Kef reference 107/2 recap

[Macca]

Unstable operating system.

[fatmarley]

Makes you wonder how many speakers out there have been recapped and sound worse for it.

[andyrlb]

Makes you wonder how many speakers out there have been recapped and sound worse for it.

Yes that’s what I thought, hopefully it just applies to the old Kef reference models , I’m still tempted to try one with new caps in it.


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[Lawrence001]

I was wondering if they've already been recapped by a previous owner hence your findings, but it's hard to get a definitive image of the original boards online, they might have been recapped before selling.

Incidentally, I found this video a wife made of her husband restoring their 104/2s. She says she really enjoyed the learning experience of soldering the second board herself. I must have word with my wife...

https://youtu.be/uAMvCsyZFaY

[andyrlb]

I was wondering if they've already been recapped by a previous owner hence your findings, but it's hard to get a definitive image of the original boards online, they might have been recapped before selling.

Incidentally, I found this video a wife made of her husband restoring their 104/2s. She says she really enjoyed the learning experience of soldering the second board herself. I must have word with my wife...

https://youtu.be/uAMvCsyZFaY

All the caps are original Kef marked caps and I can tell that all solder is original. My information came from an ex Kef engineer , it is a pain though that he has advised to not take notice of the marked values as it’s now impossible to know their original values albeit -/+ 2 % . Getting 2% caps now isn’t easy .


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[Beobloke]

Makes you wonder how many speakers out there have been recapped and sound worse for it.

As a former loudspeaker designer, it makes me wonder if this might make some forum "experts" (not AoS of course!) finally realise that most speaker designers aren't just charlatans who use any old shite components they have lying around in order to maximise profits...

[andyrlb]

As a former loudspeaker designer, it makes me wonder if this might make some forum "experts" (not AoS of course!) finally realise that most speaker designers aren't just charlatans who use any old shite components they have lying around in order to maximise profits...

I’ve no doubt that it happens and will continue to do so , it’ll probably get worse too !


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[sailor]

Hi Andrew, there is merit in replacing caps that are, in your case about 25 to 30 years old, with modern ones even if the original are still within spec. New caps do sound better and today there are lot more to choose from.

Consider that most speakers are built to a price point to be competitive in the market so understandably lower cost options are used. Perhaps 2000 pairs of a certain speaker are to be built and it uses 6 caps/pair at a cost of 6 pounds. To upgrade to some that cost say 40 pounds means an outlay of an extra 68000 pounds! Will probably not go down well with the accountant.

Try replacing just the caps in the tweeter circuit and while you're at it the attenuating resistors as well. The white sand cast jobs are nasty and replacing these with Mills will contribute to the improvement. I mention the tweeter because it usually has the lower value caps in circuit and therefore cheaper as an experiment.

You also get to slightly adjust the result regarding choice of cap. A Mundorf EVO in Oil is great value. It has a very slight tilt up in the extreme high frequency, or a neutral and smooth Clarity Cap CSA. I found the CSA to nicely reduce some sibilance while still remaining detailed. I mention Mundorf and Clarity Cap because I know them well but there are dozens to select from.

As you are only upgrading the tweeters on one pair of speakers it will not hurt your piggy bank too much and you will then hear for yourself what all the fuss is about.

https://www.hificollective.co.uk/catalog/-c-61_68_what all the fuss is abou429.html

[andyrlb]

Hi Andrew, there is merit in replacing caps that are, in your case about 25 to 30 years old, with modern ones even if the original are still within spec. New caps do sound better and today there are lot more to choose from.

Consider that most speakers are built to a price point to be competitive in the market so understandably lower cost options are used. Perhaps 2000 pairs of a certain speaker are to be built and it uses 6 caps/pair at a cost of 6 pounds. To upgrade to some that cost say 40 pounds means an outlay of an extra 68000 pounds! Will probably not go down well with the accountant.

Try replacing just the caps in the tweeter circuit and while you're at it the attenuating resistors as well. The white sand cast jobs are nasty and replacing these with Mills will contribute to the improvement. I mention the tweeter because it usually has the lower value caps in circuit and therefore cheaper as an experiment.

You also get to slightly adjust the result regarding choice of cap. A Mundorf EVO in Oil is great value. It has a very slight tilt up in the extreme high frequency, or a neutral and smooth Clarity Cap CSA. I found the CSA to nicely reduce some sibilance while still remaining detailed. I mention Mundorf and Clarity Cap because I know them well but there are dozens to select from.

As you are only upgrading the tweeters on one pair of speakers it will not hurt your piggy bank too much and you will then hear for yourself what all the fuss is about.

https://www.hificollective.co.uk/catalog/-c-61_68_what all the fuss is abou429.html

Thanks Charles , funny enough I spoke to Nick at Hifi collective and he too said to change the white ceramic components .

Cheers


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[Beobloke]

Personally, the resistors are the last things I would change.

If you really do have the urge to fiddle, then I agree that the component to experiment with are the capacitors in the tweeter circuit. These are directly in the signal path and so are likely to have a bigger effect than those in the midrange or bass circuits.

If it was me, though, I’d still leave them alone and enjoy them.