With so few parts, what justifies the high cost of some Class D amplifiers, including the JR Continuum S2? I understand R&D, overhead, and profit, but more and more the cost of Audio is getting crazy.GaN transistors are still a bit more expensive. Class D amps have to meet RFI regulations and to certify that sort of thing (for example, to obtain the CE mark so it can be imported into Europe) can cost quite a lot- $15K for starters. So while the actual parts cost is low, there is a bit of overhead that does not exist for traditional amplifiers.
GaN-based Class D power amps
The use of GaN-based power transistor tech is now emerging for Class D audio power amplifiers. Seems appropriate to devote a forum thread to this topic. At least 3 companies have commercial class D amps in their books:
Merrill Audio, with their model Element 118 ($36k per monoblock, 400 W into 8 ohms, 800W into 4 ohms), Element 116 ($22k per monoblock, 300 W into 8 ohms, 600W into 4 ohms) and Element 114 (coming soon).
https://merrillaudio.net
Review of Element 118 at this link:
http://www.enjoythemusic.com/superioraudio/equipment/1018/Merrill_Audio_Element_118_Monoblock_Amplif...
ADG Productions, with their Vivace Class D amp ($15k per monoblock pair, 100W into 4 ohms). (The designer emailed me indicating he has another product in the pipeline.)
http://agdproduction.com
Review of the Vivace Class D moniblocks at this link (warning: link might not work (1/11/2019)):
https://positive-feedback.com/reviews/hardware-reviews/agd-production-vivace-gantube-monoblock-ampli...
Technics SE-R1 Class D stereo amp ($17k per stereo amp, 150WPC into 8 ohms, 300WPC into 4 ohms)
https://www.technics.com/us/products/r1/se-r1.html
Preliminary review of the Technics SE-R1 at this link:
https://www.stereophile.com/content/technics-se-r1-digital-amplifier
Technics also has a lower priced GaN-based class D integrated amp in their catalog:
https://www.technics.com/us/products/grand-class/stereo-integrated-amplifier-su-g700.html
Anyone listened to or own any of these amps?
Merrill Audio, with their model Element 118 ($36k per monoblock, 400 W into 8 ohms, 800W into 4 ohms), Element 116 ($22k per monoblock, 300 W into 8 ohms, 600W into 4 ohms) and Element 114 (coming soon).
https://merrillaudio.net
Review of Element 118 at this link:
http://www.enjoythemusic.com/superioraudio/equipment/1018/Merrill_Audio_Element_118_Monoblock_Amplif...
ADG Productions, with their Vivace Class D amp ($15k per monoblock pair, 100W into 4 ohms). (The designer emailed me indicating he has another product in the pipeline.)
http://agdproduction.com
Review of the Vivace Class D moniblocks at this link (warning: link might not work (1/11/2019)):
https://positive-feedback.com/reviews/hardware-reviews/agd-production-vivace-gantube-monoblock-ampli...
Technics SE-R1 Class D stereo amp ($17k per stereo amp, 150WPC into 8 ohms, 300WPC into 4 ohms)
https://www.technics.com/us/products/r1/se-r1.html
Preliminary review of the Technics SE-R1 at this link:
https://www.stereophile.com/content/technics-se-r1-digital-amplifier
Technics also has a lower priced GaN-based class D integrated amp in their catalog:
https://www.technics.com/us/products/grand-class/stereo-integrated-amplifier-su-g700.html
Anyone listened to or own any of these amps?
Showing 10 responses by atmasphere
What it says is that the Technics amp is not a class D amp......it is a digital amp. IE....it takes only a digital signal and then converts the PCM stream to PWM to drive the switching output stage. The "analog" input on the Technics amp goes through a 24/192 A2D converter to change it to PCM so it can then get converted to PWM.'Digital amp' is a marketing term. The description above describes a class D amplifier with a digitally controlled front end. |
It is not clear whether the cheaper Technics is a digital amp or a class D amp. I will use these terms because it is very clear. A digital amp takes the analog signal and coverts it to PCM though an A2D converter and then converts it to PWM. A class D amp takes an analog signal and converts it directly to PWM. The only way I found out the larger Technics amp was a digital amp was to read the very clear review I linked to.A class D amp is class D whether or not its driven by a DAC. Pulse Width Modulation is an analog process that some Class D amps use. But that is only one encoding scheme and class D amps have at least three; the other two are Pulse Code Modulation and self-oscillating. There is no such thing as a ’digital amp’. All ’digital amps’ are actually class D amps with a digital front end. |
The quality of sound reproduced by the audio amplifier, measured by THD (Total Harmonic Distortion), DF (damping factor), and IMD (inter-modulation distortion) is influenced by the characteristics of the power transistors used.eGaN FETs’ near ideal switching performance due to lower propagation delays and faster slew rates (due to their lower gate capacitance) and zero QRR enable very short dead times to provide lower open loop distortion, lowering the THD and overall losses. This reduces feedback, driving down T-IMD and DF to provide a step jump in the sonic quality of Class-D audio amplifiers and lowering overall losses Everything I've been telling you about reducing or eliminating dead time is in the above statement from the pdf you linked, quoted above. They are so cheap now its hard to imagine why someone would not use them. |
Nope, it’s inherent in a lot of Class D. It doesn’t work quite the same way though. Some uses local feedback, which does not include the output, and some do. Class D does not have to use feedback. PWM (pulse width modulation) does not use any feedback at all. In a switching amplifier you have something called 'propagation delay'. This is a time delay caused by the fact that it takes a while for a device to switch on or off. Put a number of devices one after the other and there can be a quite measurable delay from input to output. For this reason NFB taken from the output and applied to the input will always be slightly out of sync with the signal its supposed to correct. For this reason it will add distortion of its own. Fortunately class D amps don't have to use feedback to have low distortion. |
It was stated earlier in this thread that "there are no truly digital amplifiers".There are no truly digital amplifiers. This is a fact. I refer you to the white papers of Bruno Putzeys. Take it up with him. Here is a link to a paper presented to the Audio Engineering Society in 2006: https://www.hypex.nl/img/upload/doc/an_wp/WP_All_amps_are_analogue.pdf There are of course class D amps with digital inputs, but the amplifier portion is still class D. |
No-one here should listen Ralph Karsten. He knows tubed circuits and that’s about it...Engineering school only spent a day on tubes when I was going to school. You figure it out. Actually, the first "digital amp" was the TACT. They do not have an DAC in it. They convert the PCM signal directly to PWM. There is no analog signal ever inside a TACT (except that which is generated via PWM and outputted via the speaker outs).The quotation marks above are well-placed :) If in doubt, Bruno Putzeys is one of the most-respected designers in the class D field. So who are you going to believe, him or someone marketing an amplifier? Just read the paper at the link I posted and don't shoot the messenger. |