D-EF47 Tribute To Oliver Archut U47 Build Thread.

[Silas]

Awesome. Well when I pull ground from 0v it stops all humming. What does pin 3 have to do with anything? It is not connected to anything in the microphone as far as i understand the schematic and the build. I wonder if this is dangerous to have the mic set up with out a path to earth... I wouldn't want to shock myself or any clients... It does sound great with out the hum though ;P

Ill have to get the optional switch at the shop this week.

Ground to 0v has a 50ohm resistance between the two with the unit on and 4 ohms when the unit is off... so I suppose there is a low impedance path to ground there. Kind of strange...

Ideas about safety?

If it’s any help - I recently built this mic and kept the grounding almost exactly the same as the design, to keep it safe. The only modification I did was insulate the mounting pins of the mic board from the mic body - which was creating a ground loop. Once I did that the ground buzz was gone.

The rest of it didn’t need modification and keeps it safe (still shielded correctly and grounded via a separate cable core)

Proctop has some useful notes in the M49 build as well I think.

Good luck, I love this mic!

 

[Greenie]

Hi, I am trying ti figure out how to connect the VPT230-110 from Triad, to the www.vintagemicrophonepcbkit.com D-47 PSU Pcb. I can't seem to find the voltage need of the AC inlet?
Should it be series or parallel? (Sorry if this has been answered, I have looked.)

 

[wave]

VPT-230 gives 230VAC when the secondaries are series tied.

 

[EarthTone]

Still perusing this thread before I order my components... But has anyone successfully used Cinemag's CM-2461 transformer in this mic instead of the AMI Bv8 Classic? Any thoughts on that, or one vs. another sonic characteristics? They are the same winding 6.5:1, and Cinemag cloned a really nice original for theirs. I know AMI is supposed to be amazing too but Cinemag's is like half the price...

 

[C12VR]

Still perusing this thread before I order my components... But has anyone successfully used Cinemag's CM-2461 transformer in this mic instead of the AMI Bv8 Classic? Any thoughts on that, or one vs. another sonic characteristics? They are the same winding 6.5:1, and Cinemag cloned a really nice original for theirs. I know AMI is supposed to be amazing too but Cinemag's is like half the price...

it's not really a clone per cinemag. However, as with all their stuff I'm sure it sounds great. I notice that the AMI builds tend to sound a little brighter. Not sure if this is FR or something else. I used AMI t47. perfectly adequate.

 

[Ricardus]

This is next up on my build list.

 

[neowalla]

Hello my brothers and sisters in arms...or capsules or whatever,
I am almost done populating the microphone PCB and have come to the point of terminating the transformer. I bought the Beesneez B-BV08 trafo which has 6 terminal pins (unmarked) and I need to translate that into 4 pins on the PCB (A,B,C,D). Has anyone else used this trafo and can translate Beesneez speak into Poctop language?
I measured the resistance of the coils and managed to mark the primary and secondary coils. I don't have a scope at the moment so I can't check the phase. Now I just need to know what goes to A,B,C,D. I'll go back through the build thread and see what I can find. I know not everyone who has built this has used the AMI trafo so there should be something in there to help. I did find another thread regarding a slightly different model of transformer from Beesneez and it was made pretty clear in that thread that getting a response from Beesneez is not likely so I won't bother. I'll also not bother to ever purchase anything from them if that is the level of support I can expect.
I will order an oscilloscope from Amazon and identify the + and - photograph it and post it here for the sake of the next person in this situation.

 

[terry setter]

Still perusing this thread before I order my components... But has anyone successfully used Cinemag's CM-2461 transformer in this mic instead of the AMI Bv8 Classic? Any thoughts on that, or one vs. another sonic characteristics? They are the same winding 6.5:1, and Cinemag cloned a really nice original for theirs. I know AMI is supposed to be amazing too but Cinemag's is like half the price...

The Cinemag 2461 is a wonderful sounding transformer. When building a U47 clone, I futzed and fiddled until I had the distortion measurements across the first 5 harmonics to within 2dB of my benchmark U47 long body. The final thing that got the results I needed was the Cinemag transformer, which I would characterize as adding more harmonic content than the original Neumann BV08. However, I was using a tube that was "cleaner" than my VF14M, so the combination of cleaner tube + transformer with more harmonic excitement turned out to be a very good substitute for the original U47s "dirtier" tube into a "cleaner" transformer. One thing I am finding again, and again is that transformers that look very clean and well-behaved on my scope just don't sound particularly interesting. I guess that's why I worked so hard to clone a U47, not a DPA mic. Crimson's BV08 clone is very, very well-behaved. Very high primary inductance, I'd guess, interacting with parasitic capacitance. You'd probably want to mate it with a pretty high-spirited tube to get the magic harmonic balance correct.

I don't want to challenge anyone's opinions here or burst any bubbles, but I have found the AMI T47 to be "uninteresting" by comparison to some of the others I've mentioned and it's output was slightly lower, despite the supposedly identical winding ratio.

I'll attach some shots of the Cinemag 2461, AMI T47, Andreas Grosser's (expensive!) BV08 clone, Crimson 2766 (BV08 clone), and for fun, a UTC 0-10 measured in the 30,000 Ohm to 500 Ohm configuration (that's a bit shy of 8:1). I don't have a shot of an AMI BV08 Classic, though Oliver once re-wound my broken Neumann BV08 using the original (vintage!) laminations and it sounds very true to the original.

 

[craigmorris74]

Good stuff! Would love to see Moby's BV08 on the scope.

 

[innercityman]

Hello my brothers and sisters in arms...or capsules or whatever,
I am almost done populating the microphone PCB and have come to the point of terminating the transformer. I bought the Beesneez B-BV08 trafo which has 6 terminal pins (unmarked) and I need to translate that into 4 pins on the PCB (A,B,C,D). Has anyone else used this trafo and can translate Beesneez speak into Poctop language?
I measured the resistance of the coils and managed to mark the primary and secondary coils. I don't have a scope at the moment so I can't check the phase. Now I just need to know what goes to A,B,C,D. I'll go back through the build thread and see what I can find. I know not everyone who has built this has used the AMI trafo so there should be something in there to help. I did find another thread regarding a slightly different model of transformer from Beesneez and it was made pretty clear in that thread that getting a response from Beesneez is not likely so I won't bother. I'll also not bother to ever purchase anything from them if that is the level of support I can expect.
I will order an oscilloscope from Amazon and identify the + and - photograph it and post it here for the sake of the next person in this situation.

Hi, I used a Beesneez BV08L transformer in one build. It is the same but with wires instead of pins. Same layout as Moby's BV8, follow his wiring layout.

 

[terry setter]

Good stuff! Would love to see Moby's BV08 on the scope.

Arrange to send me one. I'll scope it under the same conditions, return it to you, and post my findings. Send me a message if you want to pursue this. Not to worry, I'll send it back in prime condition.

 

[neowalla]

Hi, I used a Beesneez BV08L transformer in one build. It is the same but with wires instead of pins. Same layout as Moby's BV8, follow his wiring layout.

Wonderful! Thank you sir!

 

[neowalla]

Hi All, Just finished Final Testing this microphone, Everything Works as expected and I am incredibly happy with the sounds of this microphone , Many thanks To Oliver for this Awesome Creation.
and one of the most impressive thing not to say the least this microphone is Incredibly QUIET with this Ef800 Telefunken tube in it ,
This kit will b able to Drive Ef800 , eF802 and Ef80 Telefunken tubes
Absolutely Love it.

I am opening the Kit to the DIY community as we speak, there is some minor Adjustemet I had to do with the PSU resistance Value
there is notes on the Shared mouser BOM about Those changes.

B+
R2 = 6.8ohm 3W
R6 = 4.7 ohm 3W
R11 = 4.7 ohm 3W

H+
R1 = 20K 2W
R3 = 20K 2W
R8 = 25K pot.

The BOM do not contains the Reed Switch but are available at those location ,

the PCB is designed to support these 2 Reed Relay 24V and 48V, Only one resistor is specifically used on the psu for 24V or 48V relay. Notes are in the BOM as well, Rcoil Relay on the Psu denotes the resistance for either 24V operation or 48V operation.


RS Stock No. 291-9631 Brand RS Mfr. Part No. B48-1A72-BV631 RoHS Status Compliant Catalogue page 1186 Customer reviews (0) Add a review

http://uk.rs-online.com/web/p/reed-relays/2919631/
http://www.digikey.ca/product-search/en?vendor=0keywords=7101-24-1010 Relay Coto PN 7101-24-1010


The Silk Screen will be corrected on the next Batch if Any,

The PCB was specifically design to have package for AMI BV08 Classic Series and AMI T47 Transformer ,
Other transformer can be fitted as well. Here is the 2 Mounting Strategies that will permit the Use of about any transformer.

https://cdn.groupbuilder.com/groupdiy/u/39511/58d028199435c.zip
could not be happier with this Toy,
Thanks Oliver.

Hope you will enjoy,
Best,
Dan,

Hi Dan, I need to know the value of R9 (Rcoil relay) on the PSU.
I ordered the relay from your site (291-9631) it indicates on the order page that it is a 48V relay. The BOM link is a Mouser cart with no notes that I can discover. I did a search on this thread for "rcoil relay" and wasn't able to find this value.

 

[Murdock]

Hi Dan, I need to know the value of R9 (Rcoil relay) on the PSU.
I ordered the relay from your site (291-9631) it indicates on the order page that it is a 48V relay. The BOM link is a Mouser cart with no notes that I can discover. I did a search on this thread for "rcoil relay" and wasn't able to find this value.

As far as I remember that value depends on the relay used. Check the relay coil resistance and use a resistor as close as possible in value.
I think it is there to “mimic” the relay when it’s off so the polarization voltage stays stable.

 

[neowalla]

As far as I remember that value depends on the relay used. Check the relay coil resistance and use a resistor as close as possible in value.
I think it is there to “mimic” the relay when it’s off so the polarization voltage stays stable.

I bought the relay he sells on his site so I had hoped this was a known value. I already soldered the relay into the mic PCB. Hopefully I can still get an accurate reading.

 

[Murdock]

I bought the relay he sells on his site so I had hoped this was a known value. I already soldered the relay into the mic PCB. Hopefully I can still get an accurate reading.

Check the data sheet of the relay. It should be written in there.

 

[dmp]

This is in the 1st post of the thread.

 

[neowalla]

This is in the 1st post of the thread.

View attachment 106013

Perfect, thank you! There wasn't a data sheet in the bag that the relay came in, and I must have skipped over this. I swear I've read through this thread multiple times during this build.

 

[craigmorris74]

Will this PSU fit in the chassis offered by Collective Cases? It’s a smidge smaller than the one suggested in the BOM, but I’d love to get one that was pre drilled.
collective cases PSU

 

[EarthTone]

Will this PSU fit in the chassis offered by Collective Cases? It’s a smidge smaller than the one suggested in the BOM, but I’d love to get one that was pre drilled.
collective cases PSU

That’s the one that I bought for my upcoming ef47 build so I hope so! It looks pretty big. I bought two. Fairly certain I have seen several people post their builds with Dan’s (Collective Cases) PSU case and my feeling is it is pretty damn big so I think you will be fine.