I have one of the two Yamaha HD equiped HD-equipped model RX-4600 AV receivers in the USA for review in The Audiophile Voice in the January 2006 issue. It takes about 55dBf of signal to get it to switch into HD, so basically it might give you quieter reception if you can read by a station's tower lights. Because the requirements that digital buckets can't be overfilled without disasterous distortion, music must be made to conform to the electronics; the heck with adherance to the original waveform, and because fall-back revert to analog, the present analog needs to be further compromised to match the audio qualities of the messed-up digital. Also, the digital uses look-ahead limiting to prevent over-shoot through a delay circuit before release. This means the analog must be delayed by the same acoustic perception -- another distortion circuit is now in the regular audio path. Effectively, it will decrease a station's coverage in half.
AM HD is a BIGGER disaster. The HD reverts to 5kHz analog MONO and is not compatiable with the present C-Quam AM stereo system, which must be scrapped to run HD. You should here WOR going from crisp digital to low-modulation, low high-frequency response analog AM. Can you picture the little guy in your car radio toggling a treble cut switch? Yes folks, this is new and better --YUCK.Also, digital AM at night is a no-go because of the phase differences in the ground and sky wave when they meet, or it can happen close in to a directional-array station because phase differences are used to control patterns and power levels -- like within two miles of WOR. The digital is highly phase-critical.
Don Scott
AM HD is a BIGGER disaster. The HD reverts to 5kHz analog MONO and is not compatiable with the present C-Quam AM stereo system, which must be scrapped to run HD. You should here WOR going from crisp digital to low-modulation, low high-frequency response analog AM. Can you picture the little guy in your car radio toggling a treble cut switch? Yes folks, this is new and better --YUCK.Also, digital AM at night is a no-go because of the phase differences in the ground and sky wave when they meet, or it can happen close in to a directional-array station because phase differences are used to control patterns and power levels -- like within two miles of WOR. The digital is highly phase-critical.
Don Scott