Where's the midrange?

[Scottmoose]

I wouldn't try it. The 139 might get up to the XO point (just) but it's not going to do it with any grace at all. Lynn Olson mentions this: http://www.nutshellhifi.com/library/...r-design2.html

[andrew ivimey]

Isobariks are in a league of their own. Classics!

Kef Cadenzas, Calindas and Cantatas are all interesting. I think it is the Calinda, though might be the Cadenza that uses a passive B139, B200 and
T27 tweeter.

It has been claimed by peeps with more experience than me, that the Kef Concerto, (aka Kef kit3?) was the best single implementation if the B139, B110 and T27.

I have Cantata boxes with passive B139, blocked up hole where T27 was and Manger where B200 was. Interesting and sort of works; great clarity anyway, even if there is precious little under 80Hz. You might be surprised though.

Manger in folded quarter wave wasn't quite right either though. More experiments, I suppose.

For the telly I use Kef Cadenzas with the B200 and T27 replaced by ESS 8inch woofer and small AMT ribbons - V.nice indeed but I am far less critical when it comes to telly and watching films.

Lynne Olson is not a fan of B139s, but hey! that doesn't make it not a great speaker, even though I am a fan of the Olson / Purvine / Island Pink etc amplifiers.

[john & Jake the dog]

Hi,
I think the B139 used within it's range is pretty good at doing it's job.
I have some info on the concerto as well and this baffle could become a candidate.
Interesting to note that the B110 in the concerto/kit3 sits in a plastic tube and is secured at the back panel by a central bolt.
Mmmmm I wonder where Ivor(Isobarik) got the idea from to mount the B110 in a tube and secure it to the back panel with a bolt

[pre65]

Hi-i know some "older" designs can still work well (like my Leaks) but i think you may be better going forward,rather than backwards !

I will say it again-you would be advised to make an effort and listen to the sorts of speaker that people from this forum are making,and then decide.

I know it is difficult for you,as you said before,but there is such a WIDE range of designs available for you to choose from.

IF i had a couple of B139 s (sold mine a while ago) i might be tempted to use them as a bass driver and mate them with a Fostex full range unit,but you have heard the trouble Andrew I had with his efforts.

I am sure if you heard something like the James D design OBs,or the VoFos,or even Shadows motronomes (with the base !) you would be mightily impressed using your valve amp,which would suit them all admirably.

I bet you would like to hear the GM70 monoblocks with Isobariks.


Philip

[John T]

Hi,

As far as I remember, the T15 was never really a great success as a tweeter as we know it - it was more of an upper/mid-range (if there is such a thing!). It was soon superseded by the T27 when the LS3/5a was introduced.

[Scottmoose]

Actually Lynn doesn't dislike the 139. He just isn't blind to it's failings, such as major resonance issues as frequency increases. I don't often agree with Lynn, but I'm with him on this -139 is a great woofer, especially for the time, but it's also best left to such duties. Going 2 way with it is looking for trouble, unless you're letting something like an 4 - 41/2in FR driver take over from ~70Hz upward.

[john & Jake the dog]

Hi all,
just bagged these off Ebay fo £1,
http://cgi.ebay.co.uk/ws/eBayISAPI.d...ME:X:AAQ:UK:11 they are just round the corner so no postage.
Got them for the boxes, any suggestions as to what I could do with them.
I've already had November the 5th and plant stand from the girlfriend.:p

Dont know if I can squeeze a B110 and a B139 in or just a B200 or whether they would work due to the internal size, measurements are 52cm high x 29 cm wide x 26 cm deep.
Any more modern suggestions?
I think 60 litres may be a minimum if using the B139, don't know?

[planet10]

The B139 & T15 were one of KEFs early 2 ways. The last iteration was in the Celeste (and KefKit 2). Crossover was at 1 kHz. The T15 will go down that far, but could use a super-tweeter. The Breakup mode in the B139 really is a problem, and really shouldn't be used above 200 Hz. They were commonly XOed at 350-400 Hz -- this was a compromise to keep the cost of XO components down.

Given a desire to use these drivers, you either have bits to start a 4-way and a serious XO development program, or use the B139 as a helper woofer, and mount the T15 on the back as an ambience tweeter.

I like the B139. I sold 100s of them brand new. Scott recently worked up a box for these which i turned into a triangular TL. (It would be easy enuff to rejig it as a coffin-style box.

dave