S52 - Small Diaphragm Condenser Tube Microphone (5840, NT10/3)

[RuudNL]

It is a pity that the capsules are not available as a separate item.
Microphone Farts Parts used to sell them some time ago, for $25.

 

[craigmorris74]

I'm about to start building this mic and have a couple of questions:
1. Could I use a Primo EM-21 electret capsule for the project? If so, should I modify the build to suit it?

2. I have a generic Chinese PSU in the studio. Can I adjust it for 100V and 6V and use it with the mic? I intended to build the PSU on the board I bought from Milan, but I'm having trouble sourcing the toroid to use with it.

Thanks,
Craig

 

[Vac11]

Hi Craig:

1) polarisation voltage of s52 mic is 50V, electret capsule doesnt need it. Im not sure if its possible join this tube circuit with electret capsule. Search for 'countryman' microphone circuit (- tube circuit with electret capsule and Jensen transformer).

2) yes you can use your psu. For transformer you can check m49 thread. There are some possibilities in BOM. In any case you can use mic with 120V on B+.

Best

M.

 

[craigmorris74]

Thanks for the reply, Milan!

I'll probably just use one of the 3U cardioid flat capsules for this one.

Is there any advantage or disadvantage using the mic with 120V B+?

Thanks,
Craig

 

[k brown]

Just a reminder for those who may not know - 6205 is same tube with slightly different pin-out; sometimes easier to source than 5840.

 

[rock soderstrom]

1. Could I use a Primo EM-21 electret capsule for the project? If so, should I modify the build to suit it

Good question! Will the attached version work with an electret capsule like the EM21?
Do I really need C2?

 

[Tubetec]

Ive used the 5840/Ef732 , rock solid performer , only ever in cathode follower config though , wouldnt mind trying anode loaded version .

 

[craigmorris74]

Good question! Will the attached version work with an electret capsule like the EM21?
Do I really need C2?

would be cool to know. I haven't built my mic yet, but have a TEAC mic with an EM21 and and old MXL that are ready for new guts.

 

[Vac11]

Good question! Will the attached version work with an electret capsule like the EM21?
Do I really need C2?

I think it should work. Imho C2 is not needed. Check 'country boy' microphone schematic for inspiration too.

 

[rock soderstrom]

would be cool to know. I haven't built my mic yet, but have a TEAC mic with an EM21 and and old MXL that are ready for new guts.

I got similiar mics for dirt cheap. I want to test the differences betwen FET with P48V, Country Boy and S52 circuit.

 

[rock soderstrom]

I think it should work. Imho C2 is not needed. Check 'country boy' microphone schematic for inspiration too.

Thanks for feedback!

I am coming from the Country Boy circuit, a cathode follower with gridleak biasing.

The next step for me is to check the S52 circuit in this down stripped version. I call it the "skinny S52" circuit. AFAIK, this is the most basic tube head amp and thus the ideal canidate for a SDC mic with an electret capsule.

I am kind of uncertain about the grid biasing resistor. I am still a mic builder newbie and do not really know how to calculate them.

So my question, what effect does the value of the grid resistor have on distortion, noise, headroom and sound? How should I bias this for an electret capsule?

 

[craigmorris74]

I built second S52 microphone. Thank you Piotr for great design and all tips. For this mic I used 10pF C0G feedback capacitor for lowering the output of microphone. In C1 position I choosed 3n3F cap and in C2 1nF capacitor. R3=100M and plate R6 resistor 200K. Im going to build another two microphones.

Stock BM80 (and also Pronomic) capsule sounds a little bit "harsch" compared to Maiku SDC capsule. Cant recommend Maiku SDC capsules more. Capsules from Banzai´s KM84 body kits fit on ISK BM80, Pronomic SCM-1 bodies...

Here some detailed photos:

Did you end up preferring the version 1 or version 2 schematic with this mic? I'm about to build mine.
Thanks,
Craig

 

[Vac11]

Hi Craig, im prefering version nr. two slightly more. Its not drastical night and day difference between first and second version though....

Good luck!

M.

 

[craigmorris74]

Hi Craig, im prefering version nr. two slightly more. Its not drastical night and day difference between first and second version though....

Good luck!

M.

Thanks for the advice!

 

[klem]

has anyone compared these builds to the royer sdct? especially on drums / similar sources?

i'm wondering about how the topology of cathode follower vs anode loaded, how each topology deals with different types of sources like high transient / SPL sources like drums vs say violin.

(links are welcomed as well on this if discussed elsewhere.)