If you are in the UK you can order at Falcon Acoustic, they will have the right parts, particularly the 0.6uF film cap. They sell the Expotus brand.
The 82uF can by any standard bipolar electrolytic (e.g. "raw", not LL, "low loss", or "plain"). You can find it on German ebay. But possibly Falcon has an Alcap of that size. I think 50V would work as well.
The two Expotus film caps can be any good quality film caps and possibly could also be polypropylene. Solen sells a 0,6uF poly.
The new inductor needs to be 0.3mH, possibly air core, but not too big physically, as there is not much space on the board.
The 82uF can by any standard bipolar electrolytic (e.g. "raw", not LL, "low loss", or "plain"). You can find it on German ebay. But possibly Falcon has an Alcap of that size. I think 50V would work as well.
The two Expotus film caps can be any good quality film caps and possibly could also be polypropylene. Solen sells a 0,6uF poly.
The new inductor needs to be 0.3mH, possibly air core, but not too big physically, as there is not much space on the board.
Hi Plinky,
you could use one 0.56uF I think. There is not much space on that board. Darisus in Germany sells 0.6uF film caps. Falcon has no values under 1uF on their new website it seems.
The 2.2R resistor in series with the B110 mid driver should be at least 7W, better 10W. I used a 10W type for the 10R resistor as well. The 3R resistor could be 5W; I had a 7W from a Falcon kit at hand so used that.
you could use one 0.56uF I think. There is not much space on that board. Darisus in Germany sells 0.6uF film caps. Falcon has no values under 1uF on their new website it seems.
The 2.2R resistor in series with the B110 mid driver should be at least 7W, better 10W. I used a 10W type for the 10R resistor as well. The 3R resistor could be 5W; I had a 7W from a Falcon kit at hand so used that.
Hi
I made this crossover mod with mostly standard alcaps to my kefkit 3. I have about 65 litres closed encloser for b139 and about 0.2-0.3 litres closed encloser for b110. This crossover made huge difference to original and im in love to these speakers now.
I might need little more something in lower bass and higher mid am just wondering should i make bigger box for b110 and maybe something like 60litres open encloser for b139? Heres my example of the crossover
I have tested speakers with priboi 2x50w tube amp and Rane Ma6 6x100w amplifier and i can spot same problem with these amps. Just wondering what you guys think before i start to do anything.
I made this crossover mod with mostly standard alcaps to my kefkit 3. I have about 65 litres closed encloser for b139 and about 0.2-0.3 litres closed encloser for b110. This crossover made huge difference to original and im in love to these speakers now.
I might need little more something in lower bass and higher mid am just wondering should i make bigger box for b110 and maybe something like 60litres open encloser for b139? Heres my example of the crossover
I have tested speakers with priboi 2x50w tube amp and Rane Ma6 6x100w amplifier and i can spot same problem with these amps. Just wondering what you guys think before i start to do anything.
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Just regarding the first post, there is no foam around any KEF driver, they are all actual rubber surrounds. My KEF concerto is in everyday use since new and is now just on sixty years old, and I have zero deterioration in the drivers, they still don't fail to impress anyone. Concerto is full rich sounding speakers and the T27 tweeter is still regarded as one of the best. I have modern loudspeakers in my office and lounge, but they sound like modern loudspeakers, characterless and unfaithful like modern speakers sound, you never get that warm feeling as with the Concertos. The REF 104.II is a little like a Cadenza LITE version, the B200 motor is smaller, and the bass is lighter, but the midrange is slightly better defined. There unfortunately is nothing that beats big.
If you say you have two pairs of Concertos, I would put them on top of each other, tweeter to tweeter and tri-amp the lot. You will never want any other speakers, not even Wilsonaudios. I did this in very early years using 3 x Pioneer Spec 2 having each amp driving one drive unit, with a Pioneer three-way cross over and a Pioneer Spec1 pre amp. My younger brother bugged me to sell him one set of concertos and eventually did. I have since designed the RAS200 and Isobaric transmission line speakers that uses 2 x B139 2 x B1261 and 2x T27 tweeters in each box. I can produce a useful output at 17 Hz to 28 kHz
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Your mid enclosure is too small for the B110. If closed, a 60 liters box is to small for the B139. You could drill a vent of the right dimensions. I like the B139 in the Concerto better than in the (closed, bigger) Cantata.
Okay i bought 6" plasticpipe for b110 and i could make 2,5litres closed encloser for b110 and still get something like 62litres for b139 just wondering does it sound good to you guys? For b139 vents i have to put two pipes maybe 2".
that will make things much better for the mids.
as to the size of the whole box, I am still not sure if it would not better to have it vented (vent with right dimensions!) like the Concerto is. I cannot sea which lines are which in @planet10 's simulation above.
Remember that the Concerto (with about 60 liters) already shows a slight bass hump (i.e. enhanced bass) below 100 Hz. Can find and show KEF's own frequency graph. So with a closed box that bass hump imho will be farther upwards in f, maybe around 100Hz, and higher. --> not linear anymore.
I found that the Cantata (B139, B110, T52, different crossover) has this bass hump, although it is bigger (I think about 80 liters). If you have time you could simply construct a new enclosure and test. After listening to both the Cantata and Concerto (I own both, Concerto w "new Crossover values, Cantata w restored original Xo) I prefer the Concerto's bass.
as to the size of the whole box, I am still not sure if it would not better to have it vented (vent with right dimensions!) like the Concerto is. I cannot sea which lines are which in @planet10 's simulation above.
Remember that the Concerto (with about 60 liters) already shows a slight bass hump (i.e. enhanced bass) below 100 Hz. Can find and show KEF's own frequency graph. So with a closed box that bass hump imho will be farther upwards in f, maybe around 100Hz, and higher. --> not linear anymore.
I found that the Cantata (B139, B110, T52, different crossover) has this bass hump, although it is bigger (I think about 80 liters). If you have time you could simply construct a new enclosure and test. After listening to both the Cantata and Concerto (I own both, Concerto w "new Crossover values, Cantata w restored original Xo) I prefer the Concerto's bass.
It should be obvious. As the Q rises the peak rises and the curve does not extend as low.
dave