I developed a high interest in HIFI around 1974. My neighbor build speakers at that time and since then, has been my hobby too, even with some breaks in between. At that time the average HIFI speaker sounded very low-fi. The real sound was often masked by the phono cartridge in the record player. At that time even crystal pick up's where around. Not to mention the amps used. KEF speakers became the great hype in some circles, maybe because you could buy DIYS kits. I saw many more ugly DIYS cabinets than commercial KEF speaker.These sounded better than most (maybe all) German speakers that where around. Anyway, you where, in most cases, unable to tell what was the cause of the good sound: The speaker or the record player, maybe the amp? KEF owner usualy cared a lot about the "chain", which made them stand out from most average commercial HIFI at that time. As I had some friends that made music, I was able to hear a lot of US soeakers, from Altec, JBL and Electro Voice. These where the speakers that rocked, KEF was, sorry, simply boring.
Many years later, some of these early, self build KEF owners where able to spent some money and bought finished KEF speakers, because they fanatically promoted their soft-plastic, boring sound and religiously refused to listen to live like speakers. There sure is some music that sounds fine with these vintage KEF's. From my experience, you can allways find some music that fits a speaker, even the worst ones.
Today, with perfect amps and CD quality sources, the speaker is the most important part of the game. The "Chain" is much less important.
Today anyone connected with vintage KEF speakers blames the x-over for the lame sound. Replacements cross overs are sold for much more than the whole speaker is worth. OK, good money to be made, but be realistic: I doubt that a capacitor made from some special "Poly-XY" and a multi layer PCB will do much to improve these speakers. Maybe it is just because the chassis made from soft plastc material are not state of the art any more?
It may be the same with KEF as it is with, for example the Volkswagen Beetle or an AMC Pacer: Some still dream of it, some even buy an expensively restored one, but in the end, compared to todays standard, they are horrible cars in any aspect.
Many years later, some of these early, self build KEF owners where able to spent some money and bought finished KEF speakers, because they fanatically promoted their soft-plastic, boring sound and religiously refused to listen to live like speakers. There sure is some music that sounds fine with these vintage KEF's. From my experience, you can allways find some music that fits a speaker, even the worst ones.
Today, with perfect amps and CD quality sources, the speaker is the most important part of the game. The "Chain" is much less important.
Today anyone connected with vintage KEF speakers blames the x-over for the lame sound. Replacements cross overs are sold for much more than the whole speaker is worth. OK, good money to be made, but be realistic: I doubt that a capacitor made from some special "Poly-XY" and a multi layer PCB will do much to improve these speakers. Maybe it is just because the chassis made from soft plastc material are not state of the art any more?
It may be the same with KEF as it is with, for example the Volkswagen Beetle or an AMC Pacer: Some still dream of it, some even buy an expensively restored one, but in the end, compared to todays standard, they are horrible cars in any aspect.
In their day KEF drivers were what we would consider standard range drivers today i.e. ones produced in large volumes with wide tolerances for reasonable prices rather than top of the range drivers. For example, the midrange has a stamped steel frame with well known resonance problems in the passband, a plastic cone with substantial resonances issues requiring significant amounts of gunk to be painted on by hand, etc... Standard range drivers from 50 years ago deliver inferior technical performance compared to competent modern standard range drivers never mind modern top of the range drivers but they are not horrible if in reasonable condition and appropriately used. A 12"(ish) woofer, 5" midrange and 1" tweeter in a 70 litre(ish) cabinet is almost the definition of the appropriate configuration for a speaker capable of high fidelity sound in the home whether today or 50 years ago because it follows the laws of physics.
It isn't clear to me quite what the OP wants to do but a T27, B110 and B139 in decent condition, in a reasonably well designed cabinet with a competently designed crossover is capable of producing reasonable sound quality by modern standards. Not high sound quality (technical rather than audiophile sense) but decent assuming the drivers and crossover components are operating close to spec. 10 years ago I chucked my DIY speakers using 70s KEF drivers in a skip when moving house because they weren't worth refurbishing or the cost of transporting. Perhaps one could have described them as sounding horrible (not that I had used them for the previous 20 years) but a probably fairer description would be that they were way out of spec due to deterioration plus sound quality expectations are higher today compared to 50 years ago.
These speakers are what they are, if in perfect condition able to produce music in a very cultivated manner. They do not rock the house, nor do they have the soundstage and attack of modern drivers. The parts used in the cross over where a balance of cheap and reasonable.
What I personaly dislike, is overestimating this material and throwing loads of money and boutique material on them, for a result that is not original as well as not improving their sound beyond what today cheapest drivers can achieve. I see no sense in modifiyng them to a point that makes them a new construction. Better sell working drivers for spares, as some may need them and build something on 2022 niveau. Makes a double win for me.
What I personaly dislike, is overestimating this material and throwing loads of money and boutique material on them, for a result that is not original as well as not improving their sound beyond what today cheapest drivers can achieve. I see no sense in modifiyng them to a point that makes them a new construction. Better sell working drivers for spares, as some may need them and build something on 2022 niveau. Makes a double win for me.
Hello Eric,
don't give up on Concertos, they're great and worth investing some time/money on them but IMHO they DO need the acoustic butterworth variation and better inductors. Check https://www.diyaudio.com/community/...d-dn12-crossover-with-full-ab-circuit.370666/
I used Eschenborn schematic on post #1 and couldn't be happier, he was very pleased as well... however I changed ALL components 😅and made new boards to accomodate inside the cabs. What follows is product of my layman guessings:
-Thicker gauge air core inductors for tweeter (0,7mm) and mid units (1mm)
-Iron core 1.6mm thick inductors for bass units, changed value from 5 mh to 4.7 mh (*check below)
-Polypropylene 82uf for bass units (probably not neccesary but didn't want to remain asking myself "what if...?)
-Polypropylene 33uf for mids, 3.3uf, 0.6uf (two 0.3uf in parallel) for tweeters
I also modded the inside of cabs, but if possible try at least filling the mid woofer tube with lambs wool (or similar synthetic), use spiked stands and small silicon rubber drops (the ones you get at dollar-euro shops) between stand and speakers.
You mentioned bass... before the mods I felt a lack of lower mid bass*, now it's there, and low bass is deep, physical, no need for subwoofer
It's been a year now since the modification and whenever recordings are up to par I still get the jaw-dropping effect, everytime
don't give up on Concertos, they're great and worth investing some time/money on them but IMHO they DO need the acoustic butterworth variation and better inductors. Check https://www.diyaudio.com/community/...d-dn12-crossover-with-full-ab-circuit.370666/
I used Eschenborn schematic on post #1 and couldn't be happier, he was very pleased as well... however I changed ALL components 😅and made new boards to accomodate inside the cabs. What follows is product of my layman guessings:
-Thicker gauge air core inductors for tweeter (0,7mm) and mid units (1mm)
-Iron core 1.6mm thick inductors for bass units, changed value from 5 mh to 4.7 mh (*check below)
-Polypropylene 82uf for bass units (probably not neccesary but didn't want to remain asking myself "what if...?)
-Polypropylene 33uf for mids, 3.3uf, 0.6uf (two 0.3uf in parallel) for tweeters
I also modded the inside of cabs, but if possible try at least filling the mid woofer tube with lambs wool (or similar synthetic), use spiked stands and small silicon rubber drops (the ones you get at dollar-euro shops) between stand and speakers.
You mentioned bass... before the mods I felt a lack of lower mid bass*, now it's there, and low bass is deep, physical, no need for subwoofer
It's been a year now since the modification and whenever recordings are up to par I still get the jaw-dropping effect, everytime
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When I got my vintage Concertos, I did not like the sound, even with a recapped DN12 crossover (Alcap substitutes from Falcon). Not very detailed, too prominent mids. I experimented for months with changes to the circuit and came up with something remarkably similar to the rare AusKEF aB circuit or the CS7 circuit. see my post.
With this the Concertos sound close to the ref 105.1 (side by side comparison) with all their attributes (bass power, imaging, details), with a more magic midrange and a benign bass hump. They sound very competent. They sound even better to me than the Cantatas which I now also own (less directional, less boxy).
To achieve this result, it is necessary to strictly follow my circuit design down to capacitor type and particular spec. Substituting e.g. a Mundorf e-cap plain with a polyporopylene, as some have done here, will completely change the whole sound balance.
I learned that slight changes in one crossover section (i.e. treble) can have audible effects in another band (i.e. mids). KEF implemented the aB filter in order to also tame resonances audible in the mid band.
In my experience all classic KEF speakers will reveal deficits in amplification. If they sound sub par, it’s possible that the amp is not good enough. It’s not so much about power but about quality. Contemporary consumer amps are often far from great. Vintage amps all suffer from deteriorated electrolytics.
With this the Concertos sound close to the ref 105.1 (side by side comparison) with all their attributes (bass power, imaging, details), with a more magic midrange and a benign bass hump. They sound very competent. They sound even better to me than the Cantatas which I now also own (less directional, less boxy).
To achieve this result, it is necessary to strictly follow my circuit design down to capacitor type and particular spec. Substituting e.g. a Mundorf e-cap plain with a polyporopylene, as some have done here, will completely change the whole sound balance.
I learned that slight changes in one crossover section (i.e. treble) can have audible effects in another band (i.e. mids). KEF implemented the aB filter in order to also tame resonances audible in the mid band.
In my experience all classic KEF speakers will reveal deficits in amplification. If they sound sub par, it’s possible that the amp is not good enough. It’s not so much about power but about quality. Contemporary consumer amps are often far from great. Vintage amps all suffer from deteriorated electrolytics.
sounds very interesting, thanks for trying my circuit.
In the previous post I was somewhat critical of deviating from the values and types I found. But there are other solutions for crossover circuits for these drivers for sure.
If you use different inductors, you change the compound resistance/ impedance in the respective sections. This might pair well/ not well with changes in caps. In your case it seems to work nicely
I always speculated what would happen if the ESR of the big parallel cap in the bass circuit was changed… but never tried. Your results (by using a low ESR polypropylene there) sound encouraging.
Hello Mr. Marintz.
Sorry for my late answer. But thank you for your input.
I already read about the acoustic butterworth variation from Mr. Eschenborn .
This modification would make a big difference.
The only problem is that I'm afraid to get started.
Unforunately , I don't have the technical know-how of specialists such as Mr. Eschenborn, system7 (Steve) , etc..
OR , and MAYBE, when I should have a simple, but clear manual of all the different steps to take.
As well as , and most importantly : a clear listing of the different components… then maybe …
Another problem for me is the (technical) language.
Mostly I have to use Google-translate , but even then, it stays very difficult for me to understand all what’s been written.
A lot of DIY-audio-members gave me their advice about changing these COs in the past.
Also Mr. Eschenborn. Who I respect very much.
At some point I was advised to do a simple modification (please see example in attachment).
I was going to think about this during the winter and maybe start on it..
But : I have already taken the first step ... I already have a pair of spare crossovers..
if it had to go wrong
However, the hardest part for me , is finding the CORRECT parts.
I think there are a lot more shops - like Falcon for instance -in the UK than in Belgium.
A simple example :
Months ago I was advised by another member of DIY-Audio (Mr. Jean-Paul), to replace the PCB connectors by Phoenix thermal blocs 1703091.
But difficult to buy in Belgium, unless per 20 or even 100 pieces ..
https://www.mouser.be/ProductDetail/Phoenix-Contact/1703091/?qs=YjJcVSlHJPXSs4ICjVsssQ==
In the meantime I soldered the wires directly to the PCB to ensure a good connection…
Perhaps the simplest (and least stressful) would be to buy the crossovers from Falcon.
https://www.falconacoustics.co.uk/c...gers-monitor-upgrade-super-power-network.html
However, they are quite expensive and it would cost me a lot of money to get these to Belgium (due to Brexit).
I think it would cost me about €300 for 1 pair of crossovers.
But no doubt the acoustic butterworth variation from Mr. Eschenborn would be much much better.
I am still very satisfied with my Concertos. And a few months ago I was even able to buy a third pair , but at that moment I was thinking of possibly buying the Kef 104.2 instead…
And when I finally decided to buy the Concertos anyway, they had just been sold...
So , I have to keep listening to my Kef Cadenza’s in my garage.. (I have 3 pair of Cadenza’s…)
(So Yes, you can call me a Kef-loudspeaker-fan).
Bottemline : yes , I am still very interested in the acoustic butterworth variation from Mr. Eschenborn.
BUT : unfortunately I fear that it will remain a dream.
Eric.
Attachments
Hi Eric,
I still believe that you can upgrade the Concertos to extremely pleasing speakers. With the right amplification (high quality solid state) there won't be much more to wish (although the upgrade lust is always lurking). They also need to be on low stands. The T27 is still a pleasing tweeter and the original B110 has a nice midrange. Think of the Concerto with the adequate crossover as a full range LS3/5a. No need to look further – if only for curiosity.
The old Falcon drawings you posted can be used in order to upgrade the DN12 board to what Falcon calls their "improved" version. I tried this simplified aB circuit and found it unconvincing. The Falcon website in your link however shows the whole thing on a new board which cannot be mounted on the baffle. Lots of more tinkering work. Not a good idea. I have not been convinced by all crossover designs Falcon offers, neither by all the cap choices they made for their model-specific recap kits.
I found a picture of another improved network (by Falcon? by KEF?) in one of the last Concertos sold, already with the newer B139 bass driver, see here: https://www.aussieaudiomart.com/det...o-speakers-with-new-crossover/images/1360155/
I think we could walk you through modifying the spare crossovers into "my" version. They will still fit in their places but it is better to turn them around – component side facing outwards. Also the covers will still fit, but the tissue might be pushed a bit outward by the bigger components on the crossovers.
You could also send me your spare crossovers, I'd get the parts, put them into place and send the boards back, with you paying shipping and parts only (around 60 euros I would guess, but prices need to be checked). I won't be near my own Concertos in the next weeks, so I'd probably have to do this without a final test, but it should be ok. I've a lot of work, so it could well take some weeks. If you are interested, send me a PM. I am in mainland Europe.
What amplifier do you use @Eric Stockman ? Again, those old KEFs just show how great – or not so great – your amplification is. My experience is that they rarely limit the performance of great silicon you throw at them, they just get better and better the higher the amp quality is. If you use something a bit older, you might think about having it refreshed by a good shop specializing in vintage hifi restorations (again, PM).
I still believe that you can upgrade the Concertos to extremely pleasing speakers. With the right amplification (high quality solid state) there won't be much more to wish (although the upgrade lust is always lurking). They also need to be on low stands. The T27 is still a pleasing tweeter and the original B110 has a nice midrange. Think of the Concerto with the adequate crossover as a full range LS3/5a. No need to look further – if only for curiosity.
The old Falcon drawings you posted can be used in order to upgrade the DN12 board to what Falcon calls their "improved" version. I tried this simplified aB circuit and found it unconvincing. The Falcon website in your link however shows the whole thing on a new board which cannot be mounted on the baffle. Lots of more tinkering work. Not a good idea. I have not been convinced by all crossover designs Falcon offers, neither by all the cap choices they made for their model-specific recap kits.
I found a picture of another improved network (by Falcon? by KEF?) in one of the last Concertos sold, already with the newer B139 bass driver, see here: https://www.aussieaudiomart.com/det...o-speakers-with-new-crossover/images/1360155/
I think we could walk you through modifying the spare crossovers into "my" version. They will still fit in their places but it is better to turn them around – component side facing outwards. Also the covers will still fit, but the tissue might be pushed a bit outward by the bigger components on the crossovers.
You could also send me your spare crossovers, I'd get the parts, put them into place and send the boards back, with you paying shipping and parts only (around 60 euros I would guess, but prices need to be checked). I won't be near my own Concertos in the next weeks, so I'd probably have to do this without a final test, but it should be ok. I've a lot of work, so it could well take some weeks. If you are interested, send me a PM. I am in mainland Europe.
What amplifier do you use @Eric Stockman ? Again, those old KEFs just show how great – or not so great – your amplification is. My experience is that they rarely limit the performance of great silicon you throw at them, they just get better and better the higher the amp quality is. If you use something a bit older, you might think about having it refreshed by a good shop specializing in vintage hifi restorations (again, PM).
Hi Eric,
As said, at least for me Mr. Escheborn's mod is the way to go, surely he can guide you better than myself... very kink offer on his part!
I guess it's not neccesary to change-upgrade all components as I did given Escheborn's so positive results even keeping original boards and inductors.
I wouldn't worry so much about these Mouser conectors, unless they're easy to get... maybe you could look for someting similar at an electronic parts shop in your area? After doing some tests I got all parts from the Polish shop loudspeakershop.eu , mainly because I wanted different inductors, resistors and certain caps (Jantzen electrolytics and polypropylenes).
Good luck and be patient!
As said, at least for me Mr. Escheborn's mod is the way to go, surely he can guide you better than myself... very kink offer on his part!
I guess it's not neccesary to change-upgrade all components as I did given Escheborn's so positive results even keeping original boards and inductors.
I wouldn't worry so much about these Mouser conectors, unless they're easy to get... maybe you could look for someting similar at an electronic parts shop in your area? After doing some tests I got all parts from the Polish shop loudspeakershop.eu , mainly because I wanted different inductors, resistors and certain caps (Jantzen electrolytics and polypropylenes).
Good luck and be patient!
Mr. Marintz, do you have pictures about this inside transformation ?
And also of the stands ... please...
Do you mean you have to fill that hole next to the woofer (the 'reflex tube'?) with lams wool ? 🐑
I've read a few articles about stands last year.
Some people say that if it is a FLOOR speaker, it should be on the floor and not on a stand.
Mr. Eschenborn also says I have to put them on stands.
I would like to try it out though, and if I can , make a few stands myself.
Perhaps I can make wooden stands
.About spikes ... don't spikes damage the floor ?
I must say : My concerto's produce lotts of bass , but perhaps that's due to my amplifier.
On both my sets of Concerto's , I use a vintage (but powerfull) Pioneer amplifier SA-8500. Heeps of bass 😍
And yet , the sound is so much better when played in the greatest room.
I only have a small 'man cave' (4m x 4m x 2.4m) ; the other room is about 8m x 5m x 2.6m .
I also use double shielded interlinks (RCA)
Some people also say that an expensive interlink cable (RCA) is a waste of money.
I don't use very expensive interlinks (mine are between €75 and €110 per pair of RCA cables).
Personally I just think that a double shielded cable PROTECTS the original signal better than a single shielded cable.
Concerto was designed & used with floor placement. Short stands improve things.
I remeber that amplifier. We sold few of them. You could do a lot better. And in today’s world not all that much power (60W 8, limited into 4Ω).
dave
I remeber that amplifier. We sold few of them. You could do a lot better. And in today’s world not all that much power (60W 8, limited into 4Ω).
dave
Concerto was provided from KEF with optional factory wood stands.
Good example here:
https://www.canuckaudiomart.com/det...f-concerto-speakers-with-feet/images/2019704/
Good example here:
https://www.canuckaudiomart.com/det...f-concerto-speakers-with-feet/images/2019704/
I bougt my first one around 1975 I think for about €500. My second one last year for €450. You are probably right when you say I could do much better , but could you give an example of such an amplifier ? And what would be better ? Because to me , my Pioneer gives me lots of bass , treble and power. OK, the Pioneer hasn't got a subwoofer output , or bluetooth-connexion and probably much other features. But a subwoofer I don't need with my combo.
Do you mean that with another amplifier , the sound would be much better? My SA-8500 produces 60Watts nominal. If I would turn up the volume towards the max , my Concerto's would blow up...