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

GroupDIY Audio Forum

Help Support GroupDIY Audio Forum:

camshash

Well-known member
Joined
Sep 4, 2021
Messages
52
Location
Michigan
What M7 capsule? A real Neumann one, with PVC that has been self-destructing for 60 years? A reskinned one? Reskinned by who? A Sigfried Thiersch Blue Line M7 PVC (I own 2) or his Mylar one? Or a Gefell from the mid 90's (I own 1)--which Klaus Heyne strongly approved of in that era? I built a FET47 specifically for kick drum and used a mylar capsule because, although I like the sound of PVC--ESPECIALLY from that era of Gefell, it seemed like mylar would be more resilient/trouble-free in the long run.
I see, looks like a I got a lot of research to do. Thanks for the insight
 

Delta Sigma

Well-known member
Joined
Dec 4, 2010
Messages
446
Location
Winnipeg
Hey guys, does anyone have any sound samples of how the 47FET from vintagemicrophonepcbkit.com sounds? How does their D7 capsule compare to an actual M7 capsule? Would I get similar results using micparts.com RK47 capsule?

Also, is it the capsule or the circuit that causes a microphone to be super sensitive and cause overshoot distortion? I want to use it as a Kick out mic so it must be able to handle high SPL

Any insight is appreciated, thanks!

I used a Maiku K47 in my build. Sounds great. In other builds I have compared a Maiku K47 to a Beesneez M7 and K7 (K47). I preferred the Beesneez both times. I haven't heard Dany's D7 but people rave about it. Personally, I wouldn't bother with the RK47.

For use as a kick mic, make sure you install the pad switch. If you search this thread, someone posted the part number that fits Dany's PCB.
 

JMPGuitars

Well-known member
Joined
Apr 30, 2018
Messages
108
I just finished a second U47FET. Originally I built one with the AMI T47, and Beesneez K47 capsule, but I didn't love how the powdercoating and a couple other things turned out. So I swapped the capsule with a generic one, and built a new mic with the Cinemag transformer. I have a recording of the original with the Beesneez capsule, and I'll compare that to the new mic, and compare it to the old mic with the generic capsule. I'm curious how different things will sound.

Here's the new one:

_JMP2726.png


It sounds great, exceptionally low noise too.

Thanks,
Josh
 

camshash

Well-known member
Joined
Sep 4, 2021
Messages
52
Location
Michigan
I just finished a second U47FET. Originally I built one with the AMI T47, and Beesneez K47 capsule, but I didn't love how the powdercoating and a couple other things turned out. So I swapped the capsule with a generic one, and built a new mic with the Cinemag transformer. I have a recording of the original with the Beesneez capsule, and I'll compare that to the new mic, and compare it to the old mic with the generic capsule. I'm curious how different things will sound.

Here's the new one:

View attachment 85105


It sounds great, exceptionally low noise too.

Thanks,
Josh
Would love to hear the recordings, what sound source are you primarily using it for? What capsule did you swap into the new one?
 

JMPGuitars

Well-known member
Joined
Apr 30, 2018
Messages
108
Would love to hear the recordings, what sound source are you primarily using it for? What capsule did you swap into the new one?
I might do a proper comparison video or something of the clips, I dunno yet. It'll be a while before I have time.

The new one has the Beesneez K47. The old one now has the popular budget (I think Chinese?) capsule with the blue on the outside of the capsule plates.

I mostly do voiceovers myself, but I'm going to experiment with singers and instruments at some point. I'm also going to compare with a U47-EF800 mic.
 

camshash

Well-known member
Joined
Sep 4, 2021
Messages
52
Location
Michigan
Is anyone aware of a ring/swivel mount that will screw onto the GT-2B body? I want to use a ring mount as its less bulky than the supplied shockmount but I cannot find a 'standard' sized one.
Thanks
 

fauxjazz

Member
Joined
Aug 5, 2020
Messages
12
Here is my build using an old T.Bone SCT2000 I had laying around, Maiku K47 and Sowter 1303. Sounding great and everything fit perfectly in the body!

Currently working on a second (budget) build with a 3u M7 style capsule and GZT47 Transformer.

I emailed Guosheng to ask if the GZT87 Transformer would be appropriate for a FET47 circuit, however he replied saying that, in his experience the GZT47 is better for this circuit. I'm just wondering now if anyone can tell me what effect the different transformer ratio (6.5 : 1) will have in terms of performance and frequency response? WIll it function properly or do I need to source a 9:1 alternative like the Sowter in my first build?

Thanks all,


PXL_20220106_184734814_2.jpg PXL_20220106_184427677_2.jpg
 

camshash

Well-known member
Joined
Sep 4, 2021
Messages
52
Location
Michigan
Hey guys, almost done with my build but I have some confusion on the transformer wiring.

Im using a PCB mount AMI t47 with dans amit49 pcb

Does anyone have a picture of how they wired and mounted theirs? I cant find any info on it. Thanks
 

klem

Well-known member
Joined
Oct 12, 2005
Messages
65
Location
SW
Not (m)any replies to questions over past six months, but still hopeful someone will consider helping out.

Can someone school me on hFE values as it pertains to this mic? I'm building a matched pair.

For T3-6 I used BC547B's with hFE matched between PCBs 312 - 333, usually with a variance between PCBs of 0-15 (21 at worst) per any given tran location - e.g., hFE for T3 on PCB 1 = 312, for PCB 2 = 318. I've read a good amount online but have yet to find what an acceptable range/tolerance is when trying to have a matched pair of mics. I know matching capsules matters much more, of course, but hoping someone can speak to what point does hFE have an appreciable impact on the mic's performance.

T7 also calls for BC547B but the remaining ones I had on hand had hFE values way off from each other (290 vs 400). I found two BC547C that had an hFE of 564 each. Much better match, but obviously much higher value than the BC547Bs. How does the higher current gain of the BC547C vs. the BC547B's impact the circuit? Should any other components be modified (e.g., resistors being of higher than 1/4W)?

Thanks in advance,
 

oscarhuang

Well-known member
Joined
May 22, 2020
Messages
71
Hey guys, almost done with my build but I have some confusion on the transformer wiring.

Im using a PCB mount AMI t47 with dans amit49 pcb

Does anyone have a picture of how they wired and mounted theirs? I cant find any info on it. Thanks
 

Attachments

  • QQ图片20220331165150.png
    QQ图片20220331165150.png
    449.7 KB · Views: 37

dchang0

Well-known member
Joined
Nov 24, 2016
Messages
68
I don't know if this will help you. I have an AMI T49 transformer with the optional PCB mounting kit.
You can see the wiring clearly in this photo. Assuming the T49's pin-out is identical to the T47, then you can follow my photo exactly. I can confirm that I have built two of these U47 clones and that they work great wired exactly like this photo.
 

Attachments

  • U47fetWithAMIT49PCB - 3a.jpg
    U47fetWithAMIT49PCB - 3a.jpg
    115.6 KB · Views: 26

camshash

Well-known member
Joined
Sep 4, 2021
Messages
52
Location
Michigan
I got the AMI T47 on accident, but swapped it out with the T49, everything works great, I have it mounted the same as yours but I didnt yet screw in the transformer PCB since it fits in there so snug. Also, how critical is it to use twisted pairs for the leads coming in and out of transformers?
 

klem

Well-known member
Joined
Oct 12, 2005
Messages
65
Location
SW
Hello everybody!

I apologize upfront since I'm new at this.

Would like to know if the u47fet Square PCB from @poctop , fits this Aurycle Fet Body.

Thank you for the help!

Hey there,

No, I don't think it will fit. The board is ~44mm width by 49 length (dimensions are on poctop's site if you'd like to verify), so while it would just barely fit at the top (where you would have to tap your own holes for mounting the PCBs), it likely will not fit towards the bottom as that Aurycle body tapers to 34mm.



Edit - it's nice to be able to answer a question instead of asking them!
 

RBeTT

Member
Joined
Feb 13, 2022
Messages
7
Location
Portugal
Hey there,

No, I don't think it will fit. The board is ~44mm width by 49 length (dimensions are on poctop's site if you'd like to verify), so while it would just barely fit at the top (where you would have to tap your own holes for mounting the PCBs), it likely will not fit towards the bottom as that Aurycle body tapers to 34mm.



Edit - it's nice to be able to answer a question instead of asking them!
Thank you!
 

dmp

Well-known member
Joined
Oct 28, 2009
Messages
3,308
Location
Madison, WI
How does this have a Supercardiod pattern? It seems it is just connected to just the front of a standard k47 capsule. Does the lower polarization voltage change the pattern? Or is the body characteristics important?
I have a dead shure 52a that I am thinking I could retrofit with the round pcb version.
 
Top