Are Class D amps really 5 times less powerful than A/B?

[marchone]

I've rarely seen a curt dismissal from them except in the events where people ask a question, get an accurate answer from an actual expert in the field, and then want to argue more.

The curt dismissals I referred to occurred by other posters earlier in the thread.

Not from @agedhorse or @Passinwind.

Simply posting NOT DIGITAL was unhelpful.

 

[Rich Fiscus]

26454915[/URL], member: 37018"]Every single one I'm aware of. Digital audio = assigning stepped bit values to the waveform and then converting those bit values back to analog. Class D = pulse width modulation and then associated demodulation, both analog processes.

Unless it has changed in the couple of decades since my digital electronics classes, digital = digital logic = Boolean logic. If there are no Boolean values or operators represented by a wave, it's shape is irrelevant. I know that's sort of what you said, but I just think it's even simpler than that.

 

[abarson]

Speaking of people having no clear understanding of a Watt…

How come a lemon gets soft and juicy as it ages and a lime gets hard and dry and physically smaller as it ages? Shouldn't they age the same since they are both sour citrus tree fruits? Asking for a friend.

You're not mixing enough cocktails to prevent the fruit from going bad.

 

[two fingers]

No, this is not true.

Virtually EVERY class D amp is analog, non-linear (using PWM as a modulation mechanism). I have designed many bass amps (way more than 3) and they are all analog, non-linear power sections. I have also designed many bass amps (way more than 3) that use all analog, linear power sections. I have also designed bass amps using both SMPS and non-linear line frequency analog power supplies.



This is completely wrong on so many levels. Their description of "class D" actually has nothing to do with class D but is describing SMPS which is entirely different.

No, it's not clear cut at all. Class AB is not necessarily better for wide bandwidth audio (ie. full range), there are class D amps today that are far better than class AB, though if you go back 20+ years that may not be as true).



Name one.

Combo amps w/ analog power sections... Shuttle's, ShuttleMax's and Countour 500, but there's also the Shen "LT" series that were used for uprights and other acoustic applications.



When done well, few if any can tell the difference in double-blind testing. IF they know what they are playing then obviously their eyes will tell the difference (marketing).



IMO, this is an insulting statement.



Because they DON'T!!!



I disagree with this, I have't seen it to be true on any class of amp.



Except that you don't understand how the AC input power ratings are derived and why it's done this way, that's why you are confused and accusatory. Actually, your description of audio ratings are also incorrect. When you post stuff like this, I encourage you to do some (real) research and learn about it before posting.

I have discussed this before but it seems that it needs to be "refreshed"...

The AC input power is required by safety agency standards, and it's required to be the greater of the power consumption at 1/8-rated audio power into the lowest or most demanding load, or if intended for crest factor, than that higher number MAY be used. This is entirely independent of the amplifier class.

Why is it done this way? Because 1/8-rated audio power represents the average internal thermal loads that the amplifier will see under long term (ie. continuous) use when presented with an average full range signal driven to the point of clipping. There are a whole series of thermal tests that are performed on the amp during certification to insure that no component exceeds its safe working temperature (as defined in the standards). There are also additional thermal tests that are done at a series of higher power levels (called abnormal operating conditions) as well as a third series of thermal tests conducted under fault conditions.

For some companies in the pro audio world (and I do this to some extent as well), they will specify AC power consumption at 1/8-rated power (mandatory) as well as 1/4, 1/3, 1/2 and maximum rated power, this data is used for other reasons mostly related to branch circuit calculations and feeder or generator dynamic capacity in fixed and large portable installations.

I followed my standard steps for threads like this.

1) Read OP and laugh. (The statements made during that interview were laughable, by the way.)

2) Scroll until I see what @agedhorse has to say.

3) Walk away having nothing to add.

 

[Phlipper]

Us REAL audiophiles only listen to live music played by humans. It's all about loss-less compression and transients from the variation in flux capacitance. We're so much better than you cro-magnons listening to your 20 year old vinyl.

My head hurts

 

[tmvt]

No, this is not true.

Virtually EVERY class D amp is analog, non-linear (using PWM as a modulation mechanism). I have designed many bass amps (way more than 3) and they are all analog, non-linear power sections. I have also designed many bass amps (way more than 3) that use all analog, linear power sections. I have also designed bass amps using both SMPS and non-linear line frequency analog power supplies.



This is completely wrong on so many levels. Their description of "class D" actually has nothing to do with class D but is describing SMPS which is entirely different.

No, it's not clear cut at all. Class AB is not necessarily better for wide bandwidth audio (ie. full range), there are class D amps today that are far better than class AB, though if you go back 20+ years that may not be as true).



Name one.

Combo amps w/ analog power sections... Shuttle's, ShuttleMax's and Countour 500, but there's also the Shen "LT" series that were used for uprights and other acoustic applications.



When done well, few if any can tell the difference in double-blind testing. IF they know what they are playing then obviously their eyes will tell the difference (marketing).



IMO, this is an insulting statement.



Because they DON'T!!!



I disagree with this, I have't seen it to be true on any class of amp.



Except that you don't understand how the AC input power ratings are derived and why it's done this way, that's why you are confused and accusatory. Actually, your description of audio ratings are also incorrect. When you post stuff like this, I encourage you to do some (real) research and learn about it before posting.

I have discussed this before but it seems that it needs to be "refreshed"...

The AC input power is required by safety agency standards, and it's required to be the greater of the power consumption at 1/8-rated audio power into the lowest or most demanding load, or if intended for crest factor, than that higher number MAY be used. This is entirely independent of the amplifier class.

Why is it done this way? Because 1/8-rated audio power represents the average internal thermal loads that the amplifier will see under long term (ie. continuous) use when presented with an average full range signal driven to the point of clipping. There are a whole series of thermal tests that are performed on the amp during certification to insure that no component exceeds its safe working temperature (as defined in the standards). There are also additional thermal tests that are done at a series of higher power levels (called abnormal operating conditions) as well as a third series of thermal tests conducted under fault conditions.

For some companies in the pro audio world (and I do this to some extent as well), they will specify AC power consumption at 1/8-rated power (mandatory) as well as 1/4, 1/3, 1/2 and maximum rated power, this data is used for other reasons mostly related to branch circuit calculations and feeder or generator dynamic capacity in fixed and large portable installations.

Agedhorse throwing down the hammer of knowledge. And thats a wrap. We can close this thread now right?

 

[mrjim123]

@mbell75 - disregard 90+ % of this thread and simply read @agedhorse 's responses.

 

[mbell75]

No, this is not true.

Virtually EVERY class D amp is analog, non-linear (using PWM as a modulation mechanism). I have designed many bass amps (way more than 3) and they are all analog, non-linear power sections. I have also designed many bass amps (way more than 3) that use all analog, linear power sections. I have also designed bass amps using both SMPS and non-linear line frequency analog power supplies.



This is completely wrong on so many levels. Their description of "class D" actually has nothing to do with class D but is describing SMPS which is entirely different.

No, it's not clear cut at all. Class AB is not necessarily better for wide bandwidth audio (ie. full range), there are class D amps today that are far better than class AB, though if you go back 20+ years that may not be as true).



Name one.

Combo amps w/ analog power sections... Shuttle's, ShuttleMax's and Countour 500, but there's also the Shen "LT" series that were used for uprights and other acoustic applications.



When done well, few if any can tell the difference in double-blind testing. IF they know what they are playing then obviously their eyes will tell the difference (marketing).



IMO, this is an insulting statement.



Because they DON'T!!!

Great, thank you. Can you address the other point made by the President of Boss? Is it true that Class D bass amps basically lie about the numbers? That a 160 watt amp with an A/B power section is equal to an 800 watt amp with a Class D power section?

I disagree with this, I have't seen it to be true on any class of amp.



Except that you don't understand how the AC input power ratings are derived and why it's done this way, that's why you are confused and accusatory. Actually, your description of audio ratings are also incorrect. When you post stuff like this, I encourage you to do some (real) research and learn about it before posting.

I have discussed this before but it seems that it needs to be "refreshed"...

The AC input power is required by safety agency standards, and it's required to be the greater of the power consumption at 1/8-rated audio power into the lowest or most demanding load, or if intended for crest factor, than that higher number MAY be used. This is entirely independent of the amplifier class.

Why is it done this way? Because 1/8-rated audio power represents the average internal thermal loads that the amplifier will see under long term (ie. continuous) use when presented with an average full range signal driven to the point of clipping. There are a whole series of thermal tests that are performed on the amp during certification to insure that no component exceeds its safe working temperature (as defined in the standards). There are also additional thermal tests that are done at a series of higher power levels (called abnormal operating conditions) as well as a third series of thermal tests conducted under fault conditions.

For some companies in the pro audio world (and I do this to some extent as well), they will specify AC power consumption at 1/8-rated power (mandatory) as well as 1/4, 1/3, 1/2 and maximum rated power, this data is used for other reasons mostly related to branch circuit calculations and feeder or generator dynamic capacity in fixed and large portable installations.

Thank you. Can you address the comment I posted made by the President of Boss? Is it true that makers of Class D bass amps basically lie and that a 160 watt bass amp with an A/B power section is about equal to an 800 watt bass amp with a Class D power section?

 

[Wasnex]

Wasnex, can you compare/contrast your amps with regards to transient delivery? And, is there a standard measurement for this that amps can be contrasted with? I see these threads (and others) and for me, still can't really get the answers I'm looking for but I think I know better what the question is: how do amps handle transients, and you hit on this in your post above.

I do believe what we are talking about can be measured/quantified, but doing this is over my head. I believe we are actually talking about multiple factors that can be measured, so they are objective. But my understanding of the various related factors is too incomplete and shallow for me to really go too far down the rabbit hole.

Also, I believe our perception and taste plays a role, so some aspects are subjective. Our perceptions and the measurements will not always agree. This may seem counterintuitive, but the idea is some things happens in a way that the test equipment picks it up, but not our senses. Our senses may interpret two transients with the exact same magnitude in different ways, perhaps depending on how fast the transition occurs and the duration at max amplitude?

If we limited the discussion to a couple of specific amps, I could give my perception, which I generally try to do as objectively as possible. But describing how something sounds in a way that communicates what I am hearing with 100% accuracy is not really possible. Ultimately the best thing to do is try amps for yourself and draw your own conclusions.

I do think reading what other thinks about an amp can be helpful for suggesting gear to try. But in my experience, the results frequently don't match our interpretation of what we have read. I also find value in reading specs, but the specs don't necessarily tell me everything I need to know.

Sorry...wish I could give you a better answer.

 

[micguy]

There is nothing (other than cost) that prevent tube class D amps... in fact the original patents and IP from the 1930's were tube based.

One related curiosity is that the first A/D converters (I saw a picture of a 7 bit one) were vacuum tubes - the construction, while difficult to describe in words, made perfect sense once someone gave you some hints as to what was going on.

 

[pocket_groover]

I followed my standars steps for threads like this.

1) Read OP and laugh. (The statements made during that interview were laughable, by the way.)

2) Scroll until I see what @agedhorse has to say.

3) Walk away having nothing to add.

Me too. Exactly what I just did. But I DID take the time to read the whole thread so not exactly 2) above.

 

[Bobo]

A watt is a watt, regardless be it tube, A/B, Class D.

The better question is are modern manufacturers fudging their power ratings?
I can tell you through the same 8 ohm cab, my old mark III peavey bass head is a lot louder than my Trace Elliot Elf despite them having similar power ratings (actually I believe the old peavy is less powerful at 8ohm than the trace is rated)

I agree. I don't think my ELF is as powerful as any of my vintage tube amps; however, I've been able to achieve a tone and volume pretty darn close to my '66 B-15n, and it only weighs 1.6 pounds and I can carry it in my coat pocket.

 

[agedhorse]

Thank you. Can you address the comment I posted made by the President of Boss? Is it true that makers of Class D bass amps basically lie and that a 160 watt bass amp with an A/B power section is about equal to an 800 watt bass amp with a Class D power section?

Not in my experience, not the manufacturers I worked for, and other quality manufacturers used the same ratings for the same class D sections.

 

[JeezyMcNuggles]

disagree with this, I have't seen it to be true on any class of amp.

I have, every amp I've ever played through has a sweet spot. On every solid state amp (class D or otherwise) up to half, they're sterile. After half, they get meaty and open. Raw, if you will. Up to a point that it starts to suck.

On a tube amp, after half, it doesn't even really get louder. It just gets more saturated. Blurred, squished. Up to the point it starts to suck.

Sweet spots.

 

[HelpImaRock]

Speaking of people having no clear understanding of a Watt…

How come a lemon gets soft and juicy as it ages and a lime gets hard and dry and physically smaller as it ages? Shouldn't they age the same since they are both sour citrus tree fruits? Asking for a friend.

Because a lemon is a hybrid of a lime and a citron and was bred for its juiciness.

 

[Boneless]

So, basically and in very simple terms. Class D amps are, by virtue of the way they work, very efficient but this comes at the cost of little to no headroom once they start being pushed. In other words, they tend to have abrupt clipping behaviour. You get a 700W Class D amp, and it *will* give you 700 "clean" watts. Usually they are 700W @ 1% THD (essentially clean for bass or even electric guitar purposes; 3% starts maybe getting noticeable on bass as some sort of mild thickening, you generally need to go beyond 5-6% to actually hear some clear distortion), beyond this power figure distortion increases comparatively rapidly. AFAIK, Class D amps tend to also be aggressively limited for this reason too. Class AB amps (both tube and solid-state) may have better clipping behaviour, but this still depends on the design, the use of negative feedback (and how much of it), if there is a limiter and whether it is defeatable, whether it is actually desirable to do so, and it also depends on how aggressive the protection is on the power devices, on the dimensioning of the power supply, on the voltage amplifier stage possibly. Sometimes there is soft clipping built into the power amplifier (and that may also be true of Class D amps), something that essentially lowers the available clean power but sounds nicer. Too many variables. That said, those 700W that many of those Class D amps the size of a textbook can deliver aren't a scam, they are actual measurements. What may mislead is that many of these amps tend to lean towards the "hifi" side of things, therefore they reserve those 700W to allowing clean transients to be reproduced quite faithfully. And that doesn't sound loud. If you feel your big-watt head sounds a bit weak, try buying a compressor first (one that you can set with lowish attack times preferably, lower yet if it's a feedback topology) and see if that helps.

 

[bdplaid]

and was bred for its juiciness.

As was I.

 

[marchone]

I have, every amp I've ever played through has a sweet spot. On every solid state amp (class D or otherwise) up to half, they're sterile. After half, they get meaty and open. Raw, if you will. Up to a point that it start to suck.

On a tube amp, after half, it doesn't even really get louder. It just gets more saturated. Blurred, squished. Up to the point it starts to suck.

Sweet spots.

Solid state to me means hi-fi. Sterile if you wish. Depending on EQ more volume gives a buzz saw effect. Call it an irrational perception. But it's there.

 

[Brother Goose]

Some people can't hear a difference between analog and digital, you are clearly one of those people. Im sure you prefer streaming music to vinyl too

Hey aren't you the person who started a thread about your open back guitar amp and picked a fight based upon the honest responses?

We're all here for you if you'd like to to talk it out.

Please don't be insulting

 

[Killing Floor]

Hold the lime. Lunch isn`t always on time.

Lukather uses high value Watts.