ln76d

I didn't investigated the feedback issues, because never had any problem with it.
Hard to say - maybe the reason is elswhere than mentioned in the other thread.
Also i don't know what sit inside the silicon replacement - so hard even to compare.


Hello, great insight , a read through the forum and have two questions just to clarify : the construction we see here ist the C version? and 2. i do have a ac701 tube and want to built it with that - all i need ist to set the right voltage in the PSU ? beside that everything has to be built like in the instructions or am i missing smthg... thanks Daniel

Hello me again, wondering about the floating scheme, building version c, do i have to make connection from point to point as seen on the floating diagram...or is it made with the connection of the components as seen in the pictures of the built...thx Daniel

ln76d

Danny  boards will let you build both B and C version.
4V for AC701 heater.
Don't understand your next questions.

Thx for your answer on the second picture on site 1 : Floating Scheme connection For C version - there are white lines between some solder points - do i have to connect them? sorry for being so noobish - i usually build gear with step by step instructions...

thekim1

Hi,
I got a problem with my m49c build.
After putting everything together i got the mic working for about an hour, then there was a loud noise in the audio input on the soundcard as the fuse broke on the m49 psu. After changing the fuse i cant get the mic to pick up audio.
Took a look inside both the psu and mic but could not se anything that had broke, the 5840 tube is still glowing when the psu is turned on.

This is the readings i got inside the mic with the pattern set to cardioid:
K: 3.74v
A: 6.35v
H+: 5.98v
FGRID: 4.18v
4: 5.95v
5: 119v
6: 55.2v
R8-R9: 40.0v


EDIT:
Found the problem, broken tube. Now everything is showing the right voltages and the mic sounds fantastic!
« Last Edit: April 08, 2018, 06:37:32 PM by thekim1 »

kpearsall

Is anyone else using a 6.3v pilot lamp? How are you wiring it? Seems obvious to run it off the heater if the PSU will handle it. However, if the mic cable isn't properly connected, unloaded you'll send maybe 24v to the bulb. It's a number 47 1 watt bulb, so should I just throw a 1 watt 625 ohm or so resistor in series or just buy extra bulbs in case I do something stupid. Is there a best practice that anyone uses to do this in a better way?

Thanks!

Thx for your answer on the second picture on site 1 : Floating Scheme connection For C version - there are white lines between some solder points - do i have to connect them? sorry for being so noobish - i usually build gear with step by step instructions...

Hopefully you've figured this out by now, but the answer is no... there are traces under the PCB that would connect these points if you were not using the floating scheme, but since you are connecting them directly to the turret pin it is unnecessary to do anything else.
~Nathan

At the risk of opening a can of worms, are there any justifiable reasons to use a tantalum cap over an electrolytic cap in C9? It is very difficult to research the subject as people seem to have emotional reactions regarding audio capacitors.  Since one is risking a dead short if the cap fails, what supposed benefits does one receive in return?
~Nathan

 

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