New class-T amplifier?

[wst3]

Originally Posted by tw

These are the same people who recommend a plug-in UPS to 'clean' power, or spend $100 on Monster Cable wires because their gold connectors make better sound. Or will mark their speaker cables because those wires have polarity - one end connected to the speaker instead of the amp causes worse sound. I also smell the Wicked Witch of the West.

Yup... I think my favorite, after the expensive power cords, is the directional cables. Pretty amazing stuff!!!

Originally Posted by tw

The original amp was Class A. Class B intead amplifies one half of a sine wave. Class C only amplifies sine wave's peak. Class AB is two class B amps where one amplifies top half of a sine wave; other amplifies the bottom half.

One quibble - Class A amplifiers are biased such that they are always on, which is why they are such pigs, and why they sound so good! They amplify the entire waveform.

Class B amplifiers are not biased so that they can only amplify one half (positive or negative) of a sine wave. They can be used as half a "push-pull" stage, or in lots of other applications.

Class AB amplifiers are biased so that they amplify just over half that sine wave, they are more efficient than Class A.

I believe (college was a LONG time ago) the thing you describe as Class AB is actually the push-pull topology. Two class B amplifiers biased so that each one can amplify one half of the sine wave. As you described, the trick is getting the point where one turns off and the other turns on to match exactly. If they don't you get rather nasty sounding cross-over distortion!

<snip>

Originally Posted by tw

Little useful is described in that white paper or article. A digital recording at 32Khz does not have all this distortion. Why then would a digital amplifier at 100 Khz have so much distortion? Well, the devil is in deatils not even implied in those articles. In theory, a Class D amp means perfect amplification - no distortion. And then we apply reality to the concept - those devilish details.

Yeah, those details! What's the difference between theory and practice???
<more snipped>

Bill

[smoothmoniker]

Originally Posted by wst3

Yup... I think my favorite, after the expensive power cords, is the directional cables. Pretty amazing stuff!!!

I was MD for an artist a few whiles ago, and we were doing auditions for guitar players to put on the road. A guy came in who obviously liked the herb, and liked it enough to get loaded up for an 11 AM audition.

The techs roll his rig in, he gets set up, plugs in, and the most god-awful buzz starts coming through his little amp. He, of course, starts bitching about the bad power in the rehearsal studio. We, of course, kindly point out that they are running very clean power, as evidenced by fact that nobody else is rattling the hell out of their speaker cones.

At this point, somebody notices that his guitar chord looks is wrapped from tip to tip in various pieces of electrical tape, that there is some serious fraying and kinking. Somebody kindly suggests that he might want to try another guitar cable, and hands him one.

"F* No! All of the cables made today are shit! My guitar cable is vintage analog; today all the cables are digital. This one is so much warmer."

And there you have it folks. If you wanna really rock, go get yourselves some "vintage analog" cables.

[tw]

Originally Posted by wst3

I believe (college was a LONG time ago) the thing you describe as Class AB is actually the push-pull topology. Two class B amplifiers biased so that each one can amplify one half of the sine wave. As you described, the trick is getting the point where one turns off and the other turns on to match exactly. If they don't you get rather nasty sounding cross-over distortion!

I had always thought class AB and push-pull were one in the same. Two Class B amps operating together to perform just like a Class A. How do class AB differ from push-pull?

Sidebar - making one half of the push-pull amp turn off exactly as the other turns on means making the design for wide temperature changes. Semiconductors change appreciably with temperature - which is why transistors are also used as temperature measurement devices. These now so common amplifiers required careful component selection so that the point of crossover did not overlap or separate for all temperatures. Class D amps must do same to avoid same distortion problems even created by room temperature change.