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

[agedhorse]

True. Might be a bad analogy. So lets try this. No house system to run thru, its an outdoor show with a loud band. If a watt is a watt and a Class D power section rated at 100 watts is no different from a 100 watt tube, A/B power section pushing 6L6s, you should be able to stack that Rumble 100 with an external 12 inch cab and keep up with an Ampeg V-4B running into a 2x12 cab right? So why pay $3k for the Ampeg rig when you can do the same thing for about $600 with a Rumble setup?

Outdoor show, loud band and no PA? Sounds like a Micky Mouse situation to me, something no pro players would agree to or be part of.

This is an absurd situation.

 

[Redbrangus]

If a watt is a watt and a Class D power section rated at 100 watts is no different from a tube, A/B power section pushing 6L6s, you should be able to stack that Rumble 100 with an external 12 inch cab and keep up with an Ampeg V-4B running into a 2x12 cab right?

You keep going to that Rumble 100 vs V-4B analogy. I really hate to defend the Rumble because I have no idea how its power rating is determined, but I suspect if both were tested under the same operating conditions, including operating at <1% distortion, they'd spec out pretty nearly the same. The difference in apparent and actual loudness has nothing to do with the circuit topology -- the harmonic content of a tube power section being operated with >20% distortion is what most folks are looking for when they opt for a tube amp. The power factor -- the portion under the curve -- measures a whole lot more than 100 watts in that circumstance. OTOH, no one much wants to hear a solid state device of any sort being operated in a manner that produces 20% THD.

 

[mbell75]

I don't see many V4-B's either actually.

Amps that get used on tour based on player preferences in addition to an amp being a commonly platform (ie. the SVT) and the type of speaker being used. From memory, I have seen Aguilar have TH-350's and 500's (class D), Fender Bassman 500/800's (class D), SWR SM-400/500/900 (class AB), Walkabout and Carbine 6/9 (class AB), Subway D, D+, WD, TT (class D), etc.

It really comes down to player preferences, the needs of the gig and the look the band is after.

Ok. By the way, why is the tube, A/B Fender Bassman only 100 watts and the tube Super Bassman only 300 watts while the Class D Bassman is 500 watts and the Class D Super Bassman 800 watts? Thats 5 times....Is it that whole thing where you need 5 times the power for a Class D amp that is supposedly not true?

 

[JimmyM]

Ok. By the way, why is the tube, A/B Fender Bassman only 100 watts and the tube Super Bassman only 300 watts while the Class D Bassman is 500 watts and the Class D Super Bassman 800 watts? Thats 5 times....Is it that whole thing where you need 5 times the power for a Class D amp that is supposedly not true?

Are you really looking for truth or do you just want to be difficult? I have had several micros ranging from 200w to 1000, as well as two of every tube amp Ampeg is best known for. I also spent plenty of time switching them in and out to compare ultimate volume levels when running clean, and when wattage was fairly close, so were clean volume levels. Not enough difference to matter. Tone was another story, but even then, it was nothing objectionable, just not quite to my liking as much but plenty good.

And the reason why they make amps in those wattages with tube amps being lower wattage is totally related to size and cost matters.

 

[bdplaid]

True. Might be a bad analogy. So lets try this. No house system to run thru, its an outdoor show with a loud band. If a watt is a watt and a Class D power section rated at 100 watts is no different from a 100 watt tube, A/B power section pushing 6L6s, you should be able to stack that Rumble 100 with an external 12 inch cab and keep up with an Ampeg V-4B running into a 2x12 cab right? So why pay $3k for the Ampeg rig when you can do the same thing for about $600 with a Rumble setup?

Absolutely not. You changed the equation when you changed cabs. Two speakers are always more efficient than one.

 

[mbell75]

Are you really looking for truth or do you just want to be difficult? I have had several micros ranging from 200w to 1000, as well as two of every tube amp Ampeg is best known for. I also spent plenty of time switching them in and out to compare ultimate volume levels when running clean, and when wattage was fairly close, so were clean volume levels. Not enough difference to matter. Tone was another story, but even then, it was nothing objectionable, just not quite to my liking as much but plenty good.

And the reason why they make amps in those wattages with tube amps being lower wattage is totally related to size and cost matters.

I want an honest answer. If a watt is a watt and a Class D power section is no different from a tube, A/B power section, why do the Class D Bassman amps have 5 times the watts? Why not 100 and 300 just like the tube amps? Also, maybe @agedhorse can answer this one. Why are the Mesa tube, A/B amps only 250 watts while their Class D are 800 wats? Hmmm, thats about 5 times more watts on the Mesa Class D amps as well. Im sensing a trend here....

 

[DJ Bebop]

Are you really looking for truth or do you just want to be difficult?

, Jimmy

 

[StereoPlayer]

8 pages, but it was pretty easy for me to pick up the two main conversational points. 3 if you're into clotheslines.

https://www.mothering.com/threads/best-clothespins.1253435/

 

[DJ Bebop]

I want an honest answer. If a watt is a watt and a Class D power section is no different from a tube, A/B power section, why do the Class D Bassman amps have 5 times the watts? Why not 100 and 300 just like the tube amps? Also, maybe @agedhorse can answer this one. Why are the Mesa tube, A/B amps only 250 watts while their Class D are 800 wats? Hmmm, thats about 5 times more watts on the Mesa Class D amps as well. Im sensing a trend here....

Because some people want more clean power?

 

[Plastalmonus]

Uhm, yeah Radkey is great but this isn't even remotely real world. Anything with the FF is going to have enormous PA support. All Isiah has to do is get his amp loud enough to be heard by a microphone. The rest is monitors and PA. I don't remember what they used on the last club tour, but I don't think it was an elf into 2 2X8 speaks..

This also has zero to do with Class D/Tube/SS watts and that rabbit hole.

I was replying to a comment that says nobody plays Class D amps on stage. Context is everything.

 

[bdplaid]

why do the Class D Bassman amps have 5 times the watts?

Probably because they can, and to my knowledge that's how the Class D power modules were/are made. Things changed when amplifier design and construction went modular. But make no mistake, if a manufacturer can up the advertised wattage, he will. Look at Behringer.

Why not 100 and 300 just like the tube amps?

I'm no tube guy, but my recollection is because it was limited by several practical design factors, such a weight, heat, cost. edit: and available wattage and amperage from the wall.
Those big transformers are a beast! And because "loud enough" is loud enough. The SVT was designed around two cabs, with 16 speakers total. That make a slit-ton of sound.

Put an SVT on top of your aforementioned single 12" cab and I bet you won't be impressed.

To that end, I challenge you to do a test. Take 3 amps of the same wattage, your V4B, a solid state A/B, and a Class D. Make sure they are all quality amps. Plug each of them into a single 12. Measure the SPL. Report back.

 

[silky smoove]

I want an honest answer. If a watt is a watt and a Class D power section is no different from a tube, A/B power section, why do the Class D Bassman amps have 5 times the watts? Why not 100 and 300 just like the tube amps? Also, maybe @agedhorse can answer this one. Why are the Mesa tube, A/B amps only 250 watts while their Class D are 800 wats? Hmmm, thats about 5 times more watts on the Mesa Class D amps as well. Im sensing a trend here....

You need to understand how power ratings are derived including, among other things, the THD factor. This has been written about extensively on this site and others. Do some research and you'll answer your own question.

 

[mbell75]

Probably because they can, and to my knowledge that's how the Class D power modules were/are made. Things changed when amplifier design and construction went modular. But make no mistake, if a manufacturer can up the advertised wattage, he will. Look at Behringer.



I'm no tube guy, but my recollection is because it was limited by several practical design factors, such a weight, heat, cost. edit: and available wattage and amperage from the wall.
Those big transformers are a beast! And because "loud enough" is loud enough. The SVT was designed around two cabs, with 16 speakers total. That make a slit-ton of sound.

Put an SVT on top of your aforementioned single 12" cab and I bet you won't be impressed.

To that end, I challenge you to do a test. Take 3 amps of the same wattage, your V4B, a solid state A/B, and a Class D. Make sure they are all quality amps. Plug each of them into a single 12. Measure the SPL. Report back.

So its just purely coincidental that just about every Class D bass amp has 5 times the watts of its tube counterpart, and has nothing to do with the fact that it takes 5 times the watts to equal the same power of a tube, A/B amp? Ok...

 

[CryingBass]

In the year 2022 ( does this post support that fact? ) IMHO gigging dudes whom want a light, reliable, amp probably select class D, and they are probably carrying 1 or 2 light-weight neo cabs, and are doing the rest with IEM's and FOH. And the audience thinks they rock. And a lot of guys that play nice venues probably skip the amp and cabs.

IF I was still gigging, at a large event, I would probably drag out my Mesa 8:88 and some very large cabs.
With roadies doing all the heavy lifting. Even when I dial it "down" to 200W, the 8:88 it is very, very "loud". But the cabs have a LOT to do with that.

A 100W D class amp with a not-so-"loud" ( probably combo ) cab? Probably not so "loud".

And loud is over-rated these days. I would wait for applause, but I would not be able to hear it. See above.

I miss the old days...

 

[Wasnex]

So that I understand this at the risk of sounding like an idiot for asking: You are saying that a class D amp that's not integrated with other stages cannot receive a PWM digital audio signal and generate an analog audio output?

\

This is intended to show how oscillator modulates the input signal to produce the PWM. The PWM signal is generated as part of the class D process.

Keep in mind audio is considered 20hz - 20kHz. The Oscillator runs at a much higher frequency...perhaps 20X the highest frequency or more?

Here's a video that should give you a better idea of the frequency differential between the PWM and the original audio signal.


I added a red box to this diagram to show the components that convert the PWM back to audio. It's basically a low pass filter.

 

[JimmyM]

I want an honest answer. If a watt is a watt and a Class D power section is no different from a tube, A/B power section, why do the Class D Bassman amps have 5 times the watts? Why not 100 and 300 just like the tube amps? Also, maybe @agedhorse can answer this one. Why are the Mesa tube, A/B amps only 250 watts while their Class D are 800 wats? Hmmm, thats about 5 times more watts on the Mesa Class D amps as well. Im sensing a trend here....

You have gotten I don't know how many honest answers, and all you want is somebody to tell you that you are right and you won't be satisfied until you get it. I'm not wasting my time anymore. Other people can do what they want but I'm not here to mollycoddle anybody.

 

[bdplaid]

So its just purely coincidental that just about every Class D bass amp has 5 times the watts of its tube counterpart, and has nothing to do with the fact that it takes 5 times the watts to equal the same power of a tube, A/B amp? Ok...

You've got this thing in you're head, or you're a troll. I'm done with you.

 

[mbell75]

You've got this thing in you're head, or you're a troll. I'm done with you.

Why is a 100 watt, tube A/B Fender Bassman a totally giggable monster of a bass amp and the 100 watt Class D Fender Rumble little more than a bedroom practice amp? Because one is a Bassman and one is a Rumble? Come on. Stop drinking the marketing kool-aid. There is a massive difference between a 100 watt A/B amp being driven by 6L6s and the other with a Class D power section.

 

[bdplaid]

Why is a 100 watt, tube A/B Fender Bassman a totally giggle monster of a bass amp and the 100 watt Class D Fender Rumble little more than a bedroom practice amp? Because one is a Bassman and one is a Rumble? Come on. Stop drinking the marketing kool-aid. There is a massive difference between a 100 watt amp being driven by 6L6s and the other with a Class D power section.

 

[mbell75]

I see we have resorted to childish insults when one can't answer a simple question. You clearly believe there is no difference between a 100 watt A/B Bassman and a 100 watt Class D Rumble. Ok