Stewart world 2.1 digital?

[Wiremessiah]

I have an old stewart power amp that has never failed me, but i never did any research on it until now, 5 years later. I looked up threads on this forum and several times it was mentioned as a digital amp. Obviously thats not a cut and dry term, but its specs state it is a class H amp, which from what i read is just a class a/b with modifications.

The only reason i ask is that i am an analog snob and all of my instruments, amps, effects, processors amd recorders are all, in some cases painstakinly, analog, and i feel slightly cheated for buying a digital amp. Please give me peace of mind. Nothing against digital, its just that like skittles i do my best to avoid it.

 

[agedhorse]

In spite of your aversion to digital, the power amp is purely analog with a commutated supply rail, and the power supply is analog switch-mode.

The only thing digital is the foolishness of some marketing departments in their promotion of such engineering inaccuracies.

 

[Wiremessiah]

Thanks, thats what i thought. I was beginning to consider digital if that amp was. I havent tried any of the new digital amps, but certain digital gear has surprised me before. Maybe i should get rid of my 67 hofner and get one of those midi basses from the 80s with buttons rather than strings.

 

[beans-on-toast]

In 1984 Peavey used the term digital energy conversion to describe their class D Deca amplifiers. The technology was new and they wanted to highlight that these amps were something completely different. The marketing term stuck.

https://assets.peavey.com/literature/manuals/80300112.pdf


Invalid Link Removed

 

[Wiremessiah]

Haha, yeah like the roland digital chorus of the 80s. Its now a prized analog device. ARP made a preset synth back in the late 70s that had "digital" in big letters on it. I guess by digital they meant it had switches instead of knobs.

 

[Wiremessiah]

In 1984 Peavey used the term digital energy conversion to describe their class D Deca amplifiers. The technology was new and they wanted to highlight that these amps were something completely different. The marketing term stuck.

https://assets.peavey.com/literature/manuals/80300112.pdf


Invalid Link Removed

Wait, class d does mean digital. Regardless of nomenclature, thats what i meant by digital. But the stewart is not class d. Or does "switching" mean the same thing?

 

[seamonkey]

Class-D is analog, dates back to the 1930's
Switch mode power supplies are analog, they date just as far back but used a mechanical vibrator relay like device in the early days.

 

[Wiremessiah]

Class-D is analog, dates back to the 1930's
Switch mode power supplies are analog, they date just as far back but used a mechanical vibrator relay like device in the early days.

But the transistor wasnt invented until 1947, and from everything i read class d is made from mosfets. Not trying to argue, i am just ignorant on the subject and only know what i read from different sources.

 

[beans-on-toast]

Wait, class d does mean digital. Regardless of nomenclature, thats what i meant by digital. But the stewart is not class d. Or does "switching" mean the same thing?

As you said at the top, the Stewart has class H amplifiers and a high frequency switch mode power supply. The power supply has a chopper, marketing has used the term digital to characterize circuits that chops. Not the same as digital. Digital can be used in the control circuit but this isn't the same as digital in the signal path. Some tube amps have solid state rectifiers, that doesn't make them solid state amps. The rectifier circuit is not in the signal pathway, although it affects it. The same can be said about your amp.

 

[seamonkey]

Class-D first used tubes - they didn't work well until modern MOSFETs and transistors were created
Patent US1874159 - Electric amplifying circuits

 

[beans-on-toast]

It's amazing how technology advanced since the first tube was introduced. In some cases the theory was there, waiting for the technology to become available. When tubes arrived, development and applications flourished. Transistors were a natural extension of tubes. The world tends to take one small step at a time.

This is still seen today in the fields of theoretical and applied physics. It can take many years for theories to be proven. They are still working on proving the groundwork that Albert Einstein provided.

 

[Wiremessiah]

As you said at the top, the Stewart has class H amplifiers and a high frequency switch mode power supply. The power supply has a chopper, marketing has used the term digital to characterize circuits that chops. Not the same as digital. Digital can be used in the control circuit but this isn't the same as digital in the signal path. Some tube amps have solid state rectifiers, that doesn't make them solid state amps. The rectifier circuit is not in the signal pathway, although it affects it. The same can be said about your amp.

Okay that makes sense. I have a digitally generated control voltage pedal i use to control parameters on analog synths, and i wouldnt call the synths digital. However, even if class d amps were created with tubes, "digital" CAN also mean non continuous, so in that sense it seems to me at the very least class d could be considered "non analog" or "non continuous" disregarding my stewart.

Not that it matters, just trying to get a handle on what class d is. I have read several articles on it, but am still out of my depth.

 

[Wiremessiah]

It's amazing how technology advanced since the first tube was introduced. In some cases the theory was there, waiting for the technology to become available. When tubes arrived, development and applications flourished. Transistors were a natural extension of tubes. The world tends to take one small step at a time.

This is still seen today in the fields of theoretical and applied physics. It can take many years for theories to be proven. They are still working on proving the groundwork that Albert Einstein provided.

I heard a crackpot theory about how the roswell ufos were contructed from semiconductor substrates and that transistors were reverse engineered from them. While its prime fascia absurd, it is sort of suspicious how the most important technological invention probably ever and forever was suddenly developed after the supposed crash. But i dont even believe in any life outside of earth, which i can back up with a complicated evidence chain that is neither here nor there or where.

 

[agedhorse]

There is nothing that is not continuous with class D, all waveforms are continuous. It is a form of a non-linear bi-state control system, but entirely analog in nature. Now class D could be done with digital control, but for a variety of reasons it hasn't to my knowledge been done this way commercially.

There is PLENTY of outstanding digital gear out there, to disparage something because of a perception that digital is inherently inferior is selling yourself short IMO.

 

[beans-on-toast]

I heard a crackpot theory about how the roswell ufos were contructed from semiconductor substrates and that transistors were reverse engineered from them. While its prime fascia absurd, it is sort of suspicious how the most important technological invention probably ever and forever was suddenly developed after the supposed crash. But i dont even believe in any life outside of earth, which i can back up with a complicated evidence chain that is neither here nor there or where.

Those theories are nonsense. Everyone knows that semiconductor manufacturing was outlined in ancient Egyptian hieroglyphs.

 

[Wiremessiah]

There is nothing that is not continuous with class D, all waveforms are continuous. It is a form of a non-linear bi-state control system, but entirely analog in nature. Now class D could be done with digital control, but for a variety of reasons it hasn't to my knowledge been done this way commercially.

There is PLENTY of outstanding digital gear out there, to disparage something because of a perception that digital is inherently inferior is selling yourself short IMO.

No i tried to make it clear i am not disparaging anything. I dont eat ginger, but that doesnt mean i am disparaging it. My analog journey is more philosophical, just like my love for vintage gear is not disparaging of modern gear. My love of analog tape and vinyl and analog synths and the simplicity i require from all of the strands i have to keep in my head led me to the all analog thing. I have thought about the convenience of digital and have a full 16 track logic and protools setup with a bunch of softsynths i acquired, but it was all too much with all of the instruments i already play. I found just pressing record on my 1" 8 track tape machine and just playing with no editing is the easiest simples and best sounding experience for me.

Theres plenty of analog and digital gear i do disparage, but i know how vast both of these worlds are so i know not to disparage them in general.

 

[agedhorse]

Your 1" analog tape machine is a lot more complicated than a digital recorder... I used to service them back in the day

 

[Wiremessiah]

Those theories are nonsense. Everyone knows that semiconductor manufacturing was outlined in ancient Egyptian hieroglyphs.

Yeah i think ben carson said something about storing semiconductors next to the grain in the pyramids.

But seriously an extraterrestrial origin for technology is no more outrageous than talking apes inventing it. If we found out the ancient egyptians were telepathic, we wouldnt be any more surprised than they would be if theh saw an iphone.

 

[Passinwind]

Wait, class d does mean digital.

Nope, it doesn't. It means the class between C and E. There are some design elements that smell somewhat digital (as BOT alluded to), but to many of us a strict definition of digital audio means there's an analog to digital interface, bitmap values stored as digital words, and then a digital to analog converter.

 

[beans-on-toast]

Okay that makes sense. I have a digitally generated control voltage pedal i use to control parameters on analog synths, and i wouldnt call the synths digital. However, even if class d amps were created with tubes, "digital" CAN also mean non continuous, so in that sense it seems to me at the very least class d could be considered "non analog" or "non continuous" disregarding my stewart.

Not that it matters, just trying to get a handle on what class d is. I have read several articles on it, but am still out of my depth.

I see digital as bytes that are manipulated with logic: AND, OR, EXCLUSIVE OR, and NOT, then interpreted. Analog is about continuously changing levels. There are fine lines as you said because it's more complicated than I characterized it.