D-EF47 Tribute To Oliver Archut U47 Build Thread.

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soliloqueen

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What is the beef with Mic & Mod?
selling off the shelf parts at 2-5x markups with work scraped from this site without credit. Borderline scam. Outrageous lies about part origin. If you want basically anything M&M sells, make a WTB thread in sales or contact chunger, or anyone else who does business with the same companies at volume. Even Dachman, who has similar issues, has more fair pricing than M&M. He's got literally the same parts up for less than half that price! Even that's still a bit high.
 
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mrgrooves666

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Feb 1, 2021
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Finishing up this great mic project, thanks Dan and Mr Archut up there. Powering up the PSU without mic connected or dummy load, I get B+ 105, H+ 30V, If I move the polar pattern switch to the other position, B+ goes to the roof 250+ or so. I've read the thread and I get some sense this might be normal and that I need to get the mic plugged or use dummy load 150K 1/2 watt for B+ and 30 ohm 4 watt for heater, to get more proper readings?
I went through every component value, orientation (for those that matter) and it seems I have everything up to spec. I don't have those resistors handy, so its either plug the mic and see if it explodes or somethin' or wait a couple of days for resistors...?
 

Purplenoise

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Finishing up this great mic project, thanks Dan and Mr Archut up there. Powering up the PSU without mic connected or dummy load, I get B+ 105, H+ 30V, If I move the polar pattern switch to the other position, B+ goes to the roof 250+ or so. I've read the thread and I get some sense this might be normal and that I need to get the mic plugged or use dummy load 150K 1/2 watt for B+ and 30 ohm 4 watt for heater, to get more proper readings?
I went through every component value, orientation (for those that matter) and it seems I have everything up to spec. I don't have those resistors handy, so its either plug the mic and see if it explodes or somethin' or wait a couple of days for resistors...?
It’s not safe to have the psu on without a load…and in order to have proper readings you need of course a proper load or the mic connected. Wait for the right resistors
 

wstratton

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Apr 2, 2020
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Beacon, NY
I decided to sell my trusty D-EF47 in pursuit of building another microphone, and I put together a quick demo video, in case anyone reading this thread in the future wants to hear what one idiosyncratic variation of this mic sounds like:

If anyone is interested in purchasing it, feel free to send me a message.
 

innercityman

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May 12, 2016
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352
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France
Hi all,

I've finished building my second D-EF47 PSU and did a rough calibration inserting dummy loads, and I can't get 105VDC on B+ with trimmer fully clockwise, the most I can get is 102V no more. I guess it comes from my power transformer which has a 200VAC secondary. So should I change the trimmer resistor with a lower value ? Or should I change the power trafo ?


Thanks for your advices
 

innercityman

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Forgot to say that I used a 150K resistor for B+ dummy load so maybe with the mic plugged in it will be fine. Otherwise, I suppose that if the trimmer is fully clockwise there is no resistance so changing it for another value will change nothing I guess.
 

TLRT

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Jan 9, 2014
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395
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Hungary
Hi all,

I've finished building my second D-EF47 PSU and did a rough calibration inserting dummy loads, and I can't get 105VDC on B+ with trimmer fully clockwise, the most I can get is 102V no more. I guess it comes from my power transformer which has a 200VAC secondary. So should I change the trimmer resistor with a lower value ? Or should I change the power trafo ?


Thanks for your advice
Lower the 2x20k B+ resistors to 12k
 

mihi_fuchs

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Sep 21, 2019
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Location
Austria / Europe
Hi all,

I'd have one question concerning the PSU. If I'm in Europe I have 230V AC from the socket - do I still need the Toroidal Transformer? As it would actually transform 230V AC to 230V AC?

Probably that's a stupid question, but thanks in advance already for any help ...

Looking forward to the first tryout of the mic,
Thanks a lot for the design!

Best regards
michael
 

rock soderstrom

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Oct 14, 2009
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This question comes up every now and then. The answer is - don't do it!
It is dangerous not to have a galavanic separation between the electric device and the mains voltage.
It threatens the life of the user and is forbidden (in at least Europe). If it comes to an incident you will be fully liable for it.
 

mihi_fuchs

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Sep 21, 2019
Messages
73
Location
Austria / Europe
This question comes up every now and then. The answer is - don't do it!
It is dangerous not to have a galavanic separation between the electric device and the mains voltage.
It threatens the life of the user and is forbidden in (at least) Europe. If it comes to an incident you will be fully liable for it.
thanks a lot for the quick reply. very much appreciated!
 

robinhuntmusic

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Joined
Jan 5, 2019
Messages
4
HI Guys,

I just completed this project. Have to say, am super happy with the sound. Really nice texture and dead silent! I will put it through its paces with proper vocal recordings. Thanks to @poctop for the great PCB, @wrentema for his insights and help. My dad for the (electronic) guardian angel he is and of course Oliver...<3

I went roughly the same way wrentema did. The body I got from Aliexpress. Well build and finished. From the inside a bit simple though. I had to be a bit creative getting the pcb in there and make it tight. The t47 transformer I got from AML, I bought some nos Telefunken EF800's and the Blueline M7 capsule from Thiersch.

The shockmount I also got from Tab Funkenwerk. For the clips to close the spider I had to made a solution as the Aliexpress body is a bit thicker. I fixed this with simple iron wire with a shrink tube over it :)

Some difficulties I had with the build was the PSU, I bought the beautiful PSU housing from Tab Funkenwerk but it was made for an original point to point wiring I guess (?) there was a metal sheet in there with holes for caps or something. I had to put the multitool to use and get it out. Then I had to arrange the custom big screened Torroid (from audiophonics), choke and pcb in a way it made sense. I made sure the 5W 50 Ohm Heater voltage potmeter made contact with the housing so that it could transfer it's heat easier.

I made sure the grounding was tight: 1 star point in the PSU where the powersocket ground is connected to, the screen of the torroid, the housing and the 7 pin XLR ground. The 3 pin XLR I connected straight to the 7 pin. In the mic I made sure there was one point where I connected the housing to the pcb. Of the PSU-PCB I did not connect the 0V line. (as this is ground and I thought it better to use just 1 connection from the pcb to the ground which is connection "7". On both the XLR plugs I connected the 'sleeve' with the ground pin.

Another difficulty I had was calibrating: With the 30 Ohm test-load resistor I never got get the H+ to 5.05v. It was always too high (lowest I got was around 6.5V). With the mic plugged in this was easier. I made sure to let the mic heat up for about an hour or so to make final adjustments, then I got easily to 105V on B+ and 5.05V on H+ (here with 240V so all resistor values are cool). It takes a serious amount of time to stabilize. The 150k resistor worked well to get into the ballpark.

I was pretty secure with making sure the 7 pin XLR connector had the right signals / voltages going over them:

1: Audio -
2: Audio +
3: Extra ground.
4: H+ (the thick wire in my Sommer cable Octave Tube)
5: B+
6: Pattern
7: Ground (the other thick wire in the Sommer tube cable)

Other info:

The little polar pattern badge I got from Ebay (opus1374), switches and lights from Conrad, The Mic case from [email protected]

Thats about it. Can't wait to record:) Thanks everybody for their info and insights!



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