Neumann U47FET Clone: D-U47 FET Microphone Project PCB Build thread

[jrmintz]

A question - the turret marked G that looks like a star ground has the insulator to keep it from contacting the board and five components attached to the top side. What attaches to the bottom side? Anything?

Thanks

 

[jrmintz]

...the isolation pin on the 47FET Just supports the HZ component that connet to the FET ,

Best,
Dan,

Ah, the answer to my question, on page 18, of this thread. Pardon my laziness...

 

[jrmintz]

http://www.sethglassman.com/FET47%20test.mp3

Unfortunately, my U47 FET is making a weird rhythmic noise and not passing audio. An mp3 of the noise is linked above. Can anyone suggest a place to start looking for the problem? Fet installed incorrectly? Thanks.

 

[jrmintz]

My voltages are definitely weird:

At the intersection of R20 and R21 I have 11V.
At point ‘B’ on the board I have 9V.
At the intersection of C7 and T5 I have 11V,
13.2V at T7 and R17,
11.4V at T5 andR16.

I’m using an outboard AKG phantom supply that’s putting out 53V, and at the pads that connect to the XLR I have 13V between pin 2 and ground and pin 3 and ground. Obviously something is pulling the voltage down.

Edit, a couple of hours later: The problem is I seem to have bought some counterfeit 2N3819s. I tested the others in the batch I bought and they read like BJTs, not JFETs, thought they're marked 2N3819.  Caveat emptor.

 

[jrmintz]

I wound up using a J201 FET in the mic and I just recorded some bass drum - it sounds amazing! I used an AMI FET47 transformer and a BeezNeez capsule. I'm really thrilled - thank you Poctop!

 

[hervemusic]

I have the same problem on my DIY U47FET
i have just a little sound
i have not gain

all the capacitors are goods and the resistors ans fet

My transformer is a cinemag 13101

Where is the problem
help me please 

 

[TillM]

I have the same problem on my DIY U47FET
i have just a little sound
i have not gain

all the capacitors are goods and the resistors ans fet

My transformer is a cinemag 13101

Where is the problem
help me please

First check again all transistor directions and if you choose the right ones.
Then check your soldering at the Hi-Z area.
Where did you source your FET ?

 

[jrmintz]

Check to be sure your fets really are fets.

 

[rockinrob86]

Will these pcbs fit in these bodies?  https://store.studio939.com/product/budget-47-body-kit

 

[Ricardus]

Check to be sure your fets really are fets.

Yes. Lots of fake 2N3819s on Ebay. I know. I bought some.

 

[useme2305]

Will these pcbs fit in these bodies?  https://store.studio939.com/product/budget-47-body-kit

yes, this body wont be too small that's for sure. the boards wont go in there without any extra holes in those rails along with some metal angles.

 

[maarvold]

Around 36 hours ago I finished my D-U47 FET build: Alctron GT-2B body, Ben & Veronica Sneesby's K7 capsule and Dr. Mark Fouxman's (Samar) transformer.  I built it specifically for kick drum and can't wait to try it.  It fired up and worked right away (THANKS!!) and, I have to say--the sound on my recorded speaking voice makes it seem like it might also be a great vocal mic: clean, fast,  'chesty' and powerful-sounding, low sibilance (a BIG plus) and it has 'vibe'.  Excited to get some hours of real recording on it.  THANKS to all who made this journey possible!!!  And I'll report back on the sonics. 

 

[Govinda Doyle]

hey guys
I just built one of these, but im having a strange noise
no sound coming from capsule but im having this rhythmical noise?
do I have the capsule connected wrong?
thanks in advance
G

https://www.dropbox.com/s/2wwcq5mohq5u96c/rhythmical%20noise.mp3?dl=0

 

[maarvold]

The 47FET I built specifically for kick drum (and love for that) has been getting some use in other areas: I used it on Dun Dun (a BIG drum with animal hide heads that still have the fur on them) and also on trombone, where it gave me an 'instant James Pankow' (of Chicago) sound.  Very happy with this mic. 

 

[Spencerleehorton]

Here is a pic of some FET47 bodies I’ve been making, these are already sold but I do have some more in the pipeline if anyone’s interested?

I’ll do some photos of the insides and my other builds to show how I’ve done it.

 

[Spencerleehorton]

this may have been covered as i havent had time to look through all the posts but what arrangement have people done for the two switches, -10db pad and LC?
one needs a DPDT style switch, do they do a sliding mini DPDT version?
the LC needs a sliding SPST, i'd like to include these into the build if i can rather than have the jumper inside.
Any info would be wonderful.

 

[vinylwall]

I'm thinking I might be interested in up to 3 of these.  Looking forward to seeing more pics of internals, etc.  Jimi Ray

 

[Spencerleehorton]

Found this one!!

https://cpc.farnell.com/te-connectivity/ase2204/slide-switch-dpdt-exact/dp/SW04237?mckv=sZIH9ErmR_dm%7Cpcrid%7C224682624125%7Ckword%7C%7Cmatch%7C%7Cplid%7C%7Cslid%7C%7Cproduct%7CSW04237%7Cpgrid%7C49734256791%7Cptaid%7Cpla-371789919038%7C&CMP=KNC-GUK-CPC-SHOPPING&gclid=Cj0KCQjwov3nBRDFARIsANgsdoHnUBXCk7bXCjhTktCfrtGimgeY4IFW5o_wGYljblPsXJmDUA_i89EaAiM2EALw_wcB

Need to find a SPST now!!

 

[Spencerleehorton]

Has anyone done the full 3 switches externally?
The original used the puck style pcbs and the switches are easily put between two pcbs.
With the square pcbs it’s a bit more tricky, would have to either put switches on top of the capsule mount or bellow capsule mount?

 

[duantro]

Has anyone done the full 3 switches externally?
The original used the puck style pcbs and the switches are easily put between two pcbs.
With the square pcbs it’s a bit more tricky, would have to either put switches on top of the capsule mount or bellow capsule mount?

It's hard to say without seeing the internals of these bodies and how much space the square pcb's have. Maybe a pcb could be made to attach to the top plate that the capsule mount is on, with standoffs?