Post by Boomer on Mar 8, 2018 4:06:07 GMT
Yeah Carl, I'd have those nameplates too.. 
Kind of cool for someone connected with Inovonics to be doing this, a company that's long been known for doing the essential things with audio processing at lower cost. I like that, when in my opinion, processor makers have oversold ever more aggressive and complicated processing that takes the soul out of the audio. The quest for the next greatest, loudest thing to sell, processor manufacturers have helped shape listeners' expectations on how recordings and voice should sound.
I've never seen Inovonics as a processor you'd get for loudness competitions. I'm familiar with their model 215 AM box, and its manual talks about the upcoming stereo on the AM band, so you know when that's from, late 1970s. Some stations liked Inovonics' David processor on FM, I heard from others it was good sound for smaller market stations.
I like that the Schlockwood is basic analog design.
I'd second that all larger commercial AM transmitters can modulate to at least +125 percent modulation. That's mostly brought about by the dynamic headroom allowed by solid state, and especially DC coupling of the audio without transformers. I don't think it's an area that most kit transmitters have thought about much though.
Really, if you just want to be on the air with good sound on a home station, a transmitter that does a good healthy +/- 100 percent modulation is all you need.
There are also two types of asymmetrical audio in AM, natural asymmetry as found in voices, where voice peaks are stronger on one side of the audio baseline than the other, and asymmetry created in the processor specifically to enforce modulation to +125, -100 percent.
Natural asymmetry just takes the sound and feeds it to the transmitter in such a way that the negative peaks just reach 100 percent, and the higher positive peaks reach as high as they want to. Feeding raw microphone audio that way, the positive peaks could easily go to 150 percent on voices, with no added clipping or distortion at the transmitter. In older times that was kept in line with 'phase fipping', where the entire wave was inverted back and forth as needed so that the side of the wave with the higher peaks was always going positive.
The modern way is to remove the asymmetrical peaks through phase rotation, then deal with peaks using an asymmetrical limiter and clipper that keeps the peaks at a maximum of -100 and +125 percent modulation. That kind of asymmetry produces audible distortion depending on the program material, density, etc., and the processor's finesse at masking the distortion.
You can do it at home with a good transmitter, processing and a scope to see it in action. The processor can be a soft clipper that works just on the negative peaks, some diodes and resistors in an adjustable circuit.
Boomer
Kind of cool for someone connected with Inovonics to be doing this, a company that's long been known for doing the essential things with audio processing at lower cost. I like that, when in my opinion, processor makers have oversold ever more aggressive and complicated processing that takes the soul out of the audio. The quest for the next greatest, loudest thing to sell, processor manufacturers have helped shape listeners' expectations on how recordings and voice should sound.
I've never seen Inovonics as a processor you'd get for loudness competitions. I'm familiar with their model 215 AM box, and its manual talks about the upcoming stereo on the AM band, so you know when that's from, late 1970s. Some stations liked Inovonics' David processor on FM, I heard from others it was good sound for smaller market stations.
I like that the Schlockwood is basic analog design.
I'd second that all larger commercial AM transmitters can modulate to at least +125 percent modulation. That's mostly brought about by the dynamic headroom allowed by solid state, and especially DC coupling of the audio without transformers. I don't think it's an area that most kit transmitters have thought about much though.
Really, if you just want to be on the air with good sound on a home station, a transmitter that does a good healthy +/- 100 percent modulation is all you need.
There are also two types of asymmetrical audio in AM, natural asymmetry as found in voices, where voice peaks are stronger on one side of the audio baseline than the other, and asymmetry created in the processor specifically to enforce modulation to +125, -100 percent.
Natural asymmetry just takes the sound and feeds it to the transmitter in such a way that the negative peaks just reach 100 percent, and the higher positive peaks reach as high as they want to. Feeding raw microphone audio that way, the positive peaks could easily go to 150 percent on voices, with no added clipping or distortion at the transmitter. In older times that was kept in line with 'phase fipping', where the entire wave was inverted back and forth as needed so that the side of the wave with the higher peaks was always going positive.
The modern way is to remove the asymmetrical peaks through phase rotation, then deal with peaks using an asymmetrical limiter and clipper that keeps the peaks at a maximum of -100 and +125 percent modulation. That kind of asymmetry produces audible distortion depending on the program material, density, etc., and the processor's finesse at masking the distortion.
You can do it at home with a good transmitter, processing and a scope to see it in action. The processor can be a soft clipper that works just on the negative peaks, some diodes and resistors in an adjustable circuit.
Boomer