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 

Amp for 105.2
Goto page 1, 2  Next
 
Post new topic   Reply to topic    SpeakerTalk Forum Index -> KEF Speakers from the 1970s
View previous topic :: View next topic  
Author Message
Dev
Junior Contributor 20+


Joined: 17 Aug 2012
Posts: 24
Location: India

PostPosted: Thu Oct 17, 2013 5:43 pm    Post subject: Amp for 105.2 Reply with quote

Hi, I have my 105.2 recapped and refurbished and pairing them with a Sansui AU-9500.

The Soundstage is fantastic but high frequencies are not reproduced as good.
Which is the ideal match for them?

I understand they were designed for solid states only.
So which amp to go for?

And originally back in late 70's & early 80's, which amp were they matched with, originally, any insight?

Gurus please guide.

Dev
Back to top
View user's profile Send private message
speakerguru
VIP Contributor 750+


Joined: 18 Nov 2005
Posts: 959
Location: Green Hut, Tovil

PostPosted: Fri Oct 18, 2013 9:05 am    Post subject: Re: Amp for 105.2 Reply with quote

Dev wrote:
I understand they were designed for solid states(sic) only.
Shocked Rolling Eyes Laughing
Your understanding is erroneous. I am at a loss to understand how you could have come to make such a statement.
Back to top
View user's profile Send private message
SaSi
Senior Contributor 200+


Joined: 24 Aug 2008
Posts: 223

PostPosted: Sat Oct 19, 2013 1:36 pm    Post subject: Reply with quote

These are not super efficient speakers of the 96dBW/1m to be effectively driven by a 10W amp.

They do need a lot of power (in the 200WRMS range) but if you have any amplifier and don't overdrive it it will do fine.

I listen to my 105.1 at moderate levels using about 1-2W of power.
Back to top
View user's profile Send private message
audiolabtower
VIP Contributor 500+


Joined: 06 Jan 2009
Posts: 544

PostPosted: Sat Oct 19, 2013 10:25 pm    Post subject: Reply with quote

They are not as efficient as modern speakers, but are a relatively easy load, so should not be difficult to drive. A solid state amp with good bass grip (damping factor) might be useful to control the B300 but this is not like saying they are totally unusable with a wide range of (or valve) amps.
Back to top
View user's profile Send private message
proffski
Über Contributor 1000+


Joined: 22 Aug 2003
Posts: 1297
Location: Tewkesbury UK

PostPosted: Sun Oct 20, 2013 1:37 pm    Post subject: Reply with quote

Back in 1974 / 1975 we happily monitored on LS35As using Leak and Lowther valve amplifiers. Even two unknown BBC made mono amplifiers.

As long as you are sensible with the volume control and know the systems limitations there should be little if any problems

Later we went onto Amcron DC150 and DC300 transistor amplifiers which did help somewhat. I still found it amazing that coming back after the weekends I quite often found that somebody had reconnected the Leak amplifiers in preference to the Amcrons... Smile
_________________
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
Thierry
Intermediate Contributor 50+


Joined: 02 Sep 2010
Posts: 72
Location: France - Outskirts of Paris

PostPosted: Sun Oct 20, 2013 4:08 pm    Post subject: Reply with quote

In my humble opinion the Quad 606 (MkI or MkII) is a very good choice.
I also used a Quad 405 and an two home made Quad hybrids using the Quad 405 boards and a swicthing mode power supply.
All of the above amps give excellent results and 140 watts per channel with the 105.2 is well enough to get a comfortable listening level on any musical program without any audible stress on the most demanding music peaks.

Thierry
_________________
http://audiolalies.blogspot.fr
Back to top
View user's profile Send private message Visit poster's website
rx7rotary
Intermediate Contributor 50+


Joined: 20 Feb 2012
Posts: 59

PostPosted: Tue Oct 22, 2013 12:49 am    Post subject: 60w Reply with quote

I have been running mine with 60w Audio Research Classic 60, without any sweat. Control of bass is fantastic, midrange and highs a brilliant.

cheers
Back to top
View user's profile Send private message
proffski
Über Contributor 1000+


Joined: 22 Aug 2003
Posts: 1297
Location: Tewkesbury UK

PostPosted: Tue Oct 22, 2013 9:09 am    Post subject: Reply with quote

Thierry wrote:
In my humble opinion the Quad 606 (MkI or MkII) is a very good choice.
I also used a Quad 405 and an two home made Quad hybrids using the Quad 405 boards and a swicthing mode power supply.
All of the above amps give excellent results and 140 watts per channel with the 105.2 is well enough to get a comfortable listening level on any musical program without any audible stress on the most demanding music peaks. Thierry


Is that a Quad 405 or 405 MKII?
_________________
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
Thierry
Intermediate Contributor 50+


Joined: 02 Sep 2010
Posts: 72
Location: France - Outskirts of Paris

PostPosted: Tue Oct 22, 2013 9:18 am    Post subject: Reply with quote

proffski wrote:
Thierry wrote:
In my humble opinion the Quad 606 (MkI or MkII) is a very good choice.
I also used a Quad 405 and an two home made Quad hybrids using the Quad 405 boards and a swicthing mode power supply.
All of the above amps give excellent results and 140 watts per channel with the 105.2 is well enough to get a comfortable listening level on any musical program without any audible stress on the most demanding music peaks. Thierry


Is that a Quad 405 or 405 MKII?


It is the first Quad 405, not the MkII.

Thierry
_________________
http://audiolalies.blogspot.fr
Back to top
View user's profile Send private message Visit poster's website
audiolabtower
VIP Contributor 500+


Joined: 06 Jan 2009
Posts: 544

PostPosted: Tue Oct 22, 2013 11:32 am    Post subject: Reply with quote

Years ago I used a 405.1 I built to the exact circuit when they first came out (bridge components matched to 0.5% with youthful enthusiasm!). The 105 is an easy load, 6 ohm minimum and not too reactive so it was a good match.

I remember the Spendor BC3 could drive it into very nasty overload (banging between the rails) before Spencer Hughes put the resistor mod in the crossover to tame the very reactive 3 ohms or so in the midrange, and Angus McKenzie's first paperback Hi-Fi Choice led Peter Walker to start the road to the surface mount pcb (no room left on main pcb) time averaged protection circuit of the 405.2.
Back to top
View user's profile Send private message
iso
Senior Contributor 200+


Joined: 29 Aug 2011
Posts: 215
Location: Finland

PostPosted: Sun Nov 24, 2013 2:16 pm    Post subject: Re: Amp for 105.2 Reply with quote

Dev wrote:
The Soundstage is fantastic but high frequencies are not reproduced as good.Dev


The problem can also be aged T52`s. After Cantata rebuild, HF reproduction of Cantatas was congested compared to modern tweeters. Kef folks explained in Kef 105 HiFi News vintage review that T52 used plastic damping ring that will harden due age... I tried 4 different T52´s and did not note too much difference.

SG may know if there is something that can be done for this.

Best Regards

Kimmo
Back to top
View user's profile Send private message
speakerguru
VIP Contributor 750+


Joined: 18 Nov 2005
Posts: 959
Location: Green Hut, Tovil

PostPosted: Sun Nov 24, 2013 11:28 pm    Post subject: Reply with quote

I worked on T52s quite a bit when developing the KM1 version. The damping ring was an over-plasticised PVC like you get on car tax disc holders (UK). It sticks to glass OK in summer and stays on, if you're lucky, for the year.
In the case of the T52 it was stuck to the diaphragm surround using a flexible hot melt adhesive. The diaphragm surround had to be sand blasted first to get a matt adhesive friendly finish and even then it was difficult to prevent or get air bubbles out. With time things tend to recover and the air bubbles may come back and the damping action could be lost.
Back to top
View user's profile Send private message
Thierry
Intermediate Contributor 50+


Joined: 02 Sep 2010
Posts: 72
Location: France - Outskirts of Paris

PostPosted: Mon Nov 25, 2013 1:46 pm    Post subject: Reply with quote

speakerguru wrote:
I worked on T52s quite a bit when developing the KM1 version.


The KM1 is one of the best loudspeaker system (if not the best) I have ever listened to in my life and the closest thing to real life music performance. Shame I couldn't afford the KM1 by then. Today I wonder how many of them are still in use, I wish I were one of their lucky owners. Congratulation for having worked on this incredible system, definitely a credit to KEF engineers, probably still unequaled today.


speakerguru wrote:
The damping ring was an over-plasticised PVC like you get on car tax disc holders (UK). It sticks to glass OK in summer and stays on, if you're lucky, for the year.
In the case of the T52 it was stuck to the diaphragm surround using a flexible hot melt adhesive. The diaphragm surround had to be sand blasted first to get a matt adhesive friendly finish and even then it was difficult to prevent or get air bubbles out. With time things tend to recover and the air bubbles may come back and the damping action could be lost.


Very interesting reading, this is exactly what makes this place unique, as far as I know there is no other forum where "the ones who really know" give us such light with an insider perspective on our beloved gear genesis. Thanks for this.

Back to the T52 : unless I am completely wrong, what you describe would rather result in an excess of brilliance than a dull sound, wouldn't it ?
Thierry
_________________
http://audiolalies.blogspot.fr
Back to top
View user's profile Send private message Visit poster's website
iso
Senior Contributor 200+


Joined: 29 Aug 2011
Posts: 215
Location: Finland

PostPosted: Mon Nov 25, 2013 6:07 pm    Post subject: Reply with quote

Thierry wrote:
Very interesting reading, this is exactly what makes this place unique, as far as I know there is no other forum where "the ones who really know" give us such light with an insider perspective on our beloved gear genesis.Thierry


Designer or someone in the design team will most likely know shortcommings of product most toroughly.

Schematics and pictures are good starting point if our aim is 100% concours restoration... even if we like to make things work as well as possible, without being 100% original.

I refurbished H/K Citation 11 from mid 70´s earlier this year. There were 5 or 6 incorrectly made groundings in wiring loom, muting relay was in series to signal. Performance of preamplifier improved considerably, when I sorted incorrect groundings and wired muting relay between ground and output. Citation 11 is most likely performing better now than when it was new... I do not feel quilty for this, even some wires in the loom are now connected slightly differently.

But anyway... it took 3-4 weeks sort this all out, even I had correct service manual. But as there was no information about physical lay out of preamp. I had to draw grounding idea from amp by using DVM. Even then some wires needed to be disconncted, before I coud be shure where the other end of wire was.

With some inside information this could have been easier. It is great to have SG here...

Best Regards

Kimmo
Back to top
View user's profile Send private message
proffski
Über Contributor 1000+


Joined: 22 Aug 2003
Posts: 1297
Location: Tewkesbury UK

PostPosted: Mon Nov 25, 2013 6:27 pm    Post subject: Reply with quote

[quote="iso"]
Thierry wrote:

With some inside information this could have been easier. It is great to have SG here...


Seconded without a moments hesitation! Smile
_________________
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
Goto page 1, 2  Next
Page 1 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