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

[paskisti]

If you want that "heft" from the class D then you'll need to introduce that at the pre-amp stage, and then let the Class D do its job and make it louder.

I would say the same. Notice that if SVT power section makes the magic then you are running it pretty loud already. Try with good preamp with compression or dirt, EQ correctly, run that into 800W (headroom) quality class D power amp and push it to similar SPL to hear actual heft.

I have done this, and I don't hear absolutely any difference between D and A/B, and no heft difference for SVT as long as cabinet remains the same.

 

[Wesley R]

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)

In the past I have said "a watt is a watt, until marketing gets a hold of it."

Around 1971 Sears had a 300 watt* bass amplifier and it had a large cabinet with something like six speakers. The 300 was some form of Peak to Peak. Many a young inexperienced, deceived bass player equated it to the same volume as an SVT. It was not.

 

[deff]

As usual with such threads, I just scrolled until I found @agedhorse's reply.

No offense here, but @Passinwind response was exactly correct and enough of an explanation to have ended the thread.

 

[agedhorse]

I'm always amazed at the sheer length of these threads. They usually run as follows:

• Thread started, with initial post containing wildly inaccurate or completely wrong information.
• @agedhorse weighs in, and puts everything straight after several pages of nonsense.
• Nonsense persists for X number of further pages.

It's a paradigm for the cosmos.

Fortunately, there were quite a few posts providing good information regarding technology.

I suggest checking Dave Rat's YT channel, he compared two PA amps with A/B and D power sections.

Interestingly he found out class D amp drops the power when pushed, compared to A/B. He also noted it is possible one simply has a limiter to avoid overheating, while the other gives it all until it breaks, so might not be related to class type at all.

Limiting algorithms in newer products are far better designed and executed for real world needs compared with older products. While this began with the older, heavier amps, we are several generations beyond that by now and there are no new designs that I am aware of using line frequency transformers, so those comparisons are moot.

Yes, I wrote that "good amps weigh a ton" in quotation marks because that's what the popular wisdom was once upon a time. Basically you really needed larger transformers with linear power supplies (even if it's not about weight, but there is a certain correlation). With SMPS technology, there is no need for this and the efficiency and effectiveness of the power supply is also greater. Still, there are many amps that are still made with traditional linear power supplies, so I'm guessing there must be something at which they are better. (I doubt that it's noise).

Yes, they are still less expensive but the gap is shrinking.

 

[Father Gino]

At the risk of jumping into a thread that I really should stay away from...

Class D is most likely reproducing the lows perfectly. If your class D is clipping then you would know about it... In fact its your old A/B tube amp that's messing up the lows. The tube amp is pushing into clipping/compression which is gently distorting those low frequencies and adding in higher frequencies that shouldn't be there.

Thing is - you (quite reasonably) LIKE those extra frequencies - they're the "heft" and "thump" you talk about.That those are missing from the Class D is theoretically a good thing. However once you get into preference then its up to you what you like.

If you want that "heft" from the class D then you'll need to introduce that at the pre-amp stage, and then let the Class D do its job and make it louder.

I'll jump a little further away. A Hammond organ goes all the way down (sorta) to low C. It's signature sound usually comes from a Leslie speaker cab with 20 or 40 watts. There is no remotely clean sound at all playing at even a moderate level by rock & roll standards. But that fuzzed out, distorted sound complete with built in screeching, dissonant harmonics is "the" sound of that beast. It really wasn't a design feature, but it's a glorious sound to my ears, so much so that they have now pretty much emulated it with modern technology that doesn't weigh 500 pounds.

Another thought is the Aguilar Tone Hammer, solid state, with a bunch of analog filters and a class D power module that does a pretty good job of emulating a tube amp.

Another thought: seems like lots of people listen to music out of crappy little speakers that sound only slightly better that the stock AM radio speaker in my 67 Buick. I've got a big, old pair of Boston Acoustic speakers and streaming, CDs or vinyl all sound really nice.

 

[bassliner50]

Output power (measured in watts) is output current X output voltage regardless of how it is developed.

 

[agedhorse]

Yes, but I'm not talking about hobbyists or small companies here (and even small companies can just buy ready-made SM power supplies and incorporate them into their designs). I'm also guessing that linear power supplies are better for "the road" since they tend to be more dependable (they hardly ever break down, and when they do, it may be trivial to repair them), but on the other hand, SM power supplies are also available off the shelf.

These days, SMPS are just as reliable and due to how they work, are easier to design protection circuits around which increases the reliability of the entire amp.

Thank you for that clarification. I think I heard that from Eden's own copy about their initial class D offering, an amp which I bought and still own. WTX-260 IIRC. Since then I have come to realize not all messaging from Eden was completely accurate. They were trying to use the lack of a processor in their amp as a marketing differentiator.

It's not true with that amp for sure.

 

[MultiScaleMale]

Here is the interview, if you're interested. Around 5:30, essentially Tube amp watts used to be greater than Class AB watts, but now tube watts and class AB watts are greater than class D watts. But of course, watts are watts. Maybe the confusion comes when you use the terms "watts" and don't specify that you're fudging the figures by using "peak" or "burst" watts versus what was generally used "RMS" watts so that you really could compare wattage figures. Our guitarist has a wedge amp that has a 2000W sticker on it. No way is it putting out 2000W, but hey it's marketing.

 

[lermgalieu]

No offense here, but @Passinwind response was exactly correct and enough of an explanation to have ended the thread.

That's great, because I certainly didn't say anything derogatory about him.

 

[agedhorse]

Here is the interview, if you're interested. Around 5:30, essentially Tube amp watts used to be greater than Class AB watts, but now tube watts and class AB watts are greater than class D watts. But of course, watts are watts. Maybe the confusion comes when you use the terms "watts" and don't specify that you're fudging the figures by using "peak" or "burst" watts versus what was generally used "RMS" watts so that you really could compare wattage figures. Our guitarist has a wedge amp that has a 2000W sticker on it. No way is it putting out 2000W, but hey it's marketing.

Agree, when marketing departments twist things around, all comparisons fall apart. That's been going on since the all tube days too.

 

[bassdude51]

I recently bought a Marantz Model 30 integrated stereo amp, $3,000. 100 watts a channel @ 8 ohm. It is class D. Was a recommended buy from Stereophile magazine.

It's a great sounding amp and I have no doubts on it's wattage rating! Verified by Stereophile's techs.

Watts are watts. Period.

 

[deff]

That's great, because I certainly didn't say anything derogatory about him.

My only point is there are more than a few people here that provide more than satisfactory explanations to these questions that we don't have to saddle up all the horses for every explanation, ba dum bum. I also feel like we use Andy as the final authority all too often for these things. Probably because he gives graciously of his time and expertise.

 

[ardgedee]

At face value it does seem weird. I'm pretty sure it was more about what the warmth of the McIntosh did for the sounds of Levene and Wobble and how the sound filed the space.

McIntosh amps have a very smoothy-smooth sound. Especially the modern ones where they're deliberately tuning them that way. I have a solid-state McIntosh receiver (MAC 4100) which sounds how audiophiles like to call "tubey", but actually prefer it to most McIntosh tubed amps because it doesn't have that smoothy-smooth signature -- I got it after trying out *all* of McIntosh's receivers, including their tubed and hybrid ones, when an acquaintance was selling off his collection. Mac fans mostly hate the MAC 4100.

Which is not to say that sound signature is bad. But while it's a McIntosh thing, they don't have a lock on it. I have a solid-state Heathkit receiver ca. 1973 and a tubed Fisher amp ca. 1960 which both also have that smoothy-smooth sound. It's not a tone that needs tubes, overkill transformers, large dollars or exotic materials to replicate. I like it when listening to bebop and post-bebop, but it tends to make modern electronic music sound kinda background-y no matter what the musicians are doing. Which isn't bad when you're using it as actual background music while working, maybe.

 

[lermgalieu]

My only point is there are more than a few people here that provide more than satisfactory explanations to these questions that we don't have to saddle up all the horses for every explanation, ba dum bum. I also feel like we use Andy as the final authority all too often for these things. Probably because he gives graciously of his time and expertise.

I think you're overthinking it, especially since my comment was said somewhat tongue in cheek to illustrate the stupidity of the thread. I am aware of @Passinwind and have read many of his knowledgeable posts in the past. Moreover, I am sure he wasn't offended that I happened to miss his response.

 

[gln1955]

My only point is there are more than a few people here that provide more than satisfactory explanations to these questions that we don't have to saddle up all the horses for every explanation, ba dum bum. I also feel like we use Andy as the final authority all too often for these things. Probably because he gives graciously of his time and expertise.

But too often other people chime in with an air of authority when in fact they don't know their ass from their elbow about the topic. It takes a while for new folks to figure out who to listen to.

 

[Coolhandjjl]

Ok, that might be true but can you name any Class D bass amps with analog power sections? I can't think of a single one. Most every Class D is digital.

Class D amps still use transistors as the output device, just like any other solid state amp.

 

[socialleper]

I don't think there is a remarkable difference in how class D and class A/B amps translate power into volume. One could argue about subjective things like tone or response.

When comparing SS to tubes, that's a different story. A 300 watt tube amp can be very loud. A 300 watt SS amp is barely good enough for small room gigs with a quiet drummer and guitar player.

 

[Coolhandjjl]

Ok. Again, every class D combo bass amp Im aware of has a digital power section. Give me some examples of class D combo bass amps with analog power sections. Thanks

They all use transistors as output devices. A transistor is not a digital device.

 

[agedhorse]

When comparing SS to tubes, that's a different story. A 300 watt tube amp can be very loud. A 300 watt SS amp is barely good enough for small room gigs with a quiet drummer and guitar player.

I haven't found this to be true when comparing using the same speakers, with the same LF extension and sensitivity.

 

[Coolhandjjl]

Then why does every Class D combo bass amp have a digital power section?

They do not. They have a class D power section.

Digital is a signal type, just as analog is a signal type.

Too many salesmen, marketing folks, and even manufacturers starting confusing their customers by incorrectly using the term 'digital' that it has taken hold as gospel. It's too late, the horse is out of the barn now, we're stuck with it.