D-EF47 Tribute To Oliver Archut U47 Build Thread.

[Purplenoise]

Hi there, been using my DIY U47 for a few weeks now and the sound is almost perfect to me

However, I get quite a bit of sibilance and find the 7kHz area quite strong compared to other 47 style mics.
Any advices on how to tame this beast ?

Body : Alctron
Capsule : Beesneez K7b (wired in cardio only, no switch or relay)
PCB : acrylic board / point to point
Tube : Siemens EF80
Transformer : AMI BV08c
Output caps : 2x K42Y-2 PIO Capacitor
PSU : Dany's PCB, set to 105V / 5.05V

Cheers !

Usually 47 capsules have a dip around 6/7k. Have you tried another capsule? Have you flipped the capsule to use the other diaphragm? Also c1 cap plays a role. If you use styrene it will be a little brighter than a film. Phillips/Mullard mustard caps will give you more apparent midrange.

 

[dasnevestheo]

Usually 47 capsules have a dip around 6/7k. Have you tried another capsule? Have you flipped the capsule to use the other diaphragm? Also c1 cap plays a role. If you use styrene it will be a little brighter than a film. Phillips/Mullard mustard caps will give you more apparent midrange.

Thanks, I haven't got another K47 to test, but I'll buy another one if I can't fix the problem.
C1/C3 are NOS PIO green russian caps

 

[dasnevestheo]

When you assemble it, is there a gap between the capsule mounting plate and the mic body?

I'm using a Beesneez K7 (not sure what 'b' is) in one of Dany's bodies. I have no sibilance issues. I did have a 4kHz resonance in my M49. I followed advice from someone in the U47 FET thread and filled that gap with foam. Fixed my 4kHz problem. I used closed cell foam used for paddlesports.

Thanks for the tip, I does not sound like a resonnance, it's just lacking that 7k dip I'm used to with 47 type mics. But I'll give it a try ! so the gap you're talking about is the 3mm round gap outside of the capsule mounting plate ?

 

[Delta Sigma]

Thanks for the tip, I does not sound like a resonnance, it's just lacking that 7k dip I'm used to with 47 type mics. But I'll give it a try ! so the gap you're talking about is the 3mm round gap outside of the capsule mounting plate ?

yes

 

[dasnevestheo]

Ok I'll see what it does thanks

 

[Purplenoise]

Thanks, I haven't got another K47 to test, but I'll buy another one if I can't fix the problem.
C1/C3 are NOS PIO green russian caps

I am talking about the 0.01uf cap...maybe it’s labeled different in your schematic

 

[dasnevestheo]

Ah yes ! It's C2 on mine I indeed put what I had in hands, which was polyester. was that a bad move ?

 

[Purplenoise]

Ah yes ! It's C2 on mine I indeed put what I had in hands, which was polyester. was that a bad move ?

No not at all. Try other types there too. As I said before Phillips/Mullard mustards tame the highs/upper mids. Styrenes are clean and very balanced. Maybe a PIO k40 at 400v is small enough to fit in there too.
Originals used ceramic ( I wouldn’t recommend those though), film ( tfm, tff wima), styrenes, and I ve seen pictures with the mustard caps also.

 

[dasnevestheo]

okay thanks for the tips, lot of things to try here that's cool

 

[Delta Sigma]

I think I have ceramics in mine. C0G/NP0 dielectric are fine for use in a mic.

 

[Purplenoise]

I think I have ceramics in mine. C0G/NP0 dielectric are fine for use in a mic.

Actually those are nice

 

[innercityman]

Hi everyone,

received yesterday the pcbs and finshed to populate them today. i'm a little confused...

I've built last year an MK-47 from ioaudio using the Zayance psu pcb. The technique to roughly calibrate B+ was to load the psu with a 2.3 or 2.4k wirewound resistor instead of the mic. I know the D-EF47 psu is not exactly the same, so if I undestood correctly... To calibrate it before pluging the mic, I have to put a jumper on top of the shelf pads socket, am I right ?

Also, not a big deal but I don't understand why after finishing poulating mic and psu pcbs, I have 2 film capacitors left... 1uf and one .47uf 250V. I used the link for the mouser cart on Dan's web site for the bom and just replaced components not produced anymore or out of stock with similar ones in values. But on the bom, there is 2x 1uf 250V caps from different brands... 1 Vishay and one CDE, also a 1uf 400V CDE cap... Weird ! And this .47uf cap that I absolutely don't know what to do with it. Could it be possible to put it on the mic instead of the first 1uf, as the pcb is labeled 0.5 or 1uf capacitor ? Could it be an improvement regarding the transformer or tube I'm using ?

Thanks for your help and advices.

 

[Delta Sigma]

Hi everyone,

received yesterday the pcbs and finshed to populate them today. i'm a little confused...

I've built last year an MK-47 from ioaudio using the Zayance psu pcb. The technique to roughly calibrate B+ was to load the psu with a 2.3 or 2.4k wirewound resistor instead of the mic. I know the D-EF47 psu is not exactly the same, so if I undestood correctly... To calibrate it before pluging the mic, I have to put a jumper on top of the shelf pads socket, am I right ?

Also, not a big deal but I don't understand why after finishing poulating mic and psu pcbs, I have 2 film capacitors left... 1uf and one .47uf 250V. I used the link for the mouser cart on Dan's web site for the bom and just replaced components not produced anymore or out of stock with similar ones in values. But on the bom, there is 2x 1uf 250V caps from different brands... 1 Vishay and one CDE, also a 1uf 400V CDE cap... Weird ! And this .47uf cap that I absolutely don't know what to do with it. Could it be possible to put it on the mic instead of the first 1uf, as the pcb is labeled 0.5 or 1uf capacitor ? Could it be an improvement regarding the transformer or tube I'm using ?

Thanks for your help and advices.

The film caps are probably different dialectrics and values. Your output cap can colour the sound a lot (relative to other caps in the circuit) so record a sample with each one and pick your favourite. Try ordering Paper in Oil or Metalized Paper caps. I order Russian ones off ebay. They take a while to arrive and sometimes are mislabeled but usually the price is right. Order a few and test the values.

As far as output cap values go:
https://groupdiy.com/index.php?topic=77529.msg988283#msg988283

I'm not sure what you mean by shorting "pads" when testing the power supply. Really, you're not calibrating your power supply with a dummy load. You're just getting it in a ballpark range and making sure you didn't make any major mistakes that'll pop a fuse or damage your mic. Just get your B+ to 105 and H+ to 5.05 with a close-ish dummy load (search thread for values; "print" thread, ctrl-f for dummy, load, etc). If your supply is good, hook up your mic and check voltages as the tube warms up. If everything seems okay, adjust your heater, then your B+, then repeat.

Dummy load for an MK-U47 would be completely different. Check the schematics of this mic and an original U47 and see how the heater is powered. Since U47 heater is off the B+, there's way more current, so way different B+ dummy load.

 

[innercityman]

The film caps are probably different dialectrics and values. Your output cap can colour the sound a lot (relative to other caps in the circuit) so record a sample with each one and pick your favourite. Try ordering Paper in Oil or Metalized Paper caps. I order Russian ones off ebay. They take a while to arrive and sometimes are mislabeled but usually the price is right. Order a few and test the values.

Very interesting thank you for advising me !

I'm not sure what you mean by shorting "pads" when testing the power supply

Didn't wrote "shorting" but "Shelf" soldering pads. On the PSU pcb, there is 2 tiny solder pads labelled "Shlf" between H+ and B+ solder pads, and on the parts list I have a Molex header with a jumper that goes there I guess. And I guess too that I have to put the jumper over the header for a rough calibration before plugging in the mic. So what you call "Dummy load" was that 2.3K resistor that is used for a rough calibration on Zayance PSU, and as far as I've understood your explanations, no dummy load for the EF47 psu calibration right ?

So after check and double check my PSU build, put the jumper over the header for a rough calibration and then plug the mic and adjust precisely the 105Vdc and 5,5Vdc... is that ok ?

 

[dasnevestheo]

I think the SHLF jumper is about grounding, not about dummy loading. But I'm not sure

 

[Delta Sigma]

Very interesting thank you for advising me !

Didn't wrote "shorting" but "Shelf" soldering pads. On the PSU pcb, there is 2 tiny solder pads labelled "Shlf" between H+ and B+ solder pads, and on the parts list I have a Molex header with a jumper that goes there I guess. And I guess too that I have to put the jumper over the header for a rough calibration before plugging in the mic. So what you call "Dummy load" was that 2.3K resistor that is used for a rough calibration on Zayance PSU, and as far as I've understood your explanations, no dummy load for the EF47 psu calibration right ?

So after check and double check my PSU build, put the jumper over the header for a rough calibration and then plug the mic and adjust precisely the 105Vdc and 5,5Vdc... is that ok ?

I couldn't load the schematic this morning,  not sure why. Sorry, misread your post. If I remember right, SHLF is for a ground lift that doesn't quite make sense to me. Check the schematic, if it's a jumper on the ground, make sure it's always in place. Might as well solder a bridge. If you want any sort of ground lift switch there are other ways you must do it to ensure proper grounding.

Are you using a relay for pattern switching? See this post and the posts that follow:
https://groupdiy.com/index.php?topic=56878.msg763677#msg763677

Pay close attention to Matt Nolan's response about switching the relay and how it affects the B+ because of current draw.

 

[Delta Sigma]

Here's a post where I try to explain the relay loading of B+:
https://groupdiy.com/index.php?topic=56878.msg979960#msg979960

 

[Purplenoise]

Hey guys, I am thinking of building a cardioid only version of the D-ef47 leaving out the relay completely. What would be the best way to do that? Connections? Mods in mic or psu? Thanks in advance.

 

[Delta Sigma]

Hey guys, I am thinking of building a cardioid only version of the D-ef47 leaving out the relay completely. What would be the best way to do that? Connections? Mods in mic or psu? Thanks in advance.

Should be easy. I cant see the power supply schematic right now but you can just leave those components out. you can leave them in too, doesn't really matter. Just don't put in the relay off current sink resistor. No real modification required. You could even use the power supply from your mic with the relay as long as the switch is off. If you flipped the switch on, there would be less current draw and your B+ would rise.

Same with the mic. Leave out the (rear diaphragm) pattern resistors and the cap that isolates the two diaphragms.

 

[innercityman]

Are you using a relay for pattern switching? See this post and the posts that follow:

Yes I am... I put the 12.1k resistor.

I think I'm good to read the 26 pages of this thread... Hopefully I'm not building a GSSL for the first time with its 500 thread pages...

Thanks anyway !