Newly Made EMGinn Expert Type Soundbox

[Watanabehi]

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)

These soundboxes' bodies are identical to the EMG type mica soundbox on UK ebay except the aluminum diaphragms. So did you buy those originally with mica diaphragms and change them to aluminum ones?

[leels1]

No just standard Exhibition type copies. I think they were Saturns. There’s a lot of similar off brand Exhibition types.

Just made some new springs from an old hacksaw blade to mimic the EMG springs. I had a friend 3D print a Wilson type back, but I could do with a lathe to make the backs out of metal and braise them to the original back.

[Inigo]

Thanks leels1 for your advice. I have to try the cup in reverse, as you said. Indeed it looks like I must work out simply another ridge in the centre just reverting my dome, making another smaller cup just in the centre of the dome.

[leels1]

Thanks leels1 for your advice. I have to try the cup in reverse, as you said. Indeed it looks like I must work out simply another ridge in the centre just reverting my dome, making another smaller cup just in the centre of the dome.

Let us know how you get on. There doesn’t seem to be that much contemporary literature about diaphragm design specially but Percy Wilson’s book is useful.

A lot of trial, error and testing!

[anchorman]

When one considers the amount of labor to make the meltrope type back, £175 is not too bad a price. I know I can't make one that inexpensively if I put any realistic value on my time. Sometimes the experimenting and time spent is the point. sometimes you just want the object.

The soundboxes he makes look to be high quality, and I've considered buying one in the past. He's gone through a couple of different designs over time, all based on an exhibition soundbox, as the original EMG soundboxes were too.

[leels1]

When one considers the amount of labor to make the meltrope type back, £175 is not too bad a price. I know I can't make one that inexpensively if I put any realistic value on my time. Sometimes the experimenting and time spent is the point. sometimes you just want the object.

The soundboxes he makes look to be high quality, and I've considered buying one in the past. He's gone through a couple of different designs over time, all based on an exhibition soundbox, as the original EMG soundboxes were too.

I guess you’re right. When purchasing a car you don’t pay for the metal and components only, you pay for the IP and design!

Just think the it’s missing a trick without an aluminium diaphragm as the mica one won’t have the same ability to manage greater frequency ranges. They are very well made, the back looks like it’s always been in unit with the Wright type fitting.

[anchorman]

When one considers the amount of labor to make the meltrope type back, £175 is not too bad a price. I know I can't make one that inexpensively if I put any realistic value on my time. Sometimes the experimenting and time spent is the point. sometimes you just want the object.

The soundboxes he makes look to be high quality, and I've considered buying one in the past. He's gone through a couple of different designs over time, all based on an exhibition soundbox, as the original EMG soundboxes were too.

I guess you’re right. When purchasing a car you don’t pay for the metal and components only, you pay for the IP and design!

Just think the it’s missing a trick without an aluminium diaphragm as the mica one won’t have the same ability to manage greater frequency ranges. They are very well made, the back looks like it’s always been in unit with the Wright type fitting.

some people prefer the sound of mica for some recordings. It's easy enough to make an aluminum diaphragm that is more than adequate for the job if that is preferred, and I'm guessing he would sell you one with an aluminum diaphragm if you wanted that.

[Watanabehi]

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.

It is 349 GBP on ebay "Buy It Now".

[Watanabehi]

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.

It is 349 GBP on ebay "Buy It Now".

I bought it with some discount. It is on its way to the US.

[anchorman]

Do you have an original to compare it to?