The esthetic beauty of tubes is appealing to many (and deemed silly to others), and with modern technological improvements accumulated over a century or so of refinement, tube amps are currently good enough to still be considered among the best sounding music reproduction devices out there. I think it's based on the relative simplicity of their designs along with the linearity of tubes relative to other things, and hats off to Class D designers for making efficient and explosively powerful amps that work well and fit into small spaces (like live sound speakers). However, for many of us tubes are simply more fun...I was floored when I first heard the little single ended amp I now use, and felt that everything I knew was sort of wrong. Dynamic range from 12wpc? Yep...matched with efficient speakers of course. Noise? No problemo...Heat? Only 4 tubes there sparky, and they last a long time. I can live with the thousands of SS A/B and D watts I use mixing live shows, and my 10 or 12 tube watts in my hifi rig...as long as tubes are available.
The Future of Audio Amplification
I have recently paired an Audio Research DS225 Class D amplifier with an Audio Research tube preamplifier (SP8 mkii). I cannot believe how wonderful and lifelike my music sounds. The DS225 replaced an Audio Research SD135 Class AB amplifier. Perhaps the SD135 is just not as good as some of the better quality amps that are out there, but it got me thinking that amazingly wonderful sonance can be achieved with a tubed pre and Class D amp. I have a hunch that as more people experience this combination, it will likely catch on and become the future path of many, if not most audiophile systems. It is interesting that Audio Research has been at the forefront of this development.
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Tubes are way cool and if not for deciding to try the latest and greatest new amp technology (Class D) first I might well have headed down the tube amp path several years back but hasn’t happened and I have little interest these days. Technology does in fact keep advancing and you don’t know what is possible until you try it so older technologies face more challenges these days than before perhaps. Looks do count though and tube amps still look way the coolest by far. |
The Technics is the "blue" uses the GaN transistors, very fast quickly settling and reduced ringing, much closer to resembling the ideal grey square wave.Hm. Seems to make a difference about what you might know about what you are looking at. In the first link above, no frequency is specified! Its clearly marketing and nothing else. In the second set of links, what we are seeing appears to be the residual imposed on the square wave. Nothing unexpected. Since the filter is low power, so is the square wave depicted. These links IOW really don’t show anything other than that at the output of a class D amp, there is a residual sine wave as I mentioned before. Really then no one one yet has been able to rid of this, and they are mightier minds than you. Only Technics has so far been able to reduce it greatly, with double the switching frequency speed and then the normal output low order filtering of it.:) That’s funny! The reason the Technics has lower residual is because for a given filter turnover frequency (probably about 80KHz), the higher the switching frequency the lower the residual. No mystery- just faster switching times. IOW, what you referred to in the Stereophile links as the ’noise’ is a red herring- its not at all what you **seem** to think you’re talking about. |
600khz v 1.5mhz switching frequency The higher the switching frequency the higher the low order output filter can be set, so by the time the residual reaches 20khz what’s left with the 1.5mhz is down nearly 3 lower in amplitude and has less phase shift in the audio band than that of normal 600khz switching frequency. Blind Freddy can see that. |
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