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

[maarvold]

I just purchased all of the bits and am excited to dive in!

What I wanted to know is if anyone can speak about it's SPL handling - I intent to use this mainly on kick drum.

Do I need to have any sort of attenuation pad?

Thank you in advance!

I built mine specifically for kick.  Using the pad jumper (or removing it--I forget which way it works) you'll be fine--even with heavy hitters (I use mine 2.5" in front of the front kick head--not inside it).  I love my mic. 

 

[egroys]

I built mine specifically for kick.  Using the pad jumper (or removing it--I forget which way it works) you'll be fine--even with heavy hitters (I use mine 2.5" in front of the front kick head--not inside it).  I love my mic.

Amazing! Thank you. Is there a way to make the pad more than -10db? And is there any loss in tone if I opt to do so?
The reason I ask is I find it to sound a lot juicier if I can crank my 1073 gain and -20 would allow me to do so!

 

[maarvold]

Amazing! Thank you. Is there a way to make the pad more than -10db? And is there any loss in tone if I opt to do so?
The reason I ask is I find it to sound a lot juicier if I can crank my 1073 gain and -20 would allow me to do so!

I'm not a designer.  I'm sure there is a way, but I'd recommend you try it with the stock build first. 

 

[RuudNL]

Using a -20 dB pad (at 'normal' levels) will degrade the signal to noise ratio.
The electronics inside the microphone will produce the same amount of noise, but the signal level will be lower.

 

[egroys]

Thank you for the heads up!

I finally went through and read all 42 pages of this thread! I saw recommendations for the SS22SDP2 switches for pad and that is exactly what I wanted.

I ordered a GT-2B body and Cinemag 13101 from Studio 939, I already have a BeesNeez K47, and I am ready for monster kick drums!

I saw Luka/Shot posted about the GT-2B body resonance. Curious if anyone has found a more permanent solution?

 

[craigmorris74]

I just purchased all of the bits and am excited to dive in!

What I wanted to know is if anyone can speak about it's SPL handling - I intent to use this mainly on kick drum.

Do I need to have any sort of attenuation pad?

Thank you in advance!

The circuit board has a spot for a  jumper that activates a pad in the mic.  It's pretty easy to try out and see if you need it or not.

 

[egroys]

Hi Luka, have you had any luck with a more permanent solution? I am about to start putting the PCBs in the the body when it comes later this week and would love to get it right on the first try.

Thank you in advance!

 

[shot]

No, I haven't yet! Not that I don't want to, but it will wait for a some time.
A good friend of mine is finishing building his studio and he already has some bookings, but he had no good vocal mic. He spent most of the money on bricks and mortar. So I borrowed my FET47 to him for next few months until he recoups and buys himself some mics.



Luka

 

[egroys]

That's funny: I had completely forgotten that--without even listening first--I did A LOT of damping on that mic body with BluTack... enough that it's tricky to remove the barrel unless I'm careful.  I typically do this with all my large diaphragm mics, so I had kind of let it go out of the memory banks.  ESPECIALLY with a mic I'm going to stick right next to a LOUD kick drum, I don't want any energy storage or rattling from the mic body itself.  And yes--I used the GT-2B.

Makes sense! Would you mind sharing any photos or explaining more about how you dampened with the Blutack? I just ordered some to give this a shot.

Thank you !

 

[egroys]

Success! First mic build and it works off the bat. Still running some tests and still intent on dampening the inside a bit but so far so good!

I thought it would have more low end than it does. It takes SPL like a champ, both with and w/o pad, which is amazing.

Low end is solid but not super beefy. I checked that the LC is off. Is there anything I should check that may have been an error? Or any specific tests I can run to make sure everything is copacetic? I realize this is a noob question, but alas, that is me!

 

[FarisElek]

Anyone hear a significant difference between AML FET47 transformer vs there cheaper T49. I believe in the power of transformers but I’ve also had excellent results with their PCB mounted cheaper transformers.

 

[Colorblind]

Anyone know where I can find a 3-pin XLR insert for the GT-2B body? I bought a partially built kit for this mic from a member here and there's no XLR connector. I know Chunger sells them for $2 but I'd rather not pay $16USD for shipping if I can avoid it.

Does Mouser carry something that would fit? Need to order the rest of the mic components from them anyway.

Thanks!

 

[Colorblind]

Would this connector fit the GT-2B body?

https://www.mouser.ca/ProductDetail/Switchcraft/QG3M?qs=sGAEpiMZZMvlX3nhDDO4AIKHbLVZLW1UpNtIlbxi9Tg%3D

 

[doqmemory]

I remember having to shave a bit off the little "key" nub that fits in the XLR channel, but the Switchcraft connector should work for the GT-2B and is quite nice.  Another option is to get a short, cheap XLR cable from Amazon and use the male end.  If you do that, make sure that you get one with screws, not the Neutrik style connector.  With free shipping, that can be cheaper than Mouser.
Here are two I have used:
https://www.amazon.com/gp/product/B01JTA5VNM/ref=ppx_yo_dt_b_asin_title_o02_s01?ie=UTF8&psc=1 and https://www.amazon.com/gp/product/B07ZJSHXRM/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

 

[Colorblind]

I remember having to shave a bit off the little "key" nub that fits in the XLR channel, but the Switchcraft connector should work for the GT-2B and is quite nice.  Another option is to get a short, cheap XLR cable from Amazon and use the male end.  If you do that, make sure that you get one with screws, not the Neutrik style connector.  With free shipping, that can be cheaper than Mouser.
Here are two I have used:
https://www.amazon.com/gp/product/B01JTA5VNM/ref=ppx_yo_dt_b_asin_title_o02_s01?ie=UTF8&psc=1 and https://www.amazon.com/gp/product/B07ZJSHXRM/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

That's perfect, thanks!

 

[Colorblind]

On the partially stuffed boards I bought recently, The previous owner used an isolation pin I haven’t seen before. The pin is soldered into place, and there is continuity between it and the adjacent solder pads.

Isn’t the purpose of the isolation pin to, uh, isolate itself from the rest of the circuit?  If I recall, the turrets in the BOM just push through the PCB and are held in place by friction, with no metal making contact. I’m probably missing something. Am I missing something?

 

[doqmemory]

Yes, the whole point of the isolation turret is to isolate from the board.  You should probably take that out and replace it with a Teflon turret.  You don't really need the turret there for the FET gate, it is just for convenience.  You can just solder all of those connections in the air.

 

[Colorblind]

Yes, the whole point of the isolation turret is to isolate from the board.  You should probably take that out and replace it with a Teflon turret.  You don't really need the turret there for the FET gate, it is just for convenience.  You can just solder all of those connections in the air.

Ok, good to know. I included the BOM turret in my mouser order, so I might try to replace this one if I can do it without damaging anything. Thanks again!

 

[JW]

Couple questions.

So the pcb is 50mm wide? Or is that the width between rails for the Chunger body? I ask because I'm thinking about attempting to build this into a DIY body from way back, made by forum member Seavote.

Also, I have a U47 (tube) style transformer from i/oaudio. Will this be fine for a 47fet transformer or are they totally different?

 

[doqmemory]

Couple questions.

So the pcb is 50mm wide? Or is that the width between rails for the Chunger body? I ask because I'm thinking about attempting to build this into a DIY body from way back, made by forum member Seavote.

Also, I have a U47 (tube) style transformer from i/oaudio. Will this be fine for a 47fet transformer or are they totally different?

Dimensions for most boards are on the order page.

47FET transformer ratio is 9:1, so U47 6.5:1 transformer is not right.  A transformer for the M49 might work, though, since the ratio 10:1 is closer.