Re: Neumann U47FET Clone: D-U47 FET Microphone Project PCB Build thread
« Reply #740 on: December 24, 2018, 07:39:37 PM »
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
Seth

The definition of insanity: "Hey, this thing could be really cool - if I had the money to fix it up, which I don't, but if I did it could be really cool - if I had the time, which I don't, but


Re: Neumann U47FET Clone: D-U47 FET Microphone Project PCB Build thread
« Reply #741 on: December 29, 2018, 09:46:21 AM »
...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...
Seth

The definition of insanity: "Hey, this thing could be really cool - if I had the money to fix it up, which I don't, but if I did it could be really cool - if I had the time, which I don't, but

Re: Neumann U47FET Clone: D-U47 FET Microphone Project PCB Build thread
« Reply #742 on: December 30, 2018, 12:31:03 PM »
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.
« Last Edit: December 30, 2018, 12:36:20 PM by jrmintz »
Seth

The definition of insanity: "Hey, this thing could be really cool - if I had the money to fix it up, which I don't, but if I did it could be really cool - if I had the time, which I don't, but

Re: Neumann U47FET Clone: D-U47 FET Microphone Project PCB Build thread
« Reply #743 on: December 30, 2018, 06:03:31 PM »
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.
« Last Edit: December 30, 2018, 10:11:45 PM by jrmintz »
Seth

The definition of insanity: "Hey, this thing could be really cool - if I had the money to fix it up, which I don't, but if I did it could be really cool - if I had the time, which I don't, but

Re: Neumann U47FET Clone: D-U47 FET Microphone Project PCB Build thread
« Reply #744 on: January 02, 2019, 01:29:18 PM »
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!
Seth

The definition of insanity: "Hey, this thing could be really cool - if I had the money to fix it up, which I don't, but if I did it could be really cool - if I had the time, which I don't, but


 

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