Changing to digital power amp

[Bob Lee (QSC)]

The Carver amps did not actually have a switch-mode power supply. They had a conventional supply with a chopper (about 1 kHz) on the AC coming into the power transformer.

The chopping of the AC produced a waveform with a high dI/dT, which allows power transfer through a smaller transformer without saturation. That concept is used in HF SMPS, but the similarity ends there. A PWM controller varied the duration of the chop in response to demands on the power supply. However, during periods of heavy demand, the PWM duty cycle would often approach 100%, meaning that the waveform once again resembled regular AC, and regular or nearly regular AC through the undersized power transformer caused core saturation and collapse of the supply rails.

It was an interesting concept, but the bugs weren't worked out. That type of power supply has not shown up in audio power amplification again.

 

[Spaldo]

I promise, this is my last post in the same thread ... All that means is that the amplifiers are class-D and the power supplies are switching power supplies. No distortion specs are give which is really a shame, almost as if they have something to hide.

I thought that too, I always check the THD specs/graphs FIRST when I look at any amp...but 'cos i lug my own crap and i knew how Markbass sounded, i was sold. I'd like to see some graphs if anyone has them (Marco?).

I also wondered about the 'digital' reference, but then i guess it's less verbose than explaining 'class D' to a punter who won't get it anyway

 

[svtb15]

Yes Like i said I am not an amp expert... But thank you for that new info.. I had no idea.. And love to learn new things.

I do remember Clair Bros owning maybe hundreds of those amps. That was one of the reasons i bought one.. But I later found out from my friend that worked with them that as soon as they got them to the shop they rebuilt the PS on each amp... Im not sure if that retri was done at the Pennsylvania Clair Shop or in house at Carver

The Carver amps did not actually have a switch-mode power supply. They had a conventional supply with a chopper (about 1 kHz) on the AC coming into the power transformer.

The chopping of the AC produced a waveform with a high dI/dT, which allows power transfer through a smaller transformer without saturation. That concept is used in HF SMPS, but the similarity ends there. A PWM controller varied the duration of the chop in response to demands on the power supply. However, during periods of heavy demand, the PWM duty cycle would often approach 100%, meaning that the waveform once again resembled regular AC, and regular or nearly regular AC through the undersized power transformer caused core saturation and collapse of the supply rails.

It was an interesting concept, but the bugs weren't worked out. That type of power supply has not shown up in audio power amplification again.