Newly Made EMGinn Expert Type Soundbox

[Watanabehi]

Hi EMG lovers,

Check out the following youtube, shared by Martin Herrick.

https://www.youtube.com/watch?v=qnxzJE7Py6w

[CarlosV]

Interesting, externally it looks identical to an Expert, apart from the diaphragm. The question is - does it perform like the Expert? The diaphragm, being a key component, may be the differentiator between the copy and the real deal. Also the later Expert model has a larger diaphragm than that of the Exhibition, and a more extensive frequency response on the low end.

[Steve]

Interesting, externally it looks identical to an Expert, apart from the diaphragm. The question is - does it perform like the Expert? The diaphragm, being a key component, may be the differentiator between the copy and the real deal. Also the later Expert model has a larger diaphragm than that of the Exhibition, and a more extensive frequency response on the low end.

I agree, Carlos, whilst it's a commendable effort, the diaphragm is fundamentally different AND smaller but the stylus bar is clearly not matching the Expert specification either. It's really an improved Exhibition dressed up as an Expert.

[leels1]

Not convinced it’s worth the price tag either. But still, if someone’s prepared to pay…

[JerryVan]

Not convinced it’s worth the price tag either. But still, if someone’s prepared to pay…

What is the price tag? I have not seen one mentioned.

[Inigo]

Just for fun, I was just prepared to launch a new post on my latest experiments with the Exhibition soundbox, which I've lately resumed, and which are also going to be my Achilles' Heel or the pit where all my failures lay... An ad-hoc reply for that much serious attempt to imitate the EMG soundbox. My own trials are a joke aside these professional modifications...
Anyway, I'll describe for posterity the modifications I've done on my Exhibition used to emulate the EMGs, or at least trying to improve the sound. Watch the photos for details.
1) The stiff metal balance springs are repositioned, using them as pressing bars, with ball bearings placed in their cupped ends, relocated so they press against the needlebar fulcrum plate (see photos). Thick rubber washers cut from gasket tubing serve as actual springs to maintain the pressure, against the screws heads. The pressure can be adjusted, with the screws pressing on the rubber washers, and also with the position of the balls on the plate, so they can be placed on the center line, just on top of the knife edges, or slightly misplaced out of the axis so they damp the needlebar vibration.
2) A handmade aluminium diaphragm, cut from a food container. Central dome, crests and valleys shaped using a handy tool with a ball point, pressing against a soft towel. This in the photos is my fourth version, where the outer flat crown has been 'spun' by hand, in the radial direction on both sides, using the ballpoint tool.
3) Modified air chamber and relaxed diaphragm edge pressure; the screws at the back of the soundbox maintain the minimum pressure on the gaskets so there are no air leaks, but the pressure on the diaphragm edge is minimum. This also enhances the air chamber behind the diaphragm. I use rubber pieces squeezed between the back and the front ring so I can press the screws against them in these intermediate positions. They are 2.5-3 turns unscrewed from the full-down position.
4) A handmade tracking alignment corrector, formed with a 158º - Ø18mm copper elbow (half-cut from a standard 135º elbow) painted in black and attached to the Exhibition rubber flange neck. This provides a much better tracking alignment with the grooves for the gooseneck tonearm.
And what?
The sound is enhanced, certainly, loude and deeper than that of a mica or glass diaphragm, but I don't like it very much. I cannot get rid of a certain 'ringing' resonance which, in my opinion, spoils the tone. I always compare my experiments with the same machine (a hornless tabletop Model III HMV Gramophone, euro version of the Victrola VI) using a HMV no 5A soundbox, which in this small horn gives a full clear round tone, with treble and some bass, and no ringing tones of any kind. I believe this is impossible to imitate with such a small thing as the Exhibition. This is kind of my tenth or twelfth experiment, and still I don't like the tone.
Herein you have some photos illustrating the modifications and the tools used, and a couple videos; one is a 1930 spanish electrical recorgding from the zarzuela 'La VIejecita', and the other is acoustic recording of De Lucia singing O Sole Mio. The videos can be seen in my YT channel. Watch https://youtu.be/TlCAUwEAqsg and https://www.youtube.com/watch?v=QUYpoNPkvJk

[CarlosV]

Herein you have some photos illustrating the modifications and the tools used, and a couple videos; one is a 1930 spanish electrical recorgding from the zarzuela 'La VIejecita', and the other is acoustic recording of De Lucia singing O Sole Mio. The videos can be seen in my YT channel. Watch https://youtu.be/TlCAUwEAqsg and https://www.youtube.com/watch?v=QUYpoNPkvJk

Iñigo, the acoustic record sounds quite nice, but there is something harsh in the electric recording. It is not possible to discern if it is due to the soundbox, the recording itsef, the horn or you tube, you are the judge on that, being able to listen in person. As far as efforts to replicate the Expert go, there are some obstacles that are hard to overcome: the material, forming and thickness of the diaphragm and the construction of the needle bar (as Steve pointed out above). These are critical in determining resonances, or their lack - there is a thread currently going on discussing loading the needle bar with dense putting to remove resonances viewtopic.php?f=7&t=56452&sid=32f5fcf39 ... d&start=10. The hybrid construction of the Expert/EMG soundbox needle bar is unique, with its aluminium base and iron/steel stem, and not easily reproducible.

[Inigo]

Carlos, thanks for the link... ZI have to test what Leoni has done.. maybe that's the right solution!

[leels1]

As others have said, the diaphragm makes all the difference, but specifically the rings and the placement of the rings. An aluminium diaphragm would be the obvious choice over mica.

After much testing of the thickness of various original diaphragms, I came to the conclusion that a regular coke can (or most other aluminium cans) is the correct thickness. In order to replicate the originals it must be annealed though to make it less "springy". It should bend and hold the bend without springing back as with the originals. I think from memory (can't find my notes) it was 0.12mm thick. A decent alu takeaway container is also good, but not the thinner pie dish type ones. These also don't need to be annealed.

The rings - I think the original EMG / Expert design is probably the best, similar to Inigo's pics. Too many rings too near the edge and it loses the piston action. I think the dome in the centre on Inigo's should go the other way though, a depression from the front rather than a dome to the front, which also helps the needle bar sit correctly so the needle is perpendicular to the record.

The video posted does sound good, and hard to tell via YouTube, but with less, and more central rings closer to the needle bar attachment, more of a "pump" would be heard to give more bass and an all round tonally better sound (not that what you can here is bad!)

These are two examples I did when I first started testing (note I did the coke can the wrong way round!) which sound OK, but need more work to make the centre piece more rigid to give more compliance.

Some UK beer cans have some good designs on them, so if you can cut it right and anneal without burning the design off, you can make some custom pictured diaphragms too! (Just a thought)

[leels1]

Not convinced it’s worth the price tag either. But still, if someone’s prepared to pay…

What is the price tag? I have not seen one mentioned.

They were £175 on ebay