Does this mean Class D amps are in fact digital ?

[beans-on-toast]

Infinity "digital amplifier", 1976 class D power amp.

And these Class D’s shouldn’t be confused with amps with Digital Signal Processing.

 

[Geri O]

View attachment 5096239

And these Class D’s shouldn’t be confused with amps with Digital Signal Processing.

I may have been a lucky man, but I had 2 of those and the Deca 1200s when they were out. I used them with a Peavey HDH system and the whole kit & kaboodle worked fine for several years. I did have to add 2 fans to the amp rack as they would overheat and shut down. The fans alleviated that.

I sold the entire rig to someone who used it for a couple of years that I know of. I lost track of him and the rig afterwards.

 

[beans-on-toast]

I may have been a lucky man, but I had 2 of those and the Deca 1200s when they were out. I used them with a Peavey HDH system and the whole kit & kaboodle worked fine for several years. I did have to add 2 fans to the amp rack as they would overheat and shut down. The fans alleviated that.

I sold the entire rig to someone who used it for a couple of years that I know of. I lost track of him and the rig afterwards.

Been using mine since 1985. No issues except for the weight.

 

[Geri O]

Been using mine since 1985. No issues except for the weight.

Yeah, heavy by today's standards, but back then, compared to a CS800.....

 

[Mingo Sanders]

Interesting, this looks like something I wrote years ago to try to explain to non-technical players a technology that's inherently difficult to explain.

Class D is not digital in the commonly accepted technically accurate sense of the word, though it uses non-linear analog techniques that have easier to understand analogies to the digital world.

Class D "encodes" the audio information in the time domain, once that time has passed it's over. It really can't be stored or manipulated in the digital domain BUT the confusion occurs because the signal itself can be stored as a PWM signal, though it can't be easily manipulated through computation except through conversion.

The "digital to analog conversion" mentioned refers to the non-linear analog (PWM) to linear analog (audio signal) conversion which is done with a high pass filter at the output of the process after the level shifting.

This is precisely how I would have said it.

 

[Mingo Sanders]

I though class H was for Horn players

Class A is for songs in the key of A
Class B is for songs in the key of B.
...
Class G is for songs in the key of G.

Class H is for all of the remaining songs.

 

[LiptonJigglers]

Nope. Nothing farther.

I've lost count the amount of times I've been told Sorry, its cheaper to throw it away and buy a new one.
So, YEP! Disposable.

 

[Mingo Sanders]

Which amp is this a manual for?

Shuttle 6.0

Rear Panel - Genz Benz Shuttle 6.0 Owner's Manual [Page 4]

 

[Geri O]

I've lost count the amount of times I've been told Sorry, its cheaper to throw it away and buy a new one.
So, YEP! Disposable.

Then you are either talking to the wrong people or getting the wrong gear.

(Or both…..

 

[ardgedee]

Shuttle 6.0

Rear Panel - Genz Benz Shuttle 6.0 Owner's Manual [Page 4]

"The class D amplifier uses digital PWM (pulse width modulation) techniques similar to those in more familiar digital to analog converters..."

This is more or less how agedhorse described it earlier in this thread, but edited down enough to make the distinction confusing.

(EDIT: Okay, somehow I missed what was written later in the same paragraph: "Essentially, a class D amplifier converts the analog signal into a logic level PWM digital signal with a digital to analog 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." That sure confuses things.)

 

[DJ Bebop]

I've lost count the amount of times I've been told Sorry, its cheaper to throw it away and buy a new one.
So, YEP! Disposable.

Could be because you had this guy look at it...

 

[agedhorse]

"The class D amplifier uses digital PWM (pulse width modulation) techniques similar to those in more familiar digital to analog converters..."

This is more or less how agedhorse described it earlier in this thread, but edited down enough to make the distinction confusing.

(EDIT: Okay, somehow I missed what was written later in the same paragraph: "Essentially, a class D amplifier converts the analog signal into a logic level PWM digital signal with a digital to analog 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." That sure confuses things.)

Agreed, it’s difficult to explain a highly technical topic in a way that non-technical people can understand (at least a little bit).

These are analogies, which highlights the simultaneous similarities and differences in class D technology.

Also, the definitions of digital and non-linear techniques have evolved over the years depending on the frame of reference, but by today’s definition class D is a non-linear technology that bears similarities to early non-computational digital techniques.

 

[Rootzilla]

I'm waiting for class F fractal amps

 

[Wisebass]

Funny thread!

"digital" like in zeros and ones?

BUT the confusion occurs because the signal itself can be stored as a PWM signal

No confusion here! I don't store my signal!

Chatgpt seems to want it both ways. It says it’s not digital, then it says digital for a while

Chatgpt is certainly biased! (digital!)


greetings

Wise(b)ass

 

[fdeck]

My college electronics textbook (The art of electronics by Horowitz and Hill, 1st ed) characterized "digital" by a property called "noise immunity." Simply put, if two digital systems receive the same input, they will produce the same output. For instance if you send an e-mail to two friends, they will both receive exactly the same message. Making this work requires adopting design conventions that always assign a signal to either a definite value, or a transition region (in voltage or time) where it is considered to be undefined.

In contrast, feeding the same signal through two Class-D amplifiers will produce measurably different signals at their outputs, for instance when observed with an oscilloscope. The simplified description of the output as swinging between two states overlooks the fact that what's happening in between the states actually contributes to the output signal.

 

[seamonkey]

In contrast, feeding the same signal through two Class-D amplifiers will produce measurably different signals at their outputs, for instance when observed with an oscilloscope.

I'm glad you qualified it as observed with an oscilloscope, because to the human ear, there is no measurable differences

If you set the parameters of the scope to match that human hearing with LPF, then it too can measure the same.

There was a problem in the history of class-d measurements where the reviewers didn't account for the signal outside of human hearing and their measuring tools didn't report accurate results. Maybe the amplifier makers could add better filtering, but it's beyond human hearing anyhow. The measuring tools decided to add better filtering.

 

[seamonkey]

Chatgpt is certainly biased! (digital!)

Agreed. It's a Large Language Model trained by all the human bias of the internet.

It's a lot like Wikipedia - in fact, it also scanned Wikipedia for its training.

 

[fdeck]

I'm glad you qualified it as observed with an oscilloscope, because to the human ear, there is no measurable differences

If you set the parameters of the scope to match that human hearing with LPF, then it too can measure the same.

There was a problem in the history of class-d measurements where the reviewers didn't account for the signal outside of human hearing and their measuring tools didn't report accurate results. Maybe the amplifier makers could add better filtering, but it's beyond human hearing anyhow. The measuring tools decided to add better filtering.

You definitely need effective filtering, like you say. If you observe the remnants of switching hash that are above the audio band but not completely filtered out, or the PWM output before filtering, the two signals will look profoundly different.

 

[pfschim]

I've lost count the amount of times I've been told Sorry, its cheaper to throw it away and buy a new one.
So, YEP! Disposable.

hey dude, we've heard your sad story more than once (whether it's relevant to the posy or not), and I'm sure everyone here on TB is sympathetic (to an extent) that, apparently, a bunch of Class D amps kicked sand in your face at the beach in front of your girlfriend, but your constant repetition on this theme of Class D amps = bad is pretty tiresome.

all the best for your recovery from this horrible experience

 

[gln1955]

I've lost count the amount of times I've been told Sorry, its cheaper to throw it away and buy a new one.
So, YEP! Disposable.

Why this is sometimes the case with cheap electronics has been explained and it doesn't apply to any halfway decent class D amp.