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 Post subject: EMG Gramophone Horns and Remanufacture.
PostPosted: Fri Dec 06, 2013 3:46 pm 
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Victor III
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EMG Gramophone Horns and Remanufacture

My interest in gramophones was aroused in the late twentieth century when rummaging around in a friend’s attic. These friends were lifelong collectors of all things “mechanical music” and their house was filled with wonderful treasures. I tripped up over a large wooden box and enquired as to what it might be. I was told that it was the base unit of an EMG gramophone. What is an EMG gramophone I asked and was told that it was the “Rolls Royce” of gramophones built mainly in the nineteen-thirties in relatively small numbers in London. This actual model, I subsequently learned, was an all-acoustic wind-up Mk IX but without horn, soundbox/reproducer or winder. It was suggested I take it home and play around with it even though I did not possess a single shellac record.

The box lay around the hall for a couple of years with many other unrelated projects intervening but one day I decided to see what could be done. By good fortune, I had become aware of the existence of gramophone specialist Ian Maxted who immediately offered to visit with all the necessary missing pieces (and a few records) to produce a working machine. The meeting was auspicious as there followed a glorious moment of revelation when I stood in front of the acoustic output and first heard the magical wonder of the sounds of an EMG gramophone. I could not believe my ears, in spite of the fact that, at that stage, we did not have the appropriate 22 inch outlet diameter horn but merely a tiny and incorrect cardboard petal substitute. However, the sound was so impressive that I was immediately hooked and determined to learn more.

There then followed a very steep and hugely enjoyable learning curve when I was introduced to many sizes of EMG and Expert instruments. Ian just happened to own one of the biggest and best on the planet---the EMG Xb Oversize (Export model with detachable bell)---which completely blew my mind. I had never before heard such a stupendous sound which was so good that I wanted to buy virtually every record he played ! The definition, clarity and presence were unsurpassed.

After a few months of searching, it became obvious that I was not going to be able to buy what I wanted since there are only a dozen or so Oversize EMG gramophones still existing anywhere in the world as far as is known. There was only one thing to do---build my own.

At this point, Ian very generously allowed me to measure his Oversize horn in the minutest detail in the full knowledge that I was then going to use that information to construct exact replicas. I still did not have a Xb base unit but began to assemble one from bits and pieces supplied mainly by Frank James---the celebrated writer of the famous definitive book on the subject. Ian supplied soundboxes/reproducers. The next discussion was as to what the material of the bells should be. The originals were made from papier appliqué as being the only cheaply available resource which was acoustically inert. I thought about this for quite a while and debated possible alternatives employing modern materials which were not available before WW2. Carbon fibre was suggested which would enable great strength with lightness but the heat processes involved would not have treated the moulds kindly. Then fibre-glass came to mind, which would also produce a strong and reasonably light horn, but traditionalists offered the opinion that use of such a material would produce a hard and bright internal surface which would promote unwanted frequencies instead of allowing the spherical wave front to develop in an unhindered and non-reflective way on its exponential voyage. Decisions, decisions…………….

In the end, I decided that the best way ahead was to make the first horn out of fibre-glass but as an experiment---nobody really knew what the answer would be from the theory but empirical evidence would be undeniable. The lower part of the horn was originally made from cast aluminium and there was no reason to alter this specification. The only variation I made was to design the patterns in one piece, more easily to ensure correct geometry---the originals had been made in two parts chiefly, I suspect, to allow machining on the available lathes and mills of the day.

The process was thus set in motion with the production of patterns, castings, moulds, jigs etc and on 25th July 2007 the very first fibre-glass EMG Xb Oversize horn came off the mould---a very exciting moment I have to say. Ian and a few friends were present and we were all enormously gratified that the sound, after some small development work, was indistinguishable from the output of Ian’s original papier appliqué Oversize horn. This gave me confidence to continue in this idiom and I decided to build eleven more horns making a round dozen in all. A further bonus was the fact that a fibre-glass bell should be more stable mechanically than the paper equivalent in the long term.

The cost of this work was considerable and I therefore determined to build complete gramophones so as to be able to control quality throughout the entire process and also allow the possibility of returning my capital investment. Horns are not available separately for this reason. Because of the extreme minority interest in very large acoustic gramophones, I thought a total production of a dozen instruments would be the right number to aim for. Production is now complete and some instruments sold---a few remain available. The original gramophones were known for being “handmade” and therefore individual/unique and I have continued in this tradition. As many original parts as I have been able to find have been incorporated into the “new” instruments which are all different. Some are wind-up, some electric, some are table models and others “pedestal” employing redundant cases from Lumière gramophones. EMG themselves converted many such cases to produce updated instruments in the nineteen-thirties incorporating their latest technology. Nothing is new……..

I have attached a pdf file which gives the story of the new horns which starts off showing the broken stubs of poorly designed early originals before the problems of mechanical “droop” were fully appreciated. The Xb design was the final development and certainly the best from all points of view, both mechanically and acoustically.

I also note below links to a few YouTube videos showing what the new horns sound like but please remember that there is no comparison between what is heard over the internet via compression and loudspeakers and what is heard when actually sitting in the same room directly in front of the horn. It is impossible to describe the actual sublime sound produced by an EMG Xb Oversize horn which can only be referred to as “holographic” to the extent that the artists and instruments appear to be in the same room as the listener---a totally magical and unique experience. The absolutely pure quality of the sound is unsurpassed. The playing of every record is an event.

Please see "Attachment" below for the main report on the story of the horns.



https://www.youtube.com/watch?v=uk8M1E_3NRI “Feeling my way” Eddie Lang

https://www.youtube.com/watch?v=XfnGy5hAuK0 “Gendarmes’ Duet” Malcolm McEachern/Williams

https://www.youtube.com/watch?v=IlWEvEUYqr4 “Bad penny blues” Humphrey Lyttelton

https://www.youtube.com/watch?v=0vc7d7gUQmk “Che faro ?” Kathleen Ferrier

https://www.youtube.com/watch?v=j4fA4CuufG4 “Amarilli” Beniamino Gigli

https://www.youtube.com/watch?v=d3rFwh0a-Us “Praeludium” Menuhin

https://www.youtube.com/watch?v=J8H1ORFlGXA “To be or not to be” Sir Lawrence Olivier

https://www.youtube.com/watch?v=XQ7gknOSLAY “Concerto for trumpet” Haydn

https://www.youtube.com/watch?v=cMCaR63d6Zc “Quintet in G Minor” Mozart

https://www.youtube.com/watch?v=F7gq4idM_OM "Kol Nidrei" Casals


Attachments:
EMGCR article v1 4 L.pdf [1.64 MiB]
Downloaded 690 times


Last edited by emgcr on Fri Dec 06, 2013 3:58 pm, edited 1 time in total.
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 Post subject: Re: EMG Gramophone Horns and Remanufacture.
PostPosted: Fri Dec 06, 2013 3:58 pm 
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Victor III
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Location: near Utopia, South East England
Wonderful to see this astonishing information publicly available Graham! Hats off to you!


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 Post subject: Re: EMG Gramophone Horns and Remanufacture.
PostPosted: Fri Dec 06, 2013 4:21 pm 
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Victor III
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Location: Hampshire, England.
Many thanks Andy and particularly for all your help with the pdf file. I am most grateful.


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 Post subject: Re: EMG Gramophone Horns and Remanufacture.
PostPosted: Sat Dec 07, 2013 8:01 am 
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Victor I
Joined: Mon Jun 13, 2011 8:05 pm
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Graham, as I go through your post, I reflect that we can learn about this whole mission mentally(the written story), aurally and visually. What a comprehensive and satisfying presentation on one of the most unique and interesting efforts in the life of the acoustic gramophone! Not to mention the intriguing little shafts of light it throws on the earlier manufacture of the horns!


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 Post subject: Re: EMG Gramophone Horns and Remanufacture.
PostPosted: Sat Dec 07, 2013 12:16 pm 
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Victor V
His epigrams are all his own, the man's an epigramophone!
Joined: Mon Oct 24, 2011 1:21 pm
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Location: The Somerset Levels, UK.
Graham, I am so pleased that you had the foresight to document every stage of your unique achievement, and that the results are now available to us all.

As you rightly say, the playing of every record on these machines is an event. So is every visit to your lovely home, where there is always something new to see and hear.

Roger.


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 Post subject: Re: EMG Gramophone Horns and Remanufacture.
PostPosted: Sun Dec 08, 2013 12:39 am 
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Victor II
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Location: Victoria. Australia
Well done Graham. Another fantastic endeavour.


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 Post subject: Re: EMG Gramophone Horns and Remanufacture.
PostPosted: Sun Dec 08, 2013 3:47 pm 
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Victor III
Joined: Wed Jan 07, 2009 11:07 pm
Posts: 926
Graham,

Two questions that I have been wondering for some time, if I may ask.

1. How does the fiberglass mate with the aluminum bracket? Do you overlay the fiberglass of the horn onto the aluminum bracket directly?
2. How did you replicate the dimensions of the aluminum bracket and the horn, at least generally speaking? Did you make a mold of the original aluminum bracket? How about the paper horn? Surely you didn't make a mold of it directly? I'm just really curious!

Garret


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 Post subject: Re: EMG Gramophone Horns and Remanufacture.
PostPosted: Sun Dec 08, 2013 7:23 pm 
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Victor III
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Hello Garret,

1. Yes, the fibre-glass continues all the way from the bell mouth right down to the "knuckle" at the centre of the aluminium casting. Originally this was the point where the casting was made in two parts but which has now been made in one. As the layers are added, so the "build" of fibre-glass is gradually tapered off towards the knuckle so that the cosmetic appeal is maintained/enhanced. This can only be done to the extent that is consistent with structural integrity of course. It is a balance. If you think about the mechanics, the bell is trying to escape from the casting but is restrained from doing so because the fibre-glass, when set hard, forms an ever-tightening "cone" and is thus self jamming. The aluminium casting is also dimpled to give an extra key to resist twist but, by nature, fibre-glass is a pretty sticky and tenacious material. An opposite requirement is demanded for the bell itself and a release agent is painted onto the surface of the final bell mould to ensure that adhesion is not present and allows the completed horn to dismount.

2. The quick answer to this question is by careful measurement---not moulding at this stage which would produce inaccuracies and is actually impracticable anyway.

The complete horn is made in two basic parts---the bell and the cygnet or swan-neck casting. To re-create the bell (originally in paper but, in this case, in fibre-glass), it is only necessary carefully to measure the main co-ordinates of the original and then make a template (in this case of wood) of the internal curve (ie the exact final desired form) on which salient points are then marked. All dimensions and positions can then be calculated from these basic references and a segmented male wooden former made which can be seen in the photographs. This former is gradually developed into the correct shape with the aid of the wooden template spun on a central axis.

To re-create the aluminium casting, I was very fortunate in having been able to buy an original which had lost its bell---a very rare article indeed and I have never seen another. Again, with the use of callipers, templates etc and by carefully measuring the original with special rulers which allow for the casting shrinkage of the aluminium, the form of the wooden pattern can be accurately carved. Wall thickness is measured and patterns and cores created accordingly from which moulds of special compacted sand are constructed. It is into these sand moulds that the molten aluminium is poured which then reveal the raw casting when cold and when the sand is broken away.


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 Post subject: Re: EMG Gramophone Horns and Remanufacture.
PostPosted: Sun Dec 08, 2013 9:46 pm 
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Victor III
Joined: Wed Jan 07, 2009 11:07 pm
Posts: 926
emgcr wrote:
Hello Garret,

2. The quick answer to this question is by careful measurement---not moulding at this stage which would produce inaccuracies and is actually impracticable anyway.

The complete horn is made in two basic parts---the bell and the cygnet or swan-neck casting. To re-create the bell (originally in paper but, in this case, in fibre-glass), it is only necessary carefully to measure the main co-ordinates of the original and then make a template (in this case of wood) of the internal curve (ie the exact final desired form) on which salient points are then marked. All dimensions and positions can then be calculated from these basic references and a segmented male wooden former made which can be seen in the photographs. This former is gradually developed into the correct shape with the aid of the wooden template spun on a central axis.

To re-create the aluminium casting, I was very fortunate in having been able to buy an original which had lost its bell---a very rare article indeed and I have never seen another. Again, with the use of callipers, templates etc and by carefully measuring the original with special rulers which allow for the casting shrinkage of the aluminium, the form of the wooden pattern can be accurately carved. Wall thickness is measured and patterns and cores created accordingly from which moulds of special compacted sand are constructed. It is into these sand moulds that the molten aluminium is poured which then reveal the raw casting when cold and when the sand is broken away.



Graham,

Thank you so much for this response, as well as the one you left to the question about tone arm rests! It is most insightful! Could you speak more about how you measured the horn and created the wood former? Did you use a lathe? I am just curious as to how you got it so precise. I am curious if this process can be easily replicated for other versions of the Expert and EMG lineup, especially as the original horns do have a limited lifespan, based upon the paper used in creating them. Did Expert/EMG craft their horns on a wood form, just as you have done? I am curious, especially for the Expert horns, as the metal plugs are significantly shorter, and the curves in the paper horn would make it more difficult to remove the completed horn from any mold that was created, if that makes sense!


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 Post subject: Re: EMG Gramophone Horns and Remanufacture.
PostPosted: Mon Dec 09, 2013 5:49 am 
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Victor III
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Location: Hampshire, England.
Nothing is done on a lathe. The curved pivoted template acts as a guide only to show exactly the shape one is aiming at which is then produced with the careful use of hand tools---jig saws, planes, spoke shaves, chisels etc. I do not know for definite how EMG made their horns but the technology has been well established for hundreds of years and it is probable that they went down the same route. The only difference would have been that the final male mould would have been directly made in wood rather than fibre-glass with intermediate processes.

As you say, the castings for Expert horns are much shorter and I think the formers were cleverly made in wood like shoe/boot trees incorporating central wedge-shaped sections which could be removed allowing the outer parts to be collapsed and withdrawn. This is only based on anecdotal information and I do not actually know if this is true or not. However, looking at the construction and bearing in mind that the material is predominantly paper, something like this must have been done. That is certainly how I should tackle the challenge but, who knows, the next thing will be to print whatever size you want....................


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