SpeakerTalk

[iso]

Kef 105.2 story in Hifi News is worth to look. Keith Howard seems to be quite objective and informative.

There is one thing that interests me in review. In lab report it seems that 105:s does´t meet factory specs anymore. As far as I remember Kef specs in 70´s and 80´s were very accurate, only slight variations were noted, but this was mostly due different ways reviewers made their own measurements.

Pair matching of this vintage unit seems to be only little worse than original factor specs, this can be due dried caps even review sample was from Kef´s museum. However it was odd to note that T52 response had rise of 7-8 dB from 8K to 15K, response fell after this quite rapidly.

Laurie Fincham suggested that this rise of treble may be due PVC damping ring hardening due age. Is it possible that there are other causes for this peak in response. I haven´t noted any rise of hf energy in my Cantatas, even I have tried 2 separate sets of T52:s from 1978 and 1979.

It is possible that T52 mounting in pod will result different directivity than conventional cab mounting. At 8+ Khz it should not make too much difference. Anyway, 7-8 dB peak in hf response should be clearly audible....

If anybody has experienced similar issues wiht T52 it would be interesting to know about it. Anyway Hifi News vintage review is worth to look.

Best Regards,

[audiolabtower]

Which issue is it please? I can't see Kef 105 in the online reports download.

[iso]

Vintage review is in the March 2012 issue.

Best Regards

[audiolabtower]

cheers, thank you

[audiolabtower]

Having read the review I see it is by Keith Howard and he mentions how Kef were so unimpressed with the quality of Haymarket "rags" reviews of the original 105 they stopped advertising with them for months in protest. Was not this the same Keith Howard the editor or deputy editor of one of those rags in those days - Hi Fi Answers? Maybe this explains his less than enthusiastic (can't play loud) piece now?

[iso]

I did not think that this vintage review was not too negative. Bass articulation was not considered too good, also can´t play loud issue, you mentioned, was mentioned. However this is true if we compare 105:s to say ATC100 or 15" Tannoys. In reality 105:s are louder than Cantatas and volume has never been issue to me with Cantatas, I have also ATC:s and 12" Tannoys. So volume issue is true only if you have living room 15m x 12 m full of rugs and soft furniture... and want to play rock concert volumes.

Rating of 75% is also pretty good for 105.2:s from Kef Museum. New Audio Research FER150 got 88% from all time ARC fan KK, new Acoustic Energy REF2 got 70% and so on.

If 105:s are delivered from Kef Museum, they are probably quite original, castors were not used as mentioned. They have most likely been overhauled, but not upgraded. If this is true, they are wired with similar bell wire that everybody used these days, There are several connectors that are at least 25 years old, and quite difficult to clean properly from oxidazion.

In my Cantata project, I noticed that these issues that were considered unimportant in 70:s are important now. Our CD players, cartridges, tonearms and preamplifiers are usually better than in 70-80´s. It is funny to note how well old Garrards, Thorens and EMT idler drive turntables are doing today.

My point is, if we sort out bugs like wiring, fuses, connectors and other similar issues that were not considered worth trouble in 70:s, performance of good vintage speakers will improve considerably. Kef:s since 70:s seems to be easy to update, as they were so advanced in crossover and drive unit designs. Also components like switches seems to be easy to clean compared to say switches that Tannoy used in their SRM series speakers.

My next project is JBL based, they are not so easy to improve even there is room for improvement and their drive units were probably best you can buy. Typical 70:s JBL crossover is 3uf and 8 uf caps and 2 L-pads... so complete crossover redesign is needed, if you like to use the speakers.

Best Regards,

[Thierry]

As a daily user of 105.2s I find this topic quite interesting.

In my opinion, when hooked to adequate amplification and source the KEF 105.2s stand amongst the best loudspeakers ever designed and still outperfom so-called "high end" systems on many aspects. Of course there are some limitations - essentially down to drivers characteristics - but still, they do their job magnificently.

For those who don't want to buy the March 2012 HiFi News issue you can download it for free from here http://www.heroturko.me/magazine/man-woman/2226436-download-hi-fi-news-uk-march-2012-hq-pdf-free.html (111 megabytes) as far as you can stand the irritating ads and links toward porn sites


By the way I wonder how HFN did measure frequency response as I did this measurement myself and did not find such irregularities.

Left and right speakers in-room frequency response. Scale has been deliberately expanded and no line smoothing has been applied (1/12th oct. scale). Peaks and canyons below 200Hz are down to the room interaction. Average SPL during measurement was 93dB :





Now have a look at HFN's Lab Report "measurement" - note the total lack of information about testing setup and conditions of measurement :

[iso]

I find this also interesting.

I used to buy new equipment from 70´s to 90´s. Then lost my interest in audio for 15 years, shortly after writing reviews in local High End Publication Musiikin Ääni for cuple of years in early 90´s. Now I have bought DIY and old hifi stuff from 2009 and enjoyed it.

Old days I mostly listened music, but now I have to get information about equipment and most often repair or tweek equipment before getting it performing as desired. I have lately felt that getting info and tweek part is more important than listening music part of hobby. I find it to be simply boring to just buy hifi and listen music.

As my income is about average, even good quality hifi equipment is so expensive as new, that it would be economically impossible to buy say 2 power amps 1 pair of speakers and 1 CD player in 1 year. Most expensive unit I have now purchased has been Conrad Johnson Premier 7B which cost 2200GBP last year, it was 9000GBP amp in 1990 in 90´s money... no wonder that only about 200 units were made 1988-1994 and absolutely no way I have been able to buy it in 90´s. It is still pretty decent amp, event there are things that could have been done better way even in 90´s.

Same was true for Cantatas. When I wanted to buy these in 70´s I did´t have enough money for these. Last year I got bad cabs but decent drive unit and crossovers for about 260E, roughly similar sum was spent for cabs and other stuff... and it took roughly 6 months to finalize project it was fun all the time.

I feel also that Cantatas are pretty decent speakers now... ATC:s have maybe more grunt and Tannoys are fine with QUAD II/22/FM1 set. But now it feels that I like Cantatas most... maybe this is as they are last in line... or maybe they are best overall... It is pretty impossible to be objective on these things.

Best Regards

[iso]

I forgot to mention that there is one thing that has bothered me recently on this vintage hifi hobby. It is weight of equipment.

There is room for couple of spare amps in the basement, but putting amp weighting 30 kg in rack is not fun. You can find room for extra speakers in the basement... but when you bring 35 kg Cantatas or 60kg ATC:s in basement via narrow stairs, this is not definitely any fun.

Best Regards,

[audiolabtower]

[iso]

Have you had these 105.1:s since new? If so... they have been good investment, since you have used them long time.

I have also admired these since last summer... but if they had been slightly smaller and more conventional, I might have got also pair of these. I have bad feeling that I will find nice pair sometime and can not refuse offer for these.

But anyway, I have couple of issues which are not clear to me.

1. I have understood that late production MK1 use same crossover that is used on early production MK2... but for some reason I have had idea that MK1 did not use series caps to modify closed box alignment. So has LF tuning changed during MK1 production run or is my information incorrect?

2. I have seen some documentation, I believe it was from Kef, that LF enclosure was redesigned for MK2 such a way that braces and bitumen damping was not needed anymore. But some pics about MK2 show that there are at least 2 vertical braces but no bitumen pads. So... has design changed during MK2:s production run and how MK1 LF enclosure was made and damped.

As you have used 105 for very long time, you can probably give honest opinion about which one of two types is best for fine tuning.

Best Regards

[audiolabtower]

Hi, yes the 105s have been the best buy I ever made, having looked a very long time for my Spendor BC1s absolutely magic midrange and holographic stereo presentation but with more output power and deeper bass, and being unable to accommodate electrostatics.

The Mk1s always had a series cap to realign the bass. Mine have 360uF which I replaced with polyester matched to 0.25% Mk2s had 450uF or 480uF depending on dates.

The enclosure changed considerably between Mk1 and 2. Mk2 had the plastic head assembly with damping cavity but more importantly the resilient mounting on the bass unit (rubber grommets) which reduces reaction forces transmitted into the baffle. I suspect this is why the damping pads were left out - at least in the pictures I have also seen, because not so much energy went into the panels of the box.

Mk1 was different with solid B300 mounting but the baffle section had a kind of double wall construction as the sides mated with the rest of the cabinet along the sloped sections. The square bottom also had more breakup of the panel sizes compared with the one piece Mk2 front. Importantly the B300 flat baffle was screwed to the rest of the box, a system that the BBC used as a measure to reduce resonance transmission to the rest of the enclosure, as well as the BBC bitumen pad trick.

Reviews of the time tended to think that the Mk2 had lower colouration but not as "quick" a bass as the Mk1. I think both are superb in good condition and would be happy with either.

[iso]

I suppose stiff vs. damped mounting of B300 has similar effects if we compare rigid braced box made say 25 mm birch plywood from Finland, yes it was originally made here, to classic BBC 9 mm birch plywood box damped with bitumen pads.

Rigid box has more high Q resonances over say 200-400 hz limit but less in lower range. BBC style box has less high Q output over 200-400 Hz and therefore is audibly cleaner. However downside is that BBC style construction loose accuracy in lower range as stiff box is quieter in lower range.

As you said detachable baffle was used to reduce Q of resonances in MK1. It was probably reasoned that if B300 can be mounted with rubber seal and mounting screws can screwed to rubber bushes, this has similar effect that detachable baffle had on MK1 and simpler LF enclosure can be made for MK2.

It must be something like that what cause of differences of LF performance. If there was any...

Best Regards

[audiolabtower]

Ah... Finnish birch ply, the BBC tested many woods in the 60s and that was the best for their purposes of low colouration

[iso]

Unfortunately at least some of our forest companies are making it in Estonia and maybe other baltic countries nowadays. But I ques most of it is still made in Finland.

My good friend Nuuska told me story about plywood. When he was working in USA in 80´s, he had told some other employees how birch plywood was made here in Finland. They did show Nuuska some US made plywood and refused to believe that such thing that Nuuska had described simply can not exist.

Best Regards