Class D amps sound inferior?

[agedhorse]

A fuse conducts when it’s working normally, and opens upon a fault.

 

[byacey]

But when it performs the purpose for which it was designed, which is to destroy itself, then the entire circuit is reduced to doing nothing.

(just in case you can't see, my tongue is firmly planted in my cheek)

But then at that point it's not doing what it was designed to do. ( The circuit.)

 

[PhatBottomBass1]

OK, we still have brain cells on this thing...

I have only my own experiences with Class D (Pascal). I have had Class H (similar to Class D, I guess), but stated also similar to A/B.

So, what are the reasons for what some hear in Class D that pose the question regarding being "inferior?" (I've discribed my specific A/B experience) but, there must be others. What are the limitations on Class D if we were to look at it like that?

 

[byacey]

OK, we still have brain cells on this thing...

I have only my own experiences with Class D (Pascal). I have had Class H (similar to Class D, I guess), but stated also similar to A/B.

So, what are the reasons for what some hear in Class D that pose the question regarding being "inferior?" (I've discribed my specific A/B experience) but, there must be others. What are the limitations on Class D if we were to look at it like that?

Class H has nothing in common with class D, Class H operates as pure, linear function. As far as limitations, I don't think anyone would find anything pleasing about a class D when it's driven into clipping.

 

[Windreaper]

Class H has nothing in common with class D, Class H operates as pure, linear function. As far as limitations, I don't think anyone would find anything pleasing about a class D when it's driven into clipping.

Not an engineer, and dunno about amp topology, but I've understood clipping is the major difference between linear and SMPS, the former soft clipping (voltage drops as current increases) while SMPS keeps going until the current limiter kicks in. So less dynamic headroom, I guess, but could just include a larger power supply if that's a problem?

 

[SteveCS]

Not an engineer, and dunno about amp topology, but I've understood clipping is the major difference between linear and SMPS, the former soft clipping (voltage drops as current increases) while SMPS keeps going until the current limiter kicks in. So less dynamic headroom, I guess, but could just include a larger power supply if that's a problem?

You describe a type of compression where the output can't keep up with the gain - normally I would call that sagging. It is a type of compression which is another way of saying less dynamic headroom in the 'linear' design, once it stops being linear.

The 'close-coupled' dynamic response is one of the things I like about my Class D - it goes where I go, not the other way around.

 

[Windreaper]

You describe a type of compression where the output can't keep up with the gain - normally I would call that sagging. It is a type of compression which is another way of saying less dynamic headroom in the 'linear' design, once it stops being linear.

The 'close-coupled' dynamic response is one of the things I like about my Class D - it goes where I go, not the other way around.

Yeah, I think that would be the correct term. I admit I'm very confused as power supply/amp interactions seem to be kind of complex with ripple also increasing when a linear supply is hit hard (in addition to lower voltage affecting clipping threshold?). In addition, there are often various soft clip circuits built into ss amps. Anyway, there shouldn't be a reason why properly designed amplifiers would sound significantly different regardless of amp/psu topology afaik.

 

[Pimmsley]

This is how bad information, old wive’s tales and urban myths get perpetuated.

Pretty much total hogwash, based upon poor quality designs using very obsolete technology and devices. While this might have been true 30-40 years ago, it hasn’t been true for the past ~20 years.

I was really enjoying my Shuttle 9.2 the other night, thought to myself how great the deep, full and punchy the sound I was getting with my settings and a pair of DB112's... one beastly amp... and also thought of you sir !

Thanks again for such a wonderful and classy amp

 

[SteveCS]

I was really enjoying my Shuttle 9.2 the other night, thought to myself how great the deep, full and punchy the sound I was getting with my settings and a pair of DB112's... one beastly amp... and also thought of you sir !

Thanks again for such a wonderful and classy amp

I'm itching to get my 6.0 out of first gear for the first time in 15 months. Venues should be re-opening soon.

 

[el murdoque]

Just tossing this in from the sideline:
Google "Richard Clark $10,000 Amplifier Challenge".
That bloke, Mr Clark has had (or still is, I don't know) a Challenge running where you can specify two amps of your choice and have to distinguish between them in an A/B/X test while listening to music.
You can specify a $200 amp and a $50k amp if you so desire.

The rules in a nutshell:
-Must listen to music (you choose what)
-You choose the cabs
-The amps must operate within their given limits and are set to the same volume - so you can't pick a weak one and a powerful one and listen for distortion. When you pick a 5W amp and a 1500W amp, you'll be running both at a level comfortable for the 5W.
-The amps are set to a flat frequency response. If one of those amps has a baked in EQ thing going that can't be set to be flat, an external EQ will be applied to even it out. You can choose which amp gets the EQ.

This has been running for a long time and AFAIK, Mr Clark has kept his ten grand.

In a way, this also translates to bass amps.
Of course, some bassists do enjoy driving their pre- or poweramp into saturation to get compression and overtones and grit into their signal, something unthinkable in the world of audiophile hifi listeners.

The thing that applies to the bass world is that as long as the poweramp operates within its given limits (clear headroom), an old lead sled and a modern Class D amp will sound identical unless they have been tinkered with.
'More heft' 'more punch' and 'quicker attack because of bigger capacitors' are myths.


It is actually quite easy to rig a passable blind test setup if you have two identical cabinets, an A/B poweramp, a Class D poweramp, a preamp and an A/B switch.The trickiest part is to match the output volume.
Set the cabs side by side and put the amps on top. The tested person gets the switch and the bass.
Run the cables so it cannot be seen where they go (especially the speaker cables) and after each guess rearrange them (or not).
If you're a firm and outspoken believer in the 'fact' that lead sleds are superior to class D, try this alone before you invite friends.

 

[PhatBottomBass1]

Class H has nothing in common with class D, Class H operates as pure, linear function.

My confusion.

AgedHorse said;

"The switch mode power supply is virtually identical to the power supplies used in all popular class D platforms."

I took this to mean that Class D was related in some potentially significant way. I am not sure if this "switch mode power supply" is a distinct item or a conceptually applied stage of another component. Engineers should be as specific as possible when speaking and possibly not using terms of art or generalities equivicating totally different ideas.

Thanks for clearing that up byacey. Class H has no equivalent aspects to Class D.

 

[PhatBottomBass1]

Just tossing this in from the sideline:
Google "Richard Clark $10,000 Amplifier Challenge".
That bloke, Mr Clark has had (or still is, I don't know) a Challenge running where you can specify two amps of your choice and have to distinguish between them in an A/B/X test while listening to music.
You can specify a $200 amp and a $50k amp if you so desire.

The rules in a nutshell:
-Must listen to music (you choose what)
-You choose the cabs
-The amps must operate within their given limits and are set to the same volume - so you can't pick a weak one and a powerful one and listen for distortion. When you pick a 5W amp and a 1500W amp, you'll be running both at a level comfortable for the 5W.
-The amps are set to a flat frequency response. If one of those amps has a baked in EQ thing going that can't be set to be flat, an external EQ will be applied to even it out. You can choose which amp gets the EQ.

This has been running for a long time and AFAIK, Mr Clark has kept his ten grand.

In a way, this also translates to bass amps.
Of course, some bassists do enjoy driving their pre- or poweramp into saturation to get compression and overtones and grit into their signal, something unthinkable in the world of audiophile hifi listeners.

The thing that applies to the bass world is that as long as the poweramp operates within its given limits (clear headroom), an old lead sled and a modern Class D amp will sound identical unless they have been tinkered with.
'More heft' 'more punch' and 'quicker attack because of bigger capacitors' are myths.


It is actually quite easy to rig a passable blind test setup if you have two identical cabinets, an A/B poweramp, a Class D poweramp, a preamp and an A/B switch.The trickiest part is to match the output volume.
Set the cabs side by side and put the amps on top. The tested person gets the switch and the bass.
Run the cables so it cannot be seen where they go (especially the speaker cables) and after each guess rearrange them (or not).
If you're a firm and outspoken believer in the 'fact' that lead sleds are superior to class D, try this alone before you invite friends.

Now this is very interesting.

Why would anyone design anything and pay more for the components to manufacture it if, in the end, there will be no discernable difference in the end product? (If it can fit in your pocket and not a flatbed truck is nice, too, though.)

I guess, if it's loud. Then that's the only significant variable in the amplification process. Given a constant dynamic input. Speakers being static.

If it amplifies the final signal, that's all the difference there is.

Great! I'm out with a 21 lbs, over engineered and cost me $600 to obtain on the used market amp. I will tell myself it is no different than any other amp, not considered to be equivalent to the non-inferior Class D amps.

It's been a pleasure learning.

 

[el murdoque]

Now this is very interesting.

Why would anyone design anything and pay more for the components to manufacture it if, in the end, there will be no discernable difference in the end product. (If it can fit in your pocket and not a flatbed truck is nice, too, though.)

I guess, if it's loud. Then that's the only significant variable in the amplification process. Given a constant dynamic input. Speakers being static.

If it amplifies the final signal, that's all the difference there is.

Great! I'm out with a 21 lbs, over engineered and cost me $600 to obtain on the used market amp that I will tell myself is no different than any other amp not considered to be equivalent to the non-inferior Class D amps.

It's been a pleasure learning.

Consider build quality, reliability, looks, feel and sound of the thing in total.
The power amp section is only one part of the amp.
In most cases, an expensive bass amp will still sound better than a very cheap one.

 

[frankie5string]

Are you sure that K wasn't an H?

Yeah, I wondered too... Last time I saw anything referring to "Class-K" it was a headphone amplifier.
Maybe the Stewart was Class-H with a switching power supply to keep the weight down?

 

[frankie5string]

Now this is very interesting.

Why would anyone design anything and pay more for the components to manufacture it if, in the end, there will be no discernable difference in the end product? (If it can fit in your pocket and not a flatbed truck is nice, too, though.)

I guess, if it's loud. Then that's the only significant variable in the amplification process. Given a constant dynamic input. Speakers being static.

The idea that a "500 watt" bass head could even exist under 10 pounds and not be expensive and custom-made like a Walter Woods was very appealing to a lot of people. It still is. The whole idea that an amplifier has to be heavy to sound good is just coming from confirmation bias for those who own heavy amps.

With modular power amps and power supplies designers get more time and space to develop unique preamps and customize the signal chain.

 

[PhatBottomBass1]

The idea that a "500 watt" bass head could even exist under 10 pounds and not be expensive and custom-made like a Walter Woods was very appealing to a lot of people. It still is. The whole idea that an amplifier has to be heavy to sound good is just coming from confirmation bias for those who own heavy amps.

With modular power amps and power supplies designers get more time and space to develop unique preamps and customize the signal chain.

I will chime in too point out my precived paradox that as amps popularity seems to be going down. The wattage seems to be increasing beyond "500 watts" @ 10 lbs and getting PA support drives reduction in other than floor-based systems with modeling and IR technology leading the way. Of course, then we circle back to is analog better than digital, does it sound as good as the "real thing" and does the audience really care if they are three sheets to the wind on Friday and Saturday night?

I can provide a solid Bass tone...I'm good.

 

[SteveCS]

Just tossing this in from the sideline:
Google "Richard Clark $10,000 Amplifier Challenge".
That bloke, Mr Clark has had (or still is, I don't know) a Challenge running where you can specify two amps of your choice and have to distinguish between them in an A/B/X test while listening to music.
You can specify a $200 amp and a $50k amp if you so desire.

The rules in a nutshell:
-Must listen to music (you choose what)
-You choose the cabs
...

I stopped reading right about here. My guess is he is talking about audiophile equipment. I know, without a shadow of a doubt, I could pick out an Ampeg Fridge from a Bassman 4x15 from a Genz or Berg FRFR, no matter what amp was driving them. Almost all of the colour in a bass rig comes from the cab..

 

[agedhorse]

My confusion.

AgedHorse said;

"The switch mode power supply is virtually identical to the power supplies used in all popular class D platforms."

I took this to mean that Class D was related in some potentially significant way. I am not sure if this "switch mode power supply" is a distinct item or a conceptually applied stage of another component. Engineers should be as specific as possible when speaking and possibly not using terms of art or generalities equivicating totally different ideas.

Thanks for clearing that up byacey. Class H has no equivalent aspects to Class D.

The switch mode power supply is a type of power supply used in power amps, and is lighter weight than the older line frequency power supplies (the other type of power supplies used in power amps).

 

[agedhorse]

Not an engineer, and dunno about amp topology, but I've understood clipping is the major difference between linear and SMPS, the former soft clipping (voltage drops as current increases) while SMPS keeps going until the current limiter kicks in. So less dynamic headroom, I guess, but could just include a larger power supply if that's a problem?

There are many ways around managing how ANY amplifier handles clipping, or overload. Some linear class AB/G/H amps don’t clip well either.

 

[Al Kraft]

In a way, this also translates to bass amps.
Of course, some bassists do enjoy driving their pre- or poweramp into saturation to get compression and overtones and grit into their signal, something unthinkable in the world of audiophile hifi listeners.

The thing that applies to the bass world is that as long as the poweramp operates within its given limits (clear headroom), an old lead sled and a modern Class D amp will sound identical unless they have been tinkered with.

I think it's hard to prove in blind testing that amplification alone (removing all other voicing and EQ differences including damping factor differences) with two properly operating power amps is noticeably different when both are operated at the same output gain within their comfortable performance envelope. However, all those caveats are often what makes one bass guitar amplifier clearly different (i.e. more or less preferable to a player) than another.

IME in real world usage it's darn hard to make a Mesa Carbine or GK MB head sound like a Mesa Walkabout or Aguilar Tone Hammer. Within the Aguilar line itself I can hear a clear difference between the DB, AG, and TH series. On one single Mesa head, the WD-800, I can hear and feel the difference between high and low damping (and even that changes with lower impedance speaker loads, how hard the amp is driven, and the frequency of the notes).

I have no doubt that when one removes all variables except gain boost most amplifiers will sound almost exactly the same. IMO the problem many folks have is recognizing/understanding the difference between intentional design voicing/circuit behavior artifacts and the particular technology or component selected by the designer to optimize voicing/behavior (along with other) design goals.