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

[mukole]

After hours of trying to get my PCB's and AMI T49 to fit into an MXL 2006 I had laying around i can say
that i don't recommend this body for the FET47.

I made it fit anyway with a bit of hacking to the body and some new holes in the PCB's. Also I had to shorten
the inside pins on the XLR connector to get the transformer in there. It also has no switches.

But I can confirm that the circuit works with with the T49, and the wiring for the T49 is correct as Dan suggested earlier,
I won't comment on the sound yet as i still have the stock MXL capsule installed and am still deciding what to use. I'm
considering the BeesNees K7, or maybe i'll try their chinese K47 for this one.

Also I need to find a better donor for my next build, has anyone else found any good donors yet?

 

[mukole]

My hack job

 

[Scrappersa]

Hmm, that makes me a bit concerned about trying a Mxl 550 since it's a bit short and thinner than the 2006. What other donor mic's would work for this Pcb? I would rather not buy the nady/alctron for $200 just for the body.  I'd just build my own body at that point.

 

[kevinkace]

I was looking at the MXL v250, but not sure on the fit (not a lot of info on that mic). The price is right at least.
http://www.musiciansfriend.com/pro-audio/mxl-v250-condenser-microphone

 

[Dylan W]

I have the MXL v250. I thought about using it for this build... the main problem seems to be a lack of transformer housing, though that may not matter. I don't have a ruler nearby but it's not the biggest body in the world. Here's a sloppy inside pic, with some Dostoyevsky for reference  .

 

[Dylan W]

And another. The body is the same model as the MXL R44/144 (though the ribbon mics have a transformer bell).

 

[kevinkace]

Hmm, ya looks pretty tight in there.

I was jut going to mention the MXL R40/R144, but I guess it's also too tight ($69 but comes with shockmount).

 

[mukole]

Indeed it is pretty tight, there's less than a millimetre to spare,I also shaved about a millimetre
Off the sides of the pcbs to get the cover back on comfortably.
not having a transformer can doesn't seem to be an issue noise wise,
And I don't think you'd get that transformer into one anyway.

I almost scored an mxl 4000 which I think would have been a great donors as it's much larger
But I was too late for that one, there seems to be very few of them around

 

[Scrappersa]

I literally just bought an MXL 4000 on ebay. I'll let you guys know how it works out! It's supposedly the same diameter as the Alctron but a bit longer. I'm tempted to put my DIY Telefunken 251 into the 4000 but I think I'm going to curb my temptation and just use it on the FET47. The other great thing is the built in switch so I can use it for the pad!

 

[Scrappersa]

Do you guys have any links to where you got the 18pf tantalum and 33pf styroflex in the USA? Or at least the voltages for those two caps.

 

[mukole]

Do you guys have any links to where you got the 18pf tantalum and 33pf styroflex in the USA? Or at least the voltages for those two caps.

I believe some of the guys buy them from this site

http://www.justradios.com/cart.html

 

[Scrappersa]

Thanks man. Do you know what the minimum voltage for each of those caps should be?

 

[mukole]

The schematic on the first page shows them as 160V which should give a good amount of headroom so if you buy the justradio's
caps they are 630V, they should be fine.
Both the 18pf and 33pf are polystyrene btw, the tantalums are all covered in the mouser BOM.

 

[Scrappersa]

Ah got it, thanks a lot. The only problem with justradios is that it's a $20 minimum purchase and I don't have anything else I need from them. Do you have any other ideas?

 

[poctop]

I literally just bought an MXL 4000 on ebay. I'll let you guys know how it works out! It's supposedly the same diameter as the Alctron but a bit longer. I'm tempted to put my DIY Telefunken 251 into the 4000 but I think I'm going to curb my temptation and just use it on the FET47. The other great thing is the built in switch so I can use it for the pad!

Yes the Mxl 4000 will work  ,  plenty of space also in there.
BEst,
Dan,

 

[BigDad]

i've a stupid question, why do that ?...

... Why not directly soldered on the circuit ?

 

[3nity]

well yeah thats really stupid question!  ;D ;D ;D ;D
Just kidding its a good question...its simply to handle high impedance better.
as simply as that.

 

[BigDad]

Thanks, I didn't know that !

 

[Spencerleehorton]

Hi Guys,

I have done a bit more investigating on donor bodies and these seem pretty good:

Aurcyle A620, Sterling Audio ST51 both are available from amazon really cheap

i just wondered on the sizes inside for mounting the PCB's.

any info very welcome.

regards

Spence.

 

[Spencerleehorton]

HI Guys,

for all of my european fellow mic tinkers you may want to check out this mic body:

Pronomic CM-11 Large-Membrane Microphone

http://www.amazon.co.uk/Pronomic-CM-11-Large-Membrane-Microphone/dp/B001KV136I

havnt got sizes yet but could be a good U47 FET mic body? anyone got any sizes?

regards

SPence.