KEF 105.4 In the House!

Kef 105/4.

I decided to pull the crossover in my 105/4's. They are serial # 3093 A&B. There is a date stamp in the base of the speaker, 16 Sept. 1983.

The results are:-

C1 240mfd 70v Alcap.
C3 240mfd 70v Alcap.
C5 20mfd + 50mfd 150v Elcap.
C6 30mfd 150v Elcap.
C7 7mfd 50v LL Alcap.
C8 50mfd 50v Alcap.
C9 12mfd 150v Alcap.
C10 3.3mfd 50v LL Alcap.
C11 4.2mfd 50v LL Alcap.
C12 4.2mfd 50v LL Alcap.

Board is SP 1129 Serial # 05498
Spending some time looking at Willem's board they are identical, except on mine C5 is 70mfd against 73mfd on Willems. Plus, apparently KEF started using Alcaps in the 105/4's
The question is should I replace the three Elcaps with Alcaps?
 

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Hello,
Did you buy the speakers new? If so, than indeed you have one of the first with alcap capacitators. Otherwise the owner before you have already replaced most of the old stuf. Remarkable i find that your xo board has nothing on the C3 and C4 bcause they used 2 higher ones on C1 and C2. Also some the resistors looking brand new. There can always be a difference in the value's of the capacitators, here a post of another forum: Kef selected the reference series caps to batches of 1% tolerance and matched drive units, inductors and caps to give a "centre response" by pairing a high inductor with a low capacitor to get the centre. So if a cap has 3.3 uF written on it, it could deliberately be 5 or 7% higher or lower than that to compensate for the rest of the circuit.
Can you place a photo of your 105.4?
Greetings.
 
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I bought them on Ebay 8/8/14, the seller bought them at a yard sale. If the original owner recapped them why would he leave the 3 Elcaps. Also the 240uf caps replacing the 2 120uf caps I would think were original. The 3 Elcaps are 150v rating and the highest rating Falcon Acoustics have is 100v in Alcaps.
I know that the 107 used Alcaps so the question is when did KEF change to Alcaps? Mine have date stamp on the inside of the cabinet of 16 Sept 83. This could be when this batch of mdf was produced. Therefor my 105.4's could be one of the last batch produced during the crossover to Alcaps.

http://www.audiokarma.org/forums/attachment.php?attachmentid=531861&d=1407524644
 
Can you post a sharp picture of the back of the crossover? Maybe you can see of c3 and c4 were earlier soldered. Treu that you have one of the last that where produced, mine are from march 1982.
And you can ask 'speakerguru' on the SpeakerTalk forum, he worked by kef and was one of the developers of the RR105 series. http://www.hifiloudspeakers.info/speakertalk/viewtopic.php?t=1585

Funny we have now 3 different crossovers on the same speaker:confused:
 
Still is, conna make a new bascabinet for the 105.4.

As you can see the new bascabinet is made with 2 seperate chambers, each B200G get it's own enclosure. This is done on advise of the man who designed this speaker for Kef more than 35 years ago. I first want to make a new cabinet as the old ones, 2 speakers in 1 enclosure. I posted this on the speakertalk forum and speakerguru (kef-designer) responded as follows: Speaking as the designer of the original 105.4, and unfettered by production considerations, I would be inclined to give each B 200 it's own enclosure, i.e. put a divider shelf in the middle of the cabinets. Each woofer would then be loaded by the identical closed box compliance. Any box resonances would be raised where they are easier to damp and may even be above the pass band of the crossover. At high levels there would be less interaction between woofers due to any unequal non-linearities. The one complication would be sealing the inter woofer wiring.


Another advantage with the new cabinet is that the speaker will be about 15 cm higher, so the listening window will be more on ear level when sitting in a chair.





 
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I made a sub for my truck and toyed with making one for home with radio shack's 18" driver until I read each driver would need a 4'x4x? some crazy number for each channel And that's where my limited understanding gets me. since both your 8" drivers are receiving the same signal wont splitting the cabinet size in 1/2 limit extension? The 105/3 uses a small enclosure for each driver to deliver flat response to 50hz but it's coupled cavity design is a whole different beast. I read a driver of a given size needs a specific size cabinet to reach desired db and I don't understand why a passive radiator wouldn't do the same thing if it wasn't so. but I work with a hammer all day so if you explain it to me type real slow:) And thanks for the lead on speakertalk I joined yesterday.
 
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With more than 1 driver in parallel - or series - covering the same frequency range, it's imperative that each get's it's own, isolated, load chamber. Reason being, not two drivers can be made identical and even closely matched, they exhibit some subtle differences in specifications, specifically (pun intended) the Q value (in other words suspension compliance) and also the dc resistance.

The 105.4 bass cabinet was "sized" to be adequate for what these two drivers needed (as a sum). Splitting the overall volume to each driver has nothing to do with load volume presented to each driver.

When both drivers fire into the same cavity, the "stronger" of the two will make the other one move in sympathy to some extent, much like a passive radiator does. This not only alters the load of the stronger driver from sealed into "somewhat ABR loaded", it alters the behavior of the weaker driver as well.
 
Thx Sasi, for your explanation.
The 105.4 has standard with the 2 B200G woofers a 40 liter volume, the new cabinets will be a bit larger, 22 liter for each woofer, so 44 liters in total.
 
i think i get it, the cabinet was sized for the volume of the drivers combined so giving them their own enclosure doesn't change the math.
 
Exactly, the parameter for the B200G sp 1075, witch is almost the same as the sp 1076 thats in the 105.4, is 20 - 25 liters in an enclosed box.
Kef took for the RR105.4, 2 x 20 liters = 40 liters.

Datasheet B200G SP1076,



 
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The new cabinets are almost finished. Of course there still lot of work to do, especially the paint which is black gloss is a patient business.




 
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They are finished! The sound is very good, bass is clean and deeper as with the standard housing. Of course i must experimate with the stuffing of the cabinets to get the ideal sound for this speaker.
And the looks are great too, looks like a smaller RR107.:thmbsp:

The result:



 
All they need now is a KEF logo and they'll be complete! Did you happen to save the labels from the 105.4 cabinets by the way? I'd want to put those onto the backs of the speakers.

They look really good, you did an excellent job on those.
 
Very sweet indeed! How do the lower frequencies sound now at lower volume? My only complaint when listening to my Kef's; they need power to sound balanced due to their bextrene cones.
 
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Yes i have saved the labels and put them already on the back. That is neccesary because every reference speaker from Kef is a little different, and is adjusted on the cross-over. Even the heads have serialnumbers witch correspondent wit the serial on the basspeakers.



And i have logo's from a set of 303's witch came very cheap, only 30 euro the set! These have the same T33A tweeter, so i have a set of spare tweeters for the RR105.4.



About the sound, i find them very fine sounding, forgiving and musical, no sharp sound at all. I had many high-end speakers, martin logan request, B&W 803 nautilus, kef XQ40, but the 105.4 is very good indeed, inspite it's age of 33 years. The sound is smooth and the imaging almost perfect. Problem with the newer type of speakers is incremental high notes, witch irritates me. And the nice bass of the 105.4 is best for my modest room. It is not the best speaker you can buy, but nowadays it's a bargain and still a high-end speaker. I think that the T33A tweeter is really a very good one, smooth, and no sharp edges. On my E405 accuphase it is with a good recording a dream!
 
influx said:
Very sweet indeed! How do the lower frequencies sound now at lower volume? My only complaint when listening to my Kef's; they need power to sound balanced due to their bextrene cones.
Click to expand...

You are right that the older Kef speakers need a bit of power to sound right. With my amp, Accuphase E405 that is not a problem. But mostly i don't play very loud. Advantage of the bextrene cones with the rubber surround is that they last a lifetime.

Here picture of the old and new design together, the mid/high head is now better on ear level when your sitting in a chair, so the stage is mutch better.

 
I,m still testing and finetuning the speakers with different kinds of damping materials. On the speakertalk forum they also advised to try 'activated carbon' as a material because kef also use this in smaller speakers with the purpose to get an stronger bass. It's the same material you use to filter an pond or swimming pool.

This i made for the lower baschambers, it is acoustical foam with latex an open celstructure. In the open holes i can put different materials to finetune the bassection.


And this is the same latex filled with baf, that did not worked fine for me, it reduced the chambers volume, with a basbump as result.


The activated carbon that is working almost 10x better as standard damping materials. http://www.kef.com/html/gb/innovation/ace/index.html and http://www.hometoys.com/content.php?post_type=1725
 
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