18Watt.com

I saw Matchless came out with a 2xEL84 15 Watt version of their C30 amps recently. I was reading their description of the C30 here:
https://www.ultrasoundampsales.com/matchless-c30
...and this seems like complete marketing BS. They claim these are "true Class A" because they ...dont have negative feedback?! The circuit has a 12ax7 long tail pair phase inverter and a double-ended output tranny. What is going on here people? They claim that "forced negative feedback" that's "inherent" in class AB represents a "cool down cycle" and their lack of NFB makes their design superior and Class A.
Am I reading this incorrectly? Because it sounds like complete hogwash in terms of operating class.

Because an amp is cathode biased and has no negative feedback loop does not mean it is operating in Class A. You can have push pull Class A with and without NFB. Class A is just the duty cycle where the tubes are biased to conduct 360 degrees. This would virtually eliminate crossover distortion. So the verbiage used to say there is no "cool down" of Class AB is trying to make a distinction that it's somehow higher performance than Class AB. That's the rub and the hype that is abused over and over and over again, preying on the frenzied hyperconsumer. Their formula is really about overdissipating the tubes with high plate plate voltages and slamming the power section with a big signal. EL84s only have about 12V of headroom anyway and a Vox voiced PI is plenty to use that up in short order. So they are trying to make the distinction that that defines Class A, but it's not. If it were, the load line would be correct, the plate and screen voltages would be much lower and the plate current much higher. That's just how they get the "Matchless sound". Nothing is engineered (more hokum). The parts are just sized up to handle the difficult operating conditions and even then, they eat tubes. A Vox AC30 is not true Class A either. Aiken's (excellent) treatise on the matter. I do agree that point to point built amps can have a sonic advantage over the same circuit built on a turret board.

colossal wrote: ↑

Mon 02/10/20 8:11 pm

I do agree that point to point built amps can have a sonic advantage over the same circuit built on a turret board.

As well as 100 disadvantages.