hifienthusiast
Vintage by heart
I is a Croft Series 7 power amp using a ECC83 driving Mosfet output stage.
Thank you. I do like the look of the Yew special editions. They are also Devialet SAM enabled. Interesting.
I am listening to a pair of vintage LS3/5a, All LS3/5a are all very similar. I have owned Rogers, Goodmans, Chartwell, Spendor, etc.
These little speakers really surprise me with their magic midrange. Living to simple music (not Pink Floyd I am afraid) with vocal, the sound is just beautiful.
Solid state amps don't give the best sound with LS3/5a. I am using Croft Micro 25 Basic pre amp and Series 7 power amp which I prefer to the Onix OA22 integrated amp I tried.
I have only just found this thread. I suppose my excuse is that I have been a little busy !
Thank you all for your kind comments.
I think the main difference in our LS3/5A is that after 50 years !! we have more knowledge.
As we are making smaller batches, I believe we are able to make a much more consistent product. Also having done more research into positioning and quantity of damping we were able to improve the basic transient and frequency response. As we had to buy 1 ton(ne) of Bextrene we have long time consistency of cone material.
When I left KEF they were producing 800 B110s per week and using ½ ton of Bextrene per year. The car industry was using many tons per week and when formulae changes were made we were the last ones to know The response changed !
LS3/5
The original B110 unit was 4-8 Ohm as we did not know whether the new transistor amplifiers were to be optimised for 4 or 8 Ohm loads. I remember a visit at home from Arthur Bailey showing me an amplifier board using a 1:1:1 Radiometal transformer as a phase splitter. This was to alleviate the problem of mismatched or none existent npn/pnp matched output. Transistor amplifiers in the mid 60s were a varied group. Some good, many cr*p. Arthur was doing design work for Arthur Radford. I still have the prototype printed circuit boards he left me, fully made up and working.
Anyway when it was obvious that it was to settle on 8 Ohms we redesigned the coil to be nominal 8 Ohm the B110 SP1003.
At the same time the T27 was changed to 8 Ohm.
Later the tooling for the Plastic enclosure case for the T27 was wearing and needed to be replaced. The T27 was virtually making no profit The Cresta II was at one time the best selling system, but loosing money on each one sold !
A redesign was needed. It also needed to be cheaper. I looked at my original design and as metal engineering technology had advanced, we used a naked design with the top plate being fine blanked and having semi-shears to position the diaphragm assy. The tooling for this was cheaper than that for a new plastic casing.
However the BBC had had some of our original units from the 1960s, but over time we had forgotten ?!
One day someone (I cannot remember who) came with a pair of LS3/5 systems. We listened and liked them. They sounded a bit like our Crest II systems. Upon testing them however I realised that they had the old 4-8 Ohm units.
When we told the BBC they were no amused. In particular as we said we could not even make them specially for them.
They later requested some of the new 8 Ohm versions and went away to develop the new version LS3/5A
Radfordman 1-10-14
At the time I had run out of the stock I had and the cost of Radiometal for the inductors was the main problem. The actual true cost of new FL6/23 networks
would have been very high. Hence our manufacture of No.23 and 23aB, the latter having better feedback than the proper LS3/5A version.
The cost of the production LS3/5A networks is still a large part of the system component cost. We could have used ferrite/iron dust, but that would not have been an LS3/5A.
13-8-15
Glad I was of some help. I tried to give as much help as I could and as I had a good amount of knowledge from KEF and more from Falcon where we developed system designs for ourselves and other manufacturers it made sense to use this to help Do-It-Yourselfers. I did start out as one myself !
Andrewsutton 1-12-14
I think these may have been mounted in a version of the Daline cabinet.
If I remember correctly by Bosa from Puerto Rico. I remember doing a coupled cavity version using a Focal 6 inch bass unit in a column system, but not sure if the design was ever published.
Gardening, playing in Big Bands and Orchestras and Grandchildren tend to get in the way. Then there is that chap from Oxford !!!
F456gtm 12-6-15
The Tabor used the Audax HD20 B25 H 2CP9 bass unit with the HD12-9D25.
This design was produced commercially by 4 companies. Our licensing was simple, you could build it as long as you bought the crossovers from Falcon.
There was a design using the B200 which was based on the Cadenza. May be it was this one you built. I seem to remember there were 2 versions One was the standard KEF Cadenza LF section and the other being the Audio Fair LF section. This was better, but had a lower sensitivity. This was never used in KEF production.
KEF Sales ! the bane of my life. There was always a fight between my design and what Sales thought would sell. I nearly got all I wanted in the RS104 (T27 with larger magnet Qt 0.8 +2.5dB sens and -3dB at 38kHz..to expensive )
That system did not do too badly !!!
Martyn, are you joking, can only be one person.
I worked it out as I posted.
Jerry B. will be annoyed with me for being slow
off the mark.
Jerry will understand.
We're the same age.
Malcolm, thank you for the above, you were, and still are, one of the Hi Fi greats.
His name is Henry, Inductorman.
And the grandchildren are mH
Close, but no cigar. The clue is in the following post from Radfordman:
Whilst we are on the subject of Falcon LS3/5As, a pair of which impressed me hugely at Cranage recently, anyone any idea what has happened with the price? I remember when they were first released they were £1250 for a short while (kicking myself!), then went up to £1450, I now see Doug Brady HiFi advertising them at a whopping £2195 (link)! I think I'm at the stage where I'd happily pay the £1450 for a pair as I just loved what I heard, but certainly not £2.2k!
Sorry Martyn, my original statement was:
"Malcolm, thank you for the above, you were, and still are, one of the Hi Fi greats"
Malcolm Jones.
If it's anyone else, I'll have to eat my hat.
The mention of the LS3/5 by Malcolm made me think of the new Chartwell / Graham Audio LS3/5.
I understand that model doesn't use a B110, although it looks very like one.
Perfectionists will, presumably, prefer 'the real thing' in shape of the Falcon Acoustics
LS3/5a.