KEF Reference 104/2; A restoration story

[mlloyd1]

Reference1042:

What replacement model tweeters did you use? I'm having trouble finding a "recommended" replacement that fits.
Thanks,
mlloyd1

[Reference1042]

Originally Posted by mlloyd1

Reference1042:

What replacement model tweeters did you use? I'm having trouble finding a "recommended" replacement that fits.
Thanks,
mlloyd1

Sp1353

Best speaking to Kef, Thats where i got mine. They were around £130. Fits like a glove.

Hope this helps

[flemo]

I recently purchased a set of Kef 104/2 and so far I am impressed. I don't really have my front end up and running at this stage to accurately gauge how they're performing, but so far I am impressed with the bottom end and the smooth top end. Not too sure what to make of the midrange at the moment.

I am also running a set of fully restored Gale 401A's and 402's, which have very good midrange, and the Kef's appear to lack midrange weight in comparison.

I read in this thread that consideration should be given to replacing the tweeters, but I was of the understanding the original tweeters were no longer produced and were not available??

I restored the Gales at no expense and upgraded all the caps and resistors with modern hi-end equivelents. I'm now wondering if perhaps the Kef crossovers could do with some attention and particularly checking the values of the caps to make sure they're still within an acceptable tolerances.

I purchased the Kef's from a young bloke and I get the feeling he drove them quite hard with a very average amplifier.

Anyway I am looking forward to hearing them properly when I get my TT running.

Cheers, Pete.

[speaker dave]

Be aware that KEF reference series used selected parts for many components. Capacitor and Inductors would be sorted into tolerance bands and a chart would show which tolerance bands to mate with which. That way KEF could use wide tolerance parts and get tighter tolerences than the competition. Drivers were built in batches of 96 and they would be sorted into best pairs. Sometimes the driver pairs would be tied to commpensated networks.

Random replacement with "better" components isn't really wise. I would measure capacitor values, and if they seemed reasonably close to marked values then leave them alone.

David S.

[dublin78]

What sort of tolerances are you talking about?

+/- 10%, or worse?

Surely if you replaced all the caps with fine tolerances as per the schematic, then this would be fine?

[mlloyd1]

also, you will incur a considerable amount of pain trying to get to the crossover network.

mlloyd1

[dublin78]

also, you will incur a considerable amount of pain trying to get to the crossover network.

That is what made me give up!

I think that some versions were easier to get at?

[speaker dave]

Originally Posted by dublin78

What sort of tolerances are you talking about?

+/- 10%, or worse?

Surely if you replaced all the caps with fine tolerances as per the schematic, then this would be fine?

They bought +-10% but sorted them into 2 or 3% groups (if I remember correctly). Replacing the caps with values exactly as marked would be to shift them from their original vaues. Not a horrible thing but less good than leaving them at their current value.

The schematic was actually a chart saying, "use this cap tolerance band with this inductor tolerance band".

David S.

[Reference1042]

Originally Posted by flemo

I recently purchased a set of Kef 104/2 and so far I am impressed. I don't really have my front end up and running at this stage to accurately gauge how they're performing, but so far I am impressed with the bottom end and the smooth top end. Not too sure what to make of the midrange at the moment.

I read in this thread that consideration should be given to replacing the tweeters, but I was of the understanding the original tweeters were no longer produced and were not available??

I restored the Gales at no expense and upgraded all the caps and resistors with modern hi-end equivelents. I'm now wondering if perhaps the Kef crossovers could do with some attention and particularly checking the values of the caps to make sure they're still within an acceptable tolerances.

I purchased the Kef's from a young bloke and I get the feeling he drove them quite hard with a very average amplifier.

Anyway I am looking forward to hearing them properly when I get my TT running.

Cheers, Pete.

My 104/2's were a serious upgrade for me when i got them about 6 years ago. At the time i was running a nad c320bee amp, and a philips cd723. While i always was happy with them i knew that the same as yourself my front end had some serious weak links that needed attention.

6 years later, and my system is now leaps and bounds ahead of where it was when i first bought the kefs, the only change i have made to the kefs is replacing the worn out original ferro-fluid tweets. And tightening up all the fixings, especially in the bottom plates as they go very loose over time (i wondered why i could never get them to stop rocking about on the spikes or feet) . And where all the bottom end had gone...lol

As for the tweets, i would recommend using the kef sp1353 with 104/2 single wire versions sp3037. They were recommended by, and purchased from kef, and sound superb, and i think are still available if you give them a call. But it depends on whether you think they need replacing, i was missing a lot of audio till i replaced mine.

Finally the crossovers, i did consider replacing the components myself, i searched the internet for advice, and numerous times the subject came up of how anal Kef were with the components used in the crossovers for the reference series, especially the 104/2's. IMO unless there is an audible issue (as a friend has with his 104ab's), they are best left alone, or should be the final thing considered for tweaking, or modding. I thought that maybe Kef knew a thing or 2 more about crossovers than me

After getting a Dacmagic 1 a few weeks ago, and replacing the caps with audio grades and oscons, and installing lm4562 opamps, the Kefs are sounding truly astounding. The stereo image, instrument separation, and level of detail still has me sitting with mouth agasp! Its just how i imagined they should have sounded all those years ago when i bought them. Ah well....better late than never.

My advice, if you aint got one, get a DAC!!

[flemo]

Originally Posted by speaker dave

Be aware that KEF reference series used selected parts for many components. Capacitor and Inductors would be sorted into tolerance bands and a chart would show which tolerance bands to mate with which. That way KEF could use wide tolerance parts and get tighter tolerences than the competition. Drivers were built in batches of 96 and they would be sorted into best pairs. Sometimes the driver pairs would be tied to commpensated networks.

Random replacement with "better" components isn't really wise. I would measure capacitor values, and if they seemed reasonably close to marked values then leave them alone.

David S.

Hi David,

I'm a big believer if it aint broke then don't fix it!! I am concerned that the previous owner may have over-driven the speakers with an underpowered amplifier.

I would only change crossover components if they require it due to being unserviceable, or if the tolerances are not acceptable to achieve maximum performance.

I am also aware that changing for change sake, or incorrect upgrading of original components can have a significant, and often detrimental impact to the the signature sound of any speaker.

But they do have the worst binding posts - just crap!! I will upgrade them to Eichmanns for sure.

I will have the crossovers and tweeters measured to ensure they are within acceptable parameters and so I can be reassured the speakers are operating as they should be. I employ a very good hi-fi technician to do this sort of work for me, and he is quite pedantic about keeping everything original and to spec.

The caps in the crossovers for the Gale 401A's I recently restored were all way out of spec with weird values. One of the 6.0 µF caps was 9.5µF, one of the
7µF caps was over 10µF, and one which should have been 80 was 110!

Cheers, Pete.