Ela-M 251 Body from Aliexpress

[thomasdf]

You can get pretty smooth results when printing with PLA with a small mesh and smoothing it out with acetone vapors.

But agreed the lathe'd plexi is the most beautiful result !

 

[Spencerleehorton]

I have ordered one, will see how the transplant goes!!

 

[Whoops]

3D printing is an option

Unfortunately I don't have access to a lathe, because that would probably deliver the smoothest and roundest results.

A lathe made one would probably very smooth

But with patience you can do it in a 3D printer.
Enable ironing and make it 100% filling
Then you need to sand the surface very well to make it smooth. Totally possible

 

[ElSmurf]

Went on a little google bender and came up with this :

https://lustercraft.com/product/clear-acrylic-cabochon-half-sphere/
There's a lot of those on Etsy. Other search keywords are dome paperweight magnifier.

Anybody know the dimensions of the dome inside the ElaM?

 

[johnchantler]

it's not exactly a dome though, right?

All the pictures I find of internals look like this:

 

[kingkorg]

it's not exactly a dome though, right?

All the pictures I find of internals look like this:

View attachment 113996

You would get the similar result, but if we go this deep, the screws, the stand and everything below the capsule will affect the sound to a certain extent. Also the exact height and the position of the capsule is quite important.

 

[johnchantler]

I have some feeling I've seen a drawing of the head basket internals but can't recall where now. capsule looks to be up quite high, rather than in the middle.... I think I will lasercut some stacked acrylic discs to roughly replicate the base — especially if I can work out how to bevel the edges.

 

[ElSmurf]

it's not exactly a dome though, right?

I got a little distracted by the shiny lathe'd dome, but you're right. And thanks for the clear pictures. Looks like 3D printing would deliver the most accurate results here. It's also a hollow structure it seems. There's also the matter of accommodating the different stand options. I'd probably get a Beesneez CK12 for this mic (unless Tim has some good news for us in the coming weeks/months) which has a cylindrical rubber mount. And then there's the mounting holes on the base plate.

I still have some things on my agenda for the coming week but I will have plenty of time to figure all of this out starting next weekend.

 

[Whoops]

it's not exactly a dome though, right?

All the pictures I find of internals look like this:

View attachment 113996

The Neumann U67 used a dome shape,
but that's not the case with the Ela-M 251, it's not really a dome.
3D Print seems like a good option

 

[Spencerleehorton]

I finally squeezed my proctop pcb in mine, kept not working and was the capsule connections touching the middle tube so I put some tape over them and tucked them out the way.
Put some thick rolled up wire in the bottom so when the bottom cap tightens it’s nice and secure and used the underneath washers to lengthen it so the pcb can fit!!

 

[lightningbefore]

I finally squeezed my proctop pcb in mine, kept not working and was the capsule connections touching the middle tube so I put some tape over them and tucked them out the way.
Put some thick rolled up wire in the bottom so when the bottom cap tightens it’s nice and secure and used the underneath washers to lengthen it so the pcb can fit!!View attachment 114680
View attachment 114681

Damn I don't want to ask you to open it up again but do you have any pics of it open and how you got it to fit?

 

[Spencerleehorton]

Early on in this thread they said about mounting the struts underneath and putting 4 washers to lengthen it, I did that and then you need to put something like a plastic pipe in the bottom so it tightens up. It’s on first or second page I think of this thread with pictures
HerbertR on page 4

 

[lightningbefore]

Ahh thanks I thought I was up to date on the thread all along but I guess I missed it.

 

[Spencerleehorton]

Always good to revisit threads from the start, I’ve got a stereo Neve 2254 I built but was a rats nest, I’ve started to rewire but I think I need to do the same and revisit my build thread as there are a few things I did which I can’t remember!!!

 

[ElSmurf]

I'll be getting Dany's D-251 for this body, just to save me the hassle of designing the acrylic stuff when I could be making music.
I'll still look into making the dome though, since this will have an actual impact on the sound it seems.

 

[ElSmurf]

Ok, I take it back. I've been looking into various mic builds and schematics of clones of the 251 and apart from the implementation of the pattern switch, the mic is a really simple circuit. I don't like the relay solution that's used in the D251 (or the Blackspade UM25) even though it's very elegant in use. It just looks so messy on the inside. And I don't like the usual 9-position pattern switch on the PSU solution either because that always seems to mess with the original circuit.

After taking another look at the original schematic (and this post on GS) it seems to me that this elusive pattern switch is nothing more than a rudimentary 3P3T rotary switch. Please correct me if I'm wrong.

If so, I think it would be very easy to implement a rotary switch with a small angle of throw and create a switch lever that looks like the original 251 construction with some acrylic and some decals. Do some filing in the body to get the T-shaped cutout and voila. A clunky 1960s switch.

 

[RuudNL]

I have been thinking about a rotary switch also.
For the time being I did it 'the simple way', a 3-position toggle switch...

 

[ElSmurf]

Looks like the biggest problem with my idea is that it seems to be impossible to find a 3P3T rotary switch with a 22.5 degree index angle. At least that what the angle on the 251 switch appears to be. 30 degree is very easy to find but that'll make the cutout even bigger since the total throw will go from 45 to 60 degrees. In theory Grayhill has the right switches for the job but they seem to have become unobtainium.

For the time being I did it 'the simple way', a 3-position toggle switch...

What switch did you use? Another solution could be to have the rotary mechanism actuate a toggle switch on the inside of the body. Or even a slide switch.

 

[kingkorg]

I have been thinking about a rotary switch also.
For the time being I did it 'the simple way', a 3-position toggle switch...

OC8 could be a great name for a mic

 

[RuudNL]

OC8 could be a great name for a mic

Of course you already understood that O C 8 stands for: Omni - Cardioid - Figure-8.
(I used a standard miniature 3-position toggle switch.)