j-p, Falcon have nothing to do with those connectors, that choice was down to KEF. And the caps are "physically" compatible, which I think would be important in Eric's case
To recreate the original sound of the Concertos on the day that Eric bought them, it is no bad idea to replace electrolytics with electrolytics.
In my previous post, I hinted at the possibility of improving that sound using different capacitor types and values.
My priority, initially, is to keep things straightforward for Eric. 🙂
Side step: Do you mean you have heard that there are issues with the Falcon replacement T27 tweeters?
Hi of course I meant KEF but OK. No, this stuff is very very old and I repaired them in the past but I recall the original T27 to break down very fast. I replaced quite a few of them then. Also replaced defective B139 and rebuilding filters with film caps. Therefore I recall taming the tweeter with a metal film 47 Ohm. Since it is so long ago I apparently deleted most from memory. I also wouldn't even accept such old stuff anymore, I recently refused Calinda's.
Yeah I get what you mean but I would do it once and then as good as possible with parts that last so no electrolytic caps. Cheaper and less work than doing it twice. Either method is fine, keeping the originals is the worst idea.
Yeah I get what you mean but I would do it once and then as good as possible with parts that last so no electrolytic caps. Cheaper and less work than doing it twice. Either method is fine, keeping the originals is the worst idea.
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Eric, this one seems to fit:
https://www.mouser.de/ProductDetail...EpiMZZMvPvGwLNS671wFuW9I0%2BPvoFWlgiXJ%2B0t4=
https://www.mouser.de/ProductDetail...EpiMZZMvPvGwLNS671wFuW9I0%2BPvoFWlgiXJ%2B0t4=
This is why it has taken me so long (weeks) to come up with my improved version of the Xover (see post #59). I had to understand that it was 1) impossible to improve the Xover by simply swapping in the same values in polypropylene nor by substituting mid quality electrolytes with high quality (low loss) ones (way off balance), and 2) it did not work to simply attenuate a bit somewhere with single components thrown in (also way off balance).
If the original DN12 Xover just needs to be restored, I'd only recommend Falcon, as they are selling caps very similar to the original Alcaps. But even after restoring it in this manner, I found that it was not the best Xover ever designed by KEF. The speakers lacked, particularly in comparison to (fully restored) the Ref 105. There is a reason that there exist so many variations for this crossover. So I started to experiment.
My conclusion is that a) replace electrolytes by electrolytes in old British speaker designs, b) improve by carefully testing where a better quality electrolytic helps (and where it makes things worse), c) try parallel resistors, d) implement the aB circuit 8and use olys only there).
I like the T27 and I did not find it particularly prone to self-destruction. It needs to be steeply cut off, though. The problems in the Concerto design are further down the frequency spectrum. The aB network has effects cascading down the frequency band. Somebody took measurements in a thread here, when he modded his KEF 104's to 104aB, I believe.
Lack in Concerto sound quality also has to do with not steep enough slopes for separating the mids. The B110 is sweet, but needs to be kept in check so to speak. Look at what KEF did in subsequent three-way designs (Cantata, C7) or in the Ls3/5a. This needs to be somewhat added.
I came up with a network which to my ears made the Concerto a serious competitor to the 105, with some areas even subjectively better (more "warmth"). But I never measured it (no devices for this at all).
Concerning replacing electrolytic caps with polypropylene there are also some interesting posts from @alan-1-b in this forum.
If the original DN12 Xover just needs to be restored, I'd only recommend Falcon, as they are selling caps very similar to the original Alcaps. But even after restoring it in this manner, I found that it was not the best Xover ever designed by KEF. The speakers lacked, particularly in comparison to (fully restored) the Ref 105. There is a reason that there exist so many variations for this crossover. So I started to experiment.
My conclusion is that a) replace electrolytes by electrolytes in old British speaker designs, b) improve by carefully testing where a better quality electrolytic helps (and where it makes things worse), c) try parallel resistors, d) implement the aB circuit 8and use olys only there).
I like the T27 and I did not find it particularly prone to self-destruction. It needs to be steeply cut off, though. The problems in the Concerto design are further down the frequency spectrum. The aB network has effects cascading down the frequency band. Somebody took measurements in a thread here, when he modded his KEF 104's to 104aB, I believe.
Lack in Concerto sound quality also has to do with not steep enough slopes for separating the mids. The B110 is sweet, but needs to be kept in check so to speak. Look at what KEF did in subsequent three-way designs (Cantata, C7) or in the Ls3/5a. This needs to be somewhat added.
I came up with a network which to my ears made the Concerto a serious competitor to the 105, with some areas even subjectively better (more "warmth"). But I never measured it (no devices for this at all).
Concerning replacing electrolytic caps with polypropylene there are also some interesting posts from @alan-1-b in this forum.
If your recollection is typical, jean-paul, the bean counters at Falcon Acoustics must be rubbing their hands in glee! 😀
The importer in the Netherlands often did not have them in stock as they were often replaced. Some KEF owners had spare T27 at home! We did not need, for instance, spare Focal T120K except when kids pulled the wires. The fact that Falcon produces replacement tweeters adds to the matter. I never have had to replace an Elac JET tweeter…… I just checked if my menory works OK, please search for “T27 defective” with duckduckgo or the like.
Now I think of it, there was a guy that burned T27 when pushing the loudness button.
The bean counters are already happy I think. 169 UK pound is a lot of money.
Now I think of it, there was a guy that burned T27 when pushing the loudness button.
The bean counters are already happy I think. 169 UK pound is a lot of money.
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New electrolytics are likely to last Eric till he's 92 - and hopefully way beyond! 🙂
All joking aside, I agree with you! That's what I would do. I'm simply offering a simpler restoration path to Eric.
No party pooper but ... I think I want to forget about old KEF stuff as they were qualitative like an Austin Allegro.
Also had my share with B&W and those foam cone rings.... It may be a blessing that these have their stuff made in China 🙂
Also had my share with B&W and those foam cone rings.... It may be a blessing that these have their stuff made in China 🙂
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Now we're talking corrosion! 😱
Attachments
Then Im afraid , one of my woofs is done...
Indeed I feel a litle scraping , and also I sometimes hear a scraping noise... when playing (pretty hard) the songs 'Pavement cracks' and 'Pale' from Annie Lennox...
I have a Pioneer Amplifier (SA-8500) which is a little to 'strong' (2x60W sinus) for the Concerto's (2x35W sinus ?)... Sometimes I forget this ..
That is a known failure of B139 when driven too hard and aging of the driver does not make it better. So a defective woofer and 2 filters to renovate. Now.. there are 2 approaches, either one wants to fix old stuff with simple methods and a little fiddling around by doing something here and there and use melt glue and tape (then stop reading from here). I can not say anything about cheap methods and accepting irregular performance etc.
Or one wants nominal performance like when they were new. For the latter a new B139 is likely needed. The B139 replacement is a whopping 190 UK pound at Falcon and for 2 equal looking and performing speakers you'll need 2 new ones. Also 2 sensitive tweeters that are very old and prone to failure.... IMO it is a miracle that both T27 still are OK (are they? Is the output of both the same?) certainly if you play loud. Let's think of Murphy's law and let's say the speakers receive new woofers and capacitors and then you play Annie Lennox very loud and a T27 fails. Add 2 x 169 UK Pound 😀
380 UK pound for the woofers alone plus 30 UK pound for the capacitor kit makes at least 410 UK Pound (with an added risk of 338 UK Pound). That is a lot of money to put in old stuff, one reason I reject stuff so old. Since you haven't spent any money on speakers in decades maybe it is time to move on and allow yourself a new pair of speakers* ?! The SA-8500 probably needs recapping too, I recapped these amplifiers 15 years ago.
*Considering the cat one could think of speakers on stands.
Or one wants nominal performance like when they were new. For the latter a new B139 is likely needed. The B139 replacement is a whopping 190 UK pound at Falcon and for 2 equal looking and performing speakers you'll need 2 new ones. Also 2 sensitive tweeters that are very old and prone to failure.... IMO it is a miracle that both T27 still are OK (are they? Is the output of both the same?) certainly if you play loud. Let's think of Murphy's law and let's say the speakers receive new woofers and capacitors and then you play Annie Lennox very loud and a T27 fails. Add 2 x 169 UK Pound 😀
380 UK pound for the woofers alone plus 30 UK pound for the capacitor kit makes at least 410 UK Pound (with an added risk of 338 UK Pound). That is a lot of money to put in old stuff, one reason I reject stuff so old. Since you haven't spent any money on speakers in decades maybe it is time to move on and allow yourself a new pair of speakers* ?! The SA-8500 probably needs recapping too, I recapped these amplifiers 15 years ago.
*Considering the cat one could think of speakers on stands.
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I haven't read the whole thread, but if an old B139 bass is rubbing voicecoil, it's a worth rotating it 180 degrees so it might behave itself. Gravity may have made it sag over the years.
Quite common fault.
Quite common fault.
Oh , thank you Jean-Paul
I've already been searching for this on the internet. Hard to get in Europe it seems. Unless I bought bag of 100 pieces ...
Indeed. In this video (see below) , almost at the end of the video , someone also rotates the B139 by 180° . Meanwhile I've ordered two B139's already..
These come out of the IMF TLS80.
About 12 years ago I had a B139 that suddenly wouldn't play anymore.
I remember the contacts by the coil were totaly erroded.
My brother in law said I couldn't save it , so I threw the B139 away.
video : KEF Concerto Speakers: Recapped, Refurbed & Compared! - YouTube
About the T27's : I already replaced these by Morel cat 298's ...
I wanted to replace the CO's by the ones Falcon sells , but they replyed to me : "The 33Mc will give you a major performance upgrade, it won't work effectively with the Morel as the aB HF section is specific to the T27".
Which is of course al Latin for me of course ...
Well that proves the reputation of T27. What Falcon means is that your choice for non original Morel tweeters makes that their filters won't work as they should as they are meant for 2 x T27. So in effect you would need 2 x T27 AND the filters. It shouldn't be latin that these speakers are over their economic lifetime 😉 In such cases I have the units measured and check the cabinet if it is worth the time/effort to put any Euro in them.
Replacing old defective woofers for other old woofers of the same age (so with a question mark), it's a choice...
Replacing old defective woofers for other old woofers of the same age (so with a question mark), it's a choice...
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If it would be about nostalgia there wouldn't be 50 Euro costing Morel tweeters in them.
Anyway optimal nostalgia comes with 2 x 33Mc, that will be 182 UK Pound and 2 x 169 UK Pound for the T27. That is 520 UK pound ex shipping. As the mighty Falcon says it makes little sense to buy 33Mc filters for the Morel tweeters. Now, just like you fitted non original tweeters you could buy non original filters but that would be "doing something" and kind of gambling. Gambling for 182 UK Pound that the filters will be OK with Morels. Then only the B139, B110 and the cabinets would be original.
For optimal "just doing something" one can replace only the caps, fit a replacement B139/turn it 180 degrees/accept the scraping, accept the non-original sound and be done with it.
Anyway optimal nostalgia comes with 2 x 33Mc, that will be 182 UK Pound and 2 x 169 UK Pound for the T27. That is 520 UK pound ex shipping. As the mighty Falcon says it makes little sense to buy 33Mc filters for the Morel tweeters. Now, just like you fitted non original tweeters you could buy non original filters but that would be "doing something" and kind of gambling. Gambling for 182 UK Pound that the filters will be OK with Morels. Then only the B139, B110 and the cabinets would be original.
For optimal "just doing something" one can replace only the caps, fit a replacement B139/turn it 180 degrees/accept the scraping, accept the non-original sound and be done with it.
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