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Multi-Way Conventional loudspeakers with crossovers

B&W Speaker refurb and v missions
B&W Speaker refurb and v missions
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Old 31st August 2018, 12:19 PM   #1
Sparkymarky is offline Sparkymarky  United Kingdom
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Default B&W Speaker refurb and v missions

So, I picked up a pair of B&W Dm100i (standmount)

Pic:
B&W Speaker refurb and v missions


B&W Speaker refurb and v missions



Made in 1984 so some 34 years young.


Now i have always (some 20 years now) used a pair of mission m72 for movie and music duties. Obviously one needed to know which were better.

Put the B&W's in place of the missions (Pioneer Av Amp (170w per channel), set to Stereo only, auto eq etc and it uses a 192/24 audio dac).

Well , what a change. Music is now absolutely delightful. Warm, open, melodic and has a real *energy* about it, really gets your toes tapping. The tweeters are so open but never harsh and the mids have a great tight midbass kick. Very little colouration at all. And to think these were a budget speaker in their day.

Blew a tweeter and mid driver in a week (not over driven just gave up).

Bought a second pair locally and set about making one good pair from two.

Cabinets opened up, small bit of foam inside and crossover screwed to rear wall. Bare walls inside etc.

B&W Speaker refurb and v missions

B&W Speaker refurb and v missions


Soldered new caps in (still kept them as original electrolytic type), lined the insides with bitumen tape including the baffle side (flashband @ 10 for two self adhesive rolls) to increase strength and dampen reflections, and added glued wadding to the sides and bottom but not the baffle side.
B&W Speaker refurb and v missions

B&W Speaker refurb and v missions


Reinstalled crossover.
B&W Speaker refurb and v missions



Back on the stands
B&W Speaker refurb and v missions

B&W Speaker refurb and v missions



Fired it up. Can i hear any difference? Too early to tell but I think a little less hollow sounding with music for sure. Not that they were particularly echo'y anyway but i feel it may have also reduced the slight colouration you could hear if up close to the speaker and added a bit more depth/sharpness/l'ess live theatre/concert hall environment' to the sound.

Whilst i was waiting for the capacitors to be delivered i put the missions back in situ. Exact same amp and position. The difference was night and day. The mission sound unbelievably awful now. Night and day. Muddy, coloured, poor imaging, the list goes on. I actually had to turn music off mid way through testing and just have nothing for a few days as my eyes/ears had been opened by the B&W's.

I actually seem to prefer the B&W's without any eq etc, so playing optical out from cd player so that the amp is doing the DAC using its relatively good quality audio chip.
I should add that i have a behemoth of a sub crossed over for music with these B&W which takes care of everything from 80hz and down, but i have it subtle so as not to impose, just reinforce.

Conclusion, sealed box B&W works for me infinitely better than rear ported missions in my room, without question. A 4 year old could point at the better speakers.

I assume they may even improve as the caps bed in, but even if they do not i need no more than what they give.

Best buy in a long time, despite needing work.
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Old 31st August 2018, 06:43 PM   #2
eriksquires is offline eriksquires  United States
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What a fun project.

You know, B&W Uses Mundorf caps in the high end. In the tweet, you might want to experiment with a Mundorf MKP or Clarity CSA. They are relatively inexpensive.

Ideally if you can measure the ESR of the caps you pulled out that would be ideal, so you know how off you might be.

Best,

E
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Old 31st August 2018, 08:39 PM   #3
Sparkymarky is offline Sparkymarky  United Kingdom
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Interesting stuff Erik. I will look into the mundorfs and clarity's. I wonder if they would best served by different capacitors though? Perhaps film type?

I do not have a way of checking the esr, i did capacitance check them and they were in tolerance e.g. the 10pf cap was 10.8pf but as to esr that remins unknown.

You're right though, a fun little project and one for which gains are being reaped. Which site do you recommend for the mundorfs/clarity's?
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Old 31st August 2018, 09:18 PM   #4
eriksquires is offline eriksquires  United States
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Audiohobby.EU (check my spelling) is closest to you.

Over here I usually buy from Parts Connexion or Madisound
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Old 1st September 2018, 12:22 PM   #5
Lojzek is online now Lojzek  Croatia
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A nice looking piece of vintage loudspeaker technology especially with the touch of a red i in the logo. One could use this enclosure even beyond the life expectance of the drive units and complement it with any other brand, refurbish the grille as well, repaint or veneer it. Good find, all in all. For how much do people sell these speakers nowadays?


p.s. Mission might have suffered a fault of some kind to sound that different than B&W.
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Old 1st September 2018, 02:32 PM   #6
Salas is online now Salas  Greece
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B&W Speaker refurb and v missions
Quote:
Originally Posted by Sparkymarky View Post
Soldered new caps in (still kept them as original electrolytic type)
Quote:
Originally Posted by eriksquires View Post
What a fun project.

You know, B&W Uses Mundorf caps in the high end. In the tweet, you might want to experiment with a Mundorf MKP or Clarity CSA. They are relatively inexpensive.

Ideally if you can measure the ESR of the caps you pulled out that would be ideal, so you know how off you might be.

Best,

E
Quote:
Originally Posted by Sparkymarky View Post
Interesting stuff Erik. I will look into the mundorfs and clarity's. I wonder if they would best served by different capacitors though? Perhaps film type?

I do not have a way of checking the esr, i did capacitance check them and they were in tolerance e.g. the 10pf cap was 10.8pf but as to esr that remins unknown.

You're right though, a fun little project and one for which gains are being reaped. Which site do you recommend for the mundorfs/clarity's?
To have used electrolytics again where they originally been was wise. Crossover components ESR should be measured at 1kHz with an LCR meter and there are significant differences of parasitic resistance between plastic film and electrolytics in the audio frequencies band that can throw the original tonal balance details off. To substitute correctly with film caps it takes tracing the original electrical filter curves and a bit of manipulation to match them. The tweeter level must be kept the same first of all. Then you may enjoy the superior film capacitors resolution benefits and extremely long stable life they offer without any tonal alteration penalties.
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Old 2nd September 2018, 05:26 PM   #7
eriksquires is offline eriksquires  United States
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Quote:
Originally Posted by Lojzek View Post
ESR is to be measured in the frequency range of interest, not just at 1 kHz. I have done some research with measurements, posted here and the NPE's are better than usually perceived to be.
They are now!

The bigger issue IMHO is old electrolytics vs. new caps of any type. So it is a good idea to measure the old caps and consider adding resistors if the change is significant.

IMHO, there is less risk in series caps than parallel caps, where small changes can affect the speaker impedance significantly, and cause odd amp/speaker interactions.


Best,

E
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Last edited by eriksquires; 2nd September 2018 at 05:31 PM.
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Old 2nd September 2018, 05:50 PM   #8
Lojzek is online now Lojzek  Croatia
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Erik, Visaton and Intertechnik have been producing good NPE's for a quite some time, 2 decades easily and perhaps you remember my post where ESR at certain frequencies was calculated by myself.

@ Salas, it looks as if your measurement of a cap is grossly inaccurate. If you load it to, for example XSim, and overlay it to a similar cap, you will see it clearly.

p.s. perhaps we should apologize to OP for hijacking the thread and move all the excess posts to a new thread and talk about it in more detail there.
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Old 2nd September 2018, 05:52 PM   #9
eriksquires is offline eriksquires  United States
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Quote:
Originally Posted by Lojzek View Post
Erik, Visaton and Intertechnik have been producing good NPE's for a quite some time, 2 decades easily
And I've been involved in audio for twice that, so my opinion of what "old capacitors" means is very different from yours!

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Old 3rd September 2018, 02:49 AM   #10
Salas is online now Salas  Greece
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B&W Speaker refurb and v missions
Quote:
Originally Posted by Lojzek View Post
@ Salas, it looks as if your measurement of a cap is grossly inaccurate. If you load it to, for example XSim, and overlay it to a similar cap, you will see it clearly.

p.s. perhaps we should apologize to OP for hijacking the thread and move all the excess posts to a new thread and talk about it in more detail there.
I thought of maybe why WT2 did that. Excess posts moved, see: Finding ESR from a capacitor's impedance curves
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