The KEF drivers from 50-60 years ago had wider tolerances than modern drivers (hence the matching business) and speaker manufacturers understandably tended to get the better ones with the DIY market tending to get the remainder. They were not high quality drivers by modern standards. Not sure how this relates to Falcon and whoever assembles them today but the website suggests they are manufactured by hand in a similar way to 50-60 years ago. This may help the marketing to retro enthusiasts but it is unlikely to help manufacturing.
Sending genuinely out of spec drivers back is normal and Falcon would be unlikely to stay in business if they refused to replace/reimburse them. They obviously won't want them back but it is very unlikely they won't accept them if you insist they are not fit for purpose and have evidence in support. It is perfectly reasonable rather than naive to expect tolerances similar to the original B139 although those weren't tight by modern standards.
If the B110s are fine and the B139s are not then there will be a reason. Businesses will normally want to know and to work with a customer to put it right. Posting here before the process of sorting things out has run it's course was possibly unwise because it raises the temperature. It is not ideal when problems happen but they do. What is perhaps of most importance is that a business will put it right and past experience suggests Falcon will do this. If they don't, and there was a period when one their competitors didn't, then that is useful to know.
Sending genuinely out of spec drivers back is normal and Falcon would be unlikely to stay in business if they refused to replace/reimburse them. They obviously won't want them back but it is very unlikely they won't accept them if you insist they are not fit for purpose and have evidence in support. It is perfectly reasonable rather than naive to expect tolerances similar to the original B139 although those weren't tight by modern standards.
If the B110s are fine and the B139s are not then there will be a reason. Businesses will normally want to know and to work with a customer to put it right. Posting here before the process of sorting things out has run it's course was possibly unwise because it raises the temperature. It is not ideal when problems happen but they do. What is perhaps of most importance is that a business will put it right and past experience suggests Falcon will do this. If they don't, and there was a period when one their competitors didn't, then that is useful to know.
It is dissapoimtinmg to hear that the Falcon KEF recreatins are not better than the original (as they advertiuse0 and even more dissapointing that he is noiit rushing to reolce the broken ones (even thou any waranty would have been voided when you had the tech disassemble them.
I would want the drivers back just to improve QC. Whoever the OEM was/is corners were cut.
dave
I would want the drivers back just to improve QC. Whoever the OEM was/is corners were cut.
dave
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Thank you, @planet10, disappointment is the main point here. I would gladly share communication with the community here once I receive the final feedback from Falcon. Perhaps, @andy19191 is right when he said I am guilty of being naive. Additionally, it was naive to believe that the weaker side would be in the spotlight for warning the community to be cautious and for raising the temperature. The original post arose upon the initial resolution of the problem; otherwise, you probably would not hear from me.
Dear Gile, I was also thinking about purchasing some new B129/B110/T27 drivers from Falcon. So I'd be grateful if you could post a followup/postmorten to the story above. Cheers, Bruce
The Tang Band W8Q-1071F 8x12 subwoofer looks reasonably close to a drop in replacement for the B139. It's 4 ohm instead of 8 and the Vas is lower, but overall the T-S parameters are not terribly different. Sensitivity is comparable.
If you can obtain it (which is somewhat doubtful, may require a large qty order) its performance will vastly exceed the B139. 12mm Xmax, higher power handling, and the excellent build quality TB is well known for.
I used its smaller cousin W69-1042J 6x9′′ subwoofer in a project and it was outstanding.
If you can obtain it (which is somewhat doubtful, may require a large qty order) its performance will vastly exceed the B139. 12mm Xmax, higher power handling, and the excellent build quality TB is well known for.
I used its smaller cousin W69-1042J 6x9′′ subwoofer in a project and it was outstanding.
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Given the known problems with the old bextrene drivers, it may be a good idea to create a list of modern substitutes?? The B139 would be a problem because of its shape of course (although SB have a similar driver SB15SFCR39, no idea how close it is electrically, & note Perry's suggestion above). It appears there were different versions of the originals, which will complicate matters.
Edit: I note that Dave has a list of B139 subs on his site!
Edit: I note that Dave has a list of B139 subs on his site!
The Focal 5N401, 5N402 are the same size as B110. Not drop-in substitutes, but are significantly better built and better engineered drivers with fewer resonances. They work great with simpler crossovers.
I made these suggestions to another builder who is interested in a KEF inspired project:
https://www.diyaudio.com/community/...und-lincoln-ne-circa-1977.422990/post-7911809
I made these suggestions to another builder who is interested in a KEF inspired project:
https://www.diyaudio.com/community/...und-lincoln-ne-circa-1977.422990/post-7911809
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Dear Gile, I was also thinking about purchasing some new B129/B110/T27 drivers from Falcon. So I'd be grateful if you could post a followup or postmorten to the story above. Were you able to return the drivers and get your money back? Or was Falcon able to supply drivers that did not have these faults? Cheers, Bruce
Gentlemen,
To be honest I find it fairly ironic that reference is made here to the "quality" of the original KEF parts. About a dozen or so B139's passed my hands, together with 2 sets of B200 and B110's. These were alle from production years 1978-1982, with the exception of the somewhat older B200's.
To make a longe story short: building quality and serial consistancy were bloody awfull, typical for many industrial products of the UK in those years. Misglued dustcaps, misaligned voice coils, T/S parameter that were not even close to the published specs (how about Fo=42Hz for a B139 after 2 years of dayly service?) And, worst of all, a very poor power handling.
The Focal 5N series in my book is incomparable to the seemingly similar B110: the Focal is built miles and miles better.
To be honest I find it fairly ironic that reference is made here to the "quality" of the original KEF parts. About a dozen or so B139's passed my hands, together with 2 sets of B200 and B110's. These were alle from production years 1978-1982, with the exception of the somewhat older B200's.
To make a longe story short: building quality and serial consistancy were bloody awfull, typical for many industrial products of the UK in those years. Misglued dustcaps, misaligned voice coils, T/S parameter that were not even close to the published specs (how about Fo=42Hz for a B139 after 2 years of dayly service?) And, worst of all, a very poor power handling.
The Focal 5N series in my book is incomparable to the seemingly similar B110: the Focal is built miles and miles better.
"To make a longe story short: building quality and serial consistancy were bloody awfull, typical for many industrial products of the UK in those years."
Let's not forget Lucas, the provider of electrical components for automobiles, known as 'Lucas, prince of darkness' for their frequent failures. I had an MG-B with an intermittent electric fuel pump whose repair necessitated laying under the rear of the car, and giving the pump a hard smack with a moderately heavy object.
Let's not forget Lucas, the provider of electrical components for automobiles, known as 'Lucas, prince of darkness' for their frequent failures. I had an MG-B with an intermittent electric fuel pump whose repair necessitated laying under the rear of the car, and giving the pump a hard smack with a moderately heavy object.
Just a bit op sidestepping for old time's sake: @ Perry: weren't you the author of the SB article "Confessions of a (former??) loudspeaker driver designer" ?
Yep, that's me. Cool that someone remembers that. Here's a little more storytelling: https://www.diyaudio.com/community/...ex-hybrid-w-single-woofer.396877/post-7294845
as well as https://www.diyaudio.com/community/threads/what-makes-a-speaker-driver-expensive.414264/post-7722973
as well as https://www.diyaudio.com/community/threads/what-makes-a-speaker-driver-expensive.414264/post-7722973
The only rational use for KEF remakes are as dropin replacement for vintage designs that still are in use. But for a de novo projects there are better cone material than bextrene and why use tweeter domes that require 4 or even 5 way designs?
One caveat is that we are doing this as a hobbby and that is hardly rational in many ways.
One caveat is that we are doing this as a hobbby and that is hardly rational in many ways.