OK, What's the Final Verdict on Class D?

[KJung]

Of course, this has more to do with keeping production costs down than it does with amp topology. When my EA iAmp 800 failed shortly after I bought it--it was part of the run that inadvertently used some counterfeit caps from China--Gary sent me a small snap-in replacement board, and I fixed it myself in about five minutes. I guess that's the difference between a $500 amp and a $1100 amp.

The primary difference between the iAmp800 and the LMII/III is failure rate and problems (noise, etc.). And, it is not in the direction that price would suggest (I am a former iAmp owner by the way).

These amps (the current batch of SMPS amps) seem to be MUCH more reliable than the old stuff. Also, the warranties on these amps are great (whether it is the excellent service you get from Genz Benz, or the wonderfully painless deal of exchanging a faulty unit with a new one that Markbass has in place, etc.). Since most electronics problems occur early in the products' life (typically right out of the box or within the first few hours of operation), repair issues are much less of an issue.

Regarding Walter, I sold my Ultra for two reasons. 1) The new SMPS amps are much superior to my ear in low end response and punch, even though they are rated much lower power-wise, and (to your point), 2) Walter is the ONLY person that can service these... when he stops working, that's all she wrote!

IMO!

 

[Bass Junkie]

2) Walter is the ONLY person that can service these... when he stops working, that's all she wrote!

Not true!! Walter has made arrangements a long time ago for someone to take the reins on servicing his amps when he retires.

 

[KJung]

Not true!! Walter has made arrangements a long time ago for someone to take the reins on servicing his amps when he retires.

Have never heard about this (and it is often discussed). That would be a good thing, although IMO his amp design is falling farther and farther behind the 'state of the art' these days. So, kind of a moot point for me anyway.

 

[Bass Junkie]

, although IMO his amp design is falling farther and farther behind the 'state of the art' these days. So, kind of a moot point for me anyway.

That's your opinion.

B String said it best back in 2005:

"I have bass player friends who can't understand why anyone
would still buy a Fender P bass, when you can buy other
basses that are technologically more advanced, play better,
and sound more complex. My answer is.... because it sounds
like music to the human ear. So.... If Woods amps were not
sonically pleasing, I don't think many people would buy them
just for the weight factor. People pay big bucks and wait for
months for an amp because these amps sound marvelous.
After having played Woods, Euphonic audio, and now owning
a Focus, I can say that if I had the bucks....Woods. It just
has something no other amp has."

I've played every micro amp on the market today and IMO the others are just starting to catch up to what Walter has been doing for years.

 

[KJung]

That's your opinion.

+1 Walter's still sound great, and I gigged one of his heads or the other for almost 20 years (I was VERY early in to the SMPS thing!). IMO, in the past two years, the SMPS amps have improved exponentially, and I moved on to newer technology that sounded better to me for my playing contexts, and was a fraction of the cost, louder, more full down low, lighter, and much less expensive (although I am lucky enough not to have to worry about price with this stuff).

If I played DB, I would still probably be playing a Walter. For EB, lots of stuff out there now that kills, whether you want fat, grindy, transparent, clean, tubey... whatever

However, nothing wrong with the Walters, and if that is 'the tone in your head', go for it!

Edit: Also, FYI, in 2005, I felt the same way as Bruce (B String). Things have changed A LOT since then IMO and IME!

 

[Walking]

It will take a decade before I know if my new carvin bx500 is long-term reliable, but I do like the sound and weight of it very much.

There is a bit of a technical distinction that may be getting passed over here... Tube amps weigh a lot because they have a power and output transformer. Transistor amps have only the power transformer as the output impedence of transistors is quite low. Transformer based gear was made lighter with toroid transformers. The weight of the transformer increases as you want to pass lower frequencies--for a given power level. That is why a good bass tube amp has a really big transformers and a switching tranformer running at 100khz is small.

Switching power supplies reduce the weight of the power transformer by running them at high frequencies. This has nothing to do with the output stage which can still be class a, b, or d. Most of the good information I found on this was on the crown amps web site. So, the lion's share of weight loss is due to the switching power supply rather than the class d versus a or ab or b.

Now, I believe my carvin has both a switching power supply and class d output. I think class d is more efficient as the power devices and heat sink on this are very small for a 500 watt amp. Maybe that takes a few pounds of a transistor amp, but a small difference compared to losing the large power transformer.

Switching power supplies are a proven technology as they are being used in howevery millions of PCs are out there. Class d output seems new to me, but it has been around a long time, as I first recall it in the well-loved crown K series.

Now, on the stylistic side, I like to put out a lot of low notes and like to just fit seamlessly in the groove with the drummer--especially when playing worship music. I was using an ashly pa amp in bridge mode into a carvin 18 inch box for a few years, and combined with a botique one-channel mice pre that had a good instrument input, that was the best and fullest tone I ever got. That low E went out for miles. The ashly is based on old transformer technology. Its probably over 10 years old, maybe 20, and still going strong. Just too heavy.

I went to an eden world traveller, and lost the fullness on the low E. Maybe it was an intentional effort to replace a pure tone with growl or some contemporary tone preference. It was way lighter in terms of weight, so a fair trade. The carvin similarly seems to do growl on the low e which in my mind is in some respects another word for running out of gas on the lowest note. I consider the carvin to be the equal of the eden in terms of tone--at least the sort of tone I value. Going from an 18 to a 2x10 loses a lot of the low e as well--again its worth losing the weight and size. I can hear that clearly as I still have both and can compare.

I considered getting a carvin PA amp and running bridge mode to get miles of power like the ashly, but decided to get something simple and small instead. Now way of knowing how it would have sounded.

As to the discussion about the visibility of the bass player in a group. I did get some compliments when I was playing at church from some people who liked my bass playing. I think most people will notice when bass is making a group sound fuller or not, but will not know what made the difference. The group leader was a singer, and I guess bass made it harder for her to hear the vocalists to see if they were on-key, and she thought I was playing too loud. Problem was, the singers had a pa but weak monitors, and the bass did not. So the church heard my bass from a distance and the vocals from the pa and it was balanced. But in the group area, the bass was louder. Anyway, enough of that.

 

[KJung]

It will take a decade before I know if my new carvin bx500 is long-term reliable, but I do like the sound and weight of it very much.

There is a bit of a technical distinction that may be getting passed over here... Tube amps weigh a lot because they have a power and output transformer. Transistor amps have only the power transformer. Transformer based gear was made lighter with toroid transformers.

Switching power supplies reduce the weight of the power transformer by running them at high frequencies. This has nothing to do with the output stage which can still be class a, b, or d. Most of the good information I found on this was on the crown amps web site.

Now, I believe my carvin has both a switching power supply and class d output. I think class d is more efficient as the power devices and heat sink on this are very small for a 500 watt amp.

Switching power supplies are a proven technology as they are being used in howevery millions of PCs are out there. Class d output seems new to me, but it has been around a long time, as I first recall it in the well-loved crown K series.

+1 Per my earlier post, the real magic is the SMPS... that's the primary driver of size and weight reduction. Even 5 years ago, I felt bass amps with switching power supplies were a compromise. Now, not at all.

Class D does allow you to move from mini size to micro size, which is also cool (e.g., comparing the class A/B LMII/LMIII to the class D F1/F500, or the class A/B Neo Pak to the Class D Shuttle), or it allows you to put a lot more power in the same sized box (e.g., comparing the class A/B SA450 to the class D SD1200).

 

[aborgman]

They're remarkably light and the manufacturers must be saving a fortune on production costs relative to retail, but now that the novelty is wearing off some and the amp mavens have had a chance to mess with them for a couple of years...has Class D really replaced the "conventional" bass amps we've all been playing for years? Are those forty-pound heads just boat anchors?

I've searched around and haven't really found anyone address this question head-on.

Thanks for any serious analysis.

Pretty much every professional touring PA setup is using class D amps - and has been for well more than a "couple years".

Class D is an old and well proven topology at this point.

 

[Bassmec]

Well the idea that a product replaces another is all part of the modernist
malaise of new for the sake of new.
The British government are a prime example of conflicts of interests
here, we have a motor vehicle scrappage scheme that promotes the destruction of older less efficient vehicles.
The facts: this is far from a green policy as the oil products used in new manufacture (not to mention the energy used in their production) far outweighs the gains in economy in the projected life span of the new vehicle.
I am keeping my 1977 5.3 liter V12 Jag and wont be replacing it with a Tata Nano any time soon.
The same with my amps, they will remain all tube lead sleds with huge cabinets because microphones just don't factor in how heavy they are to lift, however microphones seem to translate very well how heavy they sound.
Of the many almost 100% efficient class D setups that have turned up in my rehearsal studio Markbass seem to have an excellent product for the hard gigging musician without roadies, but it ain't the last 1% sonically to my ear.
they seem to lack something that I can only describe as fullness of tone the cabinets are small and boxy sounding with something lacking in the low midrange sound to my ear.
Yes they are less than the real thing but not by very much.
No they wont be taking over unless the government introduces a high road tax on the vintage amp technology and a heavy inducement scrappage scheme.
Yes they are the Tata Nano of tone but certainly not the Bugatti Vehron.

 

[craig.p]

> That's what I was wondering about. I had figured by now they'd been gigged
> hard for a couple of years by a lot of people and any shortcomings would have
> become apparent.

That's a good, valid point. But one man's "proven valid for long-term use without a cow[1] amp standing by" may be "show me in another five years and then I'll decide" for another man who demands a far longer track record under the toughest field conditions. I fall into the latter category.

Friend of the family used to be a chauffeur for a rich lady in Rhode Island. The lady owned a 20-year-old Cadillac that ran like a top and never let her down. The chauffeur kept bugging her to get a new car with power this and power that and heated this and A/C that and all the rest. After all, she could afford it, and it would be, you know, "new." Finally she told the guy, "Let the poor people buy the new cars." It wasn't that she was cheap -- it was that she wanted to see solid evidence of design longevity that bettered what she already owned and was familiar with.

Who knows. I might take the plunge sooner than later. But you can be sure I'll run the thing wfo into a dummy load for a long, long, time, and bungee it to my Sportster's grab strap for a couple hundred miles of frost-heaved spring blacktop, too, before I deem it job-worthy for me personally. (Not to mention staying on the lookout here at TB for failure trends. Let the other people test the newest designs. )

[1] Computer term for "count on working," for those who've never heard it.

 

[JimmyM]

Are you talking about tube power amps, preamps, or both?

With the way tube emulation has evolved I don't see a technical need for all tube amps/preamps either. I've played through all tube amps that sounded brittle and sterile as well as solid state that sounded rich, fat, and warm. It's all in how the manufacture designs it to sound.

I don't like using the blind tests as examples but this is one where I bet you could take all tube compared to ss and class D type amps and most bassist wouldn't be able to tell which the all tube amp is. Toss in the fact that many bassists use some sort of effect to help fatten up their tone a bit and the challenge becomes even harder.

But like you said (only differently) manufacturers will continue to produce something as long as they know they will continue to turn a profit on it.

thank god for that! btw, i am 100% positive that i could tell an svt from any other amp if i'm playing it. any fool could. and my gear is up onstage for me. it isn't up there for the audience...it's up there for me. i really don't care if anyone else can tell the difference between my svt and a hartke 3500. i can, and that's good enough.

 

[Walking]

+1 Per my earlier post, the real magic is the SMPS... that's the primary driver of size and weight reduction. Even 5 years ago, I felt bass amps with switching power supplies were a compromise. Now, not at all....

I know a lot about electronics, but its from some decades ago. I didn't look into switching technology till my son started trying to get a car amp going and it had a switching supply--then I started reading up.

Then I started thinking about how I see computer power supplies that are rated at 600 watts going for under $100. Now there is a good argument that there is inflation in PC power supply ratings, it did blow my mind when I looked at the dinky power transformer in a 300 watt power supply we took apart. Another example how solid state technology and mass production has changed the face of amplifiers.

Hearing is believing, and I still have trouble getting my mind around all that bass sound that comes out of my tiny 6 pound bass amp... Now on the speaker side, we don't have similar degree of improvements, but we have some improvements...

 

[Walking]

thank god for that! btw, i am 100% positive that i could tell an svt from any other amp if i'm playing it. any fool could. and my gear is up onstage for me. it isn't up there for the audience...it's up there for me. i really don't care if anyone else can tell the difference between my svt and a hartke 3500. i can, and that's good enough.

Just because I like something and it was right for me, I wouldn't say another man's choice wasn't right for him--at some level its all about what we enjoy and value. Long as I don't have to carry his gear...

I have kind of an ambivalent mind. I loved tube technology as I knew it cold and could fix any problem myself, and played with it as a kid. I also love trying out new technologies--its just a matter of which side wins the argument.

 

[JimmyM]

I have kind of an ambivalent mind. I loved tube technology as I knew it cold and could fix any problem myself, and played with it as a kid. I also love trying out new technologies--its just a matter of which side wins the argument.

but everyone's a winner!

 

[lindseyp]

...

Audiences pay attention to

1. Lead singer

2. Guitar player(s)

3. Horns if you have 'em, or the keys or the drummer.

4. Any other instrument that might be thrown into the mix.

5. Bass player but only if he sings at least backup. Otherwise you're number 6 behind the lights, the merchandise booth, or the hot chick begging for tips, unless you're a hot chick bass player, then you move up the list a notch or two. Maybe even close to the top if you're a hot chick bass player in a band with relatively unattractive guys.

Although there are some exceptions, such as funk, reggae, and what I refer to as urban Gospel. In those cases I suggest the bass player is no lower than 4, with the horns right afterward. I like your explanation.

 

[Bongolation]

there's no technical reason tube amps should exist in the face of all this technology

Sure there is. They have very clear technical, non-imaginary, bench-provable differences in sound (and reliability, shock resistance, etc.) from solid-state amps.

That's the question I'm asking here -- are class Ds equal or superior in purely technical terms to conventional solid-states, or not, and if not, why? -- and so far have pretty much wasted my time.

 

[Bongolation]

There is zero issue at this point with these small amps. Of course, there are some executions that are better (fatter, ballsier, etc.) than others, but this is the case with traditional, heavier amps also.

OK, good, that's what I was getting at.

But there is no inherent difference in the sound or reliability of the ultralights compared to the heavier conventional solid-states?

If not, then we can reasonably expect to see stuff like, oh, SWR 750X amps vanish from production in a few years? If sound-reinforcement power amps have gone that way then I guess so. I wasn't sure on that part.

 

[JackANSI]

OK, good, that's what I was getting at.

But there is no inherent difference in the sound or reliability of the ultralights compared to the heavier conventional solid-states?

If not, then we can reasonably expect to see stuff like, oh, SWR 750X amps vanish from production in a few years? If sound-reinforcement power amps have gone that way then I guess so. I wasn't sure on that part.

Those types of amps won't ever vanish form production just like the all-tube SVT never really went away..

There will always be those that prefer a certain type of sound..

But rest assured, no matter what type of amp you play, before long the house will be hearing it through Class-D, SMPS amps almost everywhere you go. (if the place is big enough to require PA support anyway). Heck when is the last time anyone on this thread used a tube-base power amp for their primary PA at a gig?

 

[KJung]

OK, good, that's what I was getting at.

But there is no inherent difference in the sound or reliability of the ultralights compared to the heavier conventional solid-states?

If not, then we can reasonably expect to see stuff like, oh, SWR 750X amps vanish from production in a few years? If sound-reinforcement power amps have gone that way then I guess so. I wasn't sure on that part.

I would think the market will continue to get smaller and smaller for the more traditional, lead sled type amps. I just got a report from a TB friend who has ears I trust, and he said the new Markbass SD1200 is just a slammin' hammer, and more like a big honkin' F1 than a slightly more powerful SD800. You will be seeing more and more true 'lead sled' capable executions in the ultra light category IMO.

And... having recently played a 750x provided as backline, that is a classic case of a very large, very heavy amp that does not at all justify the size and weight given the output. Most of the current batch of 500 to 600 watt micro's will EASILY keep up with that one IMO and IME.

A DB750... well.... maybe not the Micro's, but I have a feeling the 10 pound Carvin B2000 would give it MORE than a run for its money.

 

[agedhorse]

A little aritmetic:

power = voltage times current, or P=IE.

So you're saying 3000 watts = 7 amps times X volts.

Solving for X, we get X = E = 429 volts.

So you've got 430V at your outlets?

So let's solve for current, assuming 120V at the outlet.

3000W = I x 120V, and I = 25A.

Now, that's if the amp is 100 percent efficient, and it's not. So you'd better have that thing on at least a 30-amp circuit if you're going to run at full power.

You missed a critical piece of information here... duty cycle. If you were to play continuous sine waves, then the continuous long term ratings would apply to the math above BUT there is the dynamic range factor that accounts for the average power actually delivered to be considerably less. In fact, it's typically between 1/8 and 1/4 of the continuous rating. The power supply averages this all together over time. So subtract the dynamics from your above math and you will find that you will come out to a much more reasonable and accepted (by the safety agencies) numbers.