Interesting. I admit I never actually measured the output (or at least don't remember doing it a few years ago), all I cared about is that it would directly drive the composite input of our Nicom exciter to full modulation. Anything with a 3.5mm (1/8th inch) connector I found couldn't even come close.
I'm assuming you were able to find and adjust all the various software "volume controls" related the output of the sound device (got to hate the "too many volume controls" problem).
So I'm thinking in search for something USB, one should probably look for something that then requires external power so to easily be able to provide the maximum voltage swings. Granted they can do this with little inverters, which there are nice little designs out for these days, but in practice I worry that many of these might start introducing noise into your composite audio as they age. I have this love/hate relationship with the fact that everything runs off switching power supplies these days. It seems that none of them are designed to last more than a few short years with the loads they are rated for. For a broadcast facility, I'd like something that is designed to last for at least 20 years much like the vintage full sized FM broadcast transmitters I work on (okay, so we do have to routinely replace the tubes, fans, and filters in these beasts).
On 09/19/2015 10:00 AM, [email protected] wrote:
Date: Sat, 19 Sep 2015 20:34:21 +1200 From: Robert Jeffares<[email protected]> To:[email protected] Subject: Re: [RDD] Raspberry2 Message-ID:<[email protected]> Content-Type: text/plain; charset=windows-1252; format=flowed In my experience you have to put in some amplification to get the output of an M-Audio card anywhere close to line level [0dbm +4dbm] At the same time we convert from unbalanced to balanced audio. It's a standard op amp in a box exercise. 5 volt rail is limiting so we run about 12 v. Add ons include audio fail, very handy when you have automaton.. Robert _______________________________________________ Rivendell-dev mailing list [email protected] http://caspian.paravelsystems.com/mailman/listinfo/rivendell-dev
