I have the same set of Kef Coda myself, the drivers are restored by Speakerfix from Diksmuide. ( 1 tweeter was broken, the other drivers he checked, and the capacitors replaced. The cabinet was not in good shape, they were no longer airtight, I put the speakers back together myself, which is not so difficult. They sound great. I also have the KEF Chorale, from 1974, sound a little better, with a fuller bass. The woofer is a Kef B200. Nice to see this on RU-vid.
Great repair on the speaker terminals, thanks for warning folks about how fragile they are! Sorry to hear these boxes didn't turn out like you hoped. If you gotta open them up again, suggest swapping out those double ended electrolytics for dry, metallized foil caps @100v or greater. Guessing that the original 1973 use of double-end elkos vs dry caps was mainly a cost cutting measure. Foil caps were also a fair bit physically larger in '73.
The crossover networks are the weak point in these old KEF loudspeakers. The inductors aren't that great either. I thought about replacing the bipolar capacitors with foil types, but I couldn't find the right types at the parts supplier I used (Reichelt).
I just bought a pair of those SP 1034s for 35€. Pretty happy. I stapled the grille cloth on again because it got loose. Maybe I will also renew the crossover parts. The veneer needs some love too, but then they are very nice.
I have found replacing the crossover capacitors was a total waste of time. The original capacitors actually sounded much better than the new ones, so I put the old capacitors back into the crossovers.
I bought pair of used Cantatas over 30 years ago and all your drivers look familiar. It was originally a kit the previous owner built. Nice job too but I could never stand the sound of the midrange drives which may be the same as your woofers. I don't know. The best thing to happen was one of the voice coils became a little crunchy (it seemed to be off center) so I replaced them with a pair of Focals (i think, its been a while). Had to add some resistors to tone them down but boy what an improvement. Do the woofers sound shrilly in the midrange?
I never made a video about the transmissionline speakers and I don't think I ever will because there is no way to demonstrate their advantages. They are capable of reproducing frequencies down to the lower limit of the human hearing range (below 20 Hz). I don't have equipment to record such low frequencies and most viewers won't have audio systems that could reproduce what I can hear with these speakers.
These are old. I have some 5"Neoflex Focal from mid 90 that I need to replace the spiders (very nice sounding mid woofers used in Daline by JM Lab), some 6.5" 10 ohm (OK, not that great) as well but one of them just distorts and can't be repaired - took it apart and glue it back. Many newer drivers have much lower distortions, better linearity: thanks Mr. Klippel. I be playing with SB17NRX 4ohm (supposedly warmish bass reproduction good mids) and SB ring dome tweeters and see what comes out of it. Seas, ScanSpeak, others make very good spkrs - not all of them are perfect but some are really good. If money would be there, then ScanSpeak Revelator, Satori or something similar would be part of my system - not for now. Sometimes you can use older spkrs in the car - they can sound better than cheap car stereo components and car receivers don't mind 8ohm load at all, often playing cleaner with 8ohmers. One thing for sure some of the older capacitors do go bad and I would measure the drivers, just to check how they behave - REW, ARTA, HOLMImpulse as you already have good sound card. WinISD, XSim, VituixCAD for enclosure and filter design. Maybe they're not total loss.
I had a pair of KEF speakers back in the 80s. I don't remember the model but they were my first pair of quality speakers. They eventually got "foam rot" and I replaced the foam on the woofers and mid-range drivers. They never sounded as good as they were before the foam rot so I sold them. It could be that I glued the foam incorrectly but now I'll never know.
I built a pair of transmission line speakers, using KEF B139 bass units which I still have. I used the Dr Bailey design which uses triangular pipes instead of the flat panel labyrinth in his original design. IMF use to make transmission line speakers based on his original design. One thing I would point out is the capacitors you removed are not electrolytic so I suggest you put them back if you still have them. They may look like electrolytic capacitors but I think they are some sort of plastic type. Dayton/Solen Polypropylene I knew a man who had a degree in electronics and he modified a KEF crossover so I could use a conventional pair of speakers sitting on top of the transmission line speakers. I tried a pair of Rogers LS3/5a and then a pair of B&W DM4 spearers when I had the transmission line cabinets. I have been intending to get cabinet maker, to make a new pair of cabinets one day.
The big transmissionline speakers seen in the video are based on the Bailey Design too :) Replacing the capacitors in the crossover was a mistake. Thankfully I do still have the original capacitors, I just need to put them back in.
When you said you needed a pair of T27s. Instantly I shouted out I HAVE 10 ON THE SHELF, what's the problem with supply?? Then I returned to the reel world, as that was 45+ years ago. Many speaker makers used KEF drivers and almost all sounded better than Kef's own models. A few examples were, Cambridge Audio, IMF, Monitor Audio, Rogers and of course one the best small speakers that used similar drivers but a very complex cross over was the BBC version, made by a number of manufactures, the strange thing was it had a 15ohm impedance, made under licence from the BBC. Not cheap but it did sound amazing.
The BBC monitor speakers you mean are the LS3/5A. I have a pair, made by Spendor. They are amazing speakers, but they don't work with any amplifier due to the high impedance.
i would try some plastic caps in the xover ... i do not know if the same value can be used ... Plastic ones are pretty neverending and usually sound very good
It turns out the original crossover capacitors in these speakers are NOT electrolytics. So just leave them in place, they should still be fine. I have since put the original capacitors back into my KEF speakers.
@@DrCassette Thanks a lot and very good. Another thing i would try (assuming that the back panel is stiff enough) is a little wood column of good section and with length equal to the internal distance from the baffle to the back panel with two good diameter nuts and then bolt the front baffle to the rear panel by means of this column In this way the front baffle and back panel will be tightly coupled together and front panel bending reduced to a minumum. The front panel is by far the most important panel of the speaker ... if it vibrates this will reflect in some blur in the sound. I do not know by the way if the rear panel is stiff enough. As designer Andrew Jones says ... first the drivers ... they make the sound ... then the xover ... and then the cabinet. You are doing a great job indeed. Thanks and kind regards, gino
I'm sorry to hear that you're disappointed with the sound output of these KEF speakers after spending so much time rebuilding them. How long ago is it when you last heard them working? If it's a long time perhaps your hearing has changed? I've certainly noticed during my repairs and tinkerings that my hearing has started to change as I age and, whilst not obvious day to day, age related hearing loss has begun. Looks like I've got a future with comical overtones (if only I could bloody hear them)!
The last time I heard these speakers for a longer period of time must have been in early 2013. That is a fairly long time ago. I'm sure my hearing has changed, but that would be at the high frequencies. The problem I have is I get next to no low frequency output from these speakers. However, I will try setting them up in another room soon, could be that the low frequencies just got canceled out by the room acoustics.
The bipolar electrolytic capacitors are not the greatest solution for audio in my opinion, I think film capacitors are better for this purpose, plus they don't leak or dry out.
+DrCassette forget the bipolars for tweeters, even cheaper film caps do better job. Use parallel with better Metalized polypropylene like Mundorf (Dayton, ESR will do) to obtain bigger values and lower ESR. Plenty of DIY spkr stores in Germany, even in Poland there's of them than in Canada 😋.
DrCassette Yeah, mundorf are quite an overkill. I've heard that they give quite a soft sound (idk if that's true) but I know for sure that old soviet MBGO and MBGP caps give a really nice vintage soft sound, if you are a fan of that. But I'm not sure how easy it is to find them in Germany.
You must have put a lot of stress on those pliers. How did you manage to do that? Tool grade steel should be really tough. The pliers completly sheared off, there was definitly not much of a bending moment involved. It looks like the plier was stressed very close to it’s hinge point.
I was just using the pliers to tighten the nuts on the crossover board screws down again. Nothing unusual. This was part of one of these cheap tool sets, so maybe that's why it didn't last.
Considering the misuse I've metered out to some pairs of pliers over the years I'm amazed that's not happened to me! Sounds like possibly a failure due to substandard materials, rather than abuse. At least it's not an expensive pair, however galling it may be!
The problem arises from capacitors you replaced the old ones. The old black and red caps originally have a bulky ESR, which has been calculated in the overall crossover design.
I didn't like the T27 much ... I found better ones to drop in .. If you notice ... there is provision for a second capacitor for the tweeter crossover .... it's shorted out .. but you can add a 4.7uF cap there after removing the shorting link.. This gives the T27 a 3rd Order network and it increases power handling and the sound too... Also there is provision on the board to add a series notch filter across the B110.... I can't remember the component values (the schematic diagrams might show them ..) This filter gives the Coda a kind of LS/3a monitor sound used by the BBC
You may be right about them not being as good as you remember. From my own experience you have to keep them as your key speaker for a week or so and get adjusted to them. They have very different strengths and weaknesses from modern speakers and bass was invented with CD.
I have a feeling a big part of the problem are the acoustics in my room. I'll have to try setting up the speakers somewhere else. Here in my room I get not nearly as much low frequencies as there should be. Once I'm out of my room, around the corner and halfway down the basement stairs I hear plenty of low frequencies.
You are probably aware that these drive units are used in the BBC designed LS3/5a. The crossover in the LS3/5a is much more complex than the Coda's. Check out Falcon Electronics for LS3/5a crossovers.
I have Chartwell LS3/5a, plus some homemade clones. Why not make your Codas into almost LS3/5a spec by adding the LS3/5a crossover. I also have a pair of Codas, they did not compare to the LS3/5a's, so used the units to make the clone LS3/5a's . Your big speakers using KEF units, I guess you used the Concerto crossover? If so, these speakers would not compare to LS3/5a's, except of course the bass. I dismantled my Concertos.
Replacing the DN13 crossovers with LS3/5A crossovers would certainly be an interesting experiment, but too expensive for my liking. The transmissionline speakers use unmodified KEF DN12 crossovers, the same that were also used in the Concertos.
Falcon are experts in crossovers, have been for decades, in fact Falcon made the crossovers for several LS3/5a manufacturers. Falcon do make a complete and licensed LS3/5a. They also make the LS3/5a crossover on their standard board, this is not that expensive. There is also the KEF CS1a crossover, which is based on the LS3/5a, this is very good, basically a slightly simplified LS3/5a circuit. Should be quite a bit cheaper to construct, I did this many years ago. The CS1a circuit should be easy to find on the internet, alternatively, I have the details. Would be happy to pass them on.
Yes, I do realize this video is not perfect. The idea of describing what I'm about to do at the beginning of the video instead of explaining things as I go is just plain terrible. But since I'm quite busy, it's either this video or no video at all.
DrCassette Some RU-vidrs, who I won't mention on here, choose this type of production for there channel all the time. I find it slightly less interesting than watching the entire process of repair and / or refurbishment but it's still entertaining, never the less.
Yes, some RU-vidrs do this all the time, and what's worse is not only they describe what they are about to do in the beginning of the video, they repeat this after every step of work they completed. That results in terrible videos with loads of redundant information. I got carried away because coincidentally I had all parts for the project neatly lined up on the workbench. I will not make another video like this.
@@DrCassette Your video was great. I make videos as well. You tubers like to pic apart everything. I can talk about every nut and bolt and why its there.. Then they complain I'm talking to much.
@@williamstaten8102 The hardest part of making a good video is finding the balance between keeping things short and trying to explain as much as possible. I try to never make my videos any longer than 10 minutes, that way I can still enjoy them myself.
I don't see why you need to refere to the previous owner as an "Idiot", just because he didn't know to use the X-over... Fun video appart from that, and yes, old speakers didn't sound as good as we remember them to do ;-) .
If you mess about with things you don't know anything about and cause damage that could have been avoided, people have all right to call you an idiot. That's life.
Being an Idiot is one thing (this can not be re-mediated), being uneducated about something is something else (this can be re-mediated). if not, we'd all be Idiots. That's reality :-)
You are incorrect, they are all bipolar electrolytic capacitors. The Elcap branded originals are marked NP for non polarised. Were they paper in oil they would be enormous and too expensive for use in the original fairly low cost loudspeakers.
In the comments above somebody said they were polypropylene capacitors. This is getting a bit odd. Unfortunately the capacitors don't give any info on what they actually are.
DrCassette yes I think they are polypropylene try and experiment with different types see which ones comes out best! There's no fixed rule. There is a German ones are good Russians make a paper in oil in a glass tube usually top end speakers used to use paper in oil or and metal film. I wonder if they made by leak those capacitors I gather you can't find anything on internet have you not contacted KEF and ask them what a modern equivalent would be. Wharfedale used to use those capacitor as well so did bang and Olufsen. There is a company you could ask that give you advice! Wilmslow Audio make speaker kits just had a look Google it they do KEF CI series if that means anything to you.
Experimenting is not an option, the crossover is not very happy to come out of the case, just a few more times of removal and reinstallation and something will break...
![KEF Coda SP1034 HiFi speakers overhaul [no demonstration]](/img/logo.svg){kind=logo}
