What to do with KEF B139s and T15s? A TL?

The cello is largely absent and all the other instruments sound harsh and artificial - actually quite painful to listen to. I know the XOs capacitors will need replacing - but this is a still a sows ear - and it has to be the various breakups of the B139s in the crucial registers of 200 to 1000 Hz.
The 62ltr ported cabinet or one of the TL designs will bring back the cello but if you find the rest of the frequency range yukky, you are probably better off starting anew from scratch, abandoning both B139 & T15

The 'plate' I mentioned was an attempt by Laurie Fincham to alleviate some of the resonances of the early B139 in a KEF speaker using the same units.
 
@kgrlee I think what I was hearing was the combination of the upper reaches of the B139 (which is not good above 300Hz approx) and the T15 being stretched to its limit at the bottom end. I've heard, some time ago admittedly, KEF B139 three-way systems and they didn't puncture my ears like the Celestes do.

The plate you refer to I believe was fitted to some 2 way designs (but not the Celeste) for the reasons you give. Perhaps it would have been better to have used a midrange and rolled the woofer off earlier - but then a piece of wood is cheaper than another drive unit and more complex XO.
 
@planet10 Dave, I'm about to order wood - or will do after drawing up a cutting plan etc.

I think the thing to do is to build one of your B139 TL designs on t-lineloudspeakers with a satellite using a MA driver. One question is - which TL design? There's a WAF question here that potentially limits choices...

1/ Triangular design - would need a satellite on one side (as per my mockup in OO Draw). Bad WAF due to the width.
2/ Folded design. Similar WAF problem.
3/ Unfolded. A satellite could be 'mounted' on the 'slope' preserving the narrowish width. One B139 first off? with the possibility of sourcing a second if desired. Due to the narrowness the WAF is quite high - height is not a problem in our living room - only width.
4/ Your 'after Bailey' design https://t-linespeakers.org/design/foldings/tttl.html With the woofer mounted high a satellite could be on top. However I've no idea what measurements the cabinet has - or whether you worked this up into a full design.

I guess the choice is between 3 and 4, then 1, then 2.

I'll need to order an MA unit - I was thinking of a CHR70 in one of Scotts BabyLs. Or an Alpair...? Have you any thoughts on what would best partner a B139 in this case?

One quick final question - would it be advisable to double up on the baffle thickness - two sheets of 18mm ply?
 
frugal-phile™
Joined 2001
Paid Member
Note that all those lines are the “same” and the triangular one is the only one with a single driver, the others would need to be cut in half.

If you use a holey brace from th woofer to the partition you do not really need the brute force double baffle.

I like the triangiualr one personally, i irst drew that up in the clate 70s for the B200 (a by guess TL, these are modeled). The tall one was the first from the model, the rectangular one was done for a fellow in NZ.

dave
 
Thankyou.. I'll budget for the brace and work that into the cutting plan.

I have a choice of BabyTLs to choose as a satellite - using either the Pluvia 7, Alpair 6.2 or CHN70? Which would you advise would best work with the B139 in the triangular enclosure?

I'll build the satellites first and leave them as 'bare' wood to listen to in the workshop while I work on the other (and the Leak Sandwich recap etc.) I'm enthusiastically looking forward to hearing these satellites (having never heard a FR before) and getting the KEF unit to sound as it ought.
 
Found the A6.2M at a seller in France. 75Euro inc VAT. Placed it in shopping cart to estimate shipping. Price rose to 85Euro. Pondered on whether I had dementia and walked the dog to clear the air. On return price had risen to over 100Euro. I assume that they've got some form of 'interest detection' that enables airline (or these days UK railway :-( mode pricing), Very sharp, underhand and dishonest practice. Needless to say they've just lost a potential customer. :mad:

Luckily there's a respected and honest UK seller of the P7HD!
 
In an effort to understand why the A11s is not suitable I've been through the data sheets for the two drivers and am none the wiser! Is this a judgement that comes with much experience and background knowledge?

Just the check, as well, that Scotts Storm Shadow (which just says Pluvia) is suitable for the Pluvia 7.2HD - or would the Nereid plan (which says 7HD) be a better match?
 
My better half has now intervened and stated her preferences for the B139 TL cabinet. She's not so keen on @planet10 s triangular cabinet (which is a pity because I like the elegance of the triangles within it) - rather she's keener on these, in contravention of all known laws of partner household toleration:

pp-b139-tl-3d.gif



She likes the shapes and loathes boxes. To be fair she has a point - we're limited on floor space but have high ceilings. However she wishes to lacquer them in cheery colours to stand out - a combination of dark red and yellow.

That means... I have to find another pair of B139s...

So here's the newbie question - can I combine, in one cabinet,a 'racetrack' B139 with a much later model? I ask because I've potentially found two of a later model at a reasonable price.
 
You could also cut it in half. You won’t get the gains of push-push, but the depth will be half for less floor space
Do you mean literally halving the depth (so bringing the back panel forward) or halving the volume? Or are they both the same? My sense of spatial arithmetic is a tad non-existent.

@xrk971 many thanks for your kind offer but please not to spend any time. From my wifes POV it's still a box - she objects to the Celestion Ditton 25s currently in the living room on that basis - and the fact they're blandly veneered in teak.

I should have guessed at her preferences before now really - I showed her a picture 2/3 years ago of some Frugelhorns that she rather liked. Sadly, given the geography of the room (it's a very old house with lumps, bumps, alcoves etc) placing speakers against the wall (and still less the corners) is a nono. She likes interesting shapes... and as she points out I have a listening room/study/office so the living room is hers!
 
frugal-phile™
Joined 2001
Paid Member
Do you mean literally halving the depth (so bringing the back panel forward) or halving the volume?

Halving the depth, which does halve the volume, but also maintains the geometry. Imagine th evisulalization as 2 B139 traingular TLs (mirroe imaged) back to back (with the 2 unneeded backs magically going poof). That is how i designed it (from the numbers Scott derived).

dave
 
Halving the depth, which does halve the volume, but also maintains the geometry.
Just to crowbar this into my non-mathematical cranium - from the left image to the rhs - but preserving the area of the 'mouth'? I'd rather source another pair of B139s though... and I'm still tempted by the triangular design so if a third pair should turn up :)

TL-change.jpg

Sounds like the whole shape is important. Maybe something totally different? Dipole slot loaded woofer array.
Ah.... I've been looking at that for some time - and it's on my bucket list. There's about 8 speaker designs that I'd like to build, most are Scotts/Daves, but this is one of the 2 or 3 that aren't. I did listen last night to the YT files - and I'll PM you on that because I heard something very unusual - good, but unusual.

The thread started because I have a spare pair of B139s and T15s from a broken Celeste cabinet - and I wanted to build a TL with the bass units. I think I've found a possible place for the T15s - upgrading the original Leak sandwiches - but that's another thread:

https://www.diyaudio.com/community/threads/leak-sandwich-original-rebuild-and-th-parameters.408753/