Thanks for elaborating so well andy.
Regards.
I have heard 8" woofer and tweeter combination. Maybe thats why I didn't liked the sound.
Regards.
Thank you for the link to the Meniscus site. A 1750 Hz crossover seems very low for a 5.25" woofer.
I saw 3 pairs of coils in the Meniscus site picture. May be the third pair is for equalization. Anyone has the link to the detailed design article? Google did not turn up anything.
If anyone on this thread is interested, I have the following for sale.
A pair of brand new ( unused ) Falcon Acoustics LS3/5a cabinets, grille frames/cloth, foam lining and all the mounting hardware.
Also, two Kef T27s and two Kef CS1a crossover components and mounting boards.
I was going to use them, but I've now bought a Falcon LS3/5a kit to build.
I would like to sell all the components together, for £370.
That almost covers what I paid in total.
Email. milesmartyn99 at gmail dot com
I
A pair of brand new ( unused ) Falcon Acoustics LS3/5a cabinets, grille frames/cloth, foam lining and all the mounting hardware.
Also, two Kef T27s and two Kef CS1a crossover components and mounting boards.
I was going to use them, but I've now bought a Falcon LS3/5a kit to build.
I would like to sell all the components together, for £370.
That almost covers what I paid in total.
Email. milesmartyn99 at gmail dot com
I
Increasing ls3/5a internal volume to seven litres?
I notice that a number of sites describe the LS3/5a as measuring 31 by 19 by 16 cms - the BBC design document confirms this. These dimensions are described as resulting in an internal volume of "a little under five litres".
The internal dimensions of the bare LS3/5a cabinet behind the baffle measure 28 x 16.5 x 13.5 cms. This results in an internal volume of about 6.2 litres so I guess that the beech bracing, the Dedshete, the crossover, the sound absorbing foam and the space taken up by the B110 must come to about 1.2 litres which would help in adjusting the dimensions (e.g. a depth of 23.5 cms.) to result in an internal volume of seven litres as suggested by Falcon Acoustics as being more appropriate.
Sticking with 12mm ply and 1.5 cms battens this would suggest external dimensions of 31 x 26 x 16 cms. Does this make sense?
I notice that a number of sites describe the LS3/5a as measuring 31 by 19 by 16 cms - the BBC design document confirms this. These dimensions are described as resulting in an internal volume of "a little under five litres".
The internal dimensions of the bare LS3/5a cabinet behind the baffle measure 28 x 16.5 x 13.5 cms. This results in an internal volume of about 6.2 litres so I guess that the beech bracing, the Dedshete, the crossover, the sound absorbing foam and the space taken up by the B110 must come to about 1.2 litres which would help in adjusting the dimensions (e.g. a depth of 23.5 cms.) to result in an internal volume of seven litres as suggested by Falcon Acoustics as being more appropriate.
Sticking with 12mm ply and 1.5 cms battens this would suggest external dimensions of 31 x 26 x 16 cms. Does this make sense?
I just found this thread and have used search here in an attempt to keep the redundant, repetitive, and duplicative queries to a minimum.
This has not been asked. Maybe because it is a dumb question. But with this many knowledgeable KEF experts I can't resist.
How would one build a digital model of the LS3/5A crossover?
From my early reading of these digital crossovers one can specify filters, slopes, phase, timing and acronyms I don't recognize yet. I have B110's and T27's in boxes. I have thought about using them to play with a "store bought" digital crossover. I like these drivers. They are old friends. I have a working Cantata I built and still enjoy for some types of recordings. In 1984 I purchased the B139/B110/T52 and PCB 11, PCB 9 crossovers from Malcolm Jones of Falcon Acoustics.
So, with my KEF cred's established, how would I go about modeling the LS3/5A crossover in a digital crossover?
This has not been asked. Maybe because it is a dumb question. But with this many knowledgeable KEF experts I can't resist.
How would one build a digital model of the LS3/5A crossover?
From my early reading of these digital crossovers one can specify filters, slopes, phase, timing and acronyms I don't recognize yet. I have B110's and T27's in boxes. I have thought about using them to play with a "store bought" digital crossover. I like these drivers. They are old friends. I have a working Cantata I built and still enjoy for some types of recordings. In 1984 I purchased the B139/B110/T52 and PCB 11, PCB 9 crossovers from Malcolm Jones of Falcon Acoustics.
So, with my KEF cred's established, how would I go about modeling the LS3/5A crossover in a digital crossover?
What is the volume of a Kef B110?
The overall objective is to produce a relatively small, domestically acceptable, cheapish, decent sounding speaker using a T27 and a B110. Starting from the acclaimed LS3/5a as a starting point seems (to me) to make sense.
I have tried to allow for that with my "guesstimate" of 1.2 litres for it, the crossover, & etc. However, I know that the "back" of the B110 is quite substantial. This may perhaps make my calculation of internal measurements of 28 cms high x 23.5 deep x 13.5 wide for seven litres excessive. A couple of dowel braces between the sides might help absorb some volume as well as reducing resonance?
The overall objective is to produce a relatively small, domestically acceptable, cheapish, decent sounding speaker using a T27 and a B110. Starting from the acclaimed LS3/5a as a starting point seems (to me) to make sense.
$634/pair for a fully assembled bamboo cabinet and all parts necessary to build this acclaimed speaker is a great deal (http://www.diysoundgroup.com/continuum-bamboo.html).
I am tempted but working on my own ref monitor right now. (http://www.diyaudio.com/forums/full-range/273524-10f-8424-rs225-8-fast-ref-monitor.html)
Let me dig around, the XO may be on the Parts Express forum somewhere.
You might check out the Sopranos by Jeff Bagby (The cabinet measures 6.5” wide by 10.5” tall by 8” deep - tiny):
http://www.diyspeakerforum.com/viewtopic.php?f=2&t=8
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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I hope that I am not hijacking this thread on (non) LS3/5A.
I am interested in the Continuum because I am working on a project using the Dayton Audio RS28A-4.
There is a Parts Express kit using the same tweeter but a different woofer, Usher RS150-8 (PE 302-962 kit). I believe that Jeff Bagby was involved in that kit's design too. Jeff was nice enough to send me some details on the work he did with Dreydel using the same 2 drivers in the PE kit.
The original reference LS3/5a had 9mm cabinets. And don't forget that the baffle is recessed and the B110 mounted behind the baffle.
Badger Sound (affiliate of Falcon) used to recommend a deeper cabinet for their B110-based LA3/5a clone. About 23 cms if I remember right.
I didn't know that. Page six of the BBC LS3/5a design document (LINK) certainly mentions "The construction is of 12 mm (½ in) birch plywood". I believe that the front panel is still 9mm thick.
You are absolutely right, The overall external depth of the "standard" Falcon Acoustics B110/T27 Monitor Quality Compact cabinet design (LINK) was 16 cms but they recommended 23 cms.
Incidentally, I screwed up on the dimensions in an earlier post, confusing the width and the depth. The actual internal dimensions are 28 cms high x 16.5 cms wide x 13.5 cms deep. Based on these figures, I think that increasing the internal depth to 20 cms as suggested by Falcon would yield an effective internal volume of about 8 litres.
One further oddity I have noticed is that the Falcon design refers to "Two layers of 2mm Dedshete top and bottom and one layer on each side and the back". The BBC Design document doesn't include the layer of Dedshete on the back - strange?
A lot of the variations use their own version of the BBC damping panel technique. Very few use the practice of matching damping panel thickness to panel thickness.
The Stirling Broadcast cabinets use the 9mm ply of the originals. The BBC paper found no significant acoustic advantage in thicker panels. Possibly the 12mm panels are easier to handle during manufacture.
I have the Stirling cabinets (they're visible on the Resources page of the Jordan website - E.J.Jordan Designs - resources ) and find them very good. I've also constructed a wall-hanging enclosure using 9mm MDF panels, damped with bitumen pads which also sounds inert.
The Stirling Broadcast cabinets use the 9mm ply of the originals. The BBC paper found no significant acoustic advantage in thicker panels. Possibly the 12mm panels are easier to handle during manufacture.
I have the Stirling cabinets (they're visible on the Resources page of the Jordan website - E.J.Jordan Designs - resources ) and find them very good. I've also constructed a wall-hanging enclosure using 9mm MDF panels, damped with bitumen pads which also sounds inert.
I acquired a pair of 9mm LS3/5a cabinets which originally came from someone at the BBC.
They also had removeable backs.
There was no panel damping, but the foam lining was there.
I purchased bitumastic damping pads from Stirling Broadcast and a pair of matched B110s and T27s were acquired.
Falcon Acoustics 23aB crossovers were also purchased.
Sid Chaplin made me up a pair of grilles.
The result is very good indeed.
I haven't yet compared them directly to a standard LS3/5a, but
I never did like instant comparisons.
I like to live with speakers and see how they connect me to the
music.
Some LS3/5a owners appear to forget that it's all about music...
They also had removeable backs.
There was no panel damping, but the foam lining was there.
I purchased bitumastic damping pads from Stirling Broadcast and a pair of matched B110s and T27s were acquired.
Falcon Acoustics 23aB crossovers were also purchased.
Sid Chaplin made me up a pair of grilles.
The result is very good indeed.
I haven't yet compared them directly to a standard LS3/5a, but
I never did like instant comparisons.
I like to live with speakers and see how they connect me to the
music.
Some LS3/5a owners appear to forget that it's all about music...
So, I've never heard the BBC monitors or Jeff Bagby's continuum, but if you are looking for a small 2-way speaker with glass smooth response with parts cost around $300 ($470 with cabinets) I suggest my own LM-1 design. Again, never having heard the monitors you are asking about, but I did publish a technical comparison here.
The LM-1 is a nice beginner's journey, but is far below the quality level of the BBC and the continuum. LM-1 uses inexpensive drivers that makes it impossible to compare with Bagby's Continuum. At the mid price point, it is difficult to find better choice than the Aurum Cantus woofer and the Dayton Audio tweeter that Bagby used in the Continuum. These are best buy drivers compared to the KEF in the BBC monitor. (I have a pair of the ScanSpeak Revelator D2905-9900 ($500) and the Dayton Audio RS28A-4 ($100). I hope I know what I am talking about quality.) You can get the bare bone driver and crossover kit pair for the continuum for $312 at Meniscus which sounds like a better deal than the LM-1.
A vented design usually suffers in transient response when compared to a closed box. What is surprising is that the LM-1 rolls off rapidly below the mid band level as early as 150 Hz. In addition the treble above 3-4 KHz is 5dB below the mideband level. I am not sure if it is intentional or by accident. This type of LM-1 midband boost usually makes the speaker sound loud, but unnatural in balance.
The LM-1 uses simple 2nd order passive crossover which does not seem to make any attempt at BSC or woofer midband nulling. The inductor DCR is high, but it may not matter much in a vented box design. Bagby used low DCR laminated iron inductor because it is necessary for good performance. In higher quality crossover, we usually sacrifice overall efficiency to compensate for the BSC and use a larger tweeter pad to achieve better tonal balance.
Erik, the LM-1 is a nice first attempt, but your design is not quite there yet. Just wonder how you compare LM-1 to Bagby's Continuum if you never heard the Continuum? I never heard your LM-1 either. But the response curves and design schematic just look very unconventional to me. I am learning myself and had picked up a lot from other members on this forum.
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Keilau,
80% of your comments are addressed in the documentation. Please read fully before making such pointed statements, then I'll be happy to address. Some of them are just borderline ridiculous though. "Unconventional?" The schematic is as simple as you could find. If the response or the schematics look unconventional then I probably can't help you at all.
Best,
Erik
80% of your comments are addressed in the documentation. Please read fully before making such pointed statements, then I'll be happy to address. Some of them are just borderline ridiculous though. "Unconventional?" The schematic is as simple as you could find. If the response or the schematics look unconventional then I probably can't help you at all.
Best,
Erik
No driver is perfect. The crossover is used to compensate for their shortcomings. I see no attempt in LM-1 to correct the BCS and no RLC shunt across the woofer to tame the cone breakup at higher midband. That's why I call your approach unconventional. Yes, the crossover is simple and cheap. But the response curve you get with a 5 dB midband boost is, again, unconventional because most people do not design to get that kind of response curve.
See post #25 by wintermute on how he helped improve my crossover approach. I was able to verify it by my ears and by measurement. Low efficiency? Yes. But that's how you get the smooth frequency response.
http://www.diyaudio.com/forums/mult...r-modest-diy-bookshelf-speaker-project-3.html
Wintermute demonstrated the conventional way of designing a crossover as outline by Paul Carmody and accepted by many of us on this forum:
https://sites.google.com/site/undefinition/simulated-measurements
The process was based on Jeff Bagby's software. Jeff helped me in my learning too, but I have no connection to him or his commercial adventure.
You are entitled to judge what sounds best to you. I responded because I found your comparison with Continuum misleading.
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The LM-1 looks very good to me. Especially if it is a beginner's effort, it is special. The only one important consideration that is not addressed in the design is the non-linear distortion of the drivers. Most people do not address this and even think it is inaudible.
The crossover design should address the NLD. This could be the difference between cheaper designs and the more expensive design because usually expensive drivers have less compromised NLD.
Why do you think the difference in price between Continuum's drivers and LM-1's drivers matters? Is it because you can make flatter response with the more expensive drivers??? Of course the expensive one usually have lower extension but usually it is the distortion that matters.
Having said that, I have no doubt that the Continuum is a better speaker if it can be considered objective.
I agree. It is a good effort by a beginner. However, comparing it to the BBC LS3/5A and the Continuum is, should I say, presumptuous. NLD is a little too high a level of comparison. I just compared the objective (measured) and subjective (listening) perception of the frequency response. It is the most basic standard. LM-1 tried to achieve higher efficiency instead of smooth response. It is not the same as the LS3/5A or the Continuum.
The woofer and tweeter used in the LM-1 are not bad drivers. The ones in the Continuum are not superlative drivers either, but are higher quality than those Erik used in the LM-1. I have not tried the Peerless 830991, but I am very familiar with the Peerless 6.5" HDS series and the paper cone 830656. I consider the Aurum Cantus woofer used by Jeff Bagby to be higher quality, and has a higher price to go with.
I found some of the most basic consideration were missing. The LM-1 made no attempt to correct for the Baffer Step Compensation or the cone breakup. The 830991 woofer has the same 4-5 KHz cone breakup like other midbass plastic cone woofers (seen from spec sheet). When the crossover frequency is as high as in the LM-1, a RLC shunt is mandatory because the cone breakup effect is so audible.
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