KeithL
Administrator
Posts: 9,938
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Post by KeithL on Jan 30, 2020 16:42:44 GMT -5
I would not make any assumptions about what frequency they regenerate to.
400 Hz is often used in aircraft and military applications because it allows for much smaller and lighter transformers than 60 Hz. However, it has one very serious downside... 400 Hz is extremely audible so any leakage whatsoever at that frequency tends to be audible. (This applies both to leakage into the audio circuitry and physical "singing" by transformers and even cabling.) It would make far more sense to use an ultrasonic frequency, which is even more efficient to filter and regulate, and which avoids the possibility of audible noise. Designing transformers to operate at ultrasonic frequencies is a bit more complex, and costs a bit more, but they can be even smaller and more efficient.
(Hmmmm... that sounds an awful lot like what's going on inside a modern SMPS... like ours... )
O.K. new transformers have eliminated the over heating problem. Good! And as to the regenerative power supply, they must be 'regenerating' 50hz/60hz to the higher 400hz (is it 400hz for both 50 and 60hz systems?) for the audio amplifier power supplies. Seems like a lot of power supply antics!
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Post by mgbpuff on Jan 30, 2020 17:12:24 GMT -5
I would not make any assumptions about what frequency they regenerate to. 400 Hz is often used in aircraft and military applications because it allows for much smaller and lighter transformers than 60 Hz. However, it has one very serious downside... 400 Hz is extremely audible so any leakage whatsoever at that frequency tends to be audible. (This applies both to leakage into the audio circuitry and physical "singing" by transformers and even cabling.) It would make far more sense to use an ultrasonic frequency, which is even more efficient to filter and regulate, and which avoids the possibility of audible noise. Designing transformers to operate at ultrasonic frequencies is a bit more complex, and costs a bit more, but they can be even smaller and more efficient. (Hmmmm... that sounds an awful lot like what's going on inside a modern SMPS... like ours... ) O.K. new transformers have eliminated the over heating problem. Good! And as to the regenerative e power supply, they must be 'regenerating' 50hz/60hz to the higher 400hz (is it 400hz for both 50 and 60hz systems?) for the audio amplifier power supplies. Seems like a lot of power supply antics! I'm not assuming 400hz - they state so in their description of the regenerative power supply in the attached file. www.audio-gd.com/HE/HE-12017/HE-12017EN.htm "400Hz regenerative wave have higher efficiency , 50Hz regenerative wave had much far away the human ears sensitivity area than the 400Hz, boost the sound have much better analog sound like." As for noise, it looks like all the 400hz circuitry is in a completely metal enclosed compartment in the center of the unit.
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Post by audiosyndrome on Jan 30, 2020 18:58:06 GMT -5
But does it have HT bypass? No good without it unless 2 channel only system.
Russ
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Post by Boomzilla on Jan 31, 2020 0:53:21 GMT -5
But does it have HT bypass? No good without it unless 2 channel only system. Russ Hi Russ - The Audio-gd HE1 does not have a HT bypass. It is a "stereo only" component. HT isn't even mentioned by their web ad. As the manufacturer somewhat inelegantly puts it: "The right saddle must is set on the right horse ,if you had not enough good system units, and had not enough cable match experiences, don't waste the money on HE series products." And despite my paucity of "good system units" and "cable match experiences," I still like my preamp very much. It probably isn't for everyone, but... Another question that might be relevant: "If this unit died today would I buy another one?" That's a poser... I tried this unit because I just happened to find brutiarti selling one used, and because my audio amigo, garbulky, had gone gaga over the unit's specs and recommended it to me highly. The best answer I can give would be "Unless I found another preamplifier that could do what this one does in my system, then I'd probably buy another one." But I'd shop pretty hard before making that choice. Boomzilla PS: The review was performed with: Windows 10 server running Roon over Ethernet to OPPO UDP-205 converting incoming Ethernet to coaxial SP/DIF OR using its internal DACs to output balanced line-level audio Audio-gd DAC-19 using coaxial input from the Oppo to output unbalanced line-level audio to Audio-gd HE1 preamplifier (balanced or unbalanced inputs) to JL Audio CR2 electronic crossover (optional) & balanced cables to Emotiva PA-1 power amplifiers OR (unbalanced cables to) 12-watt Heathkit vacuum tube power amplifiers to Emotiva T2 loudspeakers OR Klipsch RP 600M loudspeakers (several others also) and Various subwoofers (2 at a time) by Paradigm, Velodyne, and Emotiva
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