U87 (Revision A) in BM800 microphone donor body

[Potti18]

Finally got mine finished today

You had to do some adjustments on that SC400 body or the PCB fit in perfectly? Starting mine very soon and can get one for like 10€.

 

[mihi_fuchs]

Hi @mihi_fuchs



Yes, I will do.




I have checked the U87 Building Guide and for my understanding, to refine RV10 for the best sweet spot is to generate a tone via J4. How can I do that without special equipment?

If not, which cheapest kind of machine should I be looking for?

Or preferable a portable digital tone generator or portable digital oscilloscope will do the trick for this and bullet proof for future projects?

A low distortion sine wave generator. Maybe you can use your sound card for that too. I never tried. But you can give it a go. Just be careful and start very low in volume.

I used GND on Capsule/body which i took a cable from XLR pin1 and J9, is that correct?

that's perfectly fine. Values look good too.

Good idea, let's see if I can figure it out.

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| QUESTIONS |

1. I must give a lot of gain to have a reasonable level of sound, is this normal?

Nope, make sure you have the PAD jumper in the right position. Check with guide, there is a description for it.
Additionally make sure you have put the Transformer wires in the right connection holes. If you changed the direction of the transformer that can also result in low signals.

2. When I activate phantom power and start giving gain, I hear some crackling which goes away after a few seconds ON. Is this anything with the transformer? Does it need to break in on order to have normal results?

No, a crackling noise is fine or the moment switching it on. But not for too long. The capsule is fine, is it?
The transformer has little to do with the phantom. It is more the DCDC converter. Voltages around the Transistor on the DCDC board are stable, are they?

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Always very helpful. Thank you so much @mihi_fuchs

Best Regards,

RB

 

[RBeTT]

Here you can find some good info about soldering
If i were in the US I'd try the Jli capsule you can find it here TSC-2
Never tried out for my build as I'm from Italy and shipping makes it inconvenient, but they're not so expensive so worth a try in my opinion if you are in the US.

About the cleaning process, I didn't wash the pcb as you see in the video you mentioned, I've just used some Isoprophyl alchool on a towel and a toothbrush, or cotton fioc for the HiZ junction, and the mic is incredibly silent.

One thing I receltly implemented are a pair of 22nF caps at the XLR, as I was having some RF noise.. now it works perfectly.

@antocu ,I'm kind of having the same problem with RF noise...which part specifically [on Mouser] did you use as 22nF caps specs for the XLR?

Thanks