6072a vs 12ax7 in tube mic

[Bob's Mods]

I picked up a GE JAN 6072a to try in my M9 mic because I read that it is the tube used some high end mics. I know it had been or still is used in the AKG VR12 mic but I cannot name any others. I read that this tube will work in a 12ax7 socket but with lower gain and so became curious.

For a total cost of 24 bucks a NOS GE JAN 6072a was delivered to my door and I can say, in my case that is, that this tube made a rather nice change in the sonic character of my mic. I am a believer. My previous tube was a JJ ECC83s but I also own the Rolls Royce of tubes, a new Telefunken smooth plate.

How can I describe the change? Well the tracks seems more accurate, cleaner, less grainy. If you've been swapping out 12ax7s in your tube mic, you may wish to try a 6072a tube.

You mileage may vary some from mine because I swapped a number of parts in my M9 for high grade parts. For those that are looking for alternatives to the 12ax7's in your tube mics, the 6072a is a compatible swap with a some loss of gain that is easily made up by turning up your preamp.

Bob

[PhilGood]

Just to add, the 6072a is a sturdy version of a 12AY7. It's kinda rare, but Bob is right, it's worth it!!

[smokieee]

i am looking to get a m9 could you list what you have changed?

[Bob's Mods]

Let me clear the cobwebs from my mind. I changed the chip to a Burr-Brown OPA2134, no brainer there. I changed the 100 uF coupling caps in the mic body to Black Gates. That was tricky because the Black Gates were so much fatter. I changed the DC plate cap in the mic body to a Black Gate which was tricky too. I changed the AC coupling cap to an Audio Theta film and foil and I changed some of the low voltage decoupling filter caps in the power supply to Black Gates. There were other caps in the power supply I could have swapped out with Black Gate caps but the cost was getting up there so I left the original ones in place. As a side note, I believe Nichicon electrolytics are a poor man's Black Gate.
Be advised that these cap changes in the mic main body are not for the novice. They require planning and skill because they are not plug and play replacements.
One last thing, I pulled out the inner screen. Tricky to do this in a CAD.
I will say the perfomance improvement was worth the risk and time and cost. It is not for the novice or faint of heart however as you can trash out your mic easy.
I find this to be a super instrument mic, but like all lower price point LDC mics I've tried an some I've modded, vocals are not there yet for a male voice. I still prefer a SDC for male vocals. But thats me, maybe you'll be beside yourself with the vocals.

Bob

[EleKtriKaz]

Glad to hear that it made a difference for you.

I was thinking about changing the tube in my NTK to a 6072. I haven't actually heard of anyone doing it yet...kind hoping someone will before me

[kidvybes]

Originally Posted by EleKtriKaz

Glad to hear that it made a difference for you.

I was thinking about changing the tube in my NTK to a 6072. I haven't actually heard of anyone doing it yet...kind hoping someone will before me

You might want to read this thread before messing with the NTK...Marik had some interesting input as to the tube swap:

http://homerecording.com/bbs/showthread.php?t=145032

Also, check out this thread in reference to the 6072 Cryogenic Treated...kinda interesting:

http://homerecording.com/bbs/showthread.php?t=143493