ELAM 251 build in brass

Spencerleehorton · Dec 22, 2014

hi guys,

Thought I'd share my build.
Have use 3 x 1uf caps rather than a 3uf.
Relays are 5v but haven't arrived yet along with the 4700uf caps for the psu.
Transformer is Sowter 9610 and capsule is K47 until I can afford to get an edge terminated one.

Regards

Spence.

Spencerleehorton · Dec 22, 2014

Body and inerts

Regards

Spence.

micaddict · Dec 22, 2014

Got to love brass.

Gold next?

micaddict · Dec 22, 2014

... nah, won't get the patina.

Nyquist · Dec 22, 2014

Very nice work mate.

trans4funks1 · Dec 22, 2014

I wish I had the nerve to fashion wind screen from scratch.

It's an inspiration to see someone just make it happen diy.

micaddict · Dec 23, 2014

Why do brass microphones almost always get plated anyway?

Spencerleehorton · Dec 23, 2014

this one aint gonna be plated, just polished!!!

regards

Spence.

micaddict · Dec 23, 2014

Spencerleehorton · Jan 2, 2015

Hi,

relays have arrived and i have wired them all in, everything in the mic is now wired apart from capsule.
Psu is just waiting for some 4700uf/25v to arrive then i can power up and start testing.
will update once i get some sounds.

regards

Spence.

Banzai · Jan 2, 2015

Primary reason is Oxidation. Without plating or a lacquer coating, all brass will eventually turn green'ish. Lacquer isn't an ideal solution for a commercial product as the client would have to keep up with the maintenance themselves. Instead, a coat of nickel gives the metal a semi-permanent corrosion protection (nickel tarnishes as well, but that's something else altogether). Without any protection applied, fingerprints can also become a permanent fixture on the metal unless you wipe them off right away – finger oils accelerate oxidation. Sandblasting accelerates it even more, with the metal oxidising pretty much instantly when exposed to air.

The other main reason is strength as brass is a very soft and malleable alloy: nickel has an HRC of around 50 to 60 which protects the metal from dings and scratches. Keeps your product looking good for longer, as you can also polish it from time to time.

There's also the benefit of nickel plating's slight levelling effect: it can mask small imperfections and scratches in the machined parts if a thick enough coat is applied (≈ 20µ), to give the impression of a perfectly polished part underneath.

micaddict said:
Why do brass microphones almost always get plated anyway?

Spencerleehorton · Jan 2, 2015

well, just powered up psu, not looking good at all, no B+ at XLR traced back and short somewhere, H+ stuck at 13v and wont trim?
Bias trim works and thats about it!! no smoke yet though!!

regards

Spence.

Spencerleehorton · Jan 3, 2015

This is my findings of today.

D2/D4=274v
R1/R2= 136v
R6=0.787v ?

So problem on B+ found.

Problem on H+ is that the AC wires where the wrong way round!!!!
Going to change all caps and regulator then power up again!!

Changed caps and regulator and still the same, have a short somewhere but this pcb is smaller than normal so little bit harder to find.
Might be dodgy 250k possibly as up until here everything seems fine.

Any ideas?

Regards

Spence,

micaddict · Jan 3, 2015

Banzai said:
Primary reason is Oxidation. Without plating or a lacquer coating, all brass will eventually turn green'ish. Lacquer isn't an ideal solution for a commercial product as the client would have to keep up with the maintenance themselves. Instead, a coat of nickel gives the metal a semi-permanent corrosion protection (nickel tarnishes as well, but that's something else altogether). Without any protection applied, fingerprints can also become a permanent fixture on the metal unless you wipe them off right away – finger oils accelerate oxidation. Sandblasting accelerates it even more, with the metal oxidising pretty much instantly when exposed to air.

The other main reason is strength as brass is a very soft and malleable alloy: nickel has an HRC of around 50 to 60 which protects the metal from dings and scratches. Keeps your product looking good for longer, as you can also polish it from time to time.

There's also the benefit of nickel plating's slight levelling effect: it can mask small imperfections and scratches in the machined parts if a thick enough coat is applied (≈ 20µ), to give the impression of a perfectly polished part underneath.

micaddict said:

Why do brass microphones almost always get plated anyway?

Click to expand...

I hear you.
Still, there are many brass and bronze objects that get handled often (and polished rarely). Mortars are just one example:
https://www.google.nl/search?q=brass+mortar&biw=1366&bih=667&tbm=isch&imgil=krFpfVIUTmDmuM%253A%253BzTiyYjpYGphemM%253Bhttp%25253A%25252F%25252Fwww.liveauctioneers.com%25252Fitem%25252F9531407&source=iu&pf=m&fir=krFpfVIUTmDmuM%253A%252CzTiyYjpYGphemM%252C_&usg=__6beZisQ8aZhmG8Uxzk8HXnkDSRw%3D&ved=0CC8Qyjc&ei=UC-oVIyDLIbkaP_GgKAC#facrc=_&imgdii=_&imgrc=krFpfVIUTmDmuM%253A%3BzTiyYjpYGphemM%3Bhttp%253A%252F%252Fp2.la-img.com%252F1100%252F25755%252F9531407_1_l.jpg%3Bhttp%253A%252F%252Fwww.liveauctioneers.com%252Fitem%252F9531407%3B640%3B367

Also, oxidation can be your friend. Untreated brass objects can get a nice so-called patina over time. This can even be maniplulated:
http://www.sciencecompany.com/Patina-Formulas-for-Brass-Bronze-and-Copper.aspx

Spencerleehorton · Jan 4, 2015

HI,

have sorted H+ now as had a 1Meg resistor instead of 1K!
Very strange readings with B+ up to R2/250k pot, when i measure other side of pot i get 0.854v, when i measure other side of pot i can adjust it down to 40v!!!
this is so weird? i've never seen the wrong side of a pot adjust down, as in the side that R2 and the pot are attached.
any ideas?

regards

spence.

Spencerleehorton · Jan 7, 2015

Hi guys,

Having some problems with this psu, seems the 200v after the diodes should be in the region of 270-280v putting it above the 100uf/250v cap in C1, so I will change this for 400v.
After the R1 - 75k comes down to 130/140v ish so not a problem.
I think I need to change C4 - 100uf/250v as getting strange readings on B+.

Regards

Spence.

Spencerleehorton · Jan 7, 2015

Hi,
Got it fired up finally, haven't used correct capsule so doesn't sound that good, and think I've got TXF wrong way round!
At least getting there now, more testing and tweaking will follow.

Regards

Spence.

Spencerleehorton · Jan 9, 2015

HI All,

heres a picture of the finished mic in superb polished brass finish.
This mic sounds amazing!!

regards

Spence.

micaddict · Jan 9, 2015

Nice, Spence!

It deserves a better picture, though.
I hope you don't mind me saying.
It's meant as a compliment to the mic.

Spencerleehorton · Jan 9, 2015

lol!, yeah dont worry better picture will follow when i have time! up against it all today.
I will add to anyone who hasn't built this mic, build it, it really does sound amazing.

regards

Spence.

ELAM 251 build in brass

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