SpeakerTalk Forum Index SpeakerTalk
This forum has been set up to facilitate discussion of 1970s KEF speakers and drive units. The owner of the Forum has no connection with KEF Audio.
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Two B110B drivers deteriorating at same time...audio source?
Goto page 1, 2  Next
 
Post new topic   Reply to topic    SpeakerTalk Forum Index -> DIY with KEF drive units
View previous topic :: View next topic  
Author Message
lt2525
Intermediate Contributor 25+


Joined: 14 Oct 2009
Posts: 29
Location: Canada

PostPosted: Thu Oct 15, 2009 2:27 am    Post subject: Two B110B drivers deteriorating at same time...audio source? Reply with quote

Hi,

I have had a couple of B110B SP1057 drivers powering the mid range for my Monitor Audio MA-10 speakers for close to thirty years. Both the left and right have now started to deteriorate at roughly the same time.

After 30 years of service I was starting to wonder about the type of audio being reproduced and if it might have any bearing on the recent deterioration.

For the first 27 or so years these speakers were used in a stereo setup reproducing recorded music. However for the last couple of years, I was using them largely in a home theater environment to provide the left and right parts of a 5 channel setup in conjunction with my DVD player. Would anyone care to comment on whether the digital audio from a home theater/ DVD puts more stress on these drivers, compared to plain old music?
Back to top
View user's profile Send private message
ColinR
Über Contributor 1000+


Joined: 31 Jul 2004
Posts: 1175
Location: Staffordshire

PostPosted: Thu Oct 15, 2009 4:27 pm    Post subject: Reply with quote

Probably the series electrolytic capacitors have deteriorated in your crossovers so that they are no longer blocking lower frequency content, hence greater power dissipation / cone excursion = more wear and tear.
_________________
This post or any other information supplied to this website or any other by myself is not available for any form of commercial purpose i.e. to hi-fi magazines or as sales and marketing material for sleezeBay or Audiodogging pimps and the like.
Back to top
View user's profile Send private message
lt2525
Intermediate Contributor 25+


Joined: 14 Oct 2009
Posts: 29
Location: Canada

PostPosted: Sun Oct 18, 2009 6:13 pm    Post subject: Reply with quote

ColinR wrote:
Probably the series electrolytic capacitors have deteriorated in your crossovers so that they are no longer blocking lower frequency content, hence greater power dissipation / cone excursion = more wear and tear.


Makes sense. ('Confused')

I will pull out the crossovers and see about doing a bit of maintenance before I replace the drivers.
Back to top
View user's profile Send private message
lt2525
Intermediate Contributor 25+


Joined: 14 Oct 2009
Posts: 29
Location: Canada

PostPosted: Wed Oct 21, 2009 9:40 pm    Post subject: Reply with quote

lt2525 wrote:
ColinR wrote:
Probably the series electrolytic capacitors have deteriorated in your crossovers so that they are no longer blocking lower frequency content, hence greater power dissipation / cone excursion = more wear and tear.


Makes sense. ('Confused')

I will pull out the crossovers and see about doing a bit of maintenance before I replace the drivers.


So I pulled out the crossovers to have a look at them. First impression... the PC board looks like it was made by a high school student. No component numbers, locations or anything on the board, just soldered on components.



It does say Monitor Audio on the reverse side.



Since there were no component names, I arbitrarily assigned some and then I drew up a diagram to allow me to keep track of things:


No idea of any of the coil values.



Anyway, on physical inspection, most everything looks OK except the following:
A large wattage resistor (R3) on both boards has been subject to heavy heat, causing discoloration. Impossible to tell the nominal value of the resistor from what is left.



On the right channel a smaller resistor (R5) is also starting to flake but not bad as the above. Nominal value 1R8. Left channel looks OK, however the PC board shows heat stains underneath both.

Removed the R3 resistors from both channels and measured as follows:
Right 48.5 ohms
Left 47 ohms.

Removed R 5 from both and measured:

Right 1.8 ohms
Left 1.6 ohms

So although both R3 and R5 have been subject to a lot of heat it looks like they were still functional.

Checked the remaining resistors. They all seem bang on or close to the nominal values (within 5%).

So then I checked all the capacitors and came up with following results:


----- NOMINAL ----- RIGHT --------- LEFT
C1..... 40 .............. 48.3 .............. 46.8
C2..... 40 .............. 46.6 .............. 46.9
C3..... 80 .............. 95.5 .............. 104.8
C4..... 10 .............. 11.46 ............. 9.91
C5..... 24 .............. 27 ................. 26
C6..... 10 .............. 10.59 .............. 11.12
C7..... 80 .............. 97.8 .............. 104.9
C8..... 8 .............. 8.92 ................ 8.92
C9..... 3.3 .............. 4.52 ............... 4.07
C10.... 0.5 .............. 0.7 ............... 0.37
C11.... 2.2 .............. 3.31 .............. 3.2
C12.... 8 ................ 8.52 .............. 8.23

My observation is that they all seem to be working. The actual values are higher in all cases except one (C10 left). I believe these capacitors should have a 20% tolerance. Most are within 20% except for a couple that seem to be quite far off (C9-10-11 right) (C3-7-10-11 left).

I suppose it would be normal for the value of a capacitor like these to change over time somewhat. However some of these are a fair bit off. My inclination would be to just replace the lot of them. Any recommendation as to what they should be replaced with?
Back to top
View user's profile Send private message
speakerguru
VIP Contributor 750+


Joined: 18 Nov 2005
Posts: 954
Location: Green Hut, Tovil

PostPosted: Thu Oct 22, 2009 8:36 am    Post subject: Reply with quote

Anyone who puts resistors in series with a woofer doesn't know what they are doing. Rolling Eyes Certainly not a speaker engineer. I suppose everyone has to make mistakes to learn but in the larger companies there would be someone else there to put them right.
Back to top
View user's profile Send private message
ColinR
Über Contributor 1000+


Joined: 31 Jul 2004
Posts: 1175
Location: Staffordshire

PostPosted: Thu Oct 22, 2009 9:54 am    Post subject: Reply with quote

Quote:
Anyone who puts resistors in series with a woofer doesn't know what they are doing.


A speaker company that couldn't design three-ways maybe?

You'll find the same resistive "mess" in both Monitor Audio MA1 (B139B SP1044) and MA3 (no KEF drive units) series I and II as we see in this MA10 Shocked .



Quote:
be to just replace the lot of them. Any recommendation as to what they should be replaced with?


I still think both C7s are cooked, any chance of some ESR measurements?


What capacitors can you source locally?

www.solen.ca in St Hubert have both reversible electrolytics (for parallel positions) and polyester film capacitors (for series positions), so I'd go there first before considering importing Daytons and other bits from the U.S.

Don't buy film capaciotrs >40uF, they won't fit on the PCB and you'll have to drill/ream out the locater holes.
_________________
This post or any other information supplied to this website or any other by myself is not available for any form of commercial purpose i.e. to hi-fi magazines or as sales and marketing material for sleezeBay or Audiodogging pimps and the like.
Back to top
View user's profile Send private message
lt2525
Intermediate Contributor 25+


Joined: 14 Oct 2009
Posts: 29
Location: Canada

PostPosted: Sat Oct 24, 2009 3:03 am    Post subject: Reply with quote

ColinR wrote:




Quote:
be to just replace the lot of them. Any recommendation as to what they should be replaced with?


I still think both C7s are cooked, any chance of some ESR measurements?


What capacitors can you source locally?

www.solen.ca in St Hubert have both reversible electrolytics (for parallel positions) and polyester film capacitors (for series positions), so I'd go there first before considering importing Daytons and other bits from the U.S.

Don't buy film capaciotrs >40uF, they won't fit on the PCB and you'll have to drill/ream out the locater holes.


You will have to excuse me, it's been a while since I dabbled with components like this...(I had to go look up ESR Shocked ) Now I remember what it means Very Happy
I don't really have any way to measure ESR.

However, I have come to the same conclusion as Lee in his thread regarding the 105 crossover. After 30 years it's probably time to replace the lot.

Not much of a source locally, St Hubert is a couple or 3 hours away. Probably best to order them from Solen.

I need a little clarification on the proper type. The Solen web site lists the following categories:

-Fast Capacitors 250v PA Series Metallized Polypropylene
-Fast Capacitors 400v PB Series Metallized Polypropylene
-Fast Capacitors 630v-1500v PPE, PPM & PESG Polypropylene
-Film & Foil Polypropylene Capacitors
-Metallized Teflon Capacitors
-Film & Foil Teflon Capacitors
-Polyester Capacitors

Which should I be looking at?
Back to top
View user's profile Send private message
ColinR
Über Contributor 1000+


Joined: 31 Jul 2004
Posts: 1175
Location: Staffordshire

PostPosted: Sat Oct 24, 2009 10:16 am    Post subject: Reply with quote

Stick with the 250v and 400v (150v ac & 250v ac) polypropylene, polyester (100v ac) and reversible electrolytics (63v ac) unless your into "audio ponce" badge engineered components or have Rockefeller as a surname.

"Audio ponce" is the generic name I've given to all the expensive film and foil capacitors you'll find on the Internurd.

They're mostly badge engineered Solen Canada (SCR France) or Daytons from the US.


Sound quality wise Film sound better than Polyester, which sound better than Electrolytics, probably due to the lower ESR values.


Base your component choice on the ac swing of your amplifier, series components affect the sound, parallel less so and don't spend lots of money ($CDN70~$CDN100) unless you have exceptional hearing (~$CDN150).
_________________
This post or any other information supplied to this website or any other by myself is not available for any form of commercial purpose i.e. to hi-fi magazines or as sales and marketing material for sleezeBay or Audiodogging pimps and the like.
Back to top
View user's profile Send private message
lt2525
Intermediate Contributor 25+


Joined: 14 Oct 2009
Posts: 29
Location: Canada

PostPosted: Thu Oct 29, 2009 9:03 pm    Post subject: Reply with quote

ColinR wrote:
Stick with the 250v and 400v (150v ac & 250v ac) polypropylene, polyester (100v ac) and reversible electrolytics (63v ac) unless your into "audio ponce" badge engineered components or have Rockefeller as a surname.

"Audio ponce" is the generic name I've given to all the expensive film and foil capacitors you'll find on the Internurd.

They're mostly badge engineered Solen Canada (SCR France) or Daytons from the US.


Sound quality wise Film sound better than Polyester, which sound better than Electrolytics, probably due to the lower ESR values.


Base your component choice on the ac swing of your amplifier, series components affect the sound, parallel less so and don't spend lots of money ($CDN70~$CDN100) unless you have exceptional hearing (~$CDN150).


So I was able to check the Solen catalogue and price this out. (ouch! until I priced out some other highly recommended capacitors...double and triple ouch!)
One question however. I recall from my days in electrical theory that capactitors in parallel add their value together. Referring to the sketch above I note a couple of spots where that is happening [C1 & C2, C4 & C5, C9 & C10]. Would there be any sonic effect by replacing the two in parallel with one capacitor having the combined value?
Also while we are on the subject of capacitors, I have noted some people elsewhere extolling the value of bypass capacitors. Would the learned denizens of this board have any comment on such a practice?
Back to top
View user's profile Send private message
ColinR
Über Contributor 1000+


Joined: 31 Jul 2004
Posts: 1175
Location: Staffordshire

PostPosted: Thu Oct 29, 2009 10:48 pm    Post subject: Reply with quote

Quote:
Would there be any sonic effect by replacing the two in parallel with one capacitor


No, unless the originals had a significantly large ESR.


Quote:
extolling the value of bypass capacitors


Snake Oil.

I don't know of any commercial designs by ATC, Sonus Faber, Klipsch, JBL, Yamaha, Tannoy, KEF, etc that use that particular crossover topography.

Any offers Rolling Eyes ?
_________________
This post or any other information supplied to this website or any other by myself is not available for any form of commercial purpose i.e. to hi-fi magazines or as sales and marketing material for sleezeBay or Audiodogging pimps and the like.
Back to top
View user's profile Send private message
lt2525
Intermediate Contributor 25+


Joined: 14 Oct 2009
Posts: 29
Location: Canada

PostPosted: Fri Oct 30, 2009 2:49 am    Post subject: Reply with quote

ColinR wrote:



Quote:
extolling the value of bypass capacitors


Snake Oil.

I don't know of any commercial designs by ATC, Sonus Faber, Klipsch, JBL, Yamaha, Tannoy, KEF, etc that use that particular crossover topography.

Any offers Rolling Eyes ?


OK, I was a little puzzled by some of the chatter elsewhere that seemed very enthusiastic about such a setup. I'll put this into the esoteric but ineffective category.

This reminds me of many of the "snake oil" type of audiophilia that I heard about in the late 70' and early 80's. My all time favourite was a product whose name I have long forgotten. It was simply a cube of "High quality" metal that retailed for a considerable sum. The idea was that you sat this "device?" on top of your amplifier and it would soak up stray electromagnet charges, thus somehow enhancing your audio experience. Very Happy
Back to top
View user's profile Send private message
lt2525
Intermediate Contributor 25+


Joined: 14 Oct 2009
Posts: 29
Location: Canada

PostPosted: Fri Oct 30, 2009 2:55 am    Post subject: Reply with quote

ColinR wrote:



Quote:
extolling the value of bypass capacitors


Snake Oil.

I don't know of any commercial designs by ATC, Sonus Faber, Klipsch, JBL, Yamaha, Tannoy, KEF, etc that use that particular crossover topography.

Any offers Rolling Eyes ?


OK, I was a little puzzled by some of the chatter elsewhere that seemed very enthusiastic about such a setup. I'll put this into the esoteric but ineffective category.

This reminds me of many of the "snake oil" type of audiophilia that I heard about in the late 70' and early 80's. My all time favourite was a product whose name I have long forgotten. It was simply a cube of "High quality" metal that retailed for a considerable sum. The idea was that you sat this "device?" on top of your amplifier and it would soak up stray electromagnet charges, thus somehow enhancing your audio experience. Very Happy
Back to top
View user's profile Send private message
Lee in Montreal
Senior Contributor 200+


Joined: 22 Aug 2009
Posts: 203

PostPosted: Fri Oct 30, 2009 3:12 am    Post subject: Reply with quote

lt2525 wrote:
My all time favourite was a product whose name I have long forgotten. It was simply a cube of "High quality" metal that retailed for a considerable sum. The idea was that you sat this "device?" on top of your amplifier and it would soak up stray electromagnet charges, thus somehow enhancing your audio experience. Very Happy


Now they have $1000 interconnects and speaker cables... Same scam.
_________________
Kef Calinda - since 1979
Kef Cantata - since 2009
Kef 105/2 - since 2009
Evo 105/2 - in the build
Back to top
View user's profile Send private message
audiolabtower
VIP Contributor 500+


Joined: 06 Jan 2009
Posts: 544

PostPosted: Fri Oct 30, 2009 12:59 pm    Post subject: Reply with quote

I still can't believe they put FOUR OHMS in series with the bass unit Rolling Eyes

Presumably then advised to get an amp with super low output impedance and really thick speaker cables to improve the damping factor? Laughing
Back to top
View user's profile Send private message
lt2525
Intermediate Contributor 25+


Joined: 14 Oct 2009
Posts: 29
Location: Canada

PostPosted: Sat Nov 28, 2009 11:21 pm    Post subject: Replacement drivers Reply with quote

I have contacted someone with some B110 SP1057 units that were removed from a Meridian speaker. Here are some pics






I noticed that the rear looks a bit different from the units that I have:



Can anyone comment on the difference between these?

Thanks
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    SpeakerTalk Forum Index -> DIY with KEF drive units All times are GMT + 1 Hour
Goto page 1, 2  Next
Page 1 of 2

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group