Igor

U47 FET pcb.
« on: March 14, 2012, 08:22:56 PM »
Have a Skylar body. Well, not his, but the mic one.

Now, working on this:



I want to add polarity patterns like in U87 etc.

Any recommendations for good step-up schemo for 60V polarization for capsule?
« Last Edit: October 14, 2012, 06:51:42 PM by Igor »
http://www.ij-audio.com
(new site hopefully will be up in July)


Marcocet

Re: U47 FET pcb.
« Reply #1 on: March 14, 2012, 10:49:39 PM »
Beat me to it :) I'd already started something similar, but for the 87ish style bodies that are being used for the U1621. Neumann actually made a microphone that was a fet47 circuit in a u87 style body, but I can't find the model number anywhere to bring up a picture.

Oliver at TAB has a transformer spec'd for it that I'd love to check out.

I hadn't gotten as far as stepping up the voltage yet, so I can't be much help on that front. I can't wait to see some suggestions.

EDIT: Found it. The Neumann U497, built in limited numbers for french broadcasting. It was a K47 capsule with U89 style multi-pattern fet electronics built in to a U67/87 style body. I'll start digging for schematic, though I think it's prob a long shot.
« Last Edit: March 15, 2012, 01:07:43 PM by Marcocet »

Igor

Re: U47 FET pcb.
« Reply #2 on: March 15, 2012, 12:29:20 PM »
Well-well-well... Bump! Anyone?
http://www.ij-audio.com
(new site hopefully will be up in July)

Igor

Re: U47 FET pcb.
« Reply #3 on: March 15, 2012, 12:34:08 PM »
@Marcocet: saw your comm just now, thanx.
http://www.ij-audio.com
(new site hopefully will be up in July)

spase

Re: U47 FET pcb.
« Reply #4 on: March 15, 2012, 01:02:23 PM »
Excellent work Igor!

Marcocet

Re: U47 FET pcb.
« Reply #5 on: March 15, 2012, 04:50:15 PM »
Posting the u497 schematic to the gmail account as we speak.

kante1603

Re: U47 FET pcb.
« Reply #6 on: March 15, 2012, 09:08:20 PM »
Cool Igor,

have a nice Thiersch capsule that wants a new home ;D

Cheers,

Udo.

dissonantstring

Re: U47 FET pcb.
« Reply #7 on: March 19, 2012, 01:44:48 PM »
excellent!  looking forward to it.

Moby

Re: U47 FET pcb.
« Reply #8 on: March 22, 2012, 04:39:03 PM »
Looking great mate  ;) as usual. Btw, do you have idea about output transformer?  Be aware of "modern" type of lamination since vintage lams alloy doesn't exist anymore. At least for BV8 ;)

Re: U47 FET pcb.
« Reply #9 on: March 22, 2012, 10:44:21 PM »
me want!!!!!
Adam
only got here by owning a soldering iron and bad life decisions.


craigmorris74

Re: U47 FET pcb.
« Reply #10 on: March 23, 2012, 08:27:16 AM »
Looks great! Would love to have one!

Matador

Re: U47 FET pcb.
« Reply #11 on: March 23, 2012, 05:12:17 PM »
Here's is a capsule bias circuit as explained by Zapnspark:


mad.ax

Re: U47 FET pcb.
« Reply #12 on: March 25, 2012, 07:08:56 PM »
The Neumann U497 was made for French broadcast organisation and used a uncommon 12V power supply... Keep that in mind if you want to modify its circuit for your purpose.

Or you can have a go at the U87A/U89 circuit.

Axel

Marcocet

Re: U47 FET pcb.
« Reply #13 on: March 29, 2012, 06:55:30 PM »
Anybody have any info on the transformer? I know Tab-Funkenwerk makes an exact copy but they're custom order and expensive.

KasperNyhus

Re: U47 FET pcb.
« Reply #14 on: April 01, 2012, 03:24:58 PM »
really interesting project Igor... once again!!! What capsule will suit this project? and will you maybe post a circuit? :)

Moby

Re: U47 FET pcb.
« Reply #15 on: April 01, 2012, 05:21:52 PM »
Anybody have any info on the transformer? I know Tab-Funkenwerk makes an exact copy but they're custom order and expensive.
I'm not sure about winding/ratio but it looks that lams are same as BV8. Also, it looks that shares the same but not 4 chamber bobbin. If that's true I'm sure it's not a big deal (except obsolete lamination alloy/shape). I would like to know about it too since I'm done with BV8  ;)
« Last Edit: April 24, 2012, 11:02:27 AM by Moby »

0dbfs

Re: U47 FET pcb.
« Reply #16 on: April 04, 2012, 05:06:32 PM »
I may be in for a couple PCB's depending on price and accuracy to original ckt.
These mic's are great as FOK mic's and on horns...

Cheers,
jb

Music is everything!
Audio is everything else!

mrc

Re: U47 FET pcb.
« Reply #17 on: April 08, 2012, 10:09:22 PM »
A couple of these would be a nice addition.

Moby

Re: U47 FET pcb.
« Reply #18 on: May 03, 2012, 06:44:07 PM »
Igor, did you find the DC step up solution? I never tried this circuit but maybe it's worth of trying  :o

http://www.instructables.com/id/Simplest-Ever-DC-DC-Boost-12v-to-73v/step3/Connecting-the-power-transistor/

mrc

Re: U47 FET pcb.
« Reply #19 on: May 15, 2012, 08:07:24 PM »
Bump to see how this is progressing, Igor.  I'm really interested in a pair of these...