Bunpei Posted June 10, 2018 Share Posted June 10, 2018 Professor Yamasaki of Waseda University and Bunpei tried applying not PWM but PDM (usual DSD) to an evaluation board provided by GaN Systems and preliminarily obtained a prospective results. Please read this post if you are interested in DSD; http://www.diyaudio.com/forums/class-d/323714-direct-pdm-input-gan-mode-hemt-class-amplifier.html jabbr 1 Link to comment
jabbr Posted June 12, 2018 Share Posted June 12, 2018 On 6/10/2018 at 6:49 PM, Bunpei said: Professor Yamasaki of Waseda University and Bunpei tried applying not PWM but PDM (usual DSD) to an evaluation board provided by GaN Systems and preliminarily obtained a prospective results. Please read this post if you are interested in DSD; http://www.diyaudio.com/forums/class-d/323714-direct-pdm-input-gan-mode-hemt-class-amplifier.html To be clear this is not a Class D board, rather a driver "optimized for Class D" but rather direct digital. In Class D there is an analog to digital conversion step and analog feedback. Custom room treatments for headphone users. Link to comment
Bunpei Posted June 12, 2018 Author Share Posted June 12, 2018 Hi, jabber! I appreciated your comment! This board is not indicated as “Class-D amplifier” by the manufacturer. They just say “Optimized for Class D Amplifiers”. In this context, you are right. On the other hand, as for the definition of the “Class D Amplifer”, Wiki says “the amplifying devices (transistors, usually MOSFETs) operate as electronic switches, and not as linear gain devices as in other amplifiers.” I understand an ADC module is not essential. Moreover, I was surprised that there is a member who sticked to an analog input in this forum though it depend on his sense. Professor Yamasaki and I are “full-digital” orienting audiophiles” in a sense. Link to comment
Maldur Posted June 12, 2018 Share Posted June 12, 2018 Hi, Bunbei. "Bunbei speculates the experiment by Professor Yamasaki is the first achievement of class-D audio amplifier with direct PDM input." If I remember correctly, in Japan some entusiast tries that concept in about 2011, with DSD64 input signal. Volume regulation was done via high quality regulated power supply, where increase or decrease of power voltages changes the volume level. THD level was in 0,1% class in whole audio band. Not the cleanest performance, but good enough for first try. This is very interesting idea, I must say. I have Tascam DA-3K too, and one more Amanero Combo384 for testing purposes, but sadly, I have not much spare time for that hobby. All the best, Maldur Sorry, english is not my native language. Fools and fanatics are always certain of themselves, but wiser people are full of doubts. Link to comment
Miska Posted June 13, 2018 Share Posted June 13, 2018 Sounds similar to what Estelon LYNX speakers are doing... But Estelon has their completely own amplifier. Signalyst - Developer of HQPlayer Pulse & Fidelity - Software Defined Amplifiers Link to comment
Bunpei Posted June 14, 2018 Author Share Posted June 14, 2018 On 6/13/2018 at 7:24 AM, Maldur said: If I remember correctly, in Japan some entusiast tries that concept in about 2011, with DSD64 input signal. Volume regulation was done via high quality regulated power supply, where increase or decrease of power voltages changes the volume level. Yes, your memory is correct! I asked Professor Yamasaki about that. He said, “applying GaN E-mode HEMT as a high-power switching device for 1 bit delta-sigma modulated audio signal this time might be the first trial”. He added, “Realization of such a simple & compact and energy-efficient class D audio amplifier is very valuable”. Link to comment
Bunpei Posted June 14, 2018 Author Share Posted June 14, 2018 On 6/13/2018 at 5:51 PM, Miska said: Sounds similar to what Estelon LYNX speakers are doing... But Estelon has their completely own amplifier. Thank you very much for the information. They say just “FET”. I am eager to know whether their device is of Si based or GaN based. Link to comment
Maldur Posted June 16, 2018 Share Posted June 16, 2018 On 6/13/2018 at 11:51 AM, Miska said: Sounds similar to what Estelon LYNX speakers are doing... But Estelon has their completely own amplifier. I feel myself somewhat "responsible" for that, because I promoted DSD and that DSD-amplifier idea in one other forum to Estelo'ns co-worker, sadly that person no longer works for Alfred anymore, I don't know why. Sorry, english is not my native language. Fools and fanatics are always certain of themselves, but wiser people are full of doubts. Link to comment
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