Hi Empee,Hi !
the link to the B139 Ripole as mentioned in posts 2, 9 and 11 is long gone,
but here it is:
http://forum.vegalab.ru/attachment.php?attachmentid=35379&d=1219491106
Did anyone experiment further with the idea of using B139's in a dipole ?
If so;
what's your verdict ?
(apart from the ~98dB max output)
Cheers,
Empee
nice that you catchup the same timing to this old thread. Very precious that you uploaded the link to the old thread that I have saved to my faves long ago and does not exist enymore (Lycos.de)
I'm in the process to construct one sub to consolidate to my pannel project.
I'm considering of the final shape, as long as W implementations seem to work better in terms of SPL..Have you seen those ?
Cheers
Andreas
Attachments
Hi. Glad there is someone here! I'm very interested in your project. I have a couple of B139s I want to use. My set up at the moment is an OB FAST arrangement which I'm very happy with and was thinking of giving it a little more support way down low. I've been toying with the idea of sealed enclosure for below 40Hz but would prefer to stay OB/dipole. What is your set up?
Caution on using B139 even in an enclosed sub. They do hit bottom pretty quickly, and make a horrendous clatter when they do. I used to have a sub, based on the '70s Linkwitz article, and while it sounded very good, it was rather volume-limited. Replaced by 4 12" more modern (20 years ago, modern) subs, and replaced again 10 years ago with 4 10" subs. Less expensive and more output.
The 12" woofers are HiVi M12s, they have an xmax of just over 7mm. The U frames are made out of the old KEF concerto cabinets with some extra bracing, they are 12" deep and at the moment I have them against the side walls and 4' away from the front wall. They sound very good and reach easily to 40Hz without EQ. I don't want to EQ them too much to get lower, I like the fact they are doing well without excessive excursion. I also have an extra couple of B139s they are shot (voice coils are rubbing) it's very easy to remove the magnets from these and I was toying with the idea of using them as passive radiators with the working B139's. Have you any ideas, what do you think?
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Could a subwoofer plate amp (like these: Subwoofer Plate Amplifiers in the Speaker Components Department at Parts Express | 332) be used to drive a push-pull TL design like the ones found in Transmission Line Speakers? Sorry if this sounds somewhat stupid but I'm on a tight budget and I was thinking this as a cheap solution to accompany my CS1's until I invest on a new amp system.
One has to be careful. Many subs are 4Ω which means a 2Ω parallel load. I didn’t pay attention when got my SDX10. 4Ω. So i needed to get 4 amps good into 4Ω. Fortunatly Sure had a 4x100 4Ω amp board, the local electronics wiz put it all together with a compter SMPS modified for higher voltage to make a nice little amp that drove the push-push pair just fine.
dave
Good evening Dave.
I didn't manage to build the modified Triangulated TL based on your design. I have constructed the CS1's and as I said before I'm going to make a sub using the B139B's I have left. I will go with either your original Triangulated TL (one speaker) or the push-pull design. Current amp (an old but refurbished Sharp Optonica Stereo Amp - 2x33Watts @ 8 Ohm, 2x50Watts @ 4 Ohm) has only high level outputs (it has pre-outs/main in though) so that's why I was wondering if I can use a plate amp such as Dayton Audio SPA-250 (156 watts RMS into 8 ohms @ 0.1% THD, 252 watts RMS into 4 ohms @ < 1.0% THD ) to drive the sub. What I don't know (due to my limited knowledge) is that if I go with the push-pull design, which of course will result to a 4 Ohm resistance, what the impact will be on the CS1 impedance (if any).
Oh, and one more thing: I have read that push-pull designs are cabin volume sensitive so if I add the plate amp on the cabin I will have to adjust the cabin dimensions for the extra volume the amp occupies, right?
I didn't manage to build the modified Triangulated TL based on your design. I have constructed the CS1's and as I said before I'm going to make a sub using the B139B's I have left. I will go with either your original Triangulated TL (one speaker) or the push-pull design. Current amp (an old but refurbished Sharp Optonica Stereo Amp - 2x33Watts @ 8 Ohm, 2x50Watts @ 4 Ohm) has only high level outputs (it has pre-outs/main in though) so that's why I was wondering if I can use a plate amp such as Dayton Audio SPA-250 (156 watts RMS into 8 ohms @ 0.1% THD, 252 watts RMS into 4 ohms @ < 1.0% THD ) to drive the sub. What I don't know (due to my limited knowledge) is that if I go with the push-pull design, which of course will result to a 4 Ohm resistance, what the impact will be on the CS1 impedance (if any).
Oh, and one more thing: I have read that push-pull designs are cabin volume sensitive so if I add the plate amp on the cabin I will have to adjust the cabin dimensions for the extra volume the amp occupies, right?
Most cabinet/driver combos are sensitive to volume to some extent. You do need to account for the plate-amp volume.
Personally i’d use the B139s push-push with magnet scoupled and those racetrack cones visible.
dave
Fixation screws for Kef B139 woofer.
Hello. I know this probably isn't the correct thread to ask a(nother) question about the Kef B139 , sorry about this...
Problem is , I seem to be missing a pair of screws (2)to attach the B139.
So the B139 is now fixed with only 2 screws instead of 4..
How is this possible? Don't aks me please ... Ik don't know. I bought the Kef Concentro's back in 1973... Recently I replaced the T27's , and at that moment I saw 2 screws were missing from the B139...
The passed days I searched the internet to find this screws, but no luck.
The screws are about 2cm long. It seems to be the same screw , used to atach te crossover-filter. Ik have looked closely to the screw, and the only thing I know is the screw (or rather bolt) has withworth (but which exact type of withworth??) thread , and is about 5mm diameter...and 2cm's lenght.
Can anyone of you give me the exact specifications of this screw/bolt please ? (see example)
And perhaps also were I could buy two of this bolts.
Thank you very much.
Eric
Hello. I know this probably isn't the correct thread to ask a(nother) question about the Kef B139 , sorry about this...
Problem is , I seem to be missing a pair of screws (2)to attach the B139.
So the B139 is now fixed with only 2 screws instead of 4..
How is this possible? Don't aks me please ... Ik don't know. I bought the Kef Concentro's back in 1973... Recently I replaced the T27's , and at that moment I saw 2 screws were missing from the B139...
The passed days I searched the internet to find this screws, but no luck.
The screws are about 2cm long. It seems to be the same screw , used to atach te crossover-filter. Ik have looked closely to the screw, and the only thing I know is the screw (or rather bolt) has withworth (but which exact type of withworth??) thread , and is about 5mm diameter...and 2cm's lenght.
Can anyone of you give me the exact specifications of this screw/bolt please ? (see example)
And perhaps also were I could buy two of this bolts.
Thank you very much.
Eric
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I've run a pair of B139 (mid 1970s build) for many years in a TL enclosure and been very happy with the sound. Until recently used them as a woofer to extend the low end of my North Creek Okara-11 bookshelf style speakers which they did quite well. Essentially however they were operating as woofers not as sub woofers. I recently moved across the world and left the TL boxes behind but kept the B139s. I'm currently creating a new design using the B139s in 4th order band-pass enclosures. UniBox says I should get about 98 dB max SPL within +/-1 dB from 40 Hz to 135 Hz in a total box volume of 37L which provides a floor stand for the Okara-IIs and with 10W power input. The maximum SPL is Xmax limited below 45Hz so can't really go any louder.
The B139 does not make for a good subwoofer if you want a LFE speaker for a home cinema because of the very small Xmax by modern standards.
I would not use it as a dipole either again because of the very limited Xmax. Might be OK if you only listen to classical music at moderate sound levels but that's about all IMHO.
The B139 does not make for a good subwoofer if you want a LFE speaker for a home cinema because of the very small Xmax by modern standards.
I would not use it as a dipole either again because of the very limited Xmax. Might be OK if you only listen to classical music at moderate sound levels but that's about all IMHO.
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