheaper bipolar 500uF or so, and bypass it with a smaller film cap as mentioned previously. Incidentally, with a cap this size it is common to be as much as 20% off in value due to tolerance. So don't sweat it if you can't get the value to be exactly 500uF.
Should I just replace the blue electrolytics and grey cap or should I be replacing the square caps as well?
B&W has gone to almost exclusively Mundorf caps when not using cheapies.
I'd suggest if you want to do what the brand does is consider Mundorf MKP as your starting point for cap replacement and Mundorf Supreme or Supreme Silver in Oil as your top end.
Be careful replacing shunt caps unless you can measure and compensate for the ESR. Significant changes in shunt cap ESR can lead to really unexpected effects, but no one believes me until it happens to them.
Series caps are a little safer.
Also, Mills for resistors.
Best,
E
I'd suggest if you want to do what the brand does is consider Mundorf MKP as your starting point for cap replacement and Mundorf Supreme or Supreme Silver in Oil as your top end.
Be careful replacing shunt caps unless you can measure and compensate for the ESR. Significant changes in shunt cap ESR can lead to really unexpected effects, but no one believes me until it happens to them.
Series caps are a little safer.Also, Mills for resistors.
Best,
E
Hi! Afraid I can't open your image - try attaching it as a thumbnail.
The least complicated path, and the least likely to upset the crossover characteristics, is to replace like with like.
The Mundorf electrolytics from Wilmslow audio would make good repalcements for the Alcaps. There is no real need to change film caps, where present.
Mundorf Electrolytic ECap Capacitors
The least complicated path, and the least likely to upset the crossover characteristics, is to replace like with like.
The Mundorf electrolytics from Wilmslow audio would make good repalcements for the Alcaps. There is no real need to change film caps, where present.
Mundorf Electrolytic ECap Capacitors
There are 500uF NP caps out there, but to be sure of the best quality, I would stick to the Mundorf Ecaps.
Unfortunately Wilmslow do not list a 500uF version.
To achieve the 500uF target, you can wire the following three Ecaps in parallel:
2 x 220uF plus 1 x 56uF.
No need to bypass with this arrangement.
Here is the link to download the crossover diagram from the B&W archives
http://www.bwgroupsupport.com/downloads/techmanuals/bw/DM14-TM.pdf
http://www.bwgroupsupport.com/downloads/techmanuals/bw/DM14-TM.pdf
I don't know where Galu get's his 10% idea.
If you are replacing 10% caps then the idea is that it could be 10% off, so why not replace it with a cap within 10%? That doesn't really mean that it will have no effect. Also film caps are rarely 10% parts. Usually 1 to 5%, and often are spot on.
5uF is a rare value and the one over-the-counter film cap brand I know of that produces them is the French brands SCR/Solen/Axon. But they also make 4.7uF. If a design uses 5uF I have to believe the designer picked it over 4.7uF for a reason. So if I was not buying from Solen (which I generally don't like) I'd buy 4.7 + 0.33 = 5.03, which is within 1% of the original spec.
Best,
E
If you are replacing 10% caps then the idea is that it could be 10% off, so why not replace it with a cap within 10%? That doesn't really mean that it will have no effect. Also film caps are rarely 10% parts. Usually 1 to 5%, and often are spot on.
5uF is a rare value and the one over-the-counter film cap brand I know of that produces them is the French brands SCR/Solen/Axon. But they also make 4.7uF. If a design uses 5uF I have to believe the designer picked it over 4.7uF for a reason. So if I was not buying from Solen (which I generally don't like) I'd buy 4.7 + 0.33 = 5.03, which is within 1% of the original spec.
Best,
E
From my 'close enough is good enough' school of 1960s crossover design of course!
The point I was trying to make is that a 4.7uF is a close substitute (within 6%) for a a 5uF
A 4.7uF Mundorf ECap has a 5% tolerance in its value, so could be within a whisker of 5uF anyway. - just depends!
Such small percentage differences, in my opinion, will not be audible in a loudspeaker designed around 35 years ago!
Since ESR increases with age, how are we to know what the original ESRs were over 35 years ago?
Hence my suggestion to replace electrolytics with electrolytics, since we are likely to get closer to the (unknown) original ESRs than if we replace with films.
Similarly, compensating for the lower ESRs of film capacitors with series resistors is only viable if we know the original ESRs.
The above furnishes another reason why I'm not unduly worried about a small percentage variation in replacement capacitor value!
Hi,
After reading around I have decided to go with electrolytic caps to keep to the designers brief and sound, as it seems there are issues with polys and ESR affecting the sound.
So, I am about to order replacement electrolytic capacitors and cannot make my mind up which supplier in the UK to go with
I can go for the following Alcap replacements
Alcap 5.00uF Low Loss 100VDC Electrolytic Capacitor
Capacitor Tolerance 2% (This is a black one)
Alcap 10.00uF 50VDC Electrolytic Capacitor
Capacitor Tolerance 2%
Alcap 450.00uF 50VDC Electrolytic Capacitor
Capacitor Tolerance 5%
Alcap 50.00uF High Power 100VDC Electrolytic Capacitor
Capacitor Tolerance 2%
I am paying a small surcharge to have the tolerances listed
I can recap 2 pairs of DM14s (which I have) for the same price of recapping one with the Mundorf Ecaps
The other option is to go with Mundorf Ecaps which are twice the price
(ECAP70-110) - 10uF 70V Mundorf ECap AC PLAIN electrolytic capacitor
(ECAP63-080) - 470uF 63V Mundorf ECap AC RAW electrolytic capacitor
(ECAP70-140) - 33uF 70V Mundorf ECap AC PLAIN electrolytic capacitor
(ECAP70-030) - 2.2uF 70V Mundorf ECap AC PLAIN electrolytic capacitor
(ECAP70-040) - 2.7uF 70V Mundorf ECap AC PLAIN electrolytic capacitor
Matching Charge - This is to match the pairs of caps for each speaker
Regarding replacing the grey 500uF 100v cap, the solutions I have are
The Alcaps 450uf 50v + 50uf 50v
Mundorf ECaps 470uf 63v + 33uF 70v which is to replace the 500uf 100v grey cap..
Is this OK?
Is it worth paying for the Mundorfs to be matched?
Are the Mundorfs worth twice as much as the Ecaps?
What would you recommend?
Thanks
After reading around I have decided to go with electrolytic caps to keep to the designers brief and sound, as it seems there are issues with polys and ESR affecting the sound.
So, I am about to order replacement electrolytic capacitors and cannot make my mind up which supplier in the UK to go with
I can go for the following Alcap replacements
Alcap 5.00uF Low Loss 100VDC Electrolytic Capacitor
Capacitor Tolerance 2% (This is a black one)
Alcap 10.00uF 50VDC Electrolytic Capacitor
Capacitor Tolerance 2%
Alcap 450.00uF 50VDC Electrolytic Capacitor
Capacitor Tolerance 5%
Alcap 50.00uF High Power 100VDC Electrolytic Capacitor
Capacitor Tolerance 2%
I am paying a small surcharge to have the tolerances listed
I can recap 2 pairs of DM14s (which I have) for the same price of recapping one with the Mundorf Ecaps
The other option is to go with Mundorf Ecaps which are twice the price
(ECAP70-110) - 10uF 70V Mundorf ECap AC PLAIN electrolytic capacitor
(ECAP63-080) - 470uF 63V Mundorf ECap AC RAW electrolytic capacitor
(ECAP70-140) - 33uF 70V Mundorf ECap AC PLAIN electrolytic capacitor
(ECAP70-030) - 2.2uF 70V Mundorf ECap AC PLAIN electrolytic capacitor
(ECAP70-040) - 2.7uF 70V Mundorf ECap AC PLAIN electrolytic capacitor
Matching Charge - This is to match the pairs of caps for each speaker
Regarding replacing the grey 500uF 100v cap, the solutions I have are
The Alcaps 450uf 50v + 50uf 50v
Mundorf ECaps 470uf 63v + 33uF 70v which is to replace the 500uf 100v grey cap..
Is this OK?
Is it worth paying for the Mundorfs to be matched?
Are the Mundorfs worth twice as much as the Ecaps?
What would you recommend?
Thanks
Last edited:
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