D-EF47 Tribute To Oliver Archut U47 Build Thread.

[prophei]

Hi All,

Thanks in advance for any help you give me, as I am just about to start my first build.

Some background... I bought the current kit D47 body kit from Danny, and got the power supply housing/pcb. As there are not instructions for the power supply, just a schematic, this is the part I am the most concerned with. I have done a lot of DIY, but not at such high voltages (I usually build stuff thats 9v to 15v).

The pcb board for the power supply is the D-EF47.
Transformer is the BV8 Classic
Capsule is the K7 (beez)
Tube is the Tele EF800

With his current body kit, there is an included polarity switch on the mic, and I am not sure how that does or does not relate to the power supply discussed in this thread, which seems to be based on the older mic pcb design. Am I in the right place, or is there a thread specific to this power supply that might be a better starting point for me given the above?

 

[TillM]

Look at the psu schematic.
I think you must omit R5 and R9 and of course don’t connect OM/CRD/COM.

 

[prophei]

Look at the psu schematic.
I think you must omit R5 and R9 and of course don’t connect OM/CRD/COM.

Good call out, that removes the pattern switching circuitry?

 

[rockinrob86]

My mic has started having an intermittent issue.

It will work great and sound normal as it has since I built it, and then make a tube noise/scratching sound like a bad pot or something and lose about 15db.  I've tried a different XLR to my preamp with no change and manipulating the mic cable with no change.  After a bit, it came back to normal volume, but eventually faded again.

One thing I can think of is a couple weeks back, I was using the mic with a friend and had terrible distorted sounds in my DAW, so I jumped up, opened the mic and switched the tube out.  Only to realize that my interface had just gotten "off" and I needed to shutdown and restart.  The mic worked perfectly before this and afterwards for a while, but when I first heard this problem I switched back to the original tube and reconfirmed the voltage going to the amp.  Everything was good but now I heard the mic do this last night.

The only other thing is that months ago, the back diaphragm on my capsule was punctured (long story, a mounting screw came loose and banged into it in the headbasket.  there is a visible "ding" on the back mylar of the capsule now and omni has noise.
Cardioid was unaffected, but maybe the now open back is causing an issue?

 

[iturnknobs]

Rockinrob86-

You could firstly open the mic and disconnect the rear capsule. I would probably recalibrate the B+ voltage in that case. Secondly, if the diaphragm is shorting to the backplate, this might not "correct" the problem. I am guessing that an "open" is not your issue. Without being an electronics engineer, I would probably purchase the cheapest capsule possible that works in this circuit to begin the good old "guess and check" process, if all else fails.

 

[rockinrob86]

yea, this is what I was thinking too.  It is going to be frustrating to track this one down I'm afraid

 

[geebeeVIE]

Check the connection in the PSU that powers the relais that switches cardioid/omni.... had some nasty stuff happening when the mic was set to omni but the reed relais switched back to caridoid mode - including lots of distortion and a collapsed membrane because of the rising voltages caused by an off-thrown system.

 

[rockinrob86]

It appears my issues in this mic may have been cable related.  I took a good look at the entire path from the mic to the PSU, and resoldered a few joints here and there.  There was one connection on the cable that looked dodgy, but the rest looked ok.  Finished it up and used it for a couple hours with no hiccups, so knock on wood, I think everything is back to normal!

 

[bigbeaty]

Hi guys,
I was very excited to receive my boards from Dany yesterday, and I'm looking forward to getting going with this super project.
Quick question on the mechanical, has anyone successfully built this into a thomann sct-800? It looks like a likely donor, and there's connectors etc to cannabalize. I just fear it's a bit too narrow!
Cheers,
Rich

 

[TillM]

No, the sct-800 body is too short for the pcb.

 

[bigbeaty]

Thanks TillM, Phew.. you just saved me blowing 175 Euro 

Think I'll try and get hold of an Alctron long U47.

Cheers,
Rich

 

[mosvelit]

Hello again!

Thanks for the clarification on the BV-08 connections TiIIM!!

I had another doubt regarding this point on the schematic in the PSU (attached an image of the point I'm talking about). It's what goes between x1-2 and x1-1. I assume it is the filter.

Thanks in advance!

 

[TillM]

Yes. That’s the choke.
Just connect the choke on this point.

 

[mosvelit]

Great! Thanks again TiIIM.

 

[pzjones]

Just waiting for a capsule from Thiersch and it will be ready for testing. It has been a great project and a tribute to OA. Thanks to Dany also for the PCB,s etc. More news in a few weeks hopefully.

 

[bigbeaty]

Hi folks, big thanks to Dany for bringing this project to the fore, here's mine, with FAB V8 transformer, beesneez K7 and a siemens EF800. This thing sounds simply stunning...

 

[bigbeaty]

Here's inside the PSU, I took inspiration from Spence... a £10 ex ammo box off of ebay was just the ticket!

 

[bigbeaty]

Here's the PSU. Going to save my beans for an M49 or two next. Thanks again Dany!

 

[poctop]

Hi folks, big thanks to Dany for bringing this project to the fore, here's mine, with FAB V8 transformer, beesneez K7 and a siemens EF800. This thing sounds simply stunning...

Thanks You ,
Best,
Dan,

 

[dasnevestheo]

Hey there !
I have an Eagletone CM90 which has a pretty big body, but not sure if big enough for a D47 build...
I could not find any pcb dimensions on this thread.. ?

If the circuit fits, this would be a pretty cool donor as it already has 7pin XLR wiring to a similar PSU.

If it's too small I'll just have to a make a FET one
Thanks  a lot !