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Orphan bass modules and heads reunited - sort of
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T.O. Chef
Senior Contributor 100+


Joined: 31 Aug 2007
Posts: 150
Location: Toronto Canada

PostPosted: Fri Oct 23, 2009 8:43 pm    Post subject: Reply with quote

"Tests take with the capacitors in the circuits"
???
Any comments on that?
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Lee in Montreal
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Joined: 22 Aug 2009
Posts: 203

PostPosted: Fri Oct 23, 2009 11:15 pm    Post subject: Reply with quote

I am changing all caps. They are 30 years old anyway. I am just back from Solen, in fact.
I purchased all Solen caps except for the low frequency filter (C1-C4) which are Bennic. I will put the filter back to spec, and then see what happens when I jump C1-C4.

I just retested the values of my new caps and they are as such: (values in italic are measurements of the old caps, off the board)

C1-C4 (nominal 120F) - 123F - (+2,5%) - 136,3F - 139,1F - 139,7F - 142,1F
C5 (nominal 60F) - 58,8F (two 29,9 in parallel) - (-2%) - 68F
C6 (nominal 20F) - 19,6F - (-2%) - 30,1F
C7 (nominal 7F) - 6,8F - (-3%) - 8,4F
C8 (nominal 80F) - 81,5F - (+1,8%) - 93F
C9 (nominal 10F) - 9,9F - (-1%) - 14,4F
C10 + C11 (nominal 3,3F) - 3,29 to 3,31F (four units) - (+ or -0,3%) - 4,17F
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Kef Calinda - since 1979
Kef Cantata - since 2009
Kef 105/2 - since 2009
Evo 105/2 - in the build


Last edited by Lee in Montreal on Sat Oct 24, 2009 3:29 am; edited 1 time in total
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Lee in Montreal
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Joined: 22 Aug 2009
Posts: 203

PostPosted: Sat Oct 24, 2009 1:14 am    Post subject: Reply with quote

60 minutes later, from beggining to end, plus 10 minutes swapping the boards, I have brand new 105/2.

The sound, before changing caps, was muddy, vague and had absolutely no crisp. After changing the caps, everything is more precise. Curently listening to Modern Jazz Quartet, and I can feel every instrument. Now time to do the second board and listen to a new pair of speakers. After it is done, I will experirment with jumping the 4 caps at the entry and see what it does.

Edit - Just finished the second board. I installed the 4 caps in parallel but instea of cutting the mounting "rods" after welding, and used them to jump the caps and see what happens.

On the first auditon, all I can say is WOOOO HOOO. The mids are quite surprising, but so heavenly. The heads now really stand out. They sound so nice. Very impressive. Did jumping the caps at the entry make any difference? I'll tell you tomorrow as it is not obvious at all. Maybe they only work a subsonic level, even with a 6db slope, and don't affect the 50Hz area. Will report later. So far, I spent under $160 in caps and that was a good investment.
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Kef Calinda - since 1979
Kef Cantata - since 2009
Kef 105/2 - since 2009
Evo 105/2 - in the build
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lt2525
Intermediate Contributor 25+


Joined: 14 Oct 2009
Posts: 29
Location: Canada

PostPosted: Sat Oct 24, 2009 3:06 am    Post subject: Reply with quote

Lee in Montreal wrote:
I am changing all caps. The are 30 years old anyway. I am just back from Solen, in fact.
I urchased all Solen caps except for the low frequency filter (C1-C4) which are Bennic. I will put the filter back to spec, and then see what happens when I jump C1-C4.

I just retested the values of my new caps and they are as such: (values in italic are measurements of the old caps, off the board)

C1-C4 (nominal 120F) - 123F - (+2,5%) - 136,3F - 139,1F - 139,7F - 142,1F
C5 (nominal 60F) - 58,8F (two 29,9 in parallel) - (-2%) - 68F
C6 (nominal 20F) - 19,6F - (-2%) - 30,1F
C7 (nominal 7F) - 6,8F - (-3%) - 8,4F
C8 (nominal 80F) - 81,5F - (+1,8%) - 93F
C9 (nominal 10F) - 9,9F - (-1%) - 14,4F
C10 + C11 (nominal 3,3F) - 3,29 to 3,31F (four units) - (+ or -0,3%) - 4,17F


Lee - see my thread in DIY with KEF drive units - similar readings and conclusion to yours above. I will be replacing a bunch of caps also. Can you be specific in the type of caps that you purchased from Solen. I will more than likely be ordering from them.

Thank. Smile
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Lee in Montreal
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Joined: 22 Aug 2009
Posts: 203

PostPosted: Sat Oct 24, 2009 4:39 pm    Post subject: Reply with quote

I ordered the same type as TO Chef ordered. All the caps are Solen's, except for the four units in parallel which are Blue Bennic.

I haven't noticed any sonic difference between the speaker with the four caps in duty, and the one with the caps being shorted. Therefore my next set will most like disgard the caps.

In regards of filters, my two sets are not type one and type two as I thought. They have most components pf the type one, except that L6 and C12 have been shorted, while there's room for a C13, which is not used nor shorted. That second board has individual connectors to the heads with black shrink wrap on the spades.

I will use that second board for my own custom 105/2 with 91 litre cabinets and custom heads made from hard maple wood. Before I proceed with the second board, I will remove the filters from the Franken Kefs and measure components to see the filters' architecture. Actually, I will emove a filter in the next hour and take measures. It will rain all day long and what else to do on a rainy Saturday when you are not 21 anymore? Wink

BTW The guys at Solen are great knowleadgeable people, not teenagers on their first summer job.
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Kef Calinda - since 1979
Kef Cantata - since 2009
Kef 105/2 - since 2009
Evo 105/2 - in the build
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Lee in Montreal
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Joined: 22 Aug 2009
Posts: 203

PostPosted: Sun Oct 25, 2009 12:12 am    Post subject: Reply with quote

Spent more time trying to extract some bass from the 105/2. I disconnected the protection circuit. No change. Put it back. Played with the sound deadening in the box. Marginal differences. Perhaps even just some placebo effect.

On the boards, all caps were changed. Resistances were measured and very close to nominal values. What remains are the inductors/coils. I measured continuity. Fine. But can't measure their inductance. Got me thinking now that perhaps the inductors also are out of specs. Which would result in pretty weak bass.

EDIT - After swapping several sets of interconnects, with minimal impact on the sound, I then swapped the vintage Technics SE-9070 preamp to my NAD 1300. All the bass came back. The annoying abundance of upper mids has gone. Therefore, the culprit was the pre-amp. I guess that now the preamp needs a look over... The never ending quest for the ultimate sound...

Lee
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Kef Calinda - since 1979
Kef Cantata - since 2009
Kef 105/2 - since 2009
Evo 105/2 - in the build
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Lee in Montreal
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Joined: 22 Aug 2009
Posts: 203

PostPosted: Sun Oct 25, 2009 4:27 pm    Post subject: Reply with quote

Final report on this project. Superb. It is how I can describe the sound of the 105/2. I am literally in heaven. The refurbished crossovers made a huge difference. The whole spectrum is now perfectly balanced. I can now witness how current-hungry the 105 is, just looking at my 125Wpc power amp's VU meters, even at low level. Even vocals demand a lot of juice.

Positioning of the speakers make a lot of difference with imaging and bass. Let's also precise that all tone controls are defeatd and that sound is as flat as the peamp allows.
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Kef Cantata - since 2009
Kef 105/2 - since 2009
Evo 105/2 - in the build
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