Here's the answer! YES, the Procaster can do 125% modulation but the studio can't so to do it you need to bypass the studio processor and use other processing like the Schlockwood for example or the Inovonics that has that feature.
@mark I guess when you say need to "bypass the studio processor" - that you mean to bypass the onboard processor of the Procaster? Right? That's cool it can achieve it. However, a capable processor isn't enough, both the Procaster and the Rangemaster still require an ocyliscope to properly achieve those desired positive and negative peaks.
@richpowers An oscilloscope can used to monitor your waveform to ensure proper modulation. But you don't absolutely require one.
Depending on the processor, it can be pretty easy to achieve that modulation without any monitoring. And from what I can tell, the more expensive processors have built-in monitoring displays that can verify what you're doing.
Chez Radio was stating that while their transmitter supports 125% modulation, the audio processor in the studio module does not. In fact, it has an AGC, which kind of defeats the purpose.
@richpowers You need one of two things...a modulation monitor or your ear to listen for any distortion. Or even a spectrum analyzer to see if spatter into adjacent stations. Yeah you could use an oscilloscope also to see it.
Look at the owners manual for the Schlockwood and a section is all about the positive peaks function. And yes you are correct you disable the internal processing with the studio via jumper which I am doing as I am using the external processor.
I read the commercial stations with thousands $$$ of processing gear increase the positive peaks to the allowed 125% and lower the negative peaks to 95% and what's it all about? To sound louder on the air....back to the loudness wars.
While scrounging around the Internet, I came across this article.
It reiterates the contention (with a real world example) that you may not need to overdrive your audio with 100%+ positive peaks to achieve loudness (and, presumably, range).
It sounds like they were able to achieve great sounding audio at about 85% modulation.
@artisan-radio Good food for thought, definitely, but it doesn't really translate as quite as well for a part 15 station. We've talked here before how a 100mw AM station tends to "lack the density" sound of a licenced AM powerhouse. I'm not sure that's entirely accurate, but it kind of makes sense to me. Seems that an unprocessed broadcast from a 1,000w or even a 100w station AM station is going to come across sounding "fuller" than a 100mw one no matter what its processing techniques regardless how near your radio is to the transmitter.
Part 15 lacks that "saturation" of radio waves.- Maybe anyway. It's just speculation.