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am adding a mic input to my son's guitar amp; ECC88 (6DJ8) or...

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radiance

(M)

...12AX7 or 6922EH? Which would have the richer tone? Or is there a third choice I don't know about yet? Would very much appreciate opinions. Thanks. Not concerned with power or noise so much; richness of tone is king.
Best.

"It ain't a comeback until it's left the shop" Jimmy Dunne, the first man to drive a VW Beetle faster than 200 mph, and he has the forehead scar to prove it; I will always honor him for taking a chance on me when I wanted to be an engine mechanic.

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Go to the Jensen transformer website.... - grhughes 06:15:17 07/18/06 (3)
They have a section on tube mic preamp schematics. You'll need an input transformer (you can use an octal tube socket and the tranny will plug in) and only one tube if it on the same chassis. If it's seperate then the output of the mic preamp will need to be buffered for however long the cable is between the mic preamp and the amp in which case you will need more than one tube. Good luck. Ray Hughes
"I take you as you are
And make of you what I will,
Skunk-bear, carcajou, bloodthirsty
Non-survivor.
Lord, let me die but not die out." THE LAST WOLVERINE by James Dickey
- Re: Go to the Jensen transformer website.... - ffrr 16:24:56 07/18/06 (1)
  Many microphones used by guitarists have suitable, or even switchable, impedance for feeding into microphone inputs in guitar and PA amp 6.3mm jack plug inputs, without needing a transformer (especially the cheaper microphones). It sounded to me like he just wanted to plug in a typical microphone like this, in which case a simple triode gain stage with level control, mixed into the existing channels in the guitar amp, is all he will need.
  
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  - thanks ffrr, actually, i have a harder time with input stages than outputs, this is simpler; will explore more (NT) - radiance 01:30:25 07/23/06 (0)
    thanks
    "It ain't a comeback until it's left the shop" Jimmy Dunne, the first man to drive a VW Beetle faster than 200 mph, and he has the forehead scar to prove it; I will always honor him for taking a chance on me when I wanted to be an engine mechanic.
- Thank you very much; this is a great help, will do. (NT) - radiance 10:45:36 07/18/06 (0)
  thanks
  "It ain't a comeback until it's left the shop" Jimmy Dunne, the first man to drive a VW Beetle faster than 200 mph, and he has the forehead scar to prove it; I will always honor him for taking a chance on me when I wanted to be an engine mechanic.
Re: am adding a mic input to my son's guitar amp; ECC88 (6DJ8) or... - ffrr 02:08:19 07/18/06 (1)
For guitar, stick with the 12A*7 types, most definitely. For high gain, as it is a mic input, use the 12AX7, but get a low noise one, like Electro-Harmonix EH or Sovtek LPS or something. This is more important than you might think because in most guitar amps, these input tubes get a lot of direct vibrational feedback from the speaker.
For hifi I love the EH, but 'tone' in a musician's context can be different. Then again, it is a mic input, so maybe hifi is the best choice.

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- thanks, great advice; yes, plan to isolate tubes from vibes. (NT) - radiance 10:44:04 07/18/06 (0)
  thanks
  "It ain't a comeback until it's left the shop" Jimmy Dunne, the first man to drive a VW Beetle faster than 200 mph, and he has the forehead scar to prove it; I will always honor him for taking a chance on me when I wanted to be an engine mechanic.

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