from the description, I am pretty sure that you have a ground missing to the chassis/shield/mesh of the mic. Try beeping from ground (XLR3Pin1) to all parts of the mic to find what is not electrically connected to the rest..
Jakob E.
Jakob E.
Thanks for your reply.Delta Sigma said:How are you measuring your capsule voltage? Where exactly are you putting your VM?
You should be able to read your capsule votage at the R3/R5/R6 junction. To be sure your VM isn't loading the circuit, measure across R3 then subtract that from your measured B+. Result should be the same as what you measured across R5. Don't measure to the grid (R4). That should be 0V as virtually no current flows so assume it is and only reference ground.
The front backplate (plus rear backplate in omni & rear diaphragm in fig-8) sees 0V from the junction of the R4 & the grid. The front diaphragm (plus rear diaphragm in omni & rear backplate in fig-8) sees half of your B+ from the junction of R3 & R5. No current flows through R6 so if R3 & R5 are the same value, you get half of your B+. If you want to change the capsule voltage while keeping your B+ at 120V, change the R3/R5 voltage divider.
If you want 60V on your capsule and a B+ of 120, it's probably safe to assume you have 60V on the capsule if you have all the right component values (matching R3/R5). I think you'd hear some audible issues if you had current flowing where it shouldn't in your hi-z section.
axlreddy said:Just finished mine!
The problem was sloved!
There are one jumper that I miss between R4(T2) and relay.
Thanks GroupDIY
Avgatzeblouz said:Hey, this body looks nice, which one is it ?
Delta Sigma said:Nothing wrong with 1/4W. Telefunken probably could only source 1/2W high value resistors.
Unless there is something wrong with your mic wiring, half of your B+ is at your capsule. 1M VM input impedance is quite low and will load the 500k resistors. Most modern meters will have an input impedance of 10M or greater in voltage mode.
You may want to find a voltmeter with a 10M input impedance , even for measuring your B+. Set your B+ for 120V if that's what it's supposed to be. If you want 55V at your capsule, change R3 & R5 for the correct voltage divider.
Delta Sigma said:By measuring at the junction of R3 to ground you are in parallel with R5.
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