Mod for budget Tube Mics

  • Thread starter Thread starter malcolm123
  • Start date Start date
malcolm123

malcolm123

New member
Hello All,
Has anyone out there ever made any mods for any of the budget tube mics. IE SP T's, V69, V77 etc?

How would something like a Telefunken mod or Groove tube sound with any of these mics? Would there be a significant improvement? Is it even possible?

If you have, what did you encounter with the mod?


Just curious

Thanks

Malcolm
 
i've heard about people doing it and getting good to great results my only question is how much do the groove tube and telefunken tubes stuff cost? just got me a CAD m9 which i'm LOVING but would love to hear it with a better tube
 
My guess is you'd hear a much bigger improvement by swapping out the cheap, crappy transformers that come with them. Tubes are a dime a dozen --- almost literally.
 
chessrock said:
My guess is you'd hear a much bigger improvement by swapping out the cheap, crappy transformers that come with them. Tubes are a dime a dozen --- almost literally.
Click to expand...

getting a pair of "real" input & output transformers cost more then some mics!
 
<getting a pair of "real" input & output transformers cost more then some mics!>

I am not sure if you are talking generally, but of course you know that tube mic doesn't have an input transformer.
Per Lundahl has a new LL1653 line of transformers specifically designed for tube microphones. His transformers are great and very affordable esp considering their quality. I am positive that you will definitely hear the difference. Good "audiophil" quality bypass capasitor would be also much of help. Needless to say, the resistors should be "low noise type" and be of high quality. The anode resistor should be rated at 400 volt, which most of the time is not the case. Also, very important--power supply. I suspect that many mics use so called "starving mode", when the high tension voltage on the tube is low. Tell me if I am wrong here. The filter electrolitic capasitors should be also of highest quality.

Malcolm, you asked if there would be a significant improvement. I would answer--yes, yes, and yes. You can call me a snob, but I wouldn't even consider using unmodified tube mic.
 
Teacher said:
i've heard about people doing it and getting good to great results my only question is how much do the groove tube and telefunken tubes stuff cost? just got me a CAD m9 which i'm LOVING but would love to hear it with a better tube
Click to expand...

I got the idea from C9-2001. He has the same mic as you.. the CAD M9. He installed a Groovetube in it. He can ellaborate more if he comes in. I was thinking about modding a V69 if possible or beneficial
 
Marik said:
<getting a pair of "real" input & output transformers cost more then some mics!>

I am not sure if you are talking generally, but of course you know that tube mic doesn't have an input transformer.
Per Lundahl has a new LL1653 line of transformers specifically designed for tube microphones. His transformers are great and very affordable esp considering their quality. I am positive that you will definitely hear the difference. Good "audiophil" quality bypass capasitor would be also much of help. Needless to say, the resistors should be "low noise type" and be of high quality. The anode resistor should be rated at 400 volt, which most of the time is not the case. Also, very important--power supply. I suspect that many mics use so called "starving mode", when the high tension voltage on the tube is low. Tell me if I am wrong here. The filter electrolitic capasitors should be also of highest quality.

Malcolm, you asked if there would be a significant improvement. I would answer--yes, yes, and yes. You can call me a snob, but I wouldn't even consider using unmodified tube mic.
Click to expand...


Cool, Point Well Taken.
I mean if it would be a very noticable and beneficial improvemet, I would be willing to hold off on my next mic purchase and invest that money into making a nice super mic sorta say. LOL It's not the money that it would cost to do that would bother me, but more of the total money spent on the mic and the mod compared to if I would have just taken all of that money and just bought a better mic. Or maybe the mod would bump the mic up just that far in quality to justify the cost.

Ie. $250 for a V69
$250 for the mods

Total of 500 bucks. Maybe there a mic right in the 500 buck price range that would be close in quality or better. Im just guessing for I really do not know.

follow me? Chime in guys, Say if you had a V69 and 300 bucks for another mic and your not looking to built a locker with all these different flavors. Would it be considerable to do?

Malcolm
 
if you browse the gearslutz forum there is a member named "Bang" who has either a V69 or V67 which he changed the tube and said it made it a totally different mic in a real good way.
 
Marik said:
<getting a pair of "real" input & output transformers cost more then some mics!>

I am not sure if you are talking generally,
Click to expand...

i was talkin in general but i didn't know they didn't have input trannies...thanks
 
Teacher said:
if you browse the gearslutz forum there is a member named "Bang" who has either a V69 or V67 which he changed the tube and said it made it a totally different mic in a real good way.
Click to expand...


Stupid ?

But where is this forum located. You can PM me if it's not here in HR.

thanks

Malcolm
 
Malcolm,

Before you start the project make sure that the tube doesn't work in "starving mode", i.e. the power supply should give at least 150V of HT or higher. Otherwise, you will need to completely rebuild the PSU block. In this case, it would be already more cost effective just use regular 'non-tube' mic and convert it into the 'tube' one. Also, it might be of interest to have a look at David Royer mod:

http://www.mojaveaudio.com/pdf/tape_op1.pdf
 
Marik said:
Malcolm,

Before you start the project make sure that the tube doesn't work in "starving mode", i.e. the power supply should give at least 150V of HT or higher. Otherwise, you will need to completely rebuild the PSU block. In this case, it would be already more cost effective just use regular 'non-tube' mic and convert it into the 'tube' one. Also, it might be of interest to have a look at David Royer mod:

http://www.mojaveaudio.com/pdf/tape_op1.pdf
Click to expand...

LOL,
Man I am no where near attempting to do that yet. I havent even gotten my new V69. I think it comes today. But I will use it long enough to know what it does and maybe down the line I may mess with it. But something like my V67g,, Sh@t for what it costs I would play with that if it's possible. Better yet, I would buy another one and leave one as is and play with the other. Not gonna touch the V69 yet. Unless I keep reading good things and get tempted. Plus, I would prefer to pay somebody who has knowledge to do it. Me and soldering irons dont get alone too well. LOL
 
Malcolm,

V69 is a hybrid design, so instead of output transformer it uses FET transistors.
I would suggest to try a NOS 6072 (it is a very nice tube used in original C12 and ELA 250) in place of Chinese 12AT7. They are pin compatible, so you wouldn't need to do any soldering job.
 
Marik said:
Malcolm,

V69 is a hybrid design, so instead of output transformer it uses FET transistors.
I would suggest to try a NOS 6072 (it is a very nice tube used in original C12 and ELA 250) in place of Chinese 12AT7. They are pin compatible, so you wouldn't need to do any soldering job.
Click to expand...

what would you suggest with the 12Ax7 tube in place
 
<what would you suggest with the 12Ax7 tube in place>

To me 12AX7 doesn't make much sense in a mic. It has too much gain and because of Miller effect it just doesn't work well with capasitance source, which capsule is--it rolls off the HF.
Try the same 6072A--it should work nicely instead of 12AX7. The output will be little lower, but sonics should improve.
 
What about the MXL V77? Anyone have a suggestion on a better tube for that one?

Fab
 
<What about the MXL V77? Anyone have a suggestion on a better tube for that one?>

If I am not mistaken, this mic already has 6072, which once again, is a very nice tube for the mic. You can try some NOS ones.
 
Marik, do you know anything about the 797 Audio CR998? It does have a 6072 tube. Any known mods?

http://www.797audio.com/web/Frameset.htm

I think I read once that it was a C-12 copy with some changes. I also heard it was kin to the ADK TT. It's hard to find any real info on it, though.
 
Thanks on the V77, Marik. You're exactly right on the tube that's in there.

Fab
 
<I think I read once that it was a C-12 copy with some changes. I also heard it was kin to the ADK TT. It's hard to find any real info on it, though.>

I never had chance to listen to this mic, but the fact that Mr. Mao was using Beijin products makes me feel much happier. :)

What can I say? Everybody knows that heart of the mic is capsule, providing that the rest of the circuit is good enough to reveal its qualities. Everybody knows that even C-12VR, which was supposed to be as good as original C-12 in fact was not as good, and it was made in house!
I did not see the guts of CR998 and don't know which capsule it uses, but its price range suggests very good quality parts, considering it is made in China. To say something specific, I need to see it, or to see its schematics.
 
You must log in or register to reply here.
Back
Top