Hi Everybody,
My best mate’s dad passed away a while ago. Recently we were cleaning out his old place and found a KEF speaker kit. The receipt is still in the box, purchased at the Stereo HiFi Centre in Melbourne for $400 in 1980 – it predates me by 4 years! Despite its age, everything is in absolutely immaculate condition. The crossover networks and drivers all appear absolutely perfect.
While I wouldn’t even feel qualified to call myself a novice in this field, I am the closest thing to an expert my mate knows, and I have been given the task of determining the fate of this kit. His Dad was always into HiFi, some other gear included a Yamaha A-700 amp, Wharfedale Laser 150 speakers, Yamaha HP-1 headphones… the list goes on. I would really love to complete this kit for him as a permanent, happy memory of his Dad. And I would really like to make it the best that it could be. I will be forever grateful for any help anyone can provide.
It looks like the speakers are kits to make KEF Concerto loudspeakers. But, there are some hand drawn cut sheets in the box, that my mate’s Dad had obviously intended to use and they look nothing like the concertos. I do not believe he planned to make them as per the kit design. There is an article from “HiFi News & Record Review” from May 174 entitled “A Folded Column Loudspeaker”. It seems to use the same drivers as the concerto and the cut sheet seems to match this design more closely.
So my questions are:
1. Has anybody ever seen these speakers/kits before, either the concerto or the folded horn?
2. Are they any good?
3. Should I build the concerto, or the folded column design?
4. Everything looks great, but is the age of everything likely to cause huge problems? I.e. are the caps in the crossover likely to fail and should I substitute them?
Everyone on here has been so helpful in the past and I thank you all in advance for any help you can provide me.
My best mate’s dad passed away a while ago. Recently we were cleaning out his old place and found a KEF speaker kit. The receipt is still in the box, purchased at the Stereo HiFi Centre in Melbourne for $400 in 1980 – it predates me by 4 years! Despite its age, everything is in absolutely immaculate condition. The crossover networks and drivers all appear absolutely perfect.
While I wouldn’t even feel qualified to call myself a novice in this field, I am the closest thing to an expert my mate knows, and I have been given the task of determining the fate of this kit. His Dad was always into HiFi, some other gear included a Yamaha A-700 amp, Wharfedale Laser 150 speakers, Yamaha HP-1 headphones… the list goes on. I would really love to complete this kit for him as a permanent, happy memory of his Dad. And I would really like to make it the best that it could be. I will be forever grateful for any help anyone can provide.
It looks like the speakers are kits to make KEF Concerto loudspeakers. But, there are some hand drawn cut sheets in the box, that my mate’s Dad had obviously intended to use and they look nothing like the concertos. I do not believe he planned to make them as per the kit design. There is an article from “HiFi News & Record Review” from May 174 entitled “A Folded Column Loudspeaker”. It seems to use the same drivers as the concerto and the cut sheet seems to match this design more closely.
So my questions are:
1. Has anybody ever seen these speakers/kits before, either the concerto or the folded horn?
2. Are they any good?
3. Should I build the concerto, or the folded column design?
4. Everything looks great, but is the age of everything likely to cause huge problems? I.e. are the caps in the crossover likely to fail and should I substitute them?
Everyone on here has been so helpful in the past and I thank you all in advance for any help you can provide me.
Hi There;
Sorry about your Dad's friend. You have really found something though. The KEF B139 is a classic transmission line loudspeaker. Used drivers are being sold today for a pretty sum. The rubber surround likely has survived without rotting out.
Do the speaker plans look like this?
http://www.t-linespeakers.org/projects/jakob/index.html
If it were me I'd build the transmission line (folded column) as I am a fan of those types of speaker. Of course it depends on how much room you have in your house for speakers and certainly on your woodworking skills. These look like a lot of work.
Good luck
Matt
Sorry about your Dad's friend. You have really found something though. The KEF B139 is a classic transmission line loudspeaker. Used drivers are being sold today for a pretty sum. The rubber surround likely has survived without rotting out.
Do the speaker plans look like this?
http://www.t-linespeakers.org/projects/jakob/index.html
If it were me I'd build the transmission line (folded column) as I am a fan of those types of speaker. Of course it depends on how much room you have in your house for speakers and certainly on your woodworking skills. These look like a lot of work.
Good luck
Matt
If we tell you about this website, will you tell us how you get on?
Check out the photo on the home page. Familiar?
Check out the forum.
http://www.hifiloudspeakers.info/
Check out the photo on the home page. Familiar?
Check out the forum.
http://www.hifiloudspeakers.info/
What a wonderful score... I sold a ton of these in the late 70s, early 80s.
hese deserve to be in a transmission line... there are many clasic designs (diy projects & commercial), but Scott & i recently did up a TL using modern modeling techniques -- i would suggest a variation on that. We'll be happy to help configure it to be suitable for your needs... not really small thou. I also have copies of many of the classic diy articles.
There are a number of ways it could be configured... my 1st suggestion would be a small sattelie for the B110/T27 & a single common TL or a pair of TLs for the B139s (ie like the Fried HFried H or Fried M configurations
The weak point of this is the XO, so best to keep it where it is accessible if you ever decide it is worthwhile to start tweaking things. I know what i'd do (involves biamping, and the borrowing from the Fried mid/tweeter XO in the link above)
Here is a visualization of one of the possible TL configurations:
dave
hese deserve to be in a transmission line... there are many clasic designs (diy projects & commercial), but Scott & i recently did up a TL using modern modeling techniques -- i would suggest a variation on that. We'll be happy to help configure it to be suitable for your needs... not really small thou. I also have copies of many of the classic diy articles.
There are a number of ways it could be configured... my 1st suggestion would be a small sattelie for the B110/T27 & a single common TL or a pair of TLs for the B139s (ie like the Fried HFried H or Fried M configurations
The weak point of this is the XO, so best to keep it where it is accessible if you ever decide it is worthwhile to start tweaking things. I know what i'd do (involves biamping, and the borrowing from the Fried mid/tweeter XO in the link above)
Here is a visualization of one of the possible TL configurations:
dave
Thanks for the responses everybody!
Great so it sounds like a transmission line is the way to go. I’ve attached a photo of the folded horn article (sorry I don’t have a scanner, I can scan it on Monday at work if anybody wants a better look) and some photos of the drivers themselves. There is some discolouration on the B139s, not sure if this will have an effect on sound, the rubber surrounds and everything look in great condition though.
The folded horn (TL?) in the article is interesting looking. It has the B139 mounted on the top of the enclosure. I am completely open to suggestions though and the satellite and TL woofer enclosure does sound very interesting (I may be biased though; my speakers are Edgar eve-II f in a similar configuration). Bi-amping will also be an option, we have a few old amps floating around now, the Yamaha A-700 and a Teac BX-300 are sitting in front of me right now.
Great so it sounds like a transmission line is the way to go. I’ve attached a photo of the folded horn article (sorry I don’t have a scanner, I can scan it on Monday at work if anybody wants a better look) and some photos of the drivers themselves. There is some discolouration on the B139s, not sure if this will have an effect on sound, the rubber surrounds and everything look in great condition though.
The folded horn (TL?) in the article is interesting looking. It has the B139 mounted on the top of the enclosure. I am completely open to suggestions though and the satellite and TL woofer enclosure does sound very interesting (I may be biased though; my speakers are Edgar eve-II f in a similar configuration). Bi-amping will also be an option, we have a few old amps floating around now, the Yamaha A-700 and a Teac BX-300 are sitting in front of me right now.
Yes, Sorry to hear of your mates Dads passing but great kit.
I sold all my B139's, but follow Daves advice and use them in a TL.
'
If the discolouration bothers you just glue some stiff dense paper on top, I used black paper I got from Officeworks 200GSM
Bi-amping is the way to go with these IMO, tweeters have got a lot better since the T-27 if I was to recommend changing anything ( I don't ) it would be the tweeter
Look at the last of the IMF studio reference monitors, they had the mid and tweeter set on top in a separate enclosure
Regards
Ted
I sold all my B139's, but follow Daves advice and use them in a TL.
'
If the discolouration bothers you just glue some stiff dense paper on top, I used black paper I got from Officeworks 200GSM
Bi-amping is the way to go with these IMO, tweeters have got a lot better since the T-27 if I was to recommend changing anything ( I don't ) it would be the tweeter
Look at the last of the IMF studio reference monitors, they had the mid and tweeter set on top in a separate enclosure
Regards
Ted
Those articles are the 2 Bailey articles that got things rolling, spawning Radford, IMF and TDL.
Modern TL simulation software lets us get closer to optimum, althou ny the time the later lines came along, so many had been prototyped they were getting pretty good.
If you can go active, a 100-250 Hz XO between the B139 & the B110 is suggested. Depends on the filam configuration.
dave
PS: i have both those articles (and the letters to the editor) already scanned & pdfed.
Modern TL simulation software lets us get closer to optimum, althou ny the time the later lines came along, so many had been prototyped they were getting pretty good.
If you can go active, a 100-250 Hz XO between the B139 & the B110 is suggested. Depends on the filam configuration.
dave
PS: i have both those articles (and the letters to the editor) already scanned & pdfed.
Is this http://www.marklev.com/IMF/SACM/index.html the monitor you are talking about moondog?
This article http://www.linkwitzlab.com/sb80-3wy.htm looks like the concept everybody is talking about.
But like you say planet10 I am sure TL and enclosure modelling in general has come a long way. Here are two other TLs I have found:
http://homepage.mac.com/planet10/TLS/downloads/B139-TTL-map-100707.pdf
http://www.t-linespeakers.org/classics/coffin/index.html
I also have a failed 41 Hz Amp 9 Basic attempt, from a recent Boominator project, that I could fix up for bi-amping these (It wouldn’t feel quite right using a chip amp with such retro speakers though). With the three drivers would bi-amping be the way to go, or would it be worth considering tri-amping?
This article http://www.linkwitzlab.com/sb80-3wy.htm looks like the concept everybody is talking about.
But like you say planet10 I am sure TL and enclosure modelling in general has come a long way. Here are two other TLs I have found:
http://homepage.mac.com/planet10/TLS/downloads/B139-TTL-map-100707.pdf
http://www.t-linespeakers.org/classics/coffin/index.html
I also have a failed 41 Hz Amp 9 Basic attempt, from a recent Boominator project, that I could fix up for bi-amping these (It wouldn’t feel quite right using a chip amp with such retro speakers though). With the three drivers would bi-amping be the way to go, or would it be worth considering tri-amping?
Yep!!
That link shows the IMF that was highly regarded at the time, and IMO worth cloning.
Or try and get another pair of B110s and do the top box as MTM.
But whichever way you go Bi-amping would be best and why not use a chip-amp??
Personal preference is for stereo woofers, the proposed XO of 200Hz is too high for Mono subs IMO
That link shows the IMF that was highly regarded at the time, and IMO worth cloning.
Or try and get another pair of B110s and do the top box as MTM.
But whichever way you go Bi-amping would be best and why not use a chip-amp??
Personal preference is for stereo woofers, the proposed XO of 200Hz is too high for Mono subs IMO
They do look very cool. What are the tweeter and super tweeter being used? They don’t look like the T27.
Here are some others that look similar:
http://cgi.ebay.com.au/Kef-105-2-10...286631640&_trksid=p3286.c0.m14&_trkparms=66:2|65%3A1|39%3A1|240%3A1318
You are right, the chip amp will probably be perfect, I just meant it seemed weird mating such old and new gear together.
The MTM idea up top sounds interesting but I just had a quick look on eBay, these drivers do go for silly money don’t they, a pair of B110s that have been pulled out of another set of speakers and repaired are A$150+. http://cgi.ebay.com.au/Pr-Kef-B110-...378148331&_trksid=p3286.c0.m14&_trkparms=66:2|65%3A1|39%3A1|240%3A1318
If I can find some cheap(ish) I would love to go down that route but otherwise I think I will just stick with the drivers I have.
I agree with the dual woofers vs combined sub, would like to keep them separate. So it looks like the way to go is:
• A TL for the B139 like Planet10 suggested (or like the 3rd link I put above)
• The B110 and T27 on top in a separate enclosure (passive XO, plus another B110 for MTM if I can find one)
• Bi-amped with the Amp 9B
Alright, looks like I am starting to get a plan together. Can anybody recommend some good (free) TL modelling software?
Here are some others that look similar:
http://cgi.ebay.com.au/Kef-105-2-10...286631640&_trksid=p3286.c0.m14&_trkparms=66:2|65%3A1|39%3A1|240%3A1318
You are right, the chip amp will probably be perfect, I just meant it seemed weird mating such old and new gear together.
The MTM idea up top sounds interesting but I just had a quick look on eBay, these drivers do go for silly money don’t they, a pair of B110s that have been pulled out of another set of speakers and repaired are A$150+. http://cgi.ebay.com.au/Pr-Kef-B110-...378148331&_trksid=p3286.c0.m14&_trkparms=66:2|65%3A1|39%3A1|240%3A1318
If I can find some cheap(ish) I would love to go down that route but otherwise I think I will just stick with the drivers I have.
I agree with the dual woofers vs combined sub, would like to keep them separate. So it looks like the way to go is:
• A TL for the B139 like Planet10 suggested (or like the 3rd link I put above)
• The B110 and T27 on top in a separate enclosure (passive XO, plus another B110 for MTM if I can find one)
• Bi-amped with the Amp 9B
Alright, looks like I am starting to get a plan together. Can anybody recommend some good (free) TL modelling software?
Thanks Moondog and Planet 10
Planet10, I have a few quick questions (please excuse my lack of knowledge).
1. To keep the stereo imaging/sound with a coffin style box you would need the driver and TL mouth both at the left end for the left channel and the right end for the right channel, correct?
2. What are the benefits of the “triangulated” design? Is it the same as the “avoid the square box” concept, standing waves etc?
3. The design you posted has quite a large volume before the driver in the TL. What is gained by this? I ask because it would be difficult to achieve if keeping with point 1.
Planet10, I have a few quick questions (please excuse my lack of knowledge).
1. To keep the stereo imaging/sound with a coffin style box you would need the driver and TL mouth both at the left end for the left channel and the right end for the right channel, correct?
2. What are the benefits of the “triangulated” design? Is it the same as the “avoid the square box” concept, standing waves etc?
3. The design you posted has quite a large volume before the driver in the TL. What is gained by this? I ask because it would be difficult to achieve if keeping with point 1.
tsnell said:
You have to ask the questions to gain the knowledge.
Yes
http://t-linespeakers.org/classics/coffin/index.html
Yes... but not really a concern if you XO low enuff... and getting adequate bracing on a TTL is a serious construction nightmare,
It has to be looked at as the driver offset from the end of the line. Proper driver position (taper dependent) will kill the firwst undesirable harmonic, allowing the use of less dampig allowing for more bass reinforcement & less ripple.
dave
Have a look at Wireless World
I remember this KEF-based design...I believe it was originally published in Wireless World, and was a transmission line design with two diagonal partitions inside a rectangular box, resulting in a triangular transmission line that reduced as it progressed towards the port.
I built a variant using the KEF B200 and the T27. I don't have the speakers any more, unfortunately, but they were my first foray into speaker-building.
I built them from the second article shown above: "The Transmission-Line Loudspeaker Enclosure." The triangular internal structure is shown on the second page of the article, which can be found here:
http://www.hifiloudspeakers.info/Anatomy/Articles/ArticlesGallery/Bailey/BaileyWWW1972/pages/ww72b2.htm
tim
I remember this KEF-based design...I believe it was originally published in Wireless World, and was a transmission line design with two diagonal partitions inside a rectangular box, resulting in a triangular transmission line that reduced as it progressed towards the port.
I built a variant using the KEF B200 and the T27. I don't have the speakers any more, unfortunately, but they were my first foray into speaker-building.
I built them from the second article shown above: "The Transmission-Line Loudspeaker Enclosure." The triangular internal structure is shown on the second page of the article, which can be found here:
http://www.hifiloudspeakers.info/Anatomy/Articles/ArticlesGallery/Bailey/BaileyWWW1972/pages/ww72b2.htm
tim
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