Ela-M 251 Body from Aliexpress

[JeffKall]

I, for one, have received so much joy and inspiration learning about these microphone ways from y’all who know so much more than I do. There is always a starting point but I think it’s a blurry line when then help is taken then monetized and exploited. I want to be in the idealized values of community where we share freely and help inspire and uplift each others ideas. I can see both sides… personally, I feel indebted to the mentors from this forum and I would have a lot less joy and excitement in my technical life with out your help.

I do not take the advice and guidance lightly and have so much respect and appreciation for the collective electronics knowledge and wisdom that had been shared here.

Yes, basic “trivial” electronics knowledge is easily researched but I think that sharing and helping each other along the way is important.

Using science and engineering to make tools to create art is just very inspiring and more of that in the world can never be a bad thing. It’s just greed and capitalism that stop us from freely sharing because the help might be used for ends that are not for the pure service of art and craft.

That’s just my feeling about it.



We all follow in someone’s footsteps. And whatever trail may be blazed will soon be tread by those who wish to follow.

This is such an incredibly well written and reasoned response … and I totally echo the sentiments expressed here !!!

The value of this forum and the willingness of those brilliant minds who share the benefit of their experience with us eager but decidedly green DIY disciples can not be ignored … and should never be taken for granted … or used for personal gain !!!

This forum only works when judicious amounts of integrity and respect are invoked !!!

I thank everyone here (and you know who you are) who has freely offered their knowledge and assistance to make all of us wiser and more equipped to capture the sound of music with the best tools possible !

Best Regards !!!

 

[geekmacdaddy]

Hi Guys and Gals,
I have built 2 D251's that sound amazing and function perfectly except one problem. When I engage figure 8, the voltage dies away. I have checked the capsules for conductivity between the 2 sides on both builds and it was "OL". Any thoughts on where my (wiring) error is? Cardioid and Omni functioning perfect.
Thank you
Geek

 

[Khron]

I have checked the capsules for conductivity between the 2 sides on both builds and it was "OL".

Which "sides"?

 

[geekmacdaddy]

front and rear body

 

[Khron]

CK12's and edge-terminated K67's have plastic on the sides, and the backplates are not easily accessible from the outside. So you measured between... long-enough screws inserted as deep as they go, in the mounting holes in each "backplate"?



If you're not getting definite contact with the backplates inside there, you could get a fake "not in contact" reading...

 

[geekmacdaddy]

I disconnected the body wires from the circuit and measured them.

 

[Khron]

I disconnected the body wires from the circuit and measured them.

And how certain are you that BOTH of the screws holding the wires onto the capsule, reach all the way to thread into the backplates themselves?

If you have any alligator clip attachments for your meter probes, i'd clamp a couple needles / solid wires (thinner than the capsule mounting screws), and stick those as deep as they'll go into a(n available ?) pair of mounting holes, and see if they are indeed isolated from each other.

What capsule is it, and where was it sourced from?

 

[RuudNL]

There are often small springs under the screw that make contact with the back plate.
It is very easy to lose the small springs when you remove the screw.
And once they have disappeared from the screw hole, they are hardly found again...

 

[geekmacdaddy]

That's a beautiful piece of info. Thank you Ruud. Khron, although the photo doesn't reveal it, I used leads from resistors to alligator clips. Here's a photo of my measurements. Thank you for staying with me.

 

[geekmacdaddy]

Khron, that diagram didn't come up at first when I read your message. That's beautiful.

 

[Delta Sigma]

Is the cap (C5 on Dany's schematic) good? And wired correctly? Have you checked the circuit with your meter while the capsule is disconnected? Personally, I would tape/secure loose leads with rated tape and measure what's going on while powered up with the capsule disconnected. Probably just the rear diaphragm and backplate.

You have to be really careful if you try this though. Very easy to cause a short from B+ to the mic body or other parts of the circuit.

 

[lightningbefore]

The metal capsule saddles come with capsule. Acrylic base...
https://www.aliexpress.us/item/3256...st_main.5.21ef1802j2aCNZ&gatewayAdapt=glo2usa

@geekmacdaddy is that a link to a capsule holder by itself or does the acrylic base come with it from your earlier Elam build pics? I'm enamored by the base you used as well!

 

[geekmacdaddy]

@geekmacdaddy is that a link to a capsule holder by itself or does the acrylic base come with it from your earlier Elam build pics? I'm enamored by the base you used as well!

I unscrew the mount from the Ali Express base, and screw the brass mount that comes with the capsule into it, if I'm understanding the question

 

[garp]

Mic finished, works like a charm, last update will be installation of moby's T14, to replace the chinese T14 pictured. Teflon PtP build

 

[geekmacdaddy]

That is beautiful work.

 

[thomasdf]

Beautiful ! What pins did you use ?

 

[garp]

Connector is binder 23 series, pins on teflon are simple ... nails ! This is by far one of the cheapest way to build a tube mic .

 

[wlinart]

And how did you mount the binder 23 series in the body? Any modifications needed? Thanks!

 

[garp]

Yes , metal workshop needed to forge the original base I don't trust 7 pin XLR for intensive use.

 

[thomasdf]

The good old clou ! Well done 7 pin XLR doesn't seem super durable indeed.