Hello,
There is not a lot of information about this speaker on the internet. On source I found:
Atkinson Mini TL HFN Nov78 | Resistor | Loudspeaker
The biggest problem was to find a suitable replacement for the KEF B110 and T27 that had been used in the original.
My results may also be of interest to those who are thinking of a replica of the famous BBC LS3/5A.
You can find more information on my homepage:
home of split second photography_
It's a noncommercial and safe site. I don't use cookies, analytical, tracking or advertisement tools.
So if you have questions or if your'e interested in building those, please email me.
Best regards
An externally hosted image should be here but it was not working when we last tested it.
There is not a lot of information about this speaker on the internet. On source I found:
Atkinson Mini TL HFN Nov78 | Resistor | Loudspeaker
The biggest problem was to find a suitable replacement for the KEF B110 and T27 that had been used in the original.
My results may also be of interest to those who are thinking of a replica of the famous BBC LS3/5A.
You can find more information on my homepage:
home of split second photography_
It's a noncommercial and safe site. I don't use cookies, analytical, tracking or advertisement tools.
So if you have questions or if your'e interested in building those, please email me.
Best regards
Looks a nice and tidy build but I am curious about the motivation to go for this old and not particularly popular design rather than a modern one? Did you follow the plans exactly or did you make some modifications? Have you take measurements that show the performance of the unconventional line?
I don't see a schematic there. Now, TBH, bass loading and cabinet size is a moveable feast with any design.
The BBC Ls3/5A, which I have heard, was an impressive small monitor for voices.
The 11 ohm version looked like this:
Once you get the basic idea, and this is best done by modelling it, you can really do it with any well behaved 5" polycone and 3/4" tweeter. But it is never going to go loud or bassy. 5" doesn't do that.
I think most people struggle with the Ls3/5A design because they just don't understand BW3, being locked into phase aligned solutions. And they don't see how the LCR notch has to be adjusted with different peaky drivers. Or why the bass is deliberately recessed on the baffle.
The BBC Ls3/5A, which I have heard, was an impressive small monitor for voices.
The 11 ohm version looked like this:
Once you get the basic idea, and this is best done by modelling it, you can really do it with any well behaved 5" polycone and 3/4" tweeter. But it is never going to go loud or bassy. 5" doesn't do that.
I think most people struggle with the Ls3/5A design because they just don't understand BW3, being locked into phase aligned solutions. And they don't see how the LCR notch has to be adjusted with different peaky drivers. Or why the bass is deliberately recessed on the baffle.
andy19191 and system7
The articel may be old but it's a typical/usual Transmission Line concept that you can find in many current proposals. There is truly nothing unconventional here except the size. This design never has changed and as all concepts it has it's cons and pros. But the Kefs are outdated.
So I was looking for a chassis whose TS parameters came very close to those of the B110 and luckily found the Monacor SPH-135C. And maybe this speaker can also replace the B110 in an LS3/5A - certainly not without changing the crossover. But one could try to recreate the general concept of this speaker by installing the Bodega kit in such a cabinet.
And Yes, I did measurements. Frequency response exactly follows the "Bodega's". I did some extensive tests before I sealed the enclosure which included variations of the crossover and damping.
The articel may be old but it's a typical/usual Transmission Line concept that you can find in many current proposals. There is truly nothing unconventional here except the size. This design never has changed and as all concepts it has it's cons and pros. But the Kefs are outdated.
So I was looking for a chassis whose TS parameters came very close to those of the B110 and luckily found the Monacor SPH-135C. And maybe this speaker can also replace the B110 in an LS3/5A - certainly not without changing the crossover. But one could try to recreate the general concept of this speaker by installing the Bodega kit in such a cabinet.
And Yes, I did measurements. Frequency response exactly follows the "Bodega's". I did some extensive tests before I sealed the enclosure which included variations of the crossover and damping.
According to the first page of the article it has a chamber behind the driver and a fairly short line with no stuffing. This is not a typical transmission line configuration and how it handles the compressible resonance of the line and, possibly, an incompressible slug of air in the line bouncing on the spring of the air in the chamber like a ported speaker is what I was asking about.
In the 70s I built the Daline speaker which also had a chamber and a line. It worked reasonably well but the line was stuffed and the cabinet and line resonances were known and incorporated into the design in a conventional manner. The design would have performed poorly with no stuffing in the line hence my interest.
Neat build.
As mentioned on your website, the B110 and T27 are now back in production at Falcon Acoustics. Here's the link for anyone else interested
KEF B110 REPLACEMENT SP1003. FALCON B110 8 ohm. MATCHED PAIR. MADE IN UK.
As mentioned on your website, the B110 and T27 are now back in production at Falcon Acoustics. Here's the link for anyone else interested
KEF B110 REPLACEMENT SP1003. FALCON B110 8 ohm. MATCHED PAIR. MADE IN UK.
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I have looked up the B110 sp1003 on the Kef data sheet and the Falcon site, and there is quite a discrepancy between the 2 sets of printed specs.
Kef: Qm 6.7, Qe .33, Qt .31 Vas 23.6L
Falcon Qm 3.57, Qe .24, Qt .23 Vas 19L
Does anyone with more knowledge than me have any views.
andy19191: I'm pretty sure that there is no chamber. The drawings is misleading.
Imho it's a classical TML with a heavily folded 130cm line.
Midrange: you can find a lot of information about the LS3/5A and it's clones. They still have their devotees. I didn't want to use the B110 from Falcon. Bextrene nowadays is obsolete. Maybe this material did characterize the "British Sound" but better ones have been developed since then.
Imho it's a classical TML with a heavily folded 130cm line.
Midrange: you can find a lot of information about the LS3/5A and it's clones. They still have their devotees. I didn't want to use the B110 from Falcon. Bextrene nowadays is obsolete. Maybe this material did characterize the "British Sound" but better ones have been developed since then.
To quote the designer: "This in turn led to a totally new Maxi-Line and, as with the Mini-Line and a Midi-Line which I have also constructed, no damping is used in the line, only in the de-coupling chamber."
The designer believes there is a chamber and it is de-coupling something, presumably the line, but it is the no damping part which is odd. A conventional TL uses a small amount of damping in the line in order to let the lowest resonance through but remove the higher order resonances. With no damping the higher order resonances can be expected to be present and to show up in measurements and listening.
The Bodega design you refer to appears to be a bass reflex design and not a TL according to lautsprechershop. The ports in bass reflex designs don't have stuffing but they work quite differently to a TL by using a Helmholtz resonator formed by the slug of air in the port/line and the stiffness of the air in the chamber. Is the Atkinson speaker a ported design, a Daline-type chamber and line, a TL speaker or something else?
No disagreement or confusion here.
andy19191: Ok, I see. There is a chamber.
I was pretty aware that I was using a kit designed for a vented box in a TML. It was try and error but to my surprise: It is working really really good. If the attempt had failed, I would have built the Bodega and accepted a loss of 30€.
I had been experimenting with the Cobra horns and an active subwoofer for quite a while and then connected the TML the following day. When the music started, I rushed to the subwoofer to turn it off. However, it was not switched on. A friend brought his 2-way Dalis over for comparison and I saw him pale. This may leave an impression what you get for 400€.
I was pretty aware that I was using a kit designed for a vented box in a TML. It was try and error but to my surprise: It is working really really good. If the attempt had failed, I would have built the Bodega and accepted a loss of 30€.
I had been experimenting with the Cobra horns and an active subwoofer for quite a while and then connected the TML the following day. When the music started, I rushed to the subwoofer to turn it off. However, it was not switched on. A friend brought his 2-way Dalis over for comparison and I saw him pale. This may leave an impression what you get for 400€.
I found it interesting because of what the Falcon website states:
The Falcon B110 is designed to be a genuine and exact replacement for KEF B110 SP1003 applications. A genuine B110 as used in the classic Original LS3/5a has a 5” specialist-coated Bextrene cone in a black powder-coated chassis that exactly fits the original KEF B110 chassis dimensions.
The components used in the construction of the Falcon B110 are the same as were used in the original KEF B110. The surround, spider, magnets and metalwork are all made especially for Falcon by the original manufacturers. Bextrene for the 5” cone has been specially produced again for Falcon........
My suspicion is that the mini, midi, maxi line business involved a fair amount of nonsense and it quite reasonably disappeared almost without trace. However, without measurements or a coherent explanation of what is present and/or going on one can't say anything much with any authority.
A fairly precise amount of damping is important for a well designed transmission line to operate correctly. It needs to let the lowest resonant frequency through with minimal damping but heavily damp the unwanted harmonics. Guidance on this sort of thing is on the quarter-wave website.
If you want to consider a decoupling chamber the Daline write up makes a bit more sense but, again, without measurements and supporting analysis how worthwhile it maybe is hard to quantify. Given it is rarely used I would expect not much but for a two way with a small midwoofer it might just be if competently designed. But sorting out a competent design is likely to be a challenge.
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