Neumann M269c Clone : D-M269C Tube Microphone Build Thread +(sample)

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poctop

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Kit in Stock,
http://www.groupdiy.com/index.php?topic=49675.480

Best,
Dan,
 

dandeurloo

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What are the values for the 2 styrene caps in this build? I think that C17 is 80pf but not 100% sure.  And I am not sure if C10 is suppose to be 560 or 270pf?

Thanks
 

0dbfs

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Looks like C10 is a 270pf on the schematic which is the pad switch / capacitive-divider / nfb. I think 560pf would be less attenuation while 270pf would be more. Some related notes:
http://repforums.prosoundweb.com/index.php?topic=1137.0

C17 is selected from say 80-120pf or whatever and looks like it's in the fb winding loop back to the plate. I haven't built these yet but have them almost ready to start. I believe Dany supplies a 100pf in his styro kit for the C17 position.

Cheers,
jb
 

dandeurloo

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Well, I happen to have 270 and 100pf here o I will give those a shot.  I think they are the same ones I used in my d-u67's which sound great.  I'm finally getting closer on this one. 


BTW, great link.  That made a few things I have always heard now make sense.
 

poctop

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important Information For All M49 and 269c builder

the psu pinout  connection shows that pin 3 is the cable shield lift channel with the jumper that should be by default installed on the psu , unless a specific cableshield scheme is used  and that pin 7 is the Audio Ground ,

on the M49 Mic pcb as per the original numbering the pin 7 is actually the shield from chassis and the pin 3 is the audio ground ,
since the 2 points are linked on the pcb they are basically the same but special attention must be taken to actually take into account for this properly grounding the mic and cableshield as the number are reversed on the mic end ,

take special attention to ground loop while grounding the shield of the mic cable ,


Side Note: For those having a polarity that is reversed for a known or unknow reason , remember that you can swap the wire inside the psu at the xlr output connector swapping wire pin 2 and wire pin 3 will reverse the polarity of the ouput.


the same PSU can be used for the M269C build but note that the difference is that pin 3 is the calibration input on the mic pcb not the shield ,
there is a pad on the 269 pcb labeled Cal on the mic pcb. Always have the original schematic of the mic when building as all the numbering on the mic pcb always follow the original numbering on the schematic as opposed to the psu that will always stay te same for both mics 49bc-269c ,
the remote pattern on the M269c is like the original as well that is you have to switch on the mic pattern and then on the psu to get the poper pattern , ( see schematic)  the use of a linear pot can be used in both configuration for the pattern ,

Best,
Dan,

I went to update the PsU schematic with proper labeling of the output pin of the psu and also did this little table that will help explain


Cabling connection From PsU https://cdn.groupbuilder.com/groupdiy/u/39511/58d0281993e62.jpg
 
 

whichpinishot?

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What mic are you using for a donor for the mic body and powersupply box? 
Are there any plans for another run of PCB's?  I would be interested in 3 sets if so.
Thanks!
 

poctop

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whichpinishot? said:
What mic are you using for a donor for the mic body and powersupply box? 
Are there any plans for another run of PCB's?  I would be interested in 3 sets if so.
Thanks!

available here :

http://www.vintagemicrophonepcbkit.com/index.html

Mic body available soon here : http://groupdiy.com/index.php?topic=50015.560

Best,
Dan,
 

mickdundee63

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Where are you guys sourcing AC701s from?? Also I have a KM54 without a PSU. I'm presuming I could use the PSU from this kit for that also provided I wire the cable appropriately?
 

mickdundee63

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Ah OK excuse my ignorance I see the 5840 is being used. Will figure out whether or not to adapt this PSU or P2P an N52 from schematic.
 

0dbfs

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You can calibrate B+ and H+ with the tweaker pots in this PSU to be spot-on for a AC701k. This PSU is pretty universal and quiet for either fixed or auto bias scenarios so essentially use-able with many tubes and bias schemes.

Cheers!
-jb
 

poctop

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mickdundee63 said:
Ah OK excuse my ignorance I see the 5840 is being used. Will figure out whether or not to adapt this PSU or P2P an N52 from schematic.

the psu pcb is included in the kit just FyI,
Best,
DAn,
 

mickdundee63

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Ah perfect thank you both. I will place an order. May as well build the mic as well. I found the DU-67 a lot of fun.
 

poctop

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mickdundee63 said:
Ah perfect thank you both. I will place an order. May as well build the mic as well. I found the DU-67 a lot of fun.

you are welcome,
Happy build then , :)
Best,
DAN,
 

poctop

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Any Comments on this mic ,
Let me know if anything,
Best,
Dan,
 

poctop

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the same Errata applies to the M269c with the AMI T67 Transformer.
Errata Feedback winding polarity  http://groupdiy.com/index.php?topic=50021.800 reply # 814

AMI T67 Corrected Wiring to main microphone pcb

From transformer board to mic PCB

Pad 5 ----->  mic pcb pad T1212
Pad 12 -------> mic pcb pad T55
Pad 1 --------> mic pcb pad T44
Pad 4 --------> mic pcb pad T11
Pad 7 --------> mic pcb pad T1010
Pad 10 ------> mic pcb Pad T77
 

kidvybes

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...I'm currently in possession of the prototype built by Dan for this thread...as soon as I get some reasonable vocals recorded, I will post soundfile links and comments...

;)
 

poctop

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kidvybes said:
...I'm currently in possession of the prototype built by Dan for this thread...as soon as I get some reasonable vocals recorded, I will post soundfile links and comments...

;)

+1
D:)
 

dmp

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Just trying to finish mine up...
Is the recommendation R14=150k (for AC701) and R14=100k (for 5840)?
Anyone tried both for 5840? Difference in output? Headroom?
 

poctop

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dmp said:
Just trying to finish mine up...
Is the recommendation R14=150k (for AC701) and R14=100k (for 5840)?
Anyone tried both for 5840? Difference in output? Headroom?

100K for the 5840 will get you closer to the plate current range used in this circuit.
Best,
Dan,
 

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