- Feb 12, 2006
- 60,989
- 5
- 220,789
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
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Class D Amps
- Thread starter jazztonebass
- Start date
That's a refreshing point of view from an engineer.
There's a manufacturer on this thread that point out they designed a SMPS and it sucked, and they designed a Class-D and it sucked, therefore all SMPS and Class-D suck.
It's not always the technology.. Sometimes it's the single design that is bad.
I've seen some class-AB that went crazy with NFB, other designs where crazy with no feedback. Arguments ensue that feedback is bad, feedback is good, and I see designs of NFB class-D. Who cares how the results are arrived at. It's the end results that matter, not what's inside the box. What happens is someone reads the "advertisements" and then believes the insides matter over what the actual performance and measures show.
ARRRRRGGGGGGGGHHHHHHHH!!!!
OK, I feel better now.
Listen, for one thing...I use the SVT merely as an example of an amp that other companies have tried to imitate (and if you seriously think that no other amp companies try to imitate the SVT, you would be wrong. Not all do but there are a lot who do, not the least of which is Ampeg themselves). And it's way more common in guitar world, where if it doesn't sound like a Fender or Marshall it usually gets rejected by the buying public. I am not listening to a bass amp, saying, "Hey, that doesn't sound like an SVT," and judging the topology on that. I kind of resent the implication that anyone would think I was dopey enough to be doing that.
And I also see some selective enforcement of the "rules" going here. It seems perfectly acceptable to believe that there is a big difference in the sound of tube amps vs. SS amps with an iron PT based on the topology, yet it's totally unacceptable to believe that there are differences between iron PT and SMPS amps based on the topology? Come now! This is the same kind of thing that makers of SS amps in the 70's used to sell SS amps. They'd tell us we couldn't tell the difference, and everybody could. To this day, everyone with an ear for such things can tell the difference. What has SMPS done that makes the differences indistinguishable?
And frankly, people are turning this discussion around on me to insinuate that I think the differences are a bad thing. I don't think they're a bad thing, otherwise I wouldn't own any micros. But I hear differences, and I get so many people telling me that they hear differences, even in high end PA world, that it's getting really difficult for me not to believe them. And even Jerrold and Andy don't completely agree that it's not topology-based, at least to a certain degree.
Of course different preamps sound different. Why wouldn't they? Please don't insult my intelligence by saying I can't tell the difference between the preamps causing it and the power amp. I fully take that into consideration. But it's way too easy and convenient to use the preamp as the sole reason, and I've been around a time or two and I know it's not that simple, despite not knowing how to design an amp. I am not trying to offend anyone who designs them, and I'm not trying to say they don't sound good. They do. I am just trying to say I hear differences in the three topologies that I don't think can be fully accounted for by just the preamp.
OK, I feel better now.
Listen, for one thing...I use the SVT merely as an example of an amp that other companies have tried to imitate (and if you seriously think that no other amp companies try to imitate the SVT, you would be wrong. Not all do but there are a lot who do, not the least of which is Ampeg themselves). And it's way more common in guitar world, where if it doesn't sound like a Fender or Marshall it usually gets rejected by the buying public. I am not listening to a bass amp, saying, "Hey, that doesn't sound like an SVT," and judging the topology on that. I kind of resent the implication that anyone would think I was dopey enough to be doing that.
And I also see some selective enforcement of the "rules" going here. It seems perfectly acceptable to believe that there is a big difference in the sound of tube amps vs. SS amps with an iron PT based on the topology, yet it's totally unacceptable to believe that there are differences between iron PT and SMPS amps based on the topology? Come now! This is the same kind of thing that makers of SS amps in the 70's used to sell SS amps. They'd tell us we couldn't tell the difference, and everybody could. To this day, everyone with an ear for such things can tell the difference. What has SMPS done that makes the differences indistinguishable?
And frankly, people are turning this discussion around on me to insinuate that I think the differences are a bad thing. I don't think they're a bad thing, otherwise I wouldn't own any micros. But I hear differences, and I get so many people telling me that they hear differences, even in high end PA world, that it's getting really difficult for me not to believe them. And even Jerrold and Andy don't completely agree that it's not topology-based, at least to a certain degree.
Of course different preamps sound different. Why wouldn't they? Please don't insult my intelligence by saying I can't tell the difference between the preamps causing it and the power amp. I fully take that into consideration. But it's way too easy and convenient to use the preamp as the sole reason, and I've been around a time or two and I know it's not that simple, despite not knowing how to design an amp. I am not trying to offend anyone who designs them, and I'm not trying to say they don't sound good. They do. I am just trying to say I hear differences in the three topologies that I don't think can be fully accounted for by just the preamp.
- Feb 12, 2006
- 60,989
- 5
- 220,789
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
Jimmy - I think that there certainly are differences between these specific implimentations of the various topologies, but these differences are there by design or by the specific choices in the characteristics ofthe components and architecture that were designed into them.
The same can be said of products that I have designed. The important difference is that I have identical models with specific changes that I can compare in a controlled environment... things like identical amps with class AB output stages using both a heavy line frequency power supply and an SMPS that was designed specifically to emulate the performance characteristics of the heavier power supply. The difference under all the playing conditions that we use for testing was inaudible to any of us. This product ended up becoming the NeoPak 3.5, which started out from the GBE-250/500 power amp and the ML-200 preamp.
I could have used a different approach specifically to get different results, but in this case I was looking for a lighter weight version of something that I was happy with, and had the ability to compare a very specific difference between power supplies only.
The same can be said of products that I have designed. The important difference is that I have identical models with specific changes that I can compare in a controlled environment... things like identical amps with class AB output stages using both a heavy line frequency power supply and an SMPS that was designed specifically to emulate the performance characteristics of the heavier power supply. The difference under all the playing conditions that we use for testing was inaudible to any of us. This product ended up becoming the NeoPak 3.5, which started out from the GBE-250/500 power amp and the ML-200 preamp.
I could have used a different approach specifically to get different results, but in this case I was looking for a lighter weight version of something that I was happy with, and had the ability to compare a very specific difference between power supplies only.
No worries. I'm not an engineer, so my opinion is based solely on my experience spending time listening to and playing with various topologies while designing our amp. I also think that swamp ash sounds different than alder, so my opinion should probably be taken with a grain of salt.
Both the engineers that work for me however, do have decades of experience building amps and they both feel there is definitely a difference in how various amp topologies sound and perform. Once again, simply a matter of opinions. Other extremely well respected engineers here disagree and I don't question their expertise at all, so I guess we just have to accept the fact that people have different opinions, even among the engineers and move on. If you are loving the new lightweight gear and it works for you, then that's the only thing that really matters. If it sounds good, then it is good and no amount of technical data, or double blind test should take away from the enjoyment of your gear!Some people here seem to think I have a beef against class D, which is simply not true. I will say this though. I keep hearing a lot of people saying "it's all in the execution", which is absolutely correct. I couldn't agree more, but when you realize that a lot of the class D bass amps out there all using the exact same off the shelf SMPS/class D amp modules, then I don't think it's too crazy when some players here claim that they are hearing some similarities between these class D amps, even when those modules are connected to different preamps and have some additional circuitry that has been built around them.
Patient: "Doctor, it hurts when I do this".
Doctor: "Then don't do that"
I've been giging with a GEnz Benz shuttle 9.0 for about 3 years, and about 150 gigs in that time. It's just plain great! It's worked flawless that whole time. Huge headroom and tonal control up the whazoo. 900 watts 4 lbs. Go buy one and be done, forever.
I agree, that it's all in the design. My main gigging heads are an Ashdown ABM 1 tube hybrid solid state, and a Genz Streamliner 900, 3 tube hybrid class D. I also own an Ampeg SVT, I don't take it out much after my injury.
The SVT sounds awesome, very few people argue that. But I think that sound comes from the amps entire design, the preamp, tubes, transformers, capacitors, etc. The SVT is the most commonly used tube head, probably the most used head out there. People often compare solid state heads to the SVT, and assume the SVT is much better because it's a tube head. The tubes might have a lot to do with it, but it's the entire design.
I once experimented with my Svt, I ran the preamp into a power amp. It didn't sound quite the same, but still sounded like my SVT.
I recently was encouraged to try lighter weight tube heads by a friend. I was told tubes make the amp more warm and organic. I tried the Traynor YBA-200 and some Eden 300 watt tube head. My solid state Ashdown and Streamliner sound much better than these tube heads. I think the Traynor and Eden both lacked warmth and sounded like a car with a leaking exhaust when I got some overdrive.
Honestly, other than my SVT, I haven't played a tube head I like. I tried the Orange AD200 recently, I can see why people like it, but I hated it. It's a overdrive machine. I really want to try a V4b one day, however.
It's the scroll.
Long ago, people used heuristic methods for choosing gear. When looking at a violin, they would pay close attention to the scroll and purfling, both of which are functional but have limited impact on tone. The reason had to do with how violins were made. The skill and attention to detail in those elements indicated that the maker put the same skill and attention to detail into the parts of a violin that you can't see. On the other hand, if you said that the scroll is what makes a violin sound good, knowledgeable people would snicker.
Then came the industrial age. Today, amps are designed using analytical methods, but we are still searching for heuristics to tell us how to choose amps -- visible elements that tell us whether an amp is likely to sound good. It seems like a great deal of time is spent trying to figure out which part of an amp is the scroll: The output devices? The transformers? Something else? If you confidently declare that you know what part of an amp makes it sound good, knowledgeable people will snicker.
What's happened to amps is that they can now be designed using analytical methods. We don't need to look at the scroll, because we can understand the workings of an amp in its totality. This kind of analysis is necessary because the power amp of nearly every bass amp is enclosed in a feedback loop, which makes all of the parts interdependent. And we can play tricks that make the familiar heuristics fail, such as using one technology to mimic the functionality of another, while saving weight, size, and cost.
I appreciate that we're not all engineers. I'm not an engineer when it comes to designing a switchmode bass amp, though it was fun to try and fail once. But I know enough about engineering to realize that in the absence of engineering knowledge, trying to come up with rules of thumb based on conspicuous design elements -- no matter how vehemently they are proclaimed -- is likely to be pointless.
There's no scroll.
Long ago, people used heuristic methods for choosing gear. When looking at a violin, they would pay close attention to the scroll and purfling, both of which are functional but have limited impact on tone. The reason had to do with how violins were made. The skill and attention to detail in those elements indicated that the maker put the same skill and attention to detail into the parts of a violin that you can't see. On the other hand, if you said that the scroll is what makes a violin sound good, knowledgeable people would snicker.
Then came the industrial age. Today, amps are designed using analytical methods, but we are still searching for heuristics to tell us how to choose amps -- visible elements that tell us whether an amp is likely to sound good. It seems like a great deal of time is spent trying to figure out which part of an amp is the scroll: The output devices? The transformers? Something else? If you confidently declare that you know what part of an amp makes it sound good, knowledgeable people will snicker.
What's happened to amps is that they can now be designed using analytical methods. We don't need to look at the scroll, because we can understand the workings of an amp in its totality. This kind of analysis is necessary because the power amp of nearly every bass amp is enclosed in a feedback loop, which makes all of the parts interdependent. And we can play tricks that make the familiar heuristics fail, such as using one technology to mimic the functionality of another, while saving weight, size, and cost.
I appreciate that we're not all engineers. I'm not an engineer when it comes to designing a switchmode bass amp, though it was fun to try and fail once. But I know enough about engineering to realize that in the absence of engineering knowledge, trying to come up with rules of thumb based on conspicuous design elements -- no matter how vehemently they are proclaimed -- is likely to be pointless.
There's no scroll.
- Feb 12, 2006
- 60,989
- 5
- 220,789
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
For me at this stage in my life weight is a major consideration .. and there are so may great sounding lightweight heads out now that weight is pretty much a non factor because f it's over 10lbs I will never own it.
I haven't read the whole thread - I will when I get time, but FWIW...
I have a lot of experience of a number of Class D amps (I've been through quite a few over the years!), and in every one of them there has been something missing. The best I can describe it as is 'authority'. Maybe it's inherent in the power module. Maybe it's the power management circuits. Maybe - by huge coincidence - I just don't like the sound of those particular amps. I don't know.
Anyway, I'm back on amps with lumps of iron in them, and I'm happy again.
I have a lot of experience of a number of Class D amps (I've been through quite a few over the years!), and in every one of them there has been something missing. The best I can describe it as is 'authority'. Maybe it's inherent in the power module. Maybe it's the power management circuits. Maybe - by huge coincidence - I just don't like the sound of those particular amps. I don't know.
Anyway, I'm back on amps with lumps of iron in them, and I'm happy again.
After all this (some thread!) I'm really hoping that nobody comes along to buy my Eden WT800 so I get the chance to decide to maybe keep it alongside my new Streamliner900 by using it next weekend's gig with my 410xlt.
Unlike many players I 'm not too fussed about my 'tone', that for me is the job of the instrument, as long as it sounds like its me playing and it all works for the band then I'm cool with it. Lately its become a weight issue.
Unlike many players I 'm not too fussed about my 'tone', that for me is the job of the instrument, as long as it sounds like its me playing and it all works for the band then I'm cool with it. Lately its become a weight issue.
The Class D topology applies only to power amplifiers so it makes sense to compare only power amps of different topologies. All anecdotal comparisons including preamps are nice but essentially irrelevant with respect to the question of whether there is something intrinsic in the topology that matters.
IMO there is nothing intrinsicly inferior about the Class D topology. It is used in the design of commercial power amplifiers which are expected to perform as well as any other amplifier in that category regardless of topology. If it really performs like a "wire with gain" then the details of its design shouldn't matter other than for non-performance reasons (i.e. size, weight, power consumption, lifetime cost).
IMO there is nothing intrinsicly inferior about the Class D topology. It is used in the design of commercial power amplifiers which are expected to perform as well as any other amplifier in that category regardless of topology. If it really performs like a "wire with gain" then the details of its design shouldn't matter other than for non-performance reasons (i.e. size, weight, power consumption, lifetime cost).
No, it doesn't seem perfectly acceptable to believe that there is a big difference in the sound of tube amps vs. SS amps with an iron PT based on the topology -
Pretty much all tube bass amps are a class AB topology.
Pretty much all SS amps with an iron PT are class AB topology.
Different active devices (tubes vs/ FET/transistors) - BUT THE SAME CLASS AB TOPOLOGY.
No point in having the discussion at all if we don't precisely define what we mean.
Probably just better to not think about topology at all. Doesn't matter. Every amp is different. If you prefer an SVT and I prefer a Glockenklang Blue Soul, who cares why.
The important point is for people not to eliminate entire classes of equipment based on oversimplistic reason (i.e., I will only consider a heavy amp, I will only consider a hybrid, I will only consider all solid state, I will only consider all tube, etc., etc.).
Decide on the features you want and try to play or at least read about every amp that is a possibility. Then, pick the one you dig. If it happens to weigh 100 pounds, cool (kind of
), if it happens to weight 3 pounds, cool.It is a bad mistake IMO for a potential buyer to eliminate a piece of equipment based on one feature that may or may not explain the tonality of that piece of gear (neck through versus bolt on, ash versus alder, tubes versus solid state, hybrid versus pure solid state, all tube versus not all tube, etc., etc.
