Handmade TubeMic

How about the Gyraf G7 circuit with Lundahl LL1538(XL) transformer and EF86 (or PF86, if you change heater voltage)?
The circuit is kind of a U67 inspired original design, that has been originally built just in that way, with a brass or copper tubing body and a single layer mesh grille. Max from vienna once made a few simple bodys like this for us not-so-talented-metal-workers and they fit the design nicely.
Just an idea that immediately comes to my mind after reading your post, b2.

Best regards,
Martin

Hi All!

On this w.end I've take pics of ..some Tube family...He!he!!
I always love to take pictures of Tube family in holidays..

So on going to build a Tube Mic...a big one based on neuman "u47" schematic (with mods):

A capsule, a tube, a decent ouput capacitor and a nice transformer ,I decided of course to choose a pentode I know for doing this job.

So I must choose in this Tube family the 1 or 2 for this...He!He!

For the capsule I will go with a RK-47 from microphones-parts (I've used them, they are nice and the price is great!)

A tube I've got in stock in my Tube family..

a nice paper capacitor for the output, 1µf/160v Sif-Safco or Russian one ..

A nice output transformer as T47 from Tab-FunkenverK

For the others components ...I will go with resistor from Vishay or equivalent for the Grid and polarisation voltage of the capsule (around 58-60v) and metal 1w for plate (plate voltage around 44v)

Ohers caps will be pio "green russian caps", thoses are great and cheap and some styroflex too.

For the Omni/Cardio position..I think I will go with a nice small relay...activated by a swith on the psu.

So let's see the family.

You see this paper capacitor from Sif-safco is great but a little bigger to fix in classic chinese mic host...and I didn't want to spend money in "u47" mic body..

I know and we all know that's some great people do a nice jod in machining u47 mic body..but this is not my choice.

So Hé!Hé! I must find........................a tube for this!!

.....................................................
..........................................................

Here's the tube:


I know...I will have to do metal work on it.....and build the head grill too...and build a layer for the inside to fix all the components in....

After all this job...I will have to build a decent psu for this too..

So more to come ..

all the best ,Bruno.

The work on the HeadGrill.......(Patience will be important!!!)


The result of the work HeadGrill....Body.....and the "Inside" to fix all parts...

...on the way....

The  output capacitor.. and to finish the "End Cap".


I hope you will enjoy this work !


All the best,Bruno.

And what kind of shockmount mechanism and capsule holder do you plan?

Hi !

Thank's !

For the body and end cap:

I've purchase this 2" brass tube with the end caps by a shop on ebay (nice guy and very professionnal!) I've purchase from him..a bar of brass tube 60cm long with 2 end caps for around 50$ (including the cost of shipping from usa to France).

So after ,I've done the mechanical work with a little drill as "dremel" for cutting the head brass tube to form the head.

With a vertical drill machine I've drill a hole of 20 mm diameter for the connector.

For the capsule and shockmount:

I've build another tube mic with RK47 and RK67 from Microphones-parts.Thoses capsules do a great job and are not expensives at all,Microphones-parts are great staff for sure!

I think it's a good start to fix this capsule on this "Big Mic", So I will go on with the RK67 with her dome schockmount.

All the best,Bruno.

Hi Svart!

Thank's!

you see I just want to  build this mic just to make hear my friends that's a "handmade mic" can do his job as well !

I've got friends how have spend money ..much money in mic ...as TLM103 and others from TFK ... when compared to one mods I've made on a SCT 700 T bone ..just a simple mods (tube +electronics and capsule) They said...it's a fu...k mic...

after compared to others mic I've build ...

People paid "logo".....my friends are not E.i ..they can not do much more investigation in Electronic design ...they want a "sound"...."big really sound" they are musicians, they do great  records.

BUT that's what the same with preamplifiers....and others gears.

You see ..I've build 8 years ago my first eqp1-a...

at first my friends where scared about ...because it's was not a ..."normal Eq"...parametric etc..but the sound passed in was  "musical" ,nice ...nothing much more to eqwizzz..

now...I've design a comp  of course tube Varimu ,a bit of 436...a bit of levelines..a simple one .

Good components.
Nice tube.

my pcb!

and see when i put it on!

all the best ,bruno.

Hi,

Yes It's "all" doable at home"...The cutting of the brass tube body is  doable witha handy metal saw...You only need patience and do it slowly.

The part of the body  for the "head grill" is more difficult,But with a drill as "dremel" and small cutting disc for brass or copper,it's goes well...Just need care and patience.

The inside for the components is easy to but need to build some part ...

All the best,Bruno.

Yes..I've bought this drill for this!!

The "inside"..(I didn't know how to name it...sorry) is build with small piece of aluminium...(you find it in hobby market..)not expensise at all..
and the rest is made with ..the small epoxy sheet from my pcb...(When I etched my pcb ,There is always sheet when cutting..)

The small sheet of epoxy for the tube socket need a bit work..but epoxy is easy to work!

THe head grill ...is for me the more difficult thing to do...
I've try different way to build it....the more easier is for me to build it around a " tube support" with the internal diameter of the MicBody.
I've to form it nicely ...with patience of course.

And when..you see it's gone to be right...you do 3 -4 point solders, and it ok!