Joachim Wetzel tube mic

[ruffrecords]

Hello Ian, thank you so much for your help.

I know that these microphones had different versions, and there were Hi-Z unbalanced out, like my mike, and there was also a balanced output versions with a transformer.
Could the second half of the ECC83 be used only for the balanced with transformer versions of the mic?

I can wire it that way, just need to get a proper transformer for it.

I recommend you get it working with the Hi-z output first. The you could try connecting  the output cap to the second cathode which will give you a low impedance output.

In the meanwhile, I discovered that when the transformer was rewinded the primaries and secondaries wire colors were swapped, so I changed the connections accordingly and the voltages are as follows.
The Heater voltage seems to be spot on now.

With mic connected to PSU (230VAC mains power):

B+
Ramps to 338V at power on and then settles at:
218VDC

Heater (tube heaters wired for 12V,  6,3V lamp in series with the heater out)
12.8V

That would explain all your previous symptoms. Looks like it should wok now.

Cheers

Ian

 

[Whoops]

I tested the microphone and it sounds fine.

Pluged the Hi-z unbalanced output to the Hi-Z input of my console.

In some places on the internet this mic is described as Omnidirectional, but it testing the mic it seems to me it's cardiod and not omni.
Also to achieve an omni polar pattern didn't 2 capsules had to be used?


I would like to replace the original mic cable, it's a 4 conductor unshielded cable (1 Heater,  2 Masse+ground, 3 B+,  4masse+ground), with a Shielded cable.
As the enclosure is made of plastic (only the panel is metal) I think I will shield and ground the plastic interior glueing copper foil and connecting it to ground (like it's done on guitars)
There's some residiual noise on the mic and that might help a litle bit to reduce the noise.

I would like also to modify the mic signal output , for a Low-Z balanced connection with an XLR.
What transformer could I use for this ?

thank you so much

 

[PRR]

I don't understand why the audio out is taken from the B+ terminal. ...

https://el34world.com/Forum/index.php?topic=24352.msg261650#msg261650

 

[rock soderstrom]

In case someone wants to buy such a mic, here is a link to an offer on ebay Kleinanzeigen/ germany.

Note the circuit diagram

https://www.ebay-kleinanzeigen.de/s...ampaign=socialbuttons&utm_content=app_android

 

[Csiszi34]

I tested the microphone and it sounds fine.

Pluged the Hi-z unbalanced output to the Hi-Z input of my console.

In some places on the internet this mic is described as Omnidirectional, but it testing the mic it seems to me it's cardiod and not omni.
Also to achieve an omni polar pattern didn't 2 capsules had to be used?


I would like to replace the original mic cable, it's a 4 conductor unshielded cable (1 Heater, 2 Masse+ground, 3 B+, 4masse+ground), with a Shielded cable.
As the enclosure is made of plastic (only the panel is metal) I think I will shield and ground the plastic interior glueing copper foil and connecting it to ground (like it's done on guitars)
There's some residiual noise on the mic and that might help a litle bit to reduce the noise.

I would like also to modify the mic signal output , for a Low-Z balanced connection with an XLR.
What transformer could I use for this ?

thank you so much

Dear Whoops!

I am András from Hungary and I recently managed to buy a Joachim Wetzel Leipzig 027 microphone. The microphone works perfectly except that it is very noisy. Have you solved this problem with your own microphone or can you help me how I can eliminate the noise. All I know is that you will need a transformer... But not what kind and where and how to connect it. Thank you very much in advance for your answer and help!


András

 

[Whoops]

Hello András,
I don't have the microphone any longer, a friend liked it a lot at that time and I sold it to him, as far as I know he then also sold the mic.

I'm sorry but I don't remember if I was able to reduce the noise or not, I remember that I was able to repair the mic and it was working properly and the noise figures were "acceptable"...

Record the noise that you have an post it here so we can understand what type of noise you're having and think about a possible solution.

What I can advise is for you to recap the PSU and the MIC with new Lytic capacitors.
Also make the wiring more tidy inside the PSU and the MIC.

Install shielded cable in all Audio connections and also shield the inside (connect shielding to groung) the plastic PSU box as Audio goes inside the PSU box also.