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1.  Conservation of the horn surfaces

Before treatment  After treatment 




Click on thumbnails below for full-size pictures from the conservation process

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Degraded
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Outside of
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Horn support
after
treatment

The large bell on the EMG horn is constructed of papier appliqué - a form of cardboard made by gluing strips of paper together. (Often it was strips of the Times Newspaper!). Then the horn was surfaced with beautifully printed paper. After some 80 years of inconsistent care this horn was in quite good condition given its vulnerability, but nevertheless had lost much of what have been its original quality. It seemed irresponsible to simply sit back while it deteriorated further under the inevitable chemical processes of degradation with passing time.

There has been some debate on the talking machine forum about how to conserve such horns. It has been noted that some attempts to varnish or paint such horns have resulted in serious degradation in the corresponding acoustic quality of the gramophones. In addition, there is no value in treating the surfaces with materials which will then in short order begin themselves to degrade. The correct approach is not obvious. So I decided to get help from the expert conservators at the Centre for Cultural Materials Conservation (CCMC) at the University of Melbourne.

After they had carefully examined the horn, including inspection under a microscope, we then discussed options with the paper and associated specialists. They trialled various approaches on small parts of the surface and it soon became clear that whilst other approaches helped, to get real improvement we did need an extremely light varnish to restore the surface. However, to preserve the accoustic qualities it seemed likely that the best approach was to apply the surfacing agents in a way that it did not soak into, and thus alter the properties of the material of the horn. What was needed was to consolidate the surface with sizing (a light starch derived liquid similar to that which would have been used to form the original papier appliqué) and then to lightly spray a very light varnish onto the surface. The CCMC had the right tools for this in a special chamber big enough to accommodate the horn for this process.

The nature of the problem to be solved, and the approach taken to addressing it, was described by the CCMC as follows:

1.1  The state of the horn before surface treatment

Degraded surface coating across paper covered object, resulting in a dull finish. Some fading of the paper, isolated to a single area. Abrasion and loss, with associated lifting paper around the outer rim of the gramophone horn. Localised abrasions and minor losses in the paper, covering the outer side of the horn and elbow. Abrasion and loss of paint on the metal component of the elbow.

1.2  Treatment

In order to restore the surface as best we could the Centre agreed to do the following:

1. Documentation and photography of damaged areas.

2. Testing of media and surface for saturation with various conservation-grade coatings.

3. Dry surface cleaned prior to sizing and coating.

4. Consolidation of lifting areas of paper with dilute wheat starch paste.

5. Application of a size layer overall, inside and outside of object, using 1% w/v Klucel G in ethanol, followed by a 2% solution of Klucel G in ethanol.

6. Spray application of 15% w/v MS2A ketone resin varnish in white spirits, followed by brush application of 20% w/v MS2A ketone resin varnish in white spirits, inside and outside of object.

7. Minimal inpainting/toning of losses and abrasions using Golden acrylic paints and Liquitex Gloss medium.

8. After treatment photography.

The result, as can be seen from the following photographs was spectacular. I think everyone involved with this project was very happy with the level of improvement that could be attained with the original textures and colours now glowing out from what had been quite faded and degraded surfaces. Of course it is still almost 100 years old so there are limits to what can be done, but the remaining imperfections are dwarfed by the elegant beauty of the conserved and revitalised horn. In relation to this I of course do want to acknowledge the professional expertise of Professor Robyn Sloggett, Director of the CCMC, and Libby Melzer, Peter Mitchelson and Vanessa Kowalski who so expertly implemented the treatment.

Of course the big issue is, how would it sound? Here I was relieved since there is always a risk in tinkering with the horn. But if anything the acoustic properties (see, for example Video demonstration of the gramophone with John Amadio playing Mozart) have improved with the upper registers a little brighter, but no reduction, and probably strengthening also of the base range.

For more pictures of the gramophone following treatment click here

2.  Rebuild of the Sound Box (Reproducer)

2.1  Preliminary state of the Sound Box.

The sound box is an original EMG 4-spring reproducer but unusually with a mica diaphragm which had cracked and broken around the point where the metal leaver from the needle holder connected to it. The rubber gaskets supporting the diaphragm and also the gasket holding the sound head to the tone arm tube were all very seriously perished, distorted and inflexible. Clearly the sound box needed a complete rebuild with a new mica diaphragm and all gaskets replaced. This also requires considerable expertise and I was extremely lucky that the relevant expert, by Chunny Bhamra,1 in Hong Kong was not only prepared to rebuild it for me, but also to do so pro bono. Thank you Chunny! Below are the photos that Chunny took as he meticulously rebuilt the sound box.

Click on thumbnails below for full-size pictures of the components

EMG 2151

Reproducer
bottom

EMG 2152

Reproducer
back

EMG 2153

Reproducer
front

2.2  The rebuild process by Chunny

Chunny reviewed the soundbox on receiving it and wrote:

I managed today to make a short video of your soundbox so I have a sound reference before I take it apart. It is definitely all original and I doubt very much that it has ever been rebuilt before. The sound quality , even with hardened rubber gaskets is superb for acoustic records. It does blast at high notes but overall it still performs well. I have several 2-spring EMG soundboxes that have the exact same back and the same stylus bar, except that yours is drilled for steel needles. I did try fiber needles but they broke up very quickly.
The steel washer ring for the tonearm rubber is missing. The mica diaphragm is damaged at the very center and the center hole is quite large causing the soundbox to leak.

Luckily Chunny had a stock of mica with the correct replacement.

Chunny has documented his restoration process with the following pictures and videos. It is sufficient to note that he carefully disassembled the sound box in its entirety and then piece by piece restored them to functional state or, in the case of the rubber gaskets and mica diaphragm, replaced them.

Click on thumbnails below for full-size pictures of the components

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2.3  Comparison videos of the original and rebuilt soundbox.

Chunny made two videos of the soundbox, played on his Expert Senior Gramophone, to document the difference in sound quality between the original and rebuilt states. In each case the record used was “Goodbye France” by Nora Bayes, Columbia A2678 , recorded in 1918. He also made a third video of the same record being played with a Meltrope III soundbox (with an aluminium diaphragm) for further comparison. In his opinion, the re-built mica diaphragm may even have outperformed the Meltrope III, but you can judge this yourself from the three videos which may be watched by clicking on the links below.

1. “Goodbye France” (1918) played with the original EMG 4-spring soundbox (with mica diaphragm) on the Expert Senior Gramphone. Click here, to listen to this video

2. “Goodbye France” (1918) played with the rebuilt EMG 4-spring soundbox (with mica diaphragm) on the Expert Senior Gramphone. Click here, to listen to this video

3. “Goodbye France” (1918) played with a Meltrope III soundbox (with aluminium diaphragm) on the Expert Senior Gramphone. Click here, to listen to this video

2.4  Chunny’s final comment on the soundbox

I do believe this is an all original soundbox and was built as is, by EMG. It has an original but unusual stylus bar drilled for steel needles and an original mica diaphragm. The only logical conclusion I can make is that it was especially built for a client who requested that it be tuned to play pre-electric records. It does excel at exactly that and may even sound better than ones fitted with an aluminum diaphragm.
 

1 See also Chunny Bhamra’s website at http://gramophone.hk (↑)

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Page last modified on 19 January 2016