[R-390] R392 Audio

[Chris]

Typo, meant the LM384N not 386

Sent from my outdated iPhone wireless thingy

On Jan 24, 2014, at 7:25 AM, Chris <kc9ieq at yahoo.com> wrote:

> While I don't doubt it would be somewhat involved to solid-state the audio output of a R-392;  Pray tell what is wrong with the audio quality of say, the old LM386N?  They can be run up to 28V, are capable of 4W at under 1% THD, and have a basically flat frequency response to well over 100kHz.  THD and bandwidth for this device far surpass specs of *just about* any communications receiver ever manufactured.  Not your $10,000 Marantz perhaps, but I really don't think that is the goal here.....
> 
> My .02
> Fin
> 
> Regards,
> Chris 
> 
> Sent from my outdated iPhone wireless thingy
> 
> On Jan 24, 2014, at 4:07 AM, 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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