Does this mean Class D amps are in fact digital ?

[Thegreatzambini]

So, I’ve always corrected people when they say Class D means digital, but this statement in the manual of a class D amp makes me think otherwise as it implies analog to digital and digital to analog conversion, just like any digital pedal or device…

I know the “D” doesn’t stand for digital, but are they in fact digital….

From the manual:

“Essentially, a class D amplifier converts the analog signal into a logic level PWM digital signal with an analog to digital
converter, level shifts this PWM signal up to a higher voltage and current and then reconstructs the analog signal by
passing it through what is essentially a power digital to analog converter”

 

[gtirard]

Pop-corn time…

 

[WG Plum]

Oh yay.

 

[Killing Floor]

Class D = Digital
Class A = Analog
Class A/B = Analog Bass
Class C = Casiotone/keyboard/organ
Class E = Electronic Effects

This is from my old ECE textbook.

 

[WG Plum]

@agedhorse can nip this one in the bud, once again.

 

[etoncrow]

Article at Crutchfields

Invalid Link Removed

 

[gln1955]

So, I’ve always corrected people when they say Class D means digital, but this statement in the manual of a class D amp makes me think otherwise as it implies analog to digital and digital to analog conversion, just like any digital pedal or device…

I know the “D” doesn’t stand for digital, but are they in fact digital….

From the manual:

“Essentially, a class D amplifier converts the analog signal into a logic level PWM digital signal with an analog to digital
converter, level shifts this PWM signal up to a higher voltage and current and then reconstructs the analog signal by
passing it through what is essentially a power digital to analog converter”

Which amp is this a manual for?

 

[Grinderman]

NO!!

 

[mapleglo]

 

[--Vissinger --]

no

 

[And I]

the simplest and most correct answer is "no".

Class-D amplifier - Wikipedia

 

[bigjames]

So, I’ve always corrected people when they say Class D means digital, but this statement in the manual of a class D amp makes me think otherwise as it implies analog to digital and digital to analog conversion, just like any digital pedal or device…

I know the “D” doesn’t stand for digital, but are they in fact digital….

From the manual:

“Essentially, a class D amplifier converts the analog signal into a logic level PWM digital signal with an analog to digital
converter, level shifts this PWM signal up to a higher voltage and current and then reconstructs the analog signal by
passing it through what is essentially a power digital to analog converter”

After reading countless posts on this, I believe the answer is "no". There is a switching that occurs in class D that contributes to the digital myth, but I do not believe they are technically digital. Someone more learned than I will no doubt chime in on this more eloquently.

 

[Artman]

Article at Crutchfields

Invalid Link Removed

That’s an excellent article that does a great job of explaining everything.
“D does not stand for digital
Although making a signal by rapidly switching transistors on and off resembles digital processing that uses zeros and ones, Class D amplifiers are not digital devices. Some of them might have digital control circuits, but the amplifier circuits will be strictly analog.”

 

[Wild_Bill_57]

 

[Thegreatzambini]

Thank you all ,this forum is an incredible wealth of knowledge.

 

[_One//Man//Mutiny_]

Class D = Digital
Class A = Analog
Class A/B = Analog Bass
Class C = Casiotone/keyboard/organ
Class E = Electronic Effects

This is from my old ECE textbook.

View attachment 5095142

Don’t forgot when using a Class C to use the accompanying VCR= Vitamin Casiotone Replenisher to feed the guy playing the instrument sounds pop tarts or else he won’t have the strength to!

 

[S-Bigbottom]

A post from Mr. Agedhorse.
Is it just me or are newer lighter rigs just lacking 'balls'?

I hate to break the bad news to you, but class AB amps also switch on and off, the positive going waveform devices shut off and hand off to the negative going waveform devices which turn on and then switch off as they hand the signal off to the positive going devices as the waveform becomes positive again. This happens at all frequencies simultaneously, at twice each signal's audio frequency component.

For all the snake oil discussions about class AB being continuous and class D being a switching amp, most neglect to mention that class AB/G/H are also switching amps of sorts. Managing the crossover artifacts at the hand-off points can be a bit of a challenge since they vary with temperature too.

I've designed both class AB/G/H amps and class D amps, each have their benefits and drawbacks, both can be difficult to design if looking for good, reliable results.

Here's what the current waveform looks like on a class B amp:

Class AB overlaps the dead zones by slightly forward biasing each half of the output stage, it's close but not perfect. This shows each half conducting with a slight bit of overlap:

Class D doesn't suffer from signal crossover issues, it's all based on differentiation and integration which results in a continuous signal from top to bottom and bottom to top. The switching occurs at roughly 350kHz, much faster than a typical analog to digital converter:

Here's a class G/H amp which has the same signal crossover issues as above plus additional switching of the high and low rails in and out at audio frequencies. The venerable and often worshiped CA-9 has 4 rail switches plus the signal crossover switching. If you look on a scope, the switching artifacts are visible, but like with class D, it's not audible in well executed designs.

 

[Jeff Scott]

Thank you all ,this forum is an incredible wealth of knowledge.

But, you still haven't told us what amp manual you quoted.

 

[Rabidhamster]

Amplifiers are basically all just modulating the output of a big power supply. People get freaked out about PWM but AC cycles 60 or 50 times per second depending on your location. PWM basically cycles too but may or may not go negative.

Many analog synthesizers can do PWM as well. 50/60 hz AC is always irritating but plenty of folks listen to PWM on purpose. From that standpoint, how badly could it really impact tone in a well-designed amp?

 

[brianrost]

“Essentially, a class D amplifier converts the analog signal into a logic level PWM digital signal with an analog to digital
converter, level shifts this PWM signal up to a higher voltage and current and then reconstructs the analog signal by
passing it through what is essentially a power digital to analog converter”

PWM is not a digital process. It is found in analog synthesizers.

A DAC is not required on the output, some low power class D applications simply run the signal through a low pass filter.