MXL V69 Mogami Question

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nsureit

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I'm new to recording and have a stock V69. Is the stock tube a 12AX7? Is there a tube that I might try to increase the output? I thought I read that maybe a 12AT7/ECC81 is interchangeable with the 12AX7. Any advice from anyone? Thanks.
 
nsureit said:
I'm new to recording and have a stock V69. Is the stock tube a 12AX7? Is there a tube that I might try to increase the output? I thought I read that maybe a 12AT7/ECC81 is interchangeable with the 12AX7. Any advice from anyone? Thanks.
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To increase the output? With the stock 12AX7, that's considered an ultra-high-output mic as it is---almost line level....

AFAIK, the 12AX7 is about the highest gain dual triode preamp tube out there. Any higher gain and you're talking about tubes with completely different pinouts that would require a complete redesign of the circuit.

Pin-compatible tubes:
12AX7: 100x boost
5751: 70x boost
12AT7: 60x boost
12AY7: 45x boost
12AV7: 41x boost
12AU7: 19x boost

Most people want to decrease the output of these mics because the 12AX7 oversaturates the mic's stock output transformer pretty badly as it is. The tube is really just too high gain for the rest of the mic.

If the output of the V69 isn't hot enough for your recording setup... uh... not to put too fine a point on it, but... you are using a preamp, right?
 
You actually caught me in a typo. I meant to say, is there a tube that would "change" the output (or coloration), not increase it. I'm using the MXL PS-69 preamp. Based upon your chart, an AY or AT might make for some interesting mods to this mic. I'm not unhappy with the stock V69, but tinkering with gear is most of the fun! Thank you for your informative response!
 
dgatwood said:
Most people want to decrease the output of these mics because the 12AX7 oversaturates the mic's stock output transformer pretty badly as it is.
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The V69 is transformerless. The new V69XM has a transformer. Still, a 12AX7 will give more of the artifactions known in transformerless impedance conversion.
 
PhilGood said:
The V69 is transformerless. The new V69XM has a transformer. Still, a 12AX7 will give more of the artifactions known in transformerless impedance conversion.
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My bad. I assumed it was designed based on pretty one of the same two ro three schematics as most of the other Chinese tube LDCs.

Wait... are they using the tube as the actual line driver? No op amp and no transformer? :confused:
 
V69s I have looked inside and started to trace have the tube triodes in parallel, cathode biased, set up as a charge amp with whats looks like about a gain of 1 inverting. The module has two BJTS and a Fet and stuff under an epoxy module and good caps (what circuit has this transistor count?). I did not trace it further did not want to waste time they are just sitting on a shelf. IMO expect for noise and microphonics I don't think a tube swap makes that much difference with that microphone circuit because of the circuit used.

HINT One part change can make a different with the stock circuit.

Trace the circuit if you know how and have one to understand what I am posting about.
 
To be precise, I have the V69ME. I now know that it has a 12AT7, not the AX. Interesting what one can learn if he just looks at the specs!

BTW, I'm going to need the Rosetta Stone - Microphone Edition to learn what you guys are talking about in the past few posts...:D
 
Gus said:
V69s I have looked inside and started to trace have the tube triodes in parallel, cathode biased, set up as a charge amp with whats looks like about a gain of 1 inverting. The module has two BJTS and a Fet and stuff under an epoxy module and good caps (what circuit has this transistor count?). I did not trace it further did not want to waste time they are just sitting on a shelf. IMO expect for noise and microphonics I don't think a tube swap makes that much difference with that microphone circuit because of the circuit used.

HINT One part change can make a different with the stock circuit.

Trace the circuit if you know how and have one to understand what I am posting about.
Click to expand...

I kind of went throught that whole thing too when I bought a broken one on ebay. Then I just decided to gut it and replace it with a different circuit entirely.

I may have to have a second look if I get another one.
 
To be clear I don't like it much with the changed part it is a bit smoother.

Gutting it and installing a new circuit makes good sense to me if I was going to keep them.
 
Gus said:
IMO expect for noise and microphonics I don't think a tube swap makes that much difference with that microphone circuit because of the circuit used.
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I beg to differ; the sound of my V69 changed substantially for the better when I put a Mullard 12AT7 in there. I did vocal takes on the same song through the same preamp before and after the tube swap to prove it.
 
Sorry, sorta off topic, but does the V69 have much difference with the V67G?
 
Grafolicious said:
Sorry, sorta off topic, but does the V69 have much difference with the V67G?
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The V69 is a tube mic. The V67G is an FET mic. The V69 has a big peak at around 8-10k. The V67 is generally a bit less peaky. It sort of slopes up towards 20k, but not near as much.
 
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