[AMRadio] Viking II Audio Mod Question

[wwd at netheaven.com]

In <1D1B8647FA5CD411A02800508BDFD0A002F691D2 at stpmsx03.stp.guidant.com>, on
01/30/2002 
   at 10:14 AM, "Freeberg, Scott (STP)" <Scott.Freeberg at guidant.com> said:

>Hi,

>I am cleaning up a recently acquired Viking II and discovered the
>original audio circuits had been totally removed, including tubes and
>sockets.  They were replaced with 9 pin sockets and a 12AT7 and a 12 AU7. 
>The first tube is used as a two stage preamplifier with the second stage
>(of the first tube) driving paralleled grids of second tube.  The second
>tube is all paralleled.  The plates are tied together driving the audio
>interstage transformer, the grids are tied together, and the cathodes are
>tied together.   Does this mod sound familar with anyone?  I'd like to
>get additional information to confirm the value of the input resistor and
>the wiring.  I don't know if this mod originally worked or is even wired
>up right, so I'd like to find out more about it.  I'm half inclined to
>rip it out and restore the Viking II back to the original configuration.

Why bother? It looks like an improvement to me, so fire it up. Perhaps the
audio interstage transformer is not stock, but in any event the proof is
in the performance. 

The audio was a weak point in the VII. I run a pair of 809's fed
externally, so I've never dealt with the stock situation. 

Bill
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