verified head still hurts
thanks dave, drboar, all. lotta complicated interactions...eek. hmmm. if the port is cut in the front instead of the bottom, maybe it gets closer to freddy's wheelhouse
yet another great circle of well-coupled acoustic reactances...reflections at all the non-smooth transitions, pipe modes. yet another fascinating indulgence in a realm packed with the things. cacophony of honking exceeds my grasp to hold in my attention. seems a job for summer, power tools, and beer. still numb, and still grateful for the scans and the sharing.
thanks dave, drboar, all. lotta complicated interactions...eek. hmmm. if the port is cut in the front instead of the bottom, maybe it gets closer to freddy's wheelhouse
yet another great circle of well-coupled acoustic reactances...reflections at all the non-smooth transitions, pipe modes. yet another fascinating indulgence in a realm packed with the things. cacophony of honking exceeds my grasp to hold in my attention. seems a job for summer, power tools, and beer. still numb, and still grateful for the scans and the sharing.
OK now it links to the images so the page does not overload.
http://i360.photobucket.com/albums/oo41/DrBoar/DeccaHorn/DeccaHorn1.jpg
http://i360.photobucket.com/albums/oo41/DrBoar/DeccaHorn/DeccaHorn2.jpg
http://i360.photobucket.com/albums/oo41/DrBoar/DeccaHorn/DeccaHorn3.jpg
http://i360.photobucket.com/albums/oo41/DrBoar/DeccaHorn/DeccaHorn4.jpg
http://i360.photobucket.com/albums/oo41/DrBoar/DeccaHorn/DeccaHorn1.jpg
http://i360.photobucket.com/albums/oo41/DrBoar/DeccaHorn/DeccaHorn2.jpg
http://i360.photobucket.com/albums/oo41/DrBoar/DeccaHorn/DeccaHorn3.jpg
http://i360.photobucket.com/albums/oo41/DrBoar/DeccaHorn/DeccaHorn4.jpg
Thanx Dr. I cleaned those up and made a pdf
http://p10hifi.net/forum/RWest-Build-Decca-Corner-Horn.pdf
dave
http://p10hifi.net/forum/RWest-Build-Decca-Corner-Horn.pdf
dave
HFN produced a more modern variant in the 1980s which was designed to be placed alongside a sofa - the idea being they acted as side tables either end of the sofa and you sat opposite them. No corners involved and the drivers and horn mouth faced forwards, so the entire enclosure was longer than tall (a corner horn laid on its back).
It used KEF drivers and had a mechanical filter part-way along to damp the driver. This was a plain partition with a grid of holes drilled in it.
I think Ralph West commented on it, mentioning that the drivers required damping in the horn, compared to older drivers.
Sorry, no idea of the article date or title except that they were referred to as 'Chairsides' and another variation was produced using a single driver Elac.
It used KEF drivers and had a mechanical filter part-way along to damp the driver. This was a plain partition with a grid of holes drilled in it.
I think Ralph West commented on it, mentioning that the drivers required damping in the horn, compared to older drivers.
Sorry, no idea of the article date or title except that they were referred to as 'Chairsides' and another variation was produced using a single driver Elac.
I have that issue, sadly due to spousal pressure the HFN &RR are stored in the attic and its hard to get to them. Late 70s or early 80s. I do not think HFN&RR have had much of DIY in the last 20 years. But I think they are a different kettle of tea with those forward facing drivers. The Decca Corner Horn is more rellated to the ACE horn, a Voigt pipe with upward facing driver and the Rogers horn from the 50s that had a upward facing Lowther unit. This was more of a true horn but with a unusally large chamber and a styrofoam membrane across the mouth of the horn, as I reacall.
HFN &RR also had the Paraline were the driver faced the wall, the long enclosure was either standing or lying sideways with quite long legs underneath them.
Then there was the Basset a single fold Voigt pipe using four 8" Elec drivers and a damping consisting of a back of muslin stuffed with wood shavings! This was used as a subwoofer with an active crossover.
HFN &RR also had the Paraline were the driver faced the wall, the long enclosure was either standing or lying sideways with quite long legs underneath them.
Then there was the Basset a single fold Voigt pipe using four 8" Elec drivers and a damping consisting of a back of muslin stuffed with wood shavings! This was used as a subwoofer with an active crossover.
I have the origonal booklet FIVE SPEAKERS published by miles henslow which
has tricolumn decca corner 12 inch decca corner paraline and corner concrete
horn designs The only one I have built is the corner horn but this was over 40 years ago
If anyone would like to see any of the articles I will try to post them
All the designs except the corner horn were based on voigt s quarter wave design
regards richie
has tricolumn decca corner 12 inch decca corner paraline and corner concrete
horn designs The only one I have built is the corner horn but this was over 40 years ago
If anyone would like to see any of the articles I will try to post them
All the designs except the corner horn were based on voigt s quarter wave design
regards richie
Hi devilsindetails
Is there any particulare design you are interested in because there are 78 pages and I
do not know about the leagality of posting the whole thing and whether DIY AUDIO
permits this If you would like a copy of the whole book and no one else is interested
I could photo copy it and post it to you otherwise perhaps one of the moderators
could give me some guidance
richie
Is there any particulare design you are interested in because there are 78 pages and I
do not know about the leagality of posting the whole thing and whether DIY AUDIO
permits this If you would like a copy of the whole book and no one else is interested
I could photo copy it and post it to you otherwise perhaps one of the moderators
could give me some guidance
richie
Hi Richard...Yes that would be a daunting task, indeed...let's see if there is any other interest first...with so much to do and so little time for all of us to do it in... unless the broader DIY community is interested I wouldn't want to monopolize your time. My interest in the designs is more general.
Perhaps after I've done some more research on this article and the designs I can contact you regarding a specific query. Thanks so much for the kind offer...much appreciated
Cleaned up and pdfed archive of Richie's scans.
http://p10hifi.net/forum/hifiNews-anthology-extract.pdf
Pages 7, 10, 33, 38. and 55 (at a minimum) all look like they would be a welcome addition to this document.
dave
http://p10hifi.net/forum/hifiNews-anthology-extract.pdf
Pages 7, 10, 33, 38. and 55 (at a minimum) all look like they would be a welcome addition to this document.
dave
Some construction notes on TriColumns
1. The baffle is simpler with modern fullrange drivers that are front mounted on the baffle.
Do not forget to recess the baffle if you want to have some cover on top...
2. Internal bracing and damping is needed
3. Using a elastic fabric sewn as a straight tube with a diameter slightly less than the tube makes an easy finish.
1. The baffle is simpler with modern fullrange drivers that are front mounted on the baffle.
Do not forget to recess the baffle if you want to have some cover on top...
2. Internal bracing and damping is needed
3. Using a elastic fabric sewn as a straight tube with a diameter slightly less than the tube makes an easy finish.
I have started to plan a build of a the Decca Corner horn. I will not build in original state with 9mm plywood and no damping what so ever! 12mm MDF or 11 mm OSB laminated with damping material is more likely.
The taper of the pipe is a bit unusual to say the least. Any opinions of there would be something gained by trying to get a more conventional flare?
I would keep the cabinet as is but add pieces of light softboard to fill out the sections below the driver to get a more conventional flare.
The intended 8" drivers are at 200-220 cm2.
Cross section in cm2
Start: 297
At start of baffle board: 428
At lower edge of driver cutout: 336
At the top of the divider oposite the driver: 440
At the bottom end of divider: 660
Bottom: 957
Then the final opening is a constricted slotloading, that in UK has bottom of a wall to wall carpet that the feet has sunk into to some undefined degree.
My plan would be to have the opening facing the corner and be of 50-100% of the surface area of the driver.
The taper of the pipe is a bit unusual to say the least. Any opinions of there would be something gained by trying to get a more conventional flare?
I would keep the cabinet as is but add pieces of light softboard to fill out the sections below the driver to get a more conventional flare.
The intended 8" drivers are at 200-220 cm2.
Cross section in cm2
Start: 297
At start of baffle board: 428
At lower edge of driver cutout: 336
At the top of the divider oposite the driver: 440
At the bottom end of divider: 660
Bottom: 957
Then the final opening is a constricted slotloading, that in UK has bottom of a wall to wall carpet that the feet has sunk into to some undefined degree.
My plan would be to have the opening facing the corner and be of 50-100% of the surface area of the driver.
Did Anyone ever build the Decca Corner Horn?
I have the original articles that are in Hifi News magazines and the patent documents they are easy to find. But I see that the documents are already on file here.
Did anyone ever build a stereo pair of Decca Corner Horns?
If they did what do they sound like?
I have studied the documents and read then over and over again. The Hifi News articles do not differ from the diagrams in the patents.
The diagrams here are slightly wrong, the feet do not go the total length of the front and back, they are according to the article formed by bits of wood referenced in Page 726 where it mentions 4 135 degree strips two of which project to form the feet and the 2 of 2" x 2" x 3/4" Fig 5 form the other two feet.
There is I would agree some oddness going on at the bass port or horn mouth as part of the sound will exit from the side and the front and the rest will go up the back wall extending the horn. I assume there will be cancellations all over the place as the sound waves will be in and out of phase. Not sure I get how that works, I would expect the sound to be diffused as it is the nature of the design.
In the follow up article on fitting a 12" speaker he mentions about the resonant frequency of the driver it should be between 40 and 90 Hz the lower the better and do not go above 90. What he is suggesting rather than modify the current baffle that is used for the 8" speaker.
He suggests that you make up a new baffle for the 12" speaker and fit spacers between the two until the magnet aligns with the horn taper panel. This of course will change the angle at which the sound is reflected as there is less space between the baffle and the rear walls. Which may be why it is suggested that it does not sound as good.
I have for some time wished to build a pair of these as I suspect that they sound rather good given the high prices that they fetch on eBay.
My main concern has been the use of the 12" driver which I intend to use. I have a pair of Dynastatic forget which model - which uses a Richard Allen CG12 and a Shackman electrostatic in a large sealed box.
I have of course wished to rehouse them for some time - they date from circa late 1960s.
I have reservations that they will work in the Decca Corner Horn - I do have the data for the CG12 drivers it is as follows:
Fs (Hz) 30, Qms 3.52, Qes 0.36, Qt 0.327, VAS (cu ft) 1.86, No (%) 0.51, Cms (M/N) 17.9, Mms 11.4 & Bl (Wb/m)13.7.
I would not how to model them nor do I have the program or calculations on how to do it, does anyone or can anyone model CG12 in the Decca Corner Horn for me?
I have some question which could be modeled as well:
What happens if you use a 3/4" batten on the bottom on all three sides except the rear?
Can the bass resonance be smoothed out by playing with those battens (which form the feet) and their placement?
I thinking that it may honk as suggested and how you go about smoothing that out.
As there is no internal damping what happens if you add some at the horn mouth? The sides are meant to flex and I am pretty certain damping should not be added. I assume that you or I may have to build them and then tweak them to suit the room in which they are used. The design in my opinion is both a finished object and a starting point for experimentation to match the room the speakers are working in.
Of course should it model out Ok then I would go ahead and build them. But I still have an issue how do I integrate the Shackman into the set up?
You can not place it on top as that will stop the reflected sound from exiting the rear. Nor is there enough space to attach it to the side of the cabinet at 36" as it will touch the side wall.
The only option I can think of is to make up a box which is open at the front and the rear with a cross brace across the rear which is attached to a stand to make it to the desired height so it is level with the ears and some kind of arrangement so you can change the angle with a wing & locking nut, if you catch my drift.
If the CG12 does not work in the model then that could be used for a sub bass woofer which seems a waste really and an alternative 8" driver would need to be sourced making it a 3 way system.
I would prefer to stick to the two way as that is easier enough to make an active crossover for and to drive the two drivers from two separate power amps per channel - Rebuilt Williamson amplifiers for the bass/mid and either a KT88 or 807 or EL84 single ended amp for the Shackman.
The original crossover frequency for the CG12 and Shackman is about 700 Hz of course it all looks simple but complicated and that is what is putting me off from building the Decca Corner Horns, any help much appreciated.
The reason I have over the years thought about building them and then come back to revisit the design is that I had no corners in my old living room in which I could have used them.
I have now moved and I now have 2 corners in which I can use them and hence why I am now giving this some serious thought. The two corners are not at the end of the room either but about two thirds of the way down. I have an arch in my living room and I not sure how that is going to interact with the speakers either.
The room is long and rectangular with the kitchen on the end forming an L shape, I am sat on a sofa at the boundary of the two with me sat in the middle of the room. It was originally 3 rooms well I use the term loosely - at the far end was the balcony - hence the atrium arch and the extra corners, and behind me was the kitchen wall, all those have have been removed to make a modern open living space.
It is now one large space with two windows in the south facing wall one in the living room and one in the kitchen. At the end of the living room is floor to ceiling windows, so lots of reflective space, all the windows have vertical blinds and the walls are Rockwool on concrete and covered with plaster board so the walls, ceiling and floor are relatively sound proof and inert.
For the UK it is a big space I would guess about 15' wide by about 25-30' long. Space was taken out of the hall to go into the bathroom and kitchen/living room plus the kitchen door was moved. The Hall is L shaped now and all the rooms lead off it, it is a much better layout and now contains no dead space, a utility room was added in the hall.
The flooring is carpet wall to wall throughout, I would measure the room but I have put my steel tape measure down somewhere safe and can not find it.........
I have the original articles that are in Hifi News magazines and the patent documents they are easy to find. But I see that the documents are already on file here.
Did anyone ever build a stereo pair of Decca Corner Horns?
If they did what do they sound like?
I have studied the documents and read then over and over again. The Hifi News articles do not differ from the diagrams in the patents.
The diagrams here are slightly wrong, the feet do not go the total length of the front and back, they are according to the article formed by bits of wood referenced in Page 726 where it mentions 4 135 degree strips two of which project to form the feet and the 2 of 2" x 2" x 3/4" Fig 5 form the other two feet.
There is I would agree some oddness going on at the bass port or horn mouth as part of the sound will exit from the side and the front and the rest will go up the back wall extending the horn. I assume there will be cancellations all over the place as the sound waves will be in and out of phase. Not sure I get how that works, I would expect the sound to be diffused as it is the nature of the design.
In the follow up article on fitting a 12" speaker he mentions about the resonant frequency of the driver it should be between 40 and 90 Hz the lower the better and do not go above 90. What he is suggesting rather than modify the current baffle that is used for the 8" speaker.
He suggests that you make up a new baffle for the 12" speaker and fit spacers between the two until the magnet aligns with the horn taper panel. This of course will change the angle at which the sound is reflected as there is less space between the baffle and the rear walls. Which may be why it is suggested that it does not sound as good.
I have for some time wished to build a pair of these as I suspect that they sound rather good given the high prices that they fetch on eBay.
My main concern has been the use of the 12" driver which I intend to use. I have a pair of Dynastatic forget which model - which uses a Richard Allen CG12 and a Shackman electrostatic in a large sealed box.
I have of course wished to rehouse them for some time - they date from circa late 1960s.
I have reservations that they will work in the Decca Corner Horn - I do have the data for the CG12 drivers it is as follows:
Fs (Hz) 30, Qms 3.52, Qes 0.36, Qt 0.327, VAS (cu ft) 1.86, No (%) 0.51, Cms (M/N) 17.9, Mms 11.4 & Bl (Wb/m)13.7.
I would not how to model them nor do I have the program or calculations on how to do it, does anyone or can anyone model CG12 in the Decca Corner Horn for me?
I have some question which could be modeled as well:
What happens if you use a 3/4" batten on the bottom on all three sides except the rear?
Can the bass resonance be smoothed out by playing with those battens (which form the feet) and their placement?
I thinking that it may honk as suggested and how you go about smoothing that out.
As there is no internal damping what happens if you add some at the horn mouth? The sides are meant to flex and I am pretty certain damping should not be added. I assume that you or I may have to build them and then tweak them to suit the room in which they are used. The design in my opinion is both a finished object and a starting point for experimentation to match the room the speakers are working in.
Of course should it model out Ok then I would go ahead and build them. But I still have an issue how do I integrate the Shackman into the set up?
You can not place it on top as that will stop the reflected sound from exiting the rear. Nor is there enough space to attach it to the side of the cabinet at 36" as it will touch the side wall.
The only option I can think of is to make up a box which is open at the front and the rear with a cross brace across the rear which is attached to a stand to make it to the desired height so it is level with the ears and some kind of arrangement so you can change the angle with a wing & locking nut, if you catch my drift.
If the CG12 does not work in the model then that could be used for a sub bass woofer which seems a waste really and an alternative 8" driver would need to be sourced making it a 3 way system.
I would prefer to stick to the two way as that is easier enough to make an active crossover for and to drive the two drivers from two separate power amps per channel - Rebuilt Williamson amplifiers for the bass/mid and either a KT88 or 807 or EL84 single ended amp for the Shackman.
The original crossover frequency for the CG12 and Shackman is about 700 Hz of course it all looks simple but complicated and that is what is putting me off from building the Decca Corner Horns, any help much appreciated.
The reason I have over the years thought about building them and then come back to revisit the design is that I had no corners in my old living room in which I could have used them.
I have now moved and I now have 2 corners in which I can use them and hence why I am now giving this some serious thought. The two corners are not at the end of the room either but about two thirds of the way down. I have an arch in my living room and I not sure how that is going to interact with the speakers either.
The room is long and rectangular with the kitchen on the end forming an L shape, I am sat on a sofa at the boundary of the two with me sat in the middle of the room. It was originally 3 rooms well I use the term loosely - at the far end was the balcony - hence the atrium arch and the extra corners, and behind me was the kitchen wall, all those have have been removed to make a modern open living space.
It is now one large space with two windows in the south facing wall one in the living room and one in the kitchen. At the end of the living room is floor to ceiling windows, so lots of reflective space, all the windows have vertical blinds and the walls are Rockwool on concrete and covered with plaster board so the walls, ceiling and floor are relatively sound proof and inert.
For the UK it is a big space I would guess about 15' wide by about 25-30' long. Space was taken out of the hall to go into the bathroom and kitchen/living room plus the kitchen door was moved. The Hall is L shaped now and all the rooms lead off it, it is a much better layout and now contains no dead space, a utility room was added in the hall.
The flooring is carpet wall to wall throughout, I would measure the room but I have put my steel tape measure down somewhere safe and can not find it.........
I have built the Decca Corner Horn. Posted here and at "drboarblogspot". Your drivers should work, lightconed drivers with highQ and high Fr works decently but best is low Q and low-mid Fr. Worst are high Q low Fr drivers like the KEF B200.
I was suprised how good DCH sounded with no damping what so ever! Felt glued to the walls improved them further and so on.
I was suprised how good DCH sounded with no damping what so ever! Felt glued to the walls improved them further and so on.
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