[R-390] Better BA sound

[Bob kb8tq]

Hi

If you dig back in the archives, there is a *lot* of information on doing this. If 
you want your sub-woofer to get plenty of drive, run the 0.33 uf up to 3.3 uf.
You then will get to spend quality time tracking down sources of AC hum ….

Bob

> On Jan 12, 2018, at 12:58 AM, Charles Steinmetz <csteinmetz at yandex.com> wrote:
> 
> By far the easiest way to get good sound out of the 390A is to tap line-level audio from "Diode Load" Terminal TB103 - 14 at the back of the radio and send it to the audio amplifier and speaker of your choice (see attached image for tap details).  This applies to all BAs, but in some cases you may need to go inside to tap the audio and bring it out of the box.  One trick is to take a feed from the headphone jack, if you don't want to mess around inside the radio.  But the 390A makes this easy with the "Diode Load" terminal.
> 
> The amplifier needs to have a volume control, and it can be handy to have at least rudimentary tone controls.  An old hi-fi preamp and amp, or integrated amplifier, is ideal.  I assume most of us have one or more suitable candidates buried in a closet or the garage.  If not, a trip to the local thrift store should find one.
> 
> In my case, I feed line level audio from all of the radios to the various inputs of an old NAD hi-fi integrated amplifier (I bypassed the phono preamp to get one more line input).  It has its own tone controls, plus I installed an Ashly seven-band parametric equalizer in the tape loop.  This allows greater tone control flexibility, but its main contribution is to add notch filters to the audio chain for radios (like the 390A) that don't have them.  I find this an incredibly valuable tool even with radios that *do* have their own notch filters, because there are often two or more heterodynes I want to remove.  You'll never realize just exactly how irritating and fatiguing all of those birdies are until you've lived without them!
> 
> Best regards,
> 
> Charles
> 
> 
> <R390A_line_level_audio_tap_schematic.png>______________________________________________________________
> R-390 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/r-390
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:R-390 at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html