Sorry you feel this is ot. 
The quick and short of it is Yes you can. Most of us are not Mr. Owl with his snarky 1, 2, 3 licks to get to the center of a Tootsie Pop. The correct answer is something Sheldon would say, for me it's about 850.
Btw the first speaker I fell in love with was an old Foster 2way another similar LS3/5a of the same era. Bought them off a HS friend back in '78 for $75/pr
The quick and short of it is Yes you can. Most of us are not Mr. Owl with his snarky 1, 2, 3 licks to get to the center of a Tootsie Pop. The correct answer is something Sheldon would say, for me it's about 850.
Btw the first speaker I fell in love with was an old Foster 2way another similar LS3/5a of the same era. Bought them off a HS friend back in '78 for $75/pr
I think the original question has a flaw in it. The word "better". If it means does the same but better, then I think the answer is no. The LS3/5a was a top of the range design. As a small free field monitor for the spoken voice with those drive units, it would be hard to improve on the original design.
Has there been a ported design with these drive units? This could at least be better for bass, albeit in a larger box.
Has there been a ported design with these drive units? This could at least be better for bass, albeit in a larger box.
You are quite right, "Better" is vague.
From H D Harwood et al's October 1976 document "The design of the minature monitoring loudspeaker type LS3/5A" (BBC RD 1976/29):
"This report describes the design of a miniature two-unit loudspeaker of adequate sound quality and loudness to serve as a monitor in conditions where larger existing designs would be unusable."
and
"There is a need to monitor sound programme quality in circumstances where space is at a premium and where headphones are not considered satisfactory. Such circumstances include the production-control section of a television mobile control-room, where the producer responsible for the overall production of the programme needs to monitor the output from the sound mixer but at levels lower than those used for mixing."
and
"... one of the objects of the design was to produce as small a loudspeaker as possible consistent with an adequate axial response / frequency characteristic."
From another place: "The LS3/5a is a legend, as a grade 2 monitor for OB vans for the BBC it has, since the 70's become a cult speaker. Why? Well, it is small, images well, fits in many places in the home, is quite uncoloured and plays loud enough for most home listening. It ís a beautifully smooth sounding speaker, the only shortcoming is it has no real deep bass but is still acceptable."
My emphasis above.
From everything I have read (and I have read quite a bit), the LS3/5A was primarily intended for use in outside broadcast (OB) vans and small studio control rooms. There was a very definite requirement that it should be capable of accurately reproducing live speech and music. There was also a need to be able to "swap in" a replacement speaker with identical characteristics, for example where an existing speaker had suffered damage.
The BBC LS3/5A's internal volume is about five litres. Kef's suggested internal volume for the B110 in a two-way infinite baffle cabinet is 7.26L. Kef suggested an internal volume of 4.25 litres where the B110 was used in a three-way cabinet but operating from above 400 Hz - i.e. when supplemented by a bass driver. I believe that Falcon Acoustics at some time suggested that a volume greater than five litres (50% increase?) might improve the bass reproduction?
I am aware that the B110 has at various times been used in many other designs including transmission lines (Robert Fris' Daline, P Atkinson's Mini Transmission Line and B J Webb's R50) and in the Rogers AB1 subwoofer which I suspect was intended to compensate for the LS3/5A's inadequate bass?
I believed at the time that combined with the specific reference to the Kef T27 & B110 along with the text of my opening post I would manage to elicit enough on-topic, comprehensible (to a layman) discourse to enable me to experiment with a spare pair of T27s & B110s. Clearly I was wrong.
I still believe that I made my question pretty damned clear; perhaps I should have avoided reference to thicker cabinet walls and/or MDF; mention of either of these issues obviously generates heated, esoteric and largely off-topic debate
C'est la vie . . .
From H D Harwood et al's October 1976 document "The design of the minature monitoring loudspeaker type LS3/5A" (BBC RD 1976/29):
"This report describes the design of a miniature two-unit loudspeaker of adequate sound quality and loudness to serve as a monitor in conditions where larger existing designs would be unusable."
and
"There is a need to monitor sound programme quality in circumstances where space is at a premium and where headphones are not considered satisfactory. Such circumstances include the production-control section of a television mobile control-room, where the producer responsible for the overall production of the programme needs to monitor the output from the sound mixer but at levels lower than those used for mixing."
and
"... one of the objects of the design was to produce as small a loudspeaker as possible consistent with an adequate axial response / frequency characteristic."
From another place: "The LS3/5a is a legend, as a grade 2 monitor for OB vans for the BBC it has, since the 70's become a cult speaker. Why? Well, it is small, images well, fits in many places in the home, is quite uncoloured and plays loud enough for most home listening. It ís a beautifully smooth sounding speaker, the only shortcoming is it has no real deep bass but is still acceptable."
My emphasis above.
From everything I have read (and I have read quite a bit), the LS3/5A was primarily intended for use in outside broadcast (OB) vans and small studio control rooms. There was a very definite requirement that it should be capable of accurately reproducing live speech and music. There was also a need to be able to "swap in" a replacement speaker with identical characteristics, for example where an existing speaker had suffered damage.
The BBC LS3/5A's internal volume is about five litres. Kef's suggested internal volume for the B110 in a two-way infinite baffle cabinet is 7.26L. Kef suggested an internal volume of 4.25 litres where the B110 was used in a three-way cabinet but operating from above 400 Hz - i.e. when supplemented by a bass driver. I believe that Falcon Acoustics at some time suggested that a volume greater than five litres (50% increase?) might improve the bass reproduction?
I am aware that the B110 has at various times been used in many other designs including transmission lines (Robert Fris' Daline, P Atkinson's Mini Transmission Line and B J Webb's R50) and in the Rogers AB1 subwoofer which I suspect was intended to compensate for the LS3/5A's inadequate bass?
I believed at the time that combined with the specific reference to the Kef T27 & B110 along with the text of my opening post I would manage to elicit enough on-topic, comprehensible (to a layman) discourse to enable me to experiment with a spare pair of T27s & B110s. Clearly I was wrong.
I still believe that I made my question pretty damned clear; perhaps I should have avoided reference to thicker cabinet walls and/or MDF; mention of either of these issues obviously generates heated, esoteric and largely off-topic debate
C'est la vie . . .
I don't think you were wrong.
The drivers cost you nothing extra.
The crossover could probably be half built from what you have and you buy the other half. That equals low cost.
The box since it's small and not from exotic materials will also cost very little.
To me this is an excellent design exercise. The result will be usable somewhere in your house, so the time you expend on design and build and test is not wasted.
surv1v0r. You are probably aware that the weakness of the LS3/5a design is in the bass. This is primarily caused by the box being so small. There is an upper bass hump, that means the speaker should not go near to the back wall, and that the speaker is very hard to integrate with a sub woofer. This is an area that could be changed, likely for the better.
The Falcon suggestion of 50% more volume would go a long way to alleviating this. If you were to use the LS3/5a design and (complex) crossover, the baffle should be kept, and the added volume achieved by increasing the depth. A problem in terms of making an LS3 type speaker is that your drive units are unlikely to be within the design specs, and so the results won't be exactly as LS3. What aural difference this makes is difficult to say. Not a huge amount is my guess.
Interestingly the original Kef Coda which used these drive units had exactly the volume you say they suggested:- 7.26 litres. The crossover in this design is SP1035. I know it is very simple, but cannot find the values with a cursory Google search. Crossover frequency is 3500Hz. As I said before, this design needs to go very near to the rear wall, otherwise the complication of baffle step correction becomes necessary in the crossover.
The Falcon suggestion of 50% more volume would go a long way to alleviating this. If you were to use the LS3/5a design and (complex) crossover, the baffle should be kept, and the added volume achieved by increasing the depth. A problem in terms of making an LS3 type speaker is that your drive units are unlikely to be within the design specs, and so the results won't be exactly as LS3. What aural difference this makes is difficult to say. Not a huge amount is my guess.
Interestingly the original Kef Coda which used these drive units had exactly the volume you say they suggested:- 7.26 litres. The crossover in this design is SP1035. I know it is very simple, but cannot find the values with a cursory Google search. Crossover frequency is 3500Hz. As I said before, this design needs to go very near to the rear wall, otherwise the complication of baffle step correction becomes necessary in the crossover.
Taking the OP "challenge" to the letter, how about a TL loaded B110 and a waveguide loaded T27 version? It would certainly be "non LS3" as it wouldn't be sealed and would be much larger.
IMHO, the T27 could benefit from a waveguide. Or perhaps a modest horn.
If loading the T27 differently improves the response and dispersion, I can only guess that a TL enclosure with a B110 would be better than the 5lt sealed enclosure in terms of bass extension and it could well be a "better, non LS3" application of these two drivers.
IMHO, the T27 could benefit from a waveguide. Or perhaps a modest horn.
If loading the T27 differently improves the response and dispersion, I can only guess that a TL enclosure with a B110 would be better than the 5lt sealed enclosure in terms of bass extension and it could well be a "better, non LS3" application of these two drivers.
Small cones cannot do High SPL at Low Frequencies, unless one builds big horns.
Just accept that small cones can do medium frequencies to high SPLs and upper bass to adequate SPLs.
Fancy loadings using vented/transmission Lines etc are attempts to extend the bass response. These are all doomed to failure because small cones can't do BOTH low bass AND high SPL.
If one filters the LF end with a high pass around 60Hz/70Hz/80Hz, then very good performance can be achieved with a small cone.
Just design to the limitations of the small cone.
Just accept that small cones can do medium frequencies to high SPLs and upper bass to adequate SPLs.
Fancy loadings using vented/transmission Lines etc are attempts to extend the bass response. These are all doomed to failure because small cones can't do BOTH low bass AND high SPL.
If one filters the LF end with a high pass around 60Hz/70Hz/80Hz, then very good performance can be achieved with a small cone.
Just design to the limitations of the small cone.
As we are not restricted by the size requirement, it would be possible to increase the dimensions of the baffle to allow optimisation of the driver placements using software like 'The Edge'
Tolvan Data
Morgan Jones makes a convincing argument for unconventional driver placement in his Arpeggio Loudspeaker article on DIYAudio- Morgan ended up preferring the Arpeggio speaker over his LS3/5A's!
http://www.diyaudio.com/forums/diyaudio-com-articles/158899-arpeggio-loudspeaker.html
Tolvan Data
Morgan Jones makes a convincing argument for unconventional driver placement in his Arpeggio Loudspeaker article on DIYAudio- Morgan ended up preferring the Arpeggio speaker over his LS3/5A's!
http://www.diyaudio.com/forums/diyaudio-com-articles/158899-arpeggio-loudspeaker.html
Size is in fact an issue as mentioned in the opening post:
The Daline+110 was also suggested earlier and I discounted it:
It was pointed out fairly early on that "small speakers have lumpy and lousy bass" and I accept this but wanted to hear any plausible, on-topic suggestions as to how one might minimise the problems stemming from a cabinet as small as the LS3/5A. It seems that the best suggestion may be to make the LS3/5A cabinet deeper by about 50%.
So what do you consider to be a optimal size and loading for the B110?
7 litres has been suggested for a sealed cabinet.
I am looking at a working pair of T27 on my workbench, and have a single spare B110. I also have a pair of Monacor SPH135/AD drivers, a spare pair of DN12 crossovers & have a working pair of KEF Concertos in my audio system.
I will be drawing up some enclosures soon, and I want to optimise the driver placement if possible.
7 litres has been suggested for a sealed cabinet.
I am looking at a working pair of T27 on my workbench, and have a single spare B110. I also have a pair of Monacor SPH135/AD drivers, a spare pair of DN12 crossovers & have a working pair of KEF Concertos in my audio system.
I will be drawing up some enclosures soon, and I want to optimise the driver placement if possible.
Aren't there potential "issues" with altering the height (baffle size / driver placement)?Yes a deeper box and perhaps also increase the hight to get twise the volume. You can even make a bass reflex box
How do you know what drivers are used on the Continuum? What is the crossover result from the "modern modeling techniques"?
Continuum, Pr
Dayton tweeter and Aurum Cantus woofer
2nd order xo at 1750Hz
If you look around there is a detailed article where Jeff Bagby explains the whole design.
the increase in diameter and the increase in Xmax both increase the SPL available at the LF end.
But neither define the frequency response.
You need to use the T/S parameters and model the speaker system to see the effect on frequency response.
OK. What I think I understand is the sound pressure level will increase but it will not extend low frequency response because it may depend on specific driver and speaker cabinet design. If I put it another way, if suitable drivers are chosen and proper cabinet is modelled can a good low end (lets say 50hz) be achieved in a two way speaker system ? Any example if at all as such ?
Regards.
Regards.
You not only need low end extension but also a maximum SPL sufficient to handle the peaks in the music. It is more the latter that is lost by using a driver like a 6.5" midwoofer that is too small for bass duties.
If you use a driver that is large enough for reasonable bass duties then it has problems working sufficiently well to cross to a small 1" tweeter. The high quality solution is to use a midrange to fill the gap. Another solution is to use a waveguide on the tweeter to extend the response lower and narrow the directivity to match the woofer. The simplest solution is simply to live with lowered performance of the woofer being stretched too high, the tweeter stretched to low and the strong change in directivity between the two.
Here is an example 2 way DIY kit with an extension to 40 Hz. However, it has used resonating ports to get there and it is still recommended to use a subwoofer.
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