D-EF47 Tribute To Oliver Archut U47 Build Thread.

[SparkleBear]

Has anyone else experienced large voltage spikes when switching patterns
I've changed the switch
I've got the correct resistor for the 48vdc relay
thanks

Yes, when it is clicked into the omni position, the connection is B+ (in psu) through the 14k resistor then through the relay coil then to ground.. when its clicked into card position it goes B+ > 14k > equivalent resistor to coil > ground. This should only be equalizing the voltage when it is actually clicked in. Since we are using 240v from the series secondary the voltage on that rail isn't loaded down to spec when the pattern switch is not clicked into either position. So when the switch is traveling in between pattern positions the B+ in the mic will jump up a lot. I just make sure to always switch my patterns in a quick fashion. It was a bit alarming when I discovered this.

I wonder if a capacitor could be added to lessen this voltage spike? Dany knows what he is doing though...

Hey Silas!

Man thank you for trying to explain this to me like a kindergartener like I asked! So am I understanding you correctly that pin 3 will just be wired to the thing I circled in red on the connector and then also pin 7 ? Or when you said directly to the mic body /metal shell were you referring to the mic’s actual body like the body shell that slides off ? I’m assuming not since this needs to be removed sometimes , but I want to make sure . I suppose also the metal chassis like the pcb is mounted to could be used for this instead also? Again this is assuming you’re talking about the actual mic body and not the thing on the cable I circled in red in the pic .Again I apologize for being a bit of a moron .hopefully you haven’t pulled all of your hair out yet!

I do have all different colours of wire except the two thicker wires are black and red , maybe I should have added a third colour of those also in hind sight !

Thank you again for your help and time .

Best,

Ethan

Depending on the mic body you are using usually that tab you circled will be coupled to the metal of the mic body through the setscrew that holds the xlr connector into your mic body. Sometimes there is an ring terminal scheme to connect the shield to the body via a wire... You just want to make sure that the body is part of the ground scheme with the shield to keep you safe.

 

[Thegoldenlockedlamb]

Yes, when it is clicked into the omni position, the connection is B+ (in psu) through the 14k resistor then through the relay coil then to ground.. when its clicked into card position it goes B+ > 14k > equivalent resistor to coil > ground. This should only be equalizing the voltage when it is actually clicked in. Since we are using 240v from the series secondary the voltage on that rail isn't loaded down to spec when the pattern switch is not clicked into either position. So when the switch is traveling in between pattern positions the B+ in the mic will jump up a lot. I just make sure to always switch my patterns in a quick fashion. It was a bit alarming when I discovered this.

I wonder if a capacitor could be added to lessen this voltage spike? Dany knows what he is doing though...



Depending on the mic body you are using usually that tab you circled will be coupled to the metal of the mic body through the setscrew that holds the xlr connector into your mic body. Sometimes there is an ring terminal scheme to connect the shield to the body via a wire... You just want to make sure that the body is part of the ground scheme with the shield to keep you safe.

Hey Sparklebear,

Thank you for replying , so it sounds like it more than links is pin 3 to to thing circled in red and not the body . Here is a link to the body I used , it’s from studio 939 website the mk47 mark2 https://store.studio939.com/product/mk47-microphone-body-kit

Also when talking about pin 3 , Silas said we also need to go to pin 7 , would you go from pin 3 to the table circled in red, from the red circled tab to pin 7 , or would it go from red circle tab, to pin 3 , from pin 3 to pin 7?

I definitely want to keep breathing! Haha which is why I ask all of these probably dumb questions . This is my first foray into building anything tube.

Thank you again for your help and time .

Best,

Ethan

 

[SparkleBear]

Hey Sparklebear,

Thank you for replying , so it sounds like it more than links is pin 3 to to thing circled in red and not the body . Here is a link to the body I used , it’s from studio 939 website the mk47 mark2 https://store.studio939.com/product/mk47-microphone-body-kit

I definitely want to keep breathing! Haha which is why I ask all of these probably dumb questions . This is my first foray into building anything tube.

Thank you again for your help and time .

Best,

Ethan

Hey Ethan,

That tab that you circled runs through the plastic part and there should be a set screw on the side of it. When you put it into the microphone bottom bell you will need to "unscrew" the set screw to secure it into the bottom bell. When that metal screw sets itself it is smooshing itself into the metal of the body... this is what provides the ground connection to the body. The body you linked to uses that same connector in that same way.

 

[Thegoldenlockedlamb]

Hey Ethan,

That tab that you circled runs through the plastic part and there should be a set screw on the side of it. When you put it into the microphone bottom bell you will need to "unscrew" the set screw to secure it into the bottom bell. When that metal screw sets itself it is smooshing itself into the metal of the body... this is what provides the ground connection to the body. The body you linked to uses that same connector in that same way.

Thank you again sparkle bear ! ( and Silas!) good to hear. So I’ll just solder pin 3 to that tab , and then from that tab do I need to go to pin 7 also ?

Thanks !

 

[Silas]

Thank you again sparkle bear ! ( and Silas!) good to hear. So I’ll just solder pin 3 to that tab , and then from that tab do I need to go to pin 7 also ?

Thanks !

Sounds good! You can check continuity with a multimeter between pin 3 and the mic body once you have wired it up. Also once you have built the PSU do the same and again (to the IEC ground also) and also when all connected to check your shield is connected safely.

Good luck!

S

 

[Thegoldenlockedlamb]

Sounds good! You can check continuity with a multimeter between pin 3 and the mic body once you have wired it up. Also once you have built the PSU do the same and again (to the IEC ground also) and also when all connected to check your shield is connected safely.

Good luck!

S

Hey Silas!

Man thank you so much! You and sparkle bear have been a huge help and kept me from getting electrocuted !this is another reason I love this forum is people like you guys! +1 on using the continuity function on the multimeter !


Do I still need to connect the tab to pin 7 also like you mentioned before ?

Thanks again!

Ethan

 

[Silas]

Hey Silas!

Man thank you so much! You and sparkle bear have been a huge help and kept me from getting electrocuted !this is another reason I love this forum is people like you guys! +1 on using the continuity function on the multimeter !


Do I still need to connect the tab to pin 7 also like you mentioned before ?

Thanks again!

Ethan

I would recommend connecting the ground and shield at mic body yeah.

Cheers

S

 

[donivan]

thanks sparklebear
my main concern was damage to the capsule or downstream circuits/preamps

 

[Thegoldenlockedlamb]

I would recommend connecting the ground and shield at mic body yeah.

Cheers

S

Okay good deal! I’ll finish up wiring the mic pcb and connector tonight , hopefully get the capsule in too, hopefully I don’t screw that part up either as it’s my first time messing with capsule too ! Haha

Then onto the power supply build . I’ve got all of the electrical components for the power supply except the case . I was thinking of going with collective cases for it . Which did you use for your builds ?

Thanks again , you have been a huge help!

Best,

Ethan

 

[Silas]

Okay good deal! I’ll finish up wiring the mic pcb and connector tonight , hopefully get the capsule in too, hopefully I don’t screw that part up either as it’s my first time messing with capsule too ! Haha

Then onto the power supply build . I’ve got all of the electrical components for the power supply except the case . I was thinking of going with collective cases for it . Which did you use for your builds ?

Thanks again , you have been a huge help!

Best,

Ethan

Collective cases is a good shout as it’s pre-drilled. I fabricated from blank box units but have the tools to do so.

Cheers!
S

 

[doqmemory]

Collective cases is a good shout as it’s pre-drilled. I fabricated from blank box units but have the tools to do so.

Cheers!
S

+3 for Collective Cases!

 

[Thegoldenlockedlamb]

Collective cases is a good shout as it’s pre-drilled. I fabricated from blank box units but have the tools to do so.

Cheers!
S

That’s good to hear they are pre drilled , I have some tools but I my fabricating skills aren’t the best so I think for this one I will go that route ! Thanks again for your help!

Best,

Ethan

 

[Purplenoise]

Since I built two ptp u47s my d-ef47 wasn’t getting much use…it sounds really good but it kinda lacked the depth, definition and “magic” compared to the ptp ones. It always felt a little “constricted” so just out of curiosity replaced the bv08 r with a lundahl 10:1 that i happened to have around…just to try out a different ratio.
Man that made the mic killer…much more extended in the highs and lows. I guess a higher ratio is a better match for the ef800/ef80 tubes.
Try a bv11 or anything 10:1 to check it out. It’s really impressive.

 

[rock soderstrom]

I guess a higher ratio is a better match for the ef800/ef80 tubes.
Try a bv11 or anything 10:1 to check it out. It’s really impressive.

I also have the feeling that the EF800 harmonizes better with a 10:1 transformer. This may be due to the higher internal resistance of the EF800 compared to the VF/EF14, which is twice as high! (It is Ri= 400k to 200k for the VF/UF/EF14, the EF80 got even 500k)

 

[Purplenoise]

I also have the feeling that the EF800 harmonizes better with a 10:1 transformer. This may be due to the higher internal resistance of the EF800 compared to the VF/EF14, which is twice as high! (It is Ri= 400k to 200k for the VF/UF/EF14, the EF80 got even 500k)

I have a Mullard ef80 in it which I just left since I liked it more than the tfk ef800 with the old transformer. It feels a little less mid forward with a slight more definition in the upper mids. Maybe I should try again the 800 with the new transformer

 

[Murdock]

I find it weird that still nobody has measured the actual output impedance of the EF80(0) tube in that circuit. I read several claims that the stock 6.5:1 ratio is too low. But also a lot of folks saying it fits perfectly…

 

[Purplenoise]

I find it weird that still nobody has measured the actual output impedance of the EF80(0) tube in that circuit. I read several claims that the stock 6.5:1 ratio is too low. But also a lot of folks saying it fits perfectly…

I guess it’s a matter of taste and the fact that not many people have heard a real 47. The original is really defined and extended…and some have sort of “glassy” high mids/highs. The ef800 with a bv08 sounds a little woolly and mid forward but some people think that’s “tube warmth”…almost ribbon like. The original 47 could be a very “sharp” mic on some voices.

 

[egroys]

Today my EF800 started having a tiiiiny crackling sound and now sounds like there is a fly buzzing in my room.

Probably time to replace the tube?

 

[rock soderstrom]

Today my EF800 started having a tiiiiny crackling sound and now sounds like there is a fly buzzing in my room.

Probably time to hit up Bowie?

What is the value of your grid resistor? 1G?

 

[egroys]

What is the value of your grid resistor? 1G?

This is actually a Stam SA-47 MkI that I bought before I got into DIY mics and I'm fairly certain it's just a D-EF47.
If I crack it open, where should I look to determine the grid resistor value?

The mic was SILENT yesterday...been tracking all week!