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Class D "digital" amps. Opinions on performance

#161
probably there is no answer to the original question.........

But there is also no "inherent sound" to any particular technology..... every type of credible amplification device or scheme that has been used has had good examples and bad..... You can't take the bad as "typical", because the good ones don't have the same problems.

Then also, the 'sound" is going to depend mostly on the preamp...... even a relatively bad power amp these days is likely to be good enough to avoid really noticeable problems. It won't sound inherently "dark" or whatever, at least not in MI usage.... if you talk to audiophiles, they have a whole other language, and I think each one speaks a different version of it.

Agedhorse gave the story..... Class-D is PWM, and basically changes amplitude to time duration, and back to amplitude again, for various reasons of efficiency. The process has a number of distortion mechanisms, but so does a regular analog amplifier.

There is NO REASON why it has to sound different in some particular way. Differences generally will be due to design decisions, switching frequency, design of the power supply, current limits, feedback setup, all thiose can affect sound easily, but are not really "inherent" to the technology, they are choices made for cost or any of a host of other possible reasons.

Probably the better original question might have been "what high powered micro amps do you like or hate, and why?"
 
#162
I have a couple of valve-pre heads (Ashdown & Labsystems) which i like to use as often as i can, but occasionally i like to stuff a Mark F1 into my gig-bag and rock into the gig with a 4-ohm box. One lug and I'm done.

I still have my reservations on preamps in some D-class heads but on the whole i think they're a godsend. The F1 preamp is fantastic!
 
#163
Jerrold Tiers said:
probably there is no answer to the original question.........

But there is also no "inherent sound" to any particular technology..... every type of credible amplification device or scheme that has been used has had good examples and bad..... You can't take the bad as "typical", because the good ones don't have the same problems.

Then also, the 'sound" is going to depend mostly on the preamp...... even a relatively bad power amp these days is likely to be good enough to avoid really noticeable problems. It won't sound inherently "dark" or whatever, at least not in MI usage.... if you talk to audiophiles, they have a whole other language, and I think each one speaks a different version of it.

Agedhorse gave the story..... Class-D is PWM, and basically changes amplitude to time duration, and back to amplitude again, for various reasons of efficiency. The process has a number of distortion mechanisms, but so does a regular analog amplifier.

There is NO REASON why it has to sound different in some particular way. Differences generally will be due to design decisions, switching frequency, design of the power supply, current limits, feedback setup, all thiose can affect sound easily, but are not really "inherent" to the technology, they are choices made for cost or any of a host of other possible reasons.

Probably the better original question might have been "what high powered micro amps do you like or hate, and why?"
Click to expand...

Good points.

Well, there are only two kinds of music. Good and bad. Of any category. (depending on the ear of the beholder)
And I like my old Quad and my old Mcintosh amps for different reasons and for different "applications". True, there are bad tube designs and bad solid state designs and vice versa.

It is a question of design, taste and proper application. And these micro amps will continue to improve in quality, Thanks to the competition in the market. Think of many of the early "solid state" amps that mostly concentrated on the importance of (and the customers importance on) power specs and distortion specs etc. Specs period. It still goes on. With speakers, X-maxx seems to be the buzz word today. I can give you at least 5 ways to rate or measure X-maxx that are used today.

True, the ultimate question here is "which amp to choose"? What is the best design maybe?
But it is my curiosity that led me to ask the WHY (or if) about possible inherent qualities in this type of design in my post. The wide commercial use is still relatively young.
I'm sure as time goes on that just as "solid state" amps have improved overall, the same will continue to happen here in these small feature filled packages. Remember the tube debate? Early on, there were more real reasons for it (And it still goes on). I think there will be a lot of refinenement here too with these heads (and also this wattage spec will become a bit less important).

Actually though, think of the Quad. Early commercial design of its type. And still great to this day.

Maybe a question is What makes a "real hi-fi" class D power amp better than some of these small heads might be a good question. What are the trade-offs in design? You hit the nail more squarely on the head really with that point about trade offs. There are of course limitations to "having everything" in these tiny little all in one heads.

My requirements and taste will in the end help me to choose the right little heads I buy in the future. And I'm sure this discussion will help too.
 
#164
bryanspkr said:
The wide commercial use is still relatively young.
Click to expand...

Not in pro audio. It's been around in various implimentations for ~20 years and IIRC, Peavey had the first commercial implimentation maybe 25 years ago? At THAT time there were enormous challenges to the technology but technology has come a very long way even in the last 10 years.
 
#165
agedhorse said:
Not in pro audio. It's been around in various implimentations for ~20 years and IIRC, Peavey had the first commercial implimentation maybe 25 years ago? At THAT time there were enormous challenges to the technology but technology has come a very long way even in the last 10 years.
Click to expand...

Wasn't Their head called the T-max? And they even recommended a 2ohm load?

Well, what do you think was the first compact head? I think maybe the GK. The head that was in the micro combo (112). So around 88-89 maybe. Or was it a few years later. Around 8lbs still. They were notorious for failing. Then they went back to the conventional transformer. That went from being in the bottom of the cab to being squeezed below the electronics.

The first really compact, complete and in wide use head in my memory, is the Acoustic image. Although the electronics took a while to re-tweak. Problems too early on. After my series one fried itself twice (just being left on and not in use), I didn't trust them enough to bring only one amp to a gig. Those have come a long way.
 
#166
Peavey did have a Class-D a long time ago...... Very complex, had a lot of problems with early ones, at least.

Acoustic Image, yeah..... worked OK for an amp that literally had NO heatsink..... each output was mounted on a little bitty square of copper foil on the PWB.... Now that different devices are available that approach is working OK for Peavey, but back then, not so much.
 
#167
bryanspkr said:
Wasn't Their head called the T-max? And they even recommended a 2ohm load?

Well, what do you think was the first compact head? I think maybe the GK. The head that was in the micro combo (112). So around 88-89 maybe. Or was it a few years later. Around 8lbs still. They were notorious for failing. Then they went back to the conventional transformer. That went from being in the bottom of the cab to being squeezed below the electronics.

The first really compact, complete and in wide use head in my memory, is the Acoustic image. Although the electronics took a while to re-tweak. Problems too early on. After my series one fried itself twice (just being left on and not in use), I didn't trust them enough to bring only one amp to a gig. Those have come a long way.
Click to expand...

Whatever is was wasn't the Tmax. I have one....45-50lb. leadslead bass amp. Nice amp, I consider it one of their gems, but definately not SMPS and I don't think class D either. Got a nice block of iron in there.:smug: 2U and deep.
 
#169
The Peavey amps were DECA's, and they were unreliably early on. The product was so far ahead of the curve (IMO) that they redefined "bleeding edge" and also created a new catagory called "catatrophic failure". These are the risks that sometimes come with advancing the technology. IMO, it was a very bold, very technically advanced product that had some really impressive engineering under the hood. The devices and degree of integration available at that time made this product a real challenge. As a "young" enginer, I was impressed with the approach and respect what it was, and what it ment to the industry today.
 
#171
Jerrold Tiers said:
... But there is also no "inherent sound" to any particular technology..... There is NO REASON why it has to sound different in some particular way. Differences generally will be due to design decisions, switching frequency, design of the power supply, current limits, feedback setup, all thiose can affect sound easily, but are not really "inherent" to the technology, they are choices made for cost or any of a host of other possible reasons...
Click to expand...

I sort of agree/disagree with this. As far as I can tell, most, if not all, of the micro bass amps out there are using off the shelf, drop in class D modules made by other companies, with the IcePower modules dominating the field. So, it does make me wonder if when people are generalizing the sound of the class D amps out there on the market, some of that isn't stemming from the fact that so many of the micro amps out there are using the exact same amplifier module.
 
#172
Man, some of the amp makers using off the shelf modules add custom feedback, limiters, pre-amps, listening tests, ear tuning. There is a lot of value added outside the module.

It's not a module in a box, just like some good cabinets are not just speakers in a box.

You seen to push class-ab because you have a lot invested in it. Other manufacturers have used their ears also and picked class-d. They are not compromising.
 
#173
seamonkey said:
Man, some of the amp makers using off the shelf modules add custom feedback, limiters, pre-amps, listening tests, ear tuning. There is a lot of value added outside the module.

It's not a module in a box, just like some good cabinets are not just speakers in a box.

You seen to push class-ab because you have a lot invested in it. Other manufacturers have used their ears also and picked class-d. They are not compromising.
Click to expand...

Theres Definatly a discernible difference between all the class a/b amps and class D amps I have heard. The class a/b being much better imo.
Having said that, I'm looking at switching from my class a/b power amp to a class d power amp strictly for weight savings. I play mostly clubs with decent pa systems so my rig is mainly just stage volume. I don't particularly like the class d tone, but for what it matters in a live situation vs shaving almost 30 lbs off my rig, I may go that route. Sucks getting old.
 
#176
Note that many manufacturers have both class AB/G/H AND class D products in their lines.

Designed well, there's little difference between power amp topologies these days IMO. BUT, let me qualify this with the clarification that a well designed amp is a well designed amp regardless of the topology and a well designed amp is going to sound better than a poorly designed amp and what you are really hearing is the deficiencies in the poorly designed amp and not so much the topology.
 
#177
seamonkey said:
Man, some of the amp makers using off the shelf modules add custom feedback, limiters, pre-amps, listening tests, ear tuning. There is a lot of value added outside the module.

It's not a module in a box, just like some good cabinets are not just speakers in a box.

You seen to push class-ab because you have a lot invested in it. Other manufacturers have used their ears also and picked class-d. They are not compromising.
Click to expand...

The point I was trying to make was that a lot of companies are using the same power module in their amps and maybe that has something to do with people who think all class D amps have a certain sound. Honestly, the Valkyrie was always intended to be a smaller class D from the beginning, but when comparing the preamp straight into the various amp topologies, I preferred the class A/Bs every time, although I did really like the Hypex module. This in no way reflects upon anything other than my own personal opinion. I don't believe that I have ever knocked class D, other than to say I personally like the sound and feel of some other topologies better. This is a thread asking for opinions on class D, so I gave mine.

That said, I also don't believe that all manufacturers are using class D modules simply because they prefer the sound. The class D modules are small, lightweight and generate very little heat. It's these features that make the micro heads even possible in the first place. It goes without saying that an 800watt class A/B with a transformer isn't going to fit inside a micro sized head. So, for these applications, class D is the way to go. The fact that some of these modules can be had for around $50 in quantity, is also an important consideration when you are trying to meet a specific price point. IMO, class D certainly offers huge advantages for certain applications, but I disagree that every company that uses them does so strictly because they prefer the tone of them.
 
#179
I remember very well when the Peavey Deca amps came out. I heard a lot of comments that they did not have the sound quality of professional linear power amps of the era, and I had to agree. The low end just wasn't very solid for starters.

Also Walter Woods introduced a class D amp of his own design (not an off-the shelf module) in the early mid 80's. And of course the original Walter Woods amp introduced in 1972 really was the first Mini Amp (it used an SMPS instead of a traditional linear power supply with a large and heavy iron transformer). It only weighed a few pounds.
 
#180
seamonkey said:
Fingers or "Digits" can count base 12
Face your palm at you, use your thumb to point at each joint on your fingers.
Each finger has 3 joints. 3 x 4 = 12
12 is a dozen
12 inches to a foot
12 * 12 = 144 is a gross
12 hours on a clock face
The Moon goes round the Earth 12 times a year - 12 months
12 is in unison with the Universe.
We should not be going "digital", We should be going "Base 12"

Are there any Duodecimal amplifiers?
Are Duodecimal amps good for metal?
:D
Click to expand...
Well, I disagree. Using one hand I can count to 31.
Thumb is 1
Index finger is 2
Middle finger is 4
Ring finger is 8
Pinky is 16

Use both hands and you have 1023. Include the feet and it's 1048575.

See, it's truly digital. I taught my son to count like that, and he gets to 31 in about two seconds. It's a great way to practice finger independence, too!
 

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