e.oelberg

Hi !

it is a samar 1:6.5 tx, it has no shield, anyway if the lowpass works before the tx and removes the GSM signal it must be introduced before ? or did I get that wrong ? btw my 6s6b sound great !




RFI elimination in a condenser microphone may not be a single step solution.  This assumes you are using good quality cable between the mic and power supply, and cable from the power supply audio output to the preamp, with no wiring or grounding errors.

Bypassing with capacitors can affect the sound, especially if applied across a high impedance.  You may want to try a single ferrite bead at the tube grid connection.  This should reduce RFI before the grid.  Make sure the headbasket and other metal components (connector shell, etc.) are  grounded electrically to the mic body.  Check with an ohmmeter.  RF from a poorly grounded headbasket (antenna) will couple to the high impedance capsule.  The 560 pF cap alone may work across the secondary of the output transformer...but a ferrite bead on each side of the output transformer secondary may work better.  Bad RFI cases may require bypassing the output transformer secondary with capacitor(s) and ferrite beads.  Also, make sure the audio from the mic goes straight to the XLR connector with no components to ground.  (Don't need ground loops.)  My $0.02 worth...

e.oelberg

but why don't you read what I wrote: I said I solved the radio issue, I just don't like the sound  of the lowpass and my question was how high can i put  the lowpass and still get rid of the rf noise

Murdock

but why don't you read what I wrote: I said I solved the radio issue, I just don't like the sound  of the lowpass and my question was how high can i put  the lowpass and still get rid of the rf noise

yeah, and he gave you some hints on how to solve the radio issue without the lowpass which you said you don't like, right?
And why not try yourself how high you can go? Just experiment with different values until you're satisfied.
Or try the other solution rmburrow offered you.
Or did I also get you wrong?

e.oelberg

you are right ! I'm sorry, acctually the first time i missed the tone on this forum, my fault.

RuudNL

e.oelberg Good to read that you are happy with the 6S6B in your microphone.
I used a couple of those tubes and the quality seems very consistent.
Noise is low, which is a good thing. I prefer them over a 5840.
There is a solution for every problem!

http://www.vansteenisaudio.nl

e.oelberg

Hi Ruud

I'm very happy, I ponder of kicking out an EF86 in another mic and try a 6s6b instead, very quiet, not very microphonic. The  m49oid mic is my favorite mic in my collection. I have no 5840 but ef732 and I think the russian tube is much better, but than again I didn't do a direct comparison and there are always so many things to consider.
« Last Edit: October 13, 2017, 11:57:02 AM by e.oelberg »

e.oelberg

Ruud !

did you compare it to a ac701 ? My guts tell me there can't be much of a difference in terms of noise am I right ?
Sound is always difficult to describe..

RuudNL

Unfortunately I don't have the M49 with the AC701 here anymore. (It wasn't mine.)
But from what I remember, the self noise of the tubes is in the same order.
That is: at a very low level!
I already replaced the (1/2 used) ECC83 in another tube microphone with a 6S6B.
That made a tremendous difference in self noise. In fact: the microphone is now useable!  :)
I ordered 25 of those 6S6B tubes, and the variations in self noise are in the range of only 1 dB. (I have tested them all!)
There is a solution for every problem!

http://www.vansteenisaudio.nl

justinheronmusic

First time microphone builder here:

 Can anyone help me out with how to connect the CM-6511 transformer?

 Do I tie red and orange together, and then blue and violet together?
« Last Edit: October 28, 2017, 09:06:58 PM by justinheronmusic »
Justin Heron
Artist / Recording Engineer
www.justinheron.com
www.instagram.com/justin.heron


KrIVIUM2323

Primary are : Brown , red; orange, yellow,
Secondary are : green, blue; violet, grey.
You should have primary and secondary each serial connected so:
Red and orange tied together, blue and violet tied together.

Primary 'input' is then Brown, yellow go to ground, secondary '+' output is green, '-' is grey.
The dot in cinemag's schematic give you indication about polarity.
« Last Edit: October 29, 2017, 05:24:26 AM by KrIVIUM2323 »

justinheronmusic

5840 Connection/Pinout
« Reply #331 on: October 30, 2017, 09:13:37 AM »
Thank you so much! That is a huge help.

Also, I found the tube pinout connections, I thought I would post them here for future accessibility.

5840 Tube:

Pin 1 to FGRID
Pin 2 to K
Pin 3 to H+
Pin 4 - Cut
Pin 5 and Pin 7 Tied together to A
Pin 6 toHG
Pin 8 - Cut
« Last Edit: October 30, 2017, 03:08:07 PM by justinheronmusic »
Justin Heron
Artist / Recording Engineer
www.justinheron.com
www.instagram.com/justin.heron

Rlucas41

How do you wire the 6S6B tube? The pins i mean...

TillM

Pin 1 to A
Pin 2 to H+
Pin 3 to HG
Pin 4 to Fgrid
Pin 5 to K

Rlucas41

Thanks TillM,
I have just ordered some 6S6B tubes, I have built two D49c's and both sound great, curious if the 6S6B will be a little quieter tube...