Hi Genki,
the throat of a standard Autograph is sized to fit a 15inch driver.
What Max has shown is that the whole horn can be scaled to suit any size driver with an acceptable outcome that seems to surpass any other loading type.
Try scaling using something similar to Max's method to bring the autograph down in size to match the 12inch driver. This will make it a complete redseign, but the result could be worth it if this too surpasses what any other loading can get out of the 12inch SRM.
Good luck.
the throat of a standard Autograph is sized to fit a 15inch driver.
What Max has shown is that the whole horn can be scaled to suit any size driver with an acceptable outcome that seems to surpass any other loading type.
Try scaling using something similar to Max's method to bring the autograph down in size to match the 12inch driver. This will make it a complete redseign, but the result could be worth it if this too surpasses what any other loading can get out of the 12inch SRM.
Good luck.
Hi Genki, AndrewT,
Keep the faith high.
A british commercial builder of Autograph enclosures, whose name now escapes me and wich apparently went out of bussiness, stated that his enclosures were good for 15" and for 12" Tannoy coaxials. There is no problem to adapt the supporting piece to the new measure. As for the loading...I have no technical background but I believe it won't matter. (The throat is 28 cm wide)
Sorry I had no time to study your drivers specs...
The difference in size bettwen a 15" version and a reduced 12" is not that big.
When you'll want to upgrade to a better 15" coaxial you just will have to take off the front horn and its supporting bolts and instal the new drivers!
So, my advice would be, go for the full sized Autograph, unless some heavy technical reason advices in contrary.
Keep the faith high.
A british commercial builder of Autograph enclosures, whose name now escapes me and wich apparently went out of bussiness, stated that his enclosures were good for 15" and for 12" Tannoy coaxials. There is no problem to adapt the supporting piece to the new measure. As for the loading...I have no technical background but I believe it won't matter. (The throat is 28 cm wide)
Sorry I had no time to study your drivers specs...
The difference in size bettwen a 15" version and a reduced 12" is not that big.
When you'll want to upgrade to a better 15" coaxial you just will have to take off the front horn and its supporting bolts and instal the new drivers!
So, my advice would be, go for the full sized Autograph, unless some heavy technical reason advices in contrary.
Hi Max,
About the plan again. Seems you didn't recieved my email sent through the link on this web site, here is my email for the plan. Thanks in advance:
degenki@gmail.com
For the full size. It seems very ambitious. I'm not sure where it would work with my 12x driver.
Specification is: sesitivity 92db
power 100w
imperdance 8ohm
May be I need to look for some more infor.
About the plan again. Seems you didn't recieved my email sent through the link on this web site, here is my email for the plan. Thanks in advance:
degenki@gmail.com
For the full size. It seems very ambitious. I'm not sure where it would work with my 12x driver.
Specification is: sesitivity 92db
power 100w
imperdance 8ohm
May be I need to look for some more infor.
Hi all,
The name of the company is Octave Audio Woodworking. Maybe it is still in business but its webpage is out.
If some UK mate wants these enclosures but does not want to build them, maybe he/she could consider this option. I saw the photos and their work is excellent. Cost should be very high, I imagine.
The name of the company is Octave Audio Woodworking. Maybe it is still in business but its webpage is out.
If some UK mate wants these enclosures but does not want to build them, maybe he/she could consider this option. I saw the photos and their work is excellent. Cost should be very high, I imagine.
An alternative that is simpler to build
I'm very late getting here, but perhaps not TOO TOO late. Great job on those Autographs!
I read some questions and comments that I can speak to. I recently bought a pair of GRF-R cabinets from the original owner, with intact Monitor Golds. I liked the sound very much, but the horn just kind of runs out with deep bass. Great down to ~40 hz though!
So I put the drivers and crossovers in my homebrew Jensen Imperials, the 1952 plan version, and MAN it's WONDERFUL. I've been writing about it in the Imperial forum on the Decware site, as well as in the yahoo Tannoy group, with links to plans, photos, etc. These posts are easy to find if you're interested.
The Autograph is a wonderful cabinet, but if you want the very effective horn loading and you don't have corners, or are looking for a less challenging project, consider the earliest Jensen plans. The cabinet size is about 62"h x 38"w x 26" deep. They are BIG.
I'm very late getting here, but perhaps not TOO TOO late. Great job on those Autographs!
I read some questions and comments that I can speak to. I recently bought a pair of GRF-R cabinets from the original owner, with intact Monitor Golds. I liked the sound very much, but the horn just kind of runs out with deep bass. Great down to ~40 hz though!
So I put the drivers and crossovers in my homebrew Jensen Imperials, the 1952 plan version, and MAN it's WONDERFUL. I've been writing about it in the Imperial forum on the Decware site, as well as in the yahoo Tannoy group, with links to plans, photos, etc. These posts are easy to find if you're interested.
The Autograph is a wonderful cabinet, but if you want the very effective horn loading and you don't have corners, or are looking for a less challenging project, consider the earliest Jensen plans. The cabinet size is about 62"h x 38"w x 26" deep. They are BIG.
Re: An alternative that is simpler to build
similar to the Westminster Royale:-
Enclosure type Compound horn
Dimensions 1395 x 980 x 560mm (55 x 38.6 x 22in)
I don't know how Tannoy measure these but they claim -6db down at 18Hz. Would they need to be corner loaded or is floor loading and room gain enough to get those results?
Hi,tubino said:
similar to the Westminster Royale:-
Enclosure type Compound horn
Dimensions 1395 x 980 x 560mm (55 x 38.6 x 22in)
I don't know how Tannoy measure these but they claim -6db down at 18Hz. Would they need to be corner loaded or is floor loading and room gain enough to get those results?
Hi Tubino,
Thanks for your contribution.
I did not know that speaker.
Two remarks:
I saw it lacks a front horn. IMHO the best is to have every "way" horn loaded because it gives a more coherent impulse/dynamic response. See the comments about midrange at Rick's site:
http://users.on.net/~richard.norrish/Autograph/
Not only "midrange horn" adds to overall sound presentation but note that HF-midrange-bass horns have "coaxial" firing. This is perceived.
For now I am trying to find the time to develop my own front and rear horn loaded cabinet with a fullrange speaker that will not require corner loading. I pretend that one to be my last speaker (at least for my second "main system")
Cheers,
M
Thanks for your contribution.
I did not know that speaker.
Two remarks:
I saw it lacks a front horn. IMHO the best is to have every "way" horn loaded because it gives a more coherent impulse/dynamic response. See the comments about midrange at Rick's site:
http://users.on.net/~richard.norrish/Autograph/
Not only "midrange horn" adds to overall sound presentation but note that HF-midrange-bass horns have "coaxial" firing. This is perceived.
For now I am trying to find the time to develop my own front and rear horn loaded cabinet with a fullrange speaker that will not require corner loading. I pretend that one to be my last speaker (at least for my second "main system")
Cheers,
M
Comparison of horns
Hi, thanks for the kind words. I have been reading a bit about horns, and you're certainly right about the advantages of some front horn loading... but taking this one piece at a time for the moment, I would like to find (or start, if necessary!) a comparison of different rear-loading horns, in terms of length, flare, and mouth size.
I will do this for the Tannoy GRF-R cabinets I own, but am ready to start off with examples from the Jensen plan cabinets. I would love to be able to compare what I have and know with other cabinet designs. One question that particularly interests me are the theoretical and perceived sonic differences between horns of similar size & shape, but where one has two tall skinny mouths (e.g. Autographs) vs one large rectangular or square one (e.g. Jensen Imperial).
Maker: Jensen (plans only)
Model: Imperial (in original plans, simply called Backloaded Horn for 15 inch driver)
Year: First plans, 1952. Revised (simpler) plans in 1956
Drivers: Plans recommended Jensen 610-G triaxial
Shape: Rectangular
Dimensions: 62 h x 38 w x 26 d (depends on material used)
Mouth Dimensions: 36 w x 32 h
US dimensions
Overall 62 h x 38 w x 26 d
Horn Mouth 36w x 32 h
Mouth area 1152 sq in
Equiv circular radius 19.15"
Equiv circular diameter 38.3"
Equiv circumference 120.3"
Metric dimensions
Horn Mouth 91.5 cm x 81 cm
Mouth area 7411 sq cm
Equiv circular radius 48.57 cm
Equiv circular diameter 97.14 cm
Equiv circumference 305.2 cm
Hi, thanks for the kind words. I have been reading a bit about horns, and you're certainly right about the advantages of some front horn loading... but taking this one piece at a time for the moment, I would like to find (or start, if necessary!) a comparison of different rear-loading horns, in terms of length, flare, and mouth size.
I will do this for the Tannoy GRF-R cabinets I own, but am ready to start off with examples from the Jensen plan cabinets. I would love to be able to compare what I have and know with other cabinet designs. One question that particularly interests me are the theoretical and perceived sonic differences between horns of similar size & shape, but where one has two tall skinny mouths (e.g. Autographs) vs one large rectangular or square one (e.g. Jensen Imperial).
Maker: Jensen (plans only)
Model: Imperial (in original plans, simply called Backloaded Horn for 15 inch driver)
Year: First plans, 1952. Revised (simpler) plans in 1956
Drivers: Plans recommended Jensen 610-G triaxial
Shape: Rectangular
Dimensions: 62 h x 38 w x 26 d (depends on material used)
Mouth Dimensions: 36 w x 32 h
US dimensions
Overall 62 h x 38 w x 26 d
Horn Mouth 36w x 32 h
Mouth area 1152 sq in
Equiv circular radius 19.15"
Equiv circular diameter 38.3"
Equiv circumference 120.3"
Metric dimensions
Horn Mouth 91.5 cm x 81 cm
Mouth area 7411 sq cm
Equiv circular radius 48.57 cm
Equiv circular diameter 97.14 cm
Equiv circumference 305.2 cm
Hi Tubino
What I nice looking cabinet!
You know I'm no expert, and my horn theory study has been postponed by other more urgent projects.
But, to exploit the teaching of Scottmoose and AndrewT (sorry if I fail you guys ) I'll try to argument...
The bass output will be a function of the flare rate and length of the horn and the lowest F a function of the area of the mouth, right?
The Imperial's horn lenght seems to be at least equal to Autograph's (maybe a little shorter, because Autograph has a front-back-front final fold, midway back-front length) so the bass enhancement should be comparable.
About LF floor: based on Dinsdale's articles, page 5, table#2, about minimum area (sq. feet) at wall placement, and IF I made no mistakes converting areas, the 8 sq.ft mouth should be good for 50 or so Hz (?)
http://www.volvotreter.de/downloads/Dinsdale_Horns_2.pdf
You know splitting the horn doesn't change the bass reach. The Autograph's 6.63 sq.ft mouth, corner mounted, is good for 40 or so Hz: table #3 of the same article.
Now, I've told before that the angle of the bass split mouth affects sound perception: the more on-axis the least "fat" and the more "clean" sound and vice/versa (I know I may have midbass excess but I'm happy with it and changing cables-equipment make such changes to sound that decided not to be inside the box every time tweaking the throat). Listening far behind, next to the rear wall makes the fatter sound (not bass-reflex fat but horn fat, which is a nice kind of obesity )
I hope others could opine.
Cheers,
M
What I nice looking cabinet!
You know I'm no expert, and my horn theory study has been postponed by other more urgent projects.
But, to exploit the teaching of Scottmoose and AndrewT (sorry if I fail you guys
) I'll try to argument...The bass output will be a function of the flare rate and length of the horn and the lowest F a function of the area of the mouth, right?
The Imperial's horn lenght seems to be at least equal to Autograph's (maybe a little shorter, because Autograph has a front-back-front final fold, midway back-front length) so the bass enhancement should be comparable.
About LF floor: based on Dinsdale's articles, page 5, table#2, about minimum area (sq. feet) at wall placement, and IF I made no mistakes converting areas, the 8 sq.ft mouth should be good for 50 or so Hz (?)
http://www.volvotreter.de/downloads/Dinsdale_Horns_2.pdf
You know splitting the horn doesn't change the bass reach. The Autograph's 6.63 sq.ft mouth, corner mounted, is good for 40 or so Hz: table #3 of the same article.
Now, I've told before that the angle of the bass split mouth affects sound perception: the more on-axis the least "fat" and the more "clean" sound and vice/versa (I know I may have midbass excess but I'm happy with it and changing cables-equipment make such changes to sound that decided not to be inside the box every time tweaking the throat). Listening far behind, next to the rear wall makes the fatter sound (not bass-reflex fat but horn fat, which is a nice kind of obesity
)I hope others could opine.
Cheers,
M
Max, thanks so much for the comparison of horn mouth shapes. I find this a very interesting notion...
As you see from the images I posted, the cabinet I have has the mouth bordering two sides. Over the holidays I plan to tip them over with the mouths to the outside, pushed to the corners. These beasts are confined to the basement (not fit for civilized company, in my wife's view), but there they have concrete and cinder blocks in the corner. Of course these are excellent for bass reinforcement, so I ought to get solid bass to quite low frequencies.
It would be fair to say I'm looking for a magic trick, a way to get the performance of the Autograph in an easier-to-build cabinet. I think that's pretty much what Steve Deckert intended with his redesign of the Imperial to use 2 15" drivers. But of course there are always trade-offs and compromises... so that's really what I'm trying to understand in this comparison.
Would an all-out backloaded horn look more like the tall twin mouths of the big Tannoy cabinets, or the single mouth below like the Decware Imperial? If the cabinet is NOT intended for corner use, is that a point AWAY from the tall mouths and FOR the floor-bordering rectangle?
Maybe this should be another thread...
As you see from the images I posted, the cabinet I have has the mouth bordering two sides. Over the holidays I plan to tip them over with the mouths to the outside, pushed to the corners. These beasts are confined to the basement (not fit for civilized company, in my wife's view), but there they have concrete and cinder blocks in the corner. Of course these are excellent for bass reinforcement, so I ought to get solid bass to quite low frequencies.
It would be fair to say I'm looking for a magic trick, a way to get the performance of the Autograph in an easier-to-build cabinet. I think that's pretty much what Steve Deckert intended with his redesign of the Imperial to use 2 15" drivers. But of course there are always trade-offs and compromises... so that's really what I'm trying to understand in this comparison.
Would an all-out backloaded horn look more like the tall twin mouths of the big Tannoy cabinets, or the single mouth below like the Decware Imperial? If the cabinet is NOT intended for corner use, is that a point AWAY from the tall mouths and FOR the floor-bordering rectangle?
Maybe this should be another thread...