SpeakerTalk

SaSi · Senior Contributor 200+ Joined: 24 Aug 2008 Posts: 256

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.

audiolabtower · VIP Contributor 500+ Joined: 06 Jan 2009 Posts: 686

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?

Nimo_jon · Posted: Wed Jul 11, 2018 1:20 am Post subject:

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.

speakerguru · Posted: Sat Jul 14, 2018 12:17 pm Post subject:

SaSi · Senior Contributor 200+ Joined: 24 Aug 2008 Posts: 256

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.

audiolabtower · VIP Contributor 500+ Joined: 06 Jan 2009 Posts: 686

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.

eschenborn · Posted: Thu Jan 31, 2019 10:22 am Post subject:

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.

eschenborn · Posted: Thu Jul 18, 2019 9:12 pm Post subject:

here is a slight update on my experience with the R105's. I have them in the main system now, still no recap. these are incredible speakers. they seem to get the most beauty from every piece I throw at them (spotify included).

the imaging is fantastic, the realism of the sound standing in the room breathtaking, the bass is deep and tight (who ever said that these speakers are slow must have heard them with unsuited electronics). there is so much more articulation in everything.

even stuff that sounds somehow flat on my Calindas (which are already amazing and do give an awesome plasticity and clarity) comes to life. the R105s are accurate AND forgiving, like a very wise and generous soul. will I ever need other speakers? maybe a pair of R107's, yes... and a pair of c80s. but just for curiosity.

I am driving them with an upgraded-recapped kenwood KA-6004 at the moment (kimber 4VS speaker cables). if only my neigbours would all move out and leave me alone...

thanks again for helping out! eschenborn