TDL reference standard speakers

I have been looking for a project to utilize my B-139's, and yes I am still shopping for a second pair.bawling:
Would it be practical and / or possible to replicate the TDL "top of the line" model using a more modern mid-range and tweeter?
I was thinking of the Vifa P-13 before they become totally extinct.
Did the 45 degree angle on the front firing woofers equal the benefits of front and back bass drivers?:
 

pinkmouse

diyAudio Moderator Emeritus
2002-04-03 7:15 pm
Rotherham, England
Ah, I loved those speakers! Through the rosy glow of recollection they were excellent, and extremely dynamic, but being a student at the time I could never afford them.

IIRC, the tapered front was to reduce the apparent baffle size for the mids and tweets, rather than trying to spread the bass around.
 

Bobken

Member
2002-12-23 11:22 pm
UK
Hi,

What a coincidence!

I just referred to a still-working pair of these "Reference Series" in another thread started by a countryman of yours. Seeing this pic actually reminded me that they were not IMFs as I had wrongly suggested, but TDLs, although both were designed by John Wright and shared a lot of construction/driver similarities.
Luckily, my carelessness in this other thread was not materially significant. (A "senior moment", we call it here!)

Also, the bass drivers in those are not strictly KEF B139s as far as I know, but (IIRC) they looked like some 'specials' which I believe JW had made by Elac (!), but strangely they had exactly the same shaped cast alloy baskets, and one could physically interchange them, as I tried this out temporarily. This alternative manufacturer rather puzzled me, but if my belief is correct here, maybe they were made under license from KEF, but they did not have the usual 'KEF' lettering cast into the frames, I do clearly recall. Otherwise, I might have thought that JW had standard KEFs modified by Elac for some reason best known to him.

The most (and only!) obvious difference being that unlike the 'conventional' KEFs (at least the 2 slightly different cast-alloy framed B139 versions I am aware of) which had a rigid but very light expanded polystyrene flat-faced diaphragm, these JW versions had a more conventional paper cone with a circular dust cap. Another 'oddity' I also recall was that the 2 drivers in one cabinet had different impedances (probably 8 and 4 Ohm, but could have been 8 & 16 Ohm), and the associated X'over parts values were slightly different. I guess that this was an attempt to 'separate' any fundamental similarities/characteristics to give a better and more-even 'spread' to the bass response, and it could be that the 2 transmission lines were slightly different, to help with this too.

I re-built these massive speakers for the owner a few years ago, and they sounded very impressive when on song. Incidentally, I guess that they must have been one of the earlier implementations of the MTM arrays, which later became very fashionable, or at least I hadn't seen this driver arrangement before seing these on dem in London many years ago.

Although it was a job I was paid for, I considered it to be a privilege to be able to do some work on these old mammoths, and I never thought that this would happen when I ogled at them with some amazement so many years earlier.

If you can replicate them successfully, I am sure that you would not be unhappy with the results, anyway, and they will fill a very large room with with a lot of enjoyable sounds.:)

My guess is the same as Pinkmouse's suggestion, and that the angles were intended to keep the width of baffle down as much as possible, and help reduce the diffraction effects with a less sharp transition to the side panels. The bass these monsters produce will not be very directional at those low levels, but this shape of enclosure gave rise to a mainly non-parallel sided transmission line, which is bound to have been good for the sound.

Regards,
 
Seniors moments

Bobken
I suffer from early onset "old-timers" disease myself.
I was aware of the difference in the bass drivers visually, but in the catalougue description the are described as a 'rigid polystyrene fibreglass composite' I would have to hazard a guess that they were modified at request possibly to control the cone break-up at 1K5 that people talk about?
Perhaps I should just concentrate on a sigle driver box using the B-139's, but that is an impressive unit and one day would be worth doing I am sure.
eanee
Thanx, just popped them an E-mail
Just found out that there are only 8 Vifa p-13's left at Speakerbits and probably no more that 3 dozen left in the country, i am trying to convince my partner that I "HAVE " to have them. Just in case I need them next year you understand
 

Bobken

Member
2002-12-23 11:22 pm
UK
Hi Moondog,

I am a little confused as to which diaphragms you are reffering to when you mention Polystyrene, but this is certainly what the 'normal' KEF B139s are made of. As you are probably aware, they are just like the expanded polystyrene used in packaging, with a thin foil membrane glued to the front surface. Accordingly, the cones are still very light or low mass, but also extremely rigid, with the intention of them acting like the 'ideal' piston in use.

The drivers in the TDL, though, are quite different in this respect, looking exactly like thin paper cones, with the usual circular central dust cap, but I understand that the voice-coils were the same as KEFs. However, if it is these cones which you say are rigid polystyrene/glassfibre according to what you have read, I cannot think that this claim would be false, so I must have been mistaken in my earlier comments. The surface finish and texture of the cones was just like the usual duller/slightly rough compressed paper, unlike most synthetic plastic cones I am familiar with, which are generally more shiny and smoother-finished.

Although their cast baskets are physically identical to the later KEF units (except for no 'KEF' on them), as I said, I always knew that these were Elac-sourced, although I don't now recall why. Most likely it had a badge to indicate this on the back of the drivers, and, of course, none of the drivers in those monsters were actually KEF-sourced.

Since my last post, out of curiosity/nostalgia I clicked on the pic shown on your earlier reference, and realised that although this was an Italian site, the narrative is actually in English. This explained quite a lot to me as it makes clear that TDK is/was a subsidiary company to Elac, and that all of the drivers used were made by them. Maybe I knew this at one time, but some of these obscure details grow a bit dim with passing years.

Anyway, good luck with your endeavours, and if ever you do get around to replicating these TDL monsters, I am sure there will be a lot of interest on this Forum as to how you get on with this. As recently observed in another thread, I do believe that you would be able to surpass the mid and HF performance of any 'clones' with the better drivers now on the market, but improving on the TDL LF performance with using anything other than either B139s or the similar Elacs (if they are obtainable) would certainly take some doing.

Regards,
 
Hi Bob
As you say the picture of the drivers in the web-link does appear to be paper as you describe, but reading the catalogue description it is stated "polystyrene/fibreglass" I has actually not realised that these were in English when I made the post.
WAF will be a big factor here, not the usual space matter but money.
I am suppossed to be saving for a wedding 'mine' :D
regards Ted
 

Bobken

Member
2002-12-23 11:22 pm
UK
Hi Ted,

Congratulations on the forthcoming event, and as an old married man I can only say that I hope that you will have as happy a life together as my wife and I have had.

There are some things more important in the scheme of things than our hobbies, and who knows, maybe some time in the future you may get around to constructing the ultimate TDL clone.

Good luck to you both.

Kind regards,

Bob.:)
 
tdl

Hi Moondog,

I am a little confused as to which diaphragms you are reffering to when you mention Polystyrene, but this is certainly what the 'normal' KEF B139s are made of. As you are probably aware, they are just like the expanded polystyrene used in packaging, with a thin foil membrane glued to the front surface. Accordingly, the cones are still very light or low mass, but also extremely rigid, with the intention of them acting like the 'ideal' piston in use.

The drivers in the TDL, though, are quite different in this respect, looking exactly like thin paper cones, with the usual circular central dust cap, but I understand that the voice-coils were the same as KEFs. However, if it is these cones which you say are rigid polystyrene/glassfibre according to what you have read, I cannot think that this claim would be false, so I must have been mistaken in my earlier comments. The surface finish and texture of the cones was just like the usual duller/slightly rough compressed paper, unlike most synthetic plastic cones I am familiar with, which are generally more shiny and smoother-finished.

Although their cast baskets are physically identical to the later KEF units (except for no 'KEF' on them), as I said, I always knew that these were Elac-sourced, although I don't now recall why. Most likely it had a badge to indicate this on the back of the drivers, and, of course, none of the drivers in those monsters were actually KEF-sourced.

Since my last post, out of curiosity/nostalgia I clicked on the pic shown on your earlier reference, and realised that although this was an Italian site, the narrative is actually in English. This explained quite a lot to me as it makes clear that TDK is/was a subsidiary company to Elac, and that all of the drivers used were made by them. Maybe I knew this at one time, but some of these obscure details grow a bit dim with passing years.

Anyway, good luck with your endeavours, and if ever you do get around to replicating these TDL monsters, I am sure there will be a lot of interest on this Forum as to how you get on with this. As recently observed in another thread, I do believe that you would be able to surpass the mid and HF performance of any 'clones' with the better drivers now on the market, but improving on the TDL LF performance with using anything other than either B139s or the similar Elacs (if they are obtainable) would certainly take some doing.

Regards,
IMF started using TDL drivers whe KEF stopped producing the b139 bass unit as well as the mid range driver.
 
IMF/TDL a little history.

I have been running IMFs sinve 1976. I told all my friends "sooner or later, you will run IMFs" and many of them did. Ron Bliss was the North American importer and I became accquainted with him after buying his personal pair of IMF Professional Monitor MK III improved speakers in the "LAB GREY" colored cabinets. He always tells me he wants them back but the guy I sold them to in the early 1980s will never part with them. I currently own a pair of IMF professional Monitor MK IVs and the TDL Reference Standards. IFM could not get the KEF b139 bass units nor the mid-range drivers any more because KEF stopped making them. So, IMF started buying raw drivers from TDL. After IMF went out of business, TDL hired John Wright to design an all out transmission line speaker. The result was the TDL Reference Standard which used two woofers, two mid-range drivers, two tweeters, and one super tweeted in the same cabinet. The mid-range drivers as well as the tweeters were mounted on a narrow portion of the cabinet that was maybe only 7 inches wide. Trom there, the cabinet took a 45 degree turn on both the left and right side where they mounted the woofers, one on each side. To set them up, you would angle them inwards so that the 7 inch front where the mids and tweeters are, would cross paths just in front of the listener. The imaging on these speakers was astonishing. With metal drivers, they were very fast but never metalic sounding. All IMF/TDL professional grade speakers were very low in distortion and had full dynamics even at low listening levels. People would commonly say 'THEY SOUND LIKE 'QUADS' WITH BASS". I told my wife that she can bury me in the wooden crates they were delivered in. :)
 
You could possibly replace all drivers, including the B139, with Tang Band drivers since they make two sizes of oval woofers.
One 8x12, the W8Q-1071F and a 6x9, the W69-1042J. I think the larger one is close to the B139 but I'm not sure as I never used either.

As a mid may be TB W5-1685?

Falcoacoustics are selling new Coles 4001 if thats the one used in the TDLs.
Coles 4001G & Coles 4001K New Tweeter

They also sell a few Audax tweeters with rectangular faceplates.
 
How interesting and exciting to find an exceptionally current thread on a decades old speaker just as I get a wild hair to find or DIY a pair of these speakers. I'll certainly get in contact with Falcon and Lockwood and perhaps A.O.S., though it seems the latter has pretty much moved on to their own designs.

From what I could find so far searching it seems the tweeters and super-tweeters (or replacements) are available from Falcon. I've found no source for the mids and woofers, though Lockwood certainly seems promising given they purchased all remaining spares.

The Allegro Sound site has a brochure for the Reference Standard (not 'M') that contains a schematic, but no parts values. There are cross-sectional diagrams of the cabinet construction, but I haven't found any actual construction details. Does anyone have further insights on either of these topics?

Speaking of the 'M' - has anyone ever heard both the original and the Metal versions that could contrast them?

Thanks everyone. I hoping I can find enough information to give this a try.