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 

105.2 clone with T33 tweeters?
Goto page Previous  1, 2
 
Post new topic   Reply to topic    SpeakerTalk Forum Index -> DIY with KEF drive units
View previous topic :: View next topic  
Author Message
SaSi
Senior Contributor 200+


Joined: 24 Aug 2008
Posts: 236

PostPosted: Tue Jul 10, 2018 9:33 pm    Post subject: Reply with quote

Intrigued to read you are adding ferrofluid to the T27. It was not designed to use ferrofluid. The addition may spoil the sound or may tame it a bit, as many complain it's rather bright.

For the 105.2 KEF have published (I suppose) the schematics for an active crossover so that would be my first and only choice to turn them into active. As for amplifier, a single LM3886 would not have enough juice to drive the B300. There are bridged versions available but when it comes to bridging the chipamp, the tolerances of the various components, especially the current limiting resistors at the output, become very critical and I would not trust an un-named chinese PCB for that.
Back to top
View user's profile Send private message
audiolabtower
VIP Contributor 500+


Joined: 06 Jan 2009
Posts: 588

PostPosted: Tue Jul 10, 2018 10:12 pm    Post subject: Reply with quote

I investigated that active crossover and got in touch with Laurie Fincham at THX and Siegfried Linkwitz who did the Wireless World active design with his 4th order crossovers and neither could remember anything about an active 105 circuit, so it is probable that circuit did not originate from Kef... unless Speakerguru knows otherwise?
Back to top
View user's profile Send private message
Nimo_jon
Intermediate Contributor 25+


Joined: 21 Feb 2011
Posts: 48
Location: Singapore

PostPosted: Wed Jul 11, 2018 1:20 am    Post subject: Reply with quote

Yes, the ferrofluid is meant for the T33 I am fixing, not for the T27.

The B300 is to be replaced by the Peerless 12in. I am driving it with a 200W class D amp.

SaSi wrote:
Intrigued to read you are adding ferrofluid to the T27. It was not designed to use ferrofluid. The addition may spoil the sound or may tame it a bit, as many complain it's rather bright.

For the 105.2 KEF have published (I suppose) the schematics for an active crossover so that would be my first and only choice to turn them into active. As for amplifier, a single LM3886 would not have enough juice to drive the B300. There are bridged versions available but when it comes to bridging the chipamp, the tolerances of the various components, especially the current limiting resistors at the output, become very critical and I would not trust an un-named chinese PCB for that.
Back to top
View user's profile Send private message
speakerguru
Über Contributor 1000+


Joined: 18 Nov 2005
Posts: 1011
Location: Green Hut, Tovil

PostPosted: Sat Jul 14, 2018 12:17 pm    Post subject: Reply with quote

audiolabtower wrote:
I investigated that active crossover and got in touch with Laurie Fincham at THX and Siegfried Linkwitz who did the Wireless World active design with his 4th order crossovers and neither could remember anything about an active 105 circuit, so it is probable that circuit did not originate from Kef... unless Speakerguru knows otherwise?


No. I heard rumours too, while I was at KEF, but I've never seen an active 105 design, official or unofficial ever.
Back to top
View user's profile Send private message
SaSi
Senior Contributor 200+


Joined: 24 Aug 2008
Posts: 236

PostPosted: Mon Jul 16, 2018 6:46 pm    Post subject: Reply with quote

I have a circuit diagram of an active xo for the R105.2 and also a graph of the frequency response printed on KEF "stationary" naming circuit EE28/A/1 issue 2 with a date of 6.1.82 and signed by "EC".

The actual active xo circuit isn't drawn on KEF "stationary" - just a drawing.
Back to top
View user's profile Send private message
audiolabtower
VIP Contributor 500+


Joined: 06 Jan 2009
Posts: 588

PostPosted: Mon Jul 16, 2018 9:13 pm    Post subject: Reply with quote

That is the one Fincham or Linkwitz has no knowledge of, thus not a Kef design and most probably sent in by an owner or third party.
Back to top
View user's profile Send private message
eschenborn
Introductory Contributor


Joined: 25 Feb 2018
Posts: 7
Location: Berlin, DE

PostPosted: Thu Jan 31, 2019 10:22 am    Post subject: Reply with quote

Hi all fellow KEF fans,

I am owing you an updated to my quest for a 105.2 clone with the right mid and bass drivers but with T33's instead.

I actually had no time to start building the enclosures, and I also ran into troubles regarding how to implement the various crossover modules from the B110 plus T33 (105.4) and B300B (105.2). this seems to would have worked smoothly only if the 105.2 and .4 had the same lower crossover point, but I am not sure if they do.

in the end I bought a pair of 105.1 that came up locally. I waited a bit as they were not that cheap, but then convinced myself that even the wood and the crossover parts (particularly good inductors) would be rather expensive. so I jumped.

the speakers are in good shape, with grilles. I rotated one woofer as it rubbed. I will recap the speakers soon-ish, caps from falcon have already arrived.

the 105.1 in as-is state seem flatter than my calindas, the low end is stronger in the 105.1, but – what words to use – somehow "harder". those models really sound different. I'll see what happens after the recap.

the soundstage in the 105.1 is really impressive (you turn your head for sounds seemingly to come from somewhere in the house). I replaced the remainders of the foam on top of the woofer cabinets with a thin layer of acoustic foam with that pyramid-shaped surface structures.

thanks a lot for the help I received here when I first posted my request. I will come back when I get stuck again! and good luck to all who are building right now.
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    SpeakerTalk Forum Index -> DIY with KEF drive units All times are GMT + 1 Hour
Goto page Previous  1, 2
Page 2 of 2

 
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