[R-390] R392 Audio

[Tom Frobase]

Charles was there not a solid state module developed by the military for
the 392?  How did it work?

On Friday, January 24, 2014, Charles Steinmetz <csteinmetz at yandex.com>
wrote:

> Perry wrote:
>
>  Perhaps a simpler alternate to Charles tube re-design of the audio output
>> circuit would be to use one the LM series of audio output IC's.  They range
>> from 2 to 70 watts or so output and many have been designed for high-end
>> audiophile equipment so they have low THD.  Besides needing minimum
>> additional components to use, most are under $10.
>>
>
> Perry, you have no idea how involved (or not) the R392 audio mod is.  In
> fact, installing a power amp IC would be much more work.  And while power
> ICs are fine in a lo-fi application like a communications radio, the idea
> that power output ICs are useful "for high-end audiophile equipment" is
> simply laughable.  Even halfway-decent mid-fi consumer products don't use
> them.
>
> In the context of an R392, which has a unipolar power supply, using a
> power IC would require either (i) a whopping big output capacitor or (ii) a
> bridge-type output with a DC offset of 1/2 the power supply voltage.  Both
> are problematic (the latter is a great way to blow up the IC and/or a
> speaker when you forget about the offset).
>
> Best regards,
>
> Charles
>
>
>
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