Why a tube in a (condenser) mic is a big deal?

Reproducing that Incoherent Rhetoric from the Flapping Pie Hole...
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JJ2013
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Why a tube in a (condenser) mic is a big deal?

Post by JJ2013 » Wed Apr 16, 2014 8:52 pm

Hi y'all AudioPhiles and VooooooDooooooo Heads!

As a "reminder," I am using a TS870 and feed audio in through ACC2 on back of rig (cap mod done), use a B1 Behringer condenser mic (going to my PR40 off and on) and Behringer outboard gear.

I keep reading that folks replace tubes in mics. Now, could someone explain why exactly that makes a real difference?

a) Is changing a tube to one that offers a lower gain factor somehow better as there will be more headroom ?
b) Is more headroom in hammy radio important and if so why?
c) Is changing a tube in a condenser mic to one with a lower gain factor better from a sensitivity perspective? Will the condenser then be less "hot" and perhaps easier to tame using a de-esser or a multi-band compressor?
d) Won't changing a tube to one exhibiting a lower gain factor make the power supply work harder?
e) If the power supply above works harder I would think that that fact alone will cause the audio through the mic to be "shaped" or "sculpted" differently?
f) Why would say a 12AU7 by Telefunken be better than the "same" tube by another company?
g) Why is the length of a plate in a triode important for an application in hammy radio? "Short" versus "long"?
h) Does changing the tube in a dynamic mic versus condenser mic (yeah, this question is impossible to answer.... :twisted: ) somehow provide relatively smoother sonic characteristics?
i) If one were to upgrade an inexpensive mic (dynamic or condenser), what is more important, replacing the tube or the mic capsule and why exactly? Again, keeping in mind that we're talking hammy radio and relatively reduced transmit bandwidth (even at 6 kHz) compared to say AM radio?
j) Is replacing capacitor(s) in condenser (dynamic?) mics that have different dielectrics between the plates important with regard to how "smooth" the audio sounds? If it is, I would think it won't be significant in hammy radio?

Just a short list of questions that came to mind and again, these tube questions are only ones that came to mind when thinking of their usage in mics! Tube based EQ, pre-amp, compressors etc. would be a topic that I "know" even less about :(

Sure would like common sense responses :? :)

Cheers!

JJ


P.S. I need a compass to navigate through the ever darkening waters of the VoooooooDooooooooo maze............the search for "perfection" continues.

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Post by Voodoo Guru » Sun Jun 01, 2014 2:18 am

Howdy JJ,

Tube rolling is a common practice to change the gain of that stage or for changing sonics. The later has great controversy and opinions and more can be found on this subject of Tube Rolling by searching the interweb. Best thing to do is to try yourself and see if YOU hear a difference.

As far as the gain questions you asked on the mics, It all depends upon how the mic was designed/built and the equipment that follows it. Each mic is different in design and actually changing the gain structure within the microphone might harm the performance, in other mics improve. Again, it is a "try it an see" type of thing.
In our application using the TSM Muneo Mic and the RP-520 Mic Pre, changing the 12AX7 actually hurt the performance of the mic. We opted to change the 12AX7 out in the RP-520 Mic Pre to a Command Series RCA 5751 to reduce gain to the following equipment. This worked better in our situation.
How did we know what to do?
We changed the tubes and listened! :D

On your other questions about tube/component sonics, that is a purely subjective subject. Everyone has their own opinion about this and the only way for you to be able to take a side is to change them out for yourself and use your OEM Equipment (ears) to make that determination.

We've rolled lots of tubes out in different equipment, there is one guy (Joe S) that made a list of the tubes he rolled and gave a sonic report on each one, his ears matched ours in just about every situation so we tend to trust his summation.

It's Joe's Tube Lore...
http://www.audioasylum.com/scripts/d.pl ... tubes.html

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K6HP
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Post by K6HP » Fri Jun 20, 2014 4:32 am

Hi JJ,

I've used several different microphones since I started down the dark path of Voodoo audio but my favorite so far is the Advanced Audio CM-47.

It isn't cheap but find the mic that you like on the air.
73,
Ed

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