SpeakerTalk Forum Index SpeakerTalk
This forum has been set up to facilitate discussion of 1970s KEF speakers and drive units. The owner of the Forum has no connection with KEF Audio.
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

104ab repair - advice needed

 
Post new topic   Reply to topic    SpeakerTalk Forum Index -> KEF Speakers from the 1970s
View previous topic :: View next topic  
Author Message
pmcg
Introductory Contributor


Joined: 11 Apr 2013
Posts: 1
Location: London

PostPosted: Tue Apr 16, 2013 5:42 pm    Post subject: 104ab repair - advice needed Reply with quote

Hi, I recently came into possession of a pair of 104ab speakers, having never owned a decent set of speakers before in my life. Unfortunately not really knowing what I was doing, I pushed them too hard at my birthday party, and blew one of the tweeters, one of the bass drivers and one of the capacitors in one crossover.

I need some advice on repairing them. I've managed to find a replacement b200 sp1039 on ebay, but I'm quite poor and can't stretch to the price of an original t27 (they seem to go for at least £50 from what i've seen) - so I was wondering if anyone could advise on alternatives.

I saw this advertised as a t27 replacement on ebay but wondered if anybody here had any thoughts on how good it is?

http://www.ebay.co.uk/itm/1-Silk-soft-dome-130w-flat-response-Hi-Fi-tweeter-KEF-T27-replacement-upgrade-/321088394391?pt=UK_Sound_Vision_Speaker_Parts&hash=item4ac25c1497

Also I need to replace the capacitors, as one of the ones in the crossover has visibly exploded...i found a replacement set on falcon acoustics site but wasnt sure what the difference between ALCAP 50V low loss 5% or 2% was, and which I should choose?

http://www.falconacoustics.co.uk/kef-104ab-replacement-capacitor-set.html

Many thanks for your help!

Paul
Back to top
View user's profile Send private message
Richie
Senior Contributor 100+


Joined: 06 Nov 2010
Posts: 108
Location: Northamptonshire

PostPosted: Tue Apr 16, 2013 7:37 pm    Post subject: Reply with quote

Hi Paul, this is what I did with mine.....

I was advised to replace all the caps in the crossovers as even if they werenít leaking their values would have drifted after nearly 40 years, I did this with a kit of same value caps from Falcon Acoustics, I opted for the slightly dearer Solens (2%).

I then coated all of the inside un-damped parts of the cabinets with 2mm of floor grade epoxy resin (doesnít go brittle). I rewired them internally with silver plated OFC and added some nice gold plated binding posts.

I by-passed the contour control switch and the fuse. There is a substantial brace holding the bass/midrange (B200) speaker at the back (inside) that had shrunk, so I made some wooden shims and reinstated the brace. I also removed the lose wadding inside to make the ABR (B139) work better and it did on my concrete floors but Iím not sure this would be a good idea on wood floors.

The results were very pleasing, if you want to keep them reasonably "true" I would try and find a T27, they do occasionally go cheaper than your quote on Ebay, also try Gumtree and preloved.

Best of luck
Smile
_________________
Still learning ......
Back to top
View user's profile Send private message Send e-mail Visit poster's website
Garethwatkins
Junior Contributor 20+


Joined: 18 Nov 2011
Posts: 22
Location: Tring, UK

PostPosted: Tue Apr 16, 2013 9:04 pm    Post subject: Reply with quote

That's bad luck blowing a tweeter. it sounds like the fuse was the wrong rating (or bypassed) I assume you have checked it! Even if the unknown replacement for the t27 works well it will be different in some respect so you will have a mis-matched pair.
Back to top
View user's profile Send private message
proffski
‹ber Contributor 1000+


Joined: 22 Aug 2003
Posts: 1296
Location: Tewkesbury UK

PostPosted: Wed Apr 17, 2013 8:32 am    Post subject: Reply with quote

Bad luck with the 104aB incident, I did the same to mine in a monitoring situation back in the late 1970s! Smile

Gareth is quite correct, you will have mismatched loudspeakers so the best option is to change both if you can, I doubt if the crossover will be a proper match but better than nothing.

Also note that the machined rebated cutouts are for 108 mm diameter.
The replacements are 96.5mm... you would need to make a sub-plate mounting arrangement rather than butchering the cabinet.
T27 cutout for magnet is 84mm replacement is 71mm.
_________________
I contend that for a nation to try to tax itself into prosperity is like a
man standing in a bucket and trying to lift himself up by the handle.
-Winston Churchill
Back to top
View user's profile Send private message Send e-mail
Display posts from previous:   
Post new topic   Reply to topic    SpeakerTalk Forum Index -> KEF Speakers from the 1970s All times are GMT + 1 Hour
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group