advertisement


Kef KM1 in need of repair.

Great thread, we love, love love photos put up photos. If you have a mac laptop download iPic.
 
Hi Paul. I am following your project, KEF KM-1, with great interest. I almost have to introduce myself as the villain who bought mids and tweeters on ebay. If it's any consolation, I was completely dependent on them.
I had my first run through of my KM-1 today. I still have a few small errors here, but I expect that with good help from friends I will reach the finish line. I am happy to share information and extra parts with you if desired. I'll start by sharing some completely random photos of the project. The last ones are from today. Mvh Jørgen/Jorwed (I live in Oslo, Norway.)
 
"The following error occurred:
Your content can not be submitted. This is likely because your content is spam-like or contains inappropriate elements. Please change your content or try again later. If you still have problems, please contact an administrator."

Any good tip on how to post pictures? I have a shared iCloud folder I would like to link to...
 
Jorwed said:
"The following error occurred:
Your content can not be submitted. This is likely because your content is spam-like or contains inappropriate elements. Please change your content or try again later. If you still have problems, please contact an administrator."

Any good tip on how to post pictures? I have a shared iCloud folder I would like to link to...
Click to expand...

Maybe a Google-Drive link? Otherwise upload them to Imgur.com and post links here.
 
[QUOTE="Rug Doc, post: 5095142, member: 28101"So, what are you both going to use as stands for these?[/QUOTE]

There are limited possibilities in terms of commercially available products.

One early though I had was to buy a pair of something like this:

https://www.hcfcontractfurniture.co...ouble-pedestal-dining-table-base-b-5094-p.asp

and either get them to make me two in the right height, or buy them in whatever size and then cut and weld to get the speakers where they need to be.

I don't dislike the original KEF box-section stands to be honest, and they'd be easy to replicate, again at a custom height.

I can buy the box-section steel tubing for cheap, mostly pre-cut into the lengths I need and then it's an hour with my MIG welder out in the garage to make them.

One thing which musn't be overlooked is the need to keep the gap in the base for the heatsinks unobstructed:

https://coimages.sciencemuseumgroup.org.uk/images/514/775/medium_SMG00219363.jpg

Alternatively, the way I'm doing it at the moment with my current living-room speakers is two of these per loudspeaker:

https://www.av.com/Furniture/Fisual...ion&utm_source=txn-email&utm_content=ord-line

which looks tolerably OK and was fairly cheap:

https://i.imgur.com/mAKpUdq.jpg

although, in hindsight, would have looked better if I'd put them in without the 1cm gap beween each stand. Those speakers are a bit heavy to move the stands around now so they can stay as they are for the present.
 
Paul Marchant said:
[QUOTE="Rug Doc, post: 5095142, member: 28101"So, what are you both going to use as stands for these?
Click to expand...

There are limited possibilities in terms of commercially available products.

One early though I had was to buy a pair of something like this:

https://www.hcfcontractfurniture.co...ouble-pedestal-dining-table-base-b-5094-p.asp

and either get them to make me two in the right height, or buy them in whatever size and then cut and weld to get the speakers where they need to be.

I don't dislike the original KEF box-section stands to be honest, and they'd be easy to replicate, again at a custom height.

I can buy the box-section steel tubing for cheap, mostly pre-cut into the lengths I need and then it's an hour with my MIG welder out in the garage to make them.

One thing which musn't be overlooked is the need to keep the gap in the base for the heatsinks unobstructed:

https://coimages.sciencemuseumgroup.org.uk/images/514/775/medium_SMG00219363.jpg

Alternatively, the way I'm doing it at the moment with my current living-room speakers is two of these per loudspeaker:

https://www.av.com/Furniture/Fisual...ion&utm_source=txn-email&utm_content=ord-line

which looks tolerably OK and was fairly cheap:

https://i.imgur.com/mAKpUdq.jpg

although, in hindsight, would have looked better if I'd put them in without the 1cm gap beween each stand. Those speakers are a bit heavy to move the stands around now so they can stay as they are for the present.[/QUOTE]

I wonder how much the science museum want for them? :D
 
The faulty amp-pack appears to be fixed.

It was the op-amp. I've fitted a replacement and the DC offset is gone.

In due course, I'll make up a dummy test load out of big ol' wirewound resistors. I've got an Prism Dscope computerised audio test set, and I'll do frequency response curves and distortion measurements on the amp packs as a final check, but I don't expect to find anything significant wrong.

Thing still to do include bass-driver-rotating to deal with the slightly sagged one, and sourcing two B300 dust caps from somewhere to replace the missing pair, dealing with ferrofluid and fitting the four replacement B110 dust caps.

Replacement connectors for the amp packs and speaker cables should be with me tomorrow (I think) and our wireman at work is going to look out the tool to release the pins / receptacles from the old ones to swap into the replacement connector bodies.

After that, from an electronics standpoint, I'm done, and it's just paintwork and veneer to do.

Looking promising....
 
Paul Marchant said:
The faulty amp-pack appears to be fixed.

It was the op-amp. I've fitted a replacement and the DC offset is gone.

In due course, I'll make up a dummy test load out of big ol' wirewound resistors. I've got an Prism Dscope computerised audio test set, and I'll do frequency response curves and distortion measurements on the amp packs as a final check, but I don't expect to find anything significant wrong.

Thing still to do include bass-driver-rotating to deal with the slightly sagged one, and sourcing two B300 dust caps from somewhere to replace the missing pair, dealing with ferrofluid and fitting the four replacement B110 dust caps.

Replacement connectors for the amp packs and speaker cables should be with me tomorrow (I think) and our wireman at work is going to look out the tool to release the pins / receptacles from the old ones to swap into the replacement connector bodies.

After that, from an electronics standpoint, I'm done, and it's just paintwork and veneer to do.

Looking promising....
Click to expand...

Still jealous. ;) ... pleased to hear that the amps issues are resolved. :)
 
So happy that you were able to accomplish this project successfully! Please, share with us a video of these speakers are going to sound!
 
Paul Marchant said:
The faulty amp-pack appears to be fixed.

It was the op-amp. I've fitted a replacement and the DC offset is gone.

In due course, I'll make up a dummy test load out of big ol' wirewound resistors. I've got an Prism Dscope computerised audio test set, and I'll do frequency response curves and distortion measurements on the amp packs as a final check, but I don't expect to find anything significant wrong.

Thing still to do include bass-driver-rotating to deal with the slightly sagged one, and sourcing two B300 dust caps from somewhere to replace the missing pair, dealing with ferrofluid and fitting the four replacement B110 dust caps.

Replacement connectors for the amp packs and speaker cables should be with me tomorrow (I think) and our wireman at work is going to look out the tool to release the pins / receptacles from the old ones to swap into the replacement connector bodies.

After that, from an electronics standpoint, I'm done, and it's just paintwork and veneer to do.

Looking promising....
Click to expand...

Fantastic news - now get 'em done and bring them along to the Hi-Fi Wigwam Show next month - I'm sure they'll find you a room. Hell, I'll give up the room I have just to hear these beasts!
 
So, it seems that the troublesome mid-range is still slightly off-centred (although the voice-coil and cone are now one).

I've put this moment off for too long.

In order to progress with these speakers, there are only a few things left to do.

The biggest worry was disassembling the mid to centre the coil. I have received guidance and information on how to do it, what solvents, how it's originally constructed from the former KEF designer.

I've finally plucked up the courage to have a go, and... somehow... I haven't utterly destroyed it. The last thirty minutes have been somewhat stressful, but here we are:

https://imgur.com/5Jh3DoO

Now, in theory, it's easy. Get the two correct types of glue. Shim the voice coil against the magnet to get it absolutely central, glue it back together. I think that's a job for another day. I've run out of stress-tolerance for this evening.
 
You must log in or register to reply here.


advertisement


Back
Top