Re: Neumann M49 Clone : Build Thread Puck Style (TLM49 Conversion To M49 b-c)
« Reply #560 on: January 12, 2021, 11:59:03 AM »
Are you measuring in the power supply or in the mic?

All measurements are in the mic. The rear diaphragm measurements are at the RD connection point referenced to ground.

Thanks,
Josh


Re: Neumann M49 Clone : Build Thread Puck Style (TLM49 Conversion To M49 b-c)
« Reply #561 on: January 12, 2021, 01:21:30 PM »
I just tested pin 6 on the mic PCB, referenced to ground:

F8: 116V
C: 57V
O: 0V

That's obviously correct. Should I be seeing those same voltages on the RD? That doesn't make sense given the 250M series resistance between pin 6 and HZRD. I'm not sure why somebody said RD voltage is supposed to be that?
« Last Edit: January 12, 2021, 01:33:21 PM by JMPGuitars »

Delta Sigma

Re: Neumann M49 Clone : Build Thread Puck Style (TLM49 Conversion To M49 b-c)
« Reply #562 on: January 12, 2021, 06:23:54 PM »
That's the last place you can check the voltage properly. 0, 2 and 4 volts seems right. If your DVM input impedance is 10M, in parallel with 250M puts you somewhere around 4.5V in fig-8.
Neil Fitzpatrick

Re: Neumann M49 Clone : Build Thread Puck Style (TLM49 Conversion To M49 b-c)
« Reply #563 on: January 12, 2021, 07:37:00 PM »
That's the last place you can check the voltage properly. 0, 2 and 4 volts seems right. If your DVM input impedance is 10M, in parallel with 250M puts you somewhere around 4.5V in fig-8.

That's what I figured, so that's all good. Now I've got to figure out what's going on after that point. I installed the capsule and I'm getting very low output in all modes, but F8 is definitely louder than the others. Cardioid doesn't seem to work. Tapping the screen is louder than yelling at it. I'm guessing a connection issue somewhere.

Re: Neumann M49 Clone : Build Thread Puck Style (TLM49 Conversion To M49 b-c)
« Reply #564 on: January 12, 2021, 08:18:24 PM »
Hahahahahaha. Well, I figured out the problem. I took some photos with my 42MP camera and zoomed in. Turns out, I didn't have to zoom in to see the problem. Can you see it?


Delta Sigma

Re: Neumann M49 Clone : Build Thread Puck Style (TLM49 Conversion To M49 b-c)
« Reply #565 on: January 13, 2021, 10:59:09 AM »
Not sure. Backplate screw?
Neil Fitzpatrick


Re: Neumann M49 Clone : Build Thread Puck Style (TLM49 Conversion To M49 b-c)
« Reply #567 on: January 13, 2021, 07:16:51 PM »
What's the general consensus regarding B+ with the M49b? I'm at 116V right now. What differences do people hear raising it to 118 or 120?

Re: Neumann M49 Clone : Build Thread Puck Style (TLM49 Conversion To M49 b-c)
« Reply #568 on: January 13, 2021, 09:52:21 PM »
What's the general consensus regarding B+ with the M49b? I'm at 116V right now. What differences do people hear raising it to 118 or 120?
For me it has to do with the capsule. In my 251 build I liked the b+ 118 when using the BeesNeez ck12 and 110 when using the Tim Campbell. As far as the 49 I use 115v cause that’s what is specified for the phaedrus ac701.

Re: Neumann M49 Clone : Build Thread Puck Style (TLM49 Conversion To M49 b-c)
« Reply #569 on: January 14, 2021, 08:06:38 PM »
For me it has to do with the capsule. In my 251 build I liked the b+ 118 when using the BeesNeez ck12 and 110 when using the Tim Campbell. As far as the 49 I use 115v cause that’s what is specified for the phaedrus ac701.

I'm using a BeesNeez M7 capsule, with an AMI T47 transformer, and a 5840W NOS tube. I guess I should just experiment with it.


Re: Neumann M49 Clone : Build Thread Puck Style (TLM49 Conversion To M49 b-c)
« Reply #570 on: January 14, 2021, 11:59:19 PM »
I'm using a BeesNeez M7 capsule, with an AMI T47 transformer, and a 5840W NOS tube. I guess I should just experiment with it.
Yes that is the best way. I have found that in most designs when you go lower the sound gets kinda more compressed with an emphasis in mid frequencies..more reedy, and as you increase the b+ the sensitivity increases and the sound becomes more “electric” and detailed...more modern if you will. That’s not a scientific find but rather a personal observation on my builds.

Re: Neumann M49 Clone : Build Thread Puck Style (TLM49 Conversion To M49 b-c)
« Reply #571 on: January 15, 2021, 07:55:52 AM »
Yes that is the best way. I have found that in most designs when you go lower the sound gets kinda more compressed with an emphasis in mid frequencies..more reedy, and as you increase the b+ the sensitivity increases and the sound becomes more “electric” and detailed...more modern if you will. That’s not a scientific find but rather a personal observation on my builds.

Thanks! That's exactly the kind of feedback I was looking for before experimenting.

I like cloning the Neumann NKM type supply for mic PS builds.  I especially like the way the HT is regulated by a VR tube (150B2 or US type 0A2) right off the rectifier through a resistor.  Additional RC pairs on the HT will drop the 150 vdc off the regulator and deliver clean stable voltage to the mic.  The heater voltage can be regulated using a LM317 or 7806 type circuit, or a series pass.  Instead of stabilytes in the NKM, rechargeable AA type batteries work.  Use enough of those in series for the heater voltage used.  Rechargeable batteries have lots of capacitance in a small volume.  Lots of possibilities; simple and inexpensive.

Note the 0A2 and 150B2 regulator tubes are not pin compatible.  Wire the socket accordingly.  Always use a small series resistor if batteries are used for final LV filtering.


 

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