MK7 - tube mic project

[ioaudio]

...and with dale´s m7 capsule equipped.

 

[bockaudio]

You make transformer or buy?

 

[edanderson]

he's makin em himself.  i'm guessing UI375 lams?  looks great.

ed

 

[babyhead]

I am getting wet!!!

When are you announcing the kit sale? I check every few hours....

I have an m7 begging for this.

 

[natek]

This is a very nice project, I am praying i am on top of my stuff the day you put these up...  ;D

 

[ioaudio]

thanks for the nice words!

i'm guessing UI375 lams?

no, it´s UI30/25 NOS lamination as used in the BV8
but i´m already working on a version which uses UI375 lamination from magmet.

-max

 

[ioaudio]

the stock psu needs modding for the heater rail.
we need very good ripple attuenation and dont have too much voltage to drop, i worked out something that fits in the stock housing.
rectifier --> 2xRC filter (2,2R into 10000µF/16V) --> lm317 in improved-ripple-rejection-mode --> one more RC filter. i´ll draw a schematic
once you modded the psu it´s just the matter of changing one resistor in the mic (3,9R*) and adjust the lm317 trimmer to make ef86 tubes work.
a old-school psu with LC filters is another very good (diy) option, requires a nice choke and a bigger psu housing.


-max

 

[Rossi]

Oh yesss! I have (another) Dale M7 waiting for this baby.  ;D

 

[FerrariT]

Is there a source for the donor microphones in North America?

 

[ioaudio]

the nady 1050 seems to use the same housing, but i´m sure there are more possibilities.
the grille is important.

 

[ioaudio]

thats what the set will look like. i took nylon screws for mounting, the core of the transformer can be grounded with the solder lug.
soon.

-max

 

[stitch-o]

the nady 1050 seems to use the same housing, but i´m sure there are more possibilities.
the grille is important.

This mic body and grill would seem to work, no?
http://www.groupdiy.com/index.php?topic=29710.0

 

[guavatone]

That brass body looks like it may have a smaller diameter.  Do we have a diameter spec?

io, that transformer is inspirational!!!

It looks better than some of the manufactured ones.

The anticipation is killing me.

 

[ioaudio]

no, this body should work. i tried with a 1mm thick 50mm diameter housing (48mm inside) and it fits.

 

[Rossi]

anticipating
salivating
masturbating  ;D

 

[gevermil]

I hope you put  a limit on the number people can get .
They wont last long 

 

[bradb]

yeah limit it to 2 max per person!  Good idea!

or if you want to be ultra-fair... one per person.

 

[rodabod]

anticipating
salivating
masturbating  ;D

Dude!

 

[desol]

I'd like one too. Very nice. 

 

[ioaudio]

here we go:
>>>> http://www.groupdiy.com/index.php?topic=30547.0