The rise of high-powered bass amps?

[Paul K]

I remember when this technology first came out,

 

Also too, when they first came out they often mislabeled a class A/B amp with digital switching power supply as a Class D. My Ashdown Superfly weighs in at 10 lbs (250 watt x2 @ 4 ohm), but it runs hotter'n Hades. And my now sold Mackie SRM150 personal monitor had the largest heat sinks on the back you could imagine. True class D don't need no stinkin' heat sinks that big.

[lug]

And of course everyone knows that tube watts are louder than solid state watts.

 

(ducking and running )

 

Common misconception. Tube watts have more "mojo" and mojo is perceived to be louder when actually it's just easier to hear because it's more attuned to the soul (unless you are a redhead, they have no souls)

[Griffinator]

The operative is, you can't dime an SS amp to its FULL rated power and have it still sound even remotely listenable. So many manufacturers cut off the max volume well below that level.

 

Furthermore, when the gov't came in and said you have to rate your amp max power at no more than 10% THD, tube amp manufacturers had to change their advertised specs to ridiculously low levels in order to conform, even though tube distortion even at levels well above 10% THD still sounds damned good.

[Eric VB]

And of course everyone knows that tube watts are louder than solid state watts.

 

(ducking and running )

 

Common misconception. Tube watts have more "mojo" and mojo is perceived to be louder when actually it's just easier to hear because it's more attuned to the soul (unless you are a redhead, they have no souls)

Tube watts are louder because they come in blacker cases.

[jeremy c]

Tube watts seem louder because of the blue glow of the tubes.

 

 

I like my 1000 watt Genz Benz head, but I think I need all those watts because of my speaker cabinets. In the old days when I had a 400 watt amp, I was using big speaker cabinets which were more efficient than today's speaker.

 

Now that I have an amp and speakers that I can pick up with one hand, I don't think I'll ever go back.

[Basshappi]

Wereas I have gone the opposite direction, after decades of playing through solid state amps I have gone back to using a full tube amplifier. The exception is my SS Ampeg combo but that amp is not class D.

 

I have also gone back to 2x15 cabs and will be test driving an 8x10 in the near future.

[jeremy c]

If it weren't for the weight and size issues, I think we'd all be using Ampeg amps with the 8x10 speaker cabinets.

[EddiePlaysBass]

Now that I have an amp and speakers that I can pick up with one hand, I don't think I'll ever go back.

 

Hear, hear! Well, I'm halfway there, anyway. The Barefaced 2x12 is ridiculously light (for its size) and sounds awesome. I'm only halfway there, though cos I still use my Behringer head.

 

Saw a GK MB Fusion 800 with EUR 100.- discount but since I'm not in a band and in the process of moving house (yes, after 3 years of building it, I'm finally going to move into it ) I can't really justify the expense right now.

 

If it weren't for the weight and size issues, I think we'd all be using Ampeg amps with the 8x10 speaker cabinets.

 

Hear, hear! :grin:

[Basshappi]

Well perhaps.

I would love to have a SVT and hope to acquire one someday.

But my amp is the Peavey VB-2 it is only 55 lbs and has very good top mounted handles which make moving it around, even by myself, no problem at all. My GB cab is probably near 80~100 but it has wheels and good handles so moving it isn't diifficult either.

 

I am not a sideman so load in/out is a band activity, we all help each other with equipment.

 

I often think about how much of this is driven by location.

In the city/region where I gig the venues do not provide backline or PA systems. On the rare occasion that there is a PA it is usually rudimentary at best. So my stage rig has to serve the room as well.

 

I drive a truck and in most cases I can pull right up to or very near a venues door and due to ADA regulations they all have wheelchair ramps. MOst venues do not have elevated stages if they even have a stage at all it is only a 1 foot high platform.

 

I understand that these situations are often exactly the opposite than in other areas especially many of the big cities. In those places it makes perfect sense to have small, lightweight and easily portable equipment.

 

I'm not knocking it, I think that MI tech has definitely benefited the bassplayer more than any other group (with maybe the exception of roadies). I'll probably own some at some point because it does inttrigue me and there are gigs that it would be the "right tool" for the job, even for an old school dinosaur like me.

[SteveC]

I was noodling around on a P bass the other day through one of those Fender tube heads and 810 cab. Gotta admit it sounded good. Thankfully, my church gig is all DI/IEM so I don't need an amp. My other fill in gigs are few and far between and I only need my small combo or IEM's so...

[J. Dan]

The operative is, you can't dime an SS amp to its FULL rated power and have it still sound even remotely listenable. So many manufacturers cut off the max volume well below that level.

 

Furthermore, when the gov't came in and said you have to rate your amp max power at no more than 10% THD, tube amp manufacturers had to change their advertised specs to ridiculously low levels in order to conform, even though tube distortion even at levels well above 10% THD still sounds damned good.

 

This.

 

Also, as tubes approach saturation, they naturally compress. That means as you turn up, you can increase your average level while naturally taming the peaks....so it gets louder before clipping. Then, when it DOES overdrive, it generates more even ordered harmonics as opposed to the odd-ordered harmonics generated by the hard clipping of solid state. Even ordered harmonics sound more pleasing to the ear. The result, as Griff addresses, is that a tube amp at 10% distortion will not SOUND as distorted as a solid state amp. Finally, refer to my earlier post, most tube amps were Class A designs.

[Imogene]

Still, when you have to load in/out every week? Class D/Neo sounds quite enough like a bass to me to win.

[Paul K]

Still, when you have to load in/out every week? Class D/Neo sounds quite enough like a bass to me to win.

 

Indeed. Also, since i prefer a clean sound I really like the dynamic range that a bigger amp allow before clipping. Pop! In your face! Then back down to nothing. It kills as long as you can get the drummer to do it with you. Sucks if you're just doing it alone.

[rumpelstiltskin.]

your avatar shows hair on fire, but your words are pants on fire.

 

Not all watts are equal.

 

yes they are.

 

The advantage of Class D is very high efficiency and lighter weight. Some of the more traditional amps like Class A and Class AB are much less efficient and require large heavy power transformers.

 

no such requirement exists in reality. dissipative designs (class A/B/AB) can be paired with a switching power supply just as efficient designs (class D) can be paired with a low frequency power supply (large transformer). examples of both are quite common in the marketplace. in fact, my venerable crest pro7200 is a class AB amp with a switching power supply.

 

When it comes to transients and low frequencies, the advantage a Class A or Class AB amp has is that it has a large power supply with large capacitors - capacitors store charge - so that when you need it for a low frequency or a transient peak, it's there for immediate use.

 

that's an advantage of capacitance which is neither exclusive to dissipative amp designs nor to low frequency power supplies. there are plenty of low frequency supplies that are thin on capacitance and plenty of switching designs that have an excess of capacitance.

 

The power rating in that case is RMS, and based on what the amp can put out continuously without overheating, but often it is capable of much larger short term peaks.

 

the peak power output is limited by two factors. one is the maximum voltage output of the power supply and power amp, and the other is the current output capacity of the power supply. there is always going to be a 3dB difference between RMS and peak output voltage and a 6dB difference between RMS and peak output power (because math). that's the long way of saying that having energy storage in the power supply is more about the ability to serve maximum power repeatedly over time than for a single transient. unless your load impedance is lower than the minimum rated load, you will never need more than maximum current for a single peak. but how long does that peak last and does it repeat?

 

Class D modulates the power supply based on the load requirement in real time rather than storing charge.

 

that's kind of how every amplifier works. but it's not fair to expect anyone to understand any more than an approximation of how class D works unless you have studied advanced calculus and signal processing.

 

This is very efficient, but RMS power and peak power are very close, which is why when you look more closely at power ratings, you'll see them list a power at .1% THD, 1% THD, and 10% THD, and they're likely only 3dB apart, which is not a very large transient. So if you want to be able to hit 6dB transients without heavy distortion, your RMS (average) might need to be at 25% of the rated power (250W on a 1000W amp).

 

that's actually more a commentary on a loose design than class D topology. the amp ICs that are used in your car's head unit are class AB and rated at 10% THD.

 

Also, as tubes approach saturation, they naturally compress. That means as you turn up, you can increase your average level while naturally taming the peaks....so it gets louder before clipping.

 

YES. this, by the way contradicts your previous statement that not all watts are equal. watts are watts. using peak power raings as a proxy for loudness is not very accurate.

 

Then, when it DOES overdrive, it generates more even ordered harmonics as opposed to the odd-ordered harmonics generated by the hard clipping of solid state.

 

right, but most tube amps use a push-pull output stage, which means the even order harmonics cancel in the output transformer. the fact that the tubes create primarily even order harmonics doesn't change that they also create odd order harmonics.

 

get off my lawn.

[5 string Mike]

After all is said and done, math and mechanics aside, the technology is to the point it's cheap to get high power out of a small footprint- so why not?

 

At least in my world, it seems that band gigs I'm involved in, the band gets less and less space, the stage area is in the back of some corner that's nowhere near a door, and it's a maze to get through. I'm getting over carrying and moving all that stuff.

 

It's on my radar to get away from my old 4x10 cab and big head to get a 2x10 high power mico unit from Carvin or something, maybe the Ampeg SS head with a 2x10 cab. Everywhere I've played has had a good PA support so I'm not really seeing a need to do it all from the stage.

 

I had the GK 200W 1x15 NEO combo amp and I had to get rid of it for some emergency cash and now I really miss it. Thinking of getting the 500W 2x10 version with the external speaker option and a 1x15 extension cab for the few times I might need it.

 

Punch line- I'm over the big heavy stuff...

[J. Dan]

your avatar shows hair on fire, but your words are pants on fire.

 

Not all watts are equal.

 

yes they are.

 

Of course actual watts are - I meant (and should have said) manufacturer's and different technology wattage RATINGS are not all equal.....that's just a lot more wordy.

 

While your other statements are true, mine were consistent with what you will most often find in most common amplifier designs. Yes, you can mix and match digital vs analog power supplies with different classes of output stages, and yes, there are Class AB tube amps. I still contend that if you look into Class D distortion specifications relative to real power output, a tube amp of the same rating is going to put out a lot more power before it starts to be audibly distorted, regardless of measured distortion.

 

Also, with regards to ratings/power limitations......RMS rating is not always 3dB below peak. It is if you're feeding it a sine wave, but our instruments do not produce sine waves? What's the difference between RMS and peak of a square wave? 0dB. What's the difference between RMS and peak of a 1% duty cycle pulse? Get my drift? So one limitation as you correctly point out is the power supply rails. That is where clipping comes in. The other limitation is current capacity, which of course is dependent on load. However, when you are supplying extended high RMS levels (and remember,, depending on the actual music material, this can be higher or lower - if you're already getting into clipping, your RMS is closer to your supply rail and you're delivering more continuous current), current generates heat, and heat kills semiconductors. Also, there is a limit to the current the power supply can deliver.

 

 

 

 

Edit: I'll add one more thing since it came up. The earliest "digital" amps were not class D but had the digital power supply as you describe. So yes, there were digital supplies with class AB output stages. I know of no class D amps using standard analog power supplies. In fact, all of the WEIGHT savings are in the power supply. Most of e Efficiency savings are in the class D output stage. I'm sure I'll be corrected if I'm wrong....but max theoretical efficiency of class A is 50%, 67% for class AB. Class D amps meet efficiencies in the 90's. Now, admittedly, having have the current requirements from the power supply in and of itself will reduce weight and cost with an analog supply y virtue of needing less. But not nearly to the degree of going to a digital supply.

[rumpelstiltskin.]

that's just a lot more wordy.

 

a less wordy and more technically correct way to say it is that power ratings are not a reliable measure for loudness.

 

While your other statements are true, mine were consistent with what you will most often find in most common amplifier designs.

 

didn't you know it's my job to be a pedantic ass?

 

RMS rating is not always 3dB below peak.

 

no, it's not. and i didn't say that it was. what i said was that by the nature of sine waves -- which is the universally agreed upon test signal -- the RMS voltage output is 3dB below the peak voltage. the power produced by the RMS volage is 6dB below the peak power output. again, pedantic ass. but in this case it's important to understand that amplifier performance should be predictable to a certain degree, and the underlying math supports that understanding.

 

yes, use cases are different, which is why loudspeakers typically have three ratings (RMS/program/peak). but that's not really relevant to how amplifiers are rated and how power works.

 

 

"digital" amps...digital supply.

 

nails on a chalk board, man. there's nothing digital about switching amplifiers or switching supplies. i'm not blaming you. you had the good sense to put it in quotes. but it still aggravates me.

[butcherNburn]

Way to get a bunch of people to look up the word "pedantic".

[Groove Mama]

I wonder if one can get electrocuted in an electronics pissing contest...

[jeremy c]

The power specifications that we are discussing are so strong that I think my head just exploded.

[jcadmus]

I wonder if one can get electrocuted in an electronics pissing contest...

 

No, no, this is good. Next can someone explain to me how magnets work?

[Imogene]

After all is said and done, math and mechanics aside, the technology is to the point it's cheap to get high power out of a small footprint- so why not?...

 

Punch line- I'm over the big heavy stuff...

 

I was bad at math, but yeah - I totally get the punch line!

[BargeOn]

that's just a lot more wordy.

 

snip ...

nails on a chalk board, man. there's nothing digital about switching amplifiers or switching supplies. i'm not blaming you. you had the good sense to put it in quotes. but it still aggravates me.

 

Mind if I but in?

About those nails: I just got my first, and relatively cheap class D amp. A Fender combo. I find the sound is fatiguing. My old audiophile ears don't usually let me down. Do you find this is common in the digital amps? or maybe only the low end ones (a MarkBass I heard didn't seem to have this attribute but I didn't spend much time with it).

 

Thanks

[Michele C.]

For your reference, this is an old article about class D amps in an audiophile contest. It turns out that there is a tendency to warm up the signal due to some loss in highs. This might raise some audiophile brow, but is no issue for a bass player.

 

http://www.audioholics.com/audio-amplifier/the-truth-about-digital-class-d-amplifiers

 

Bottom line: I think that if your amp is taxing your audiophile ears it might be its own fault.

[rumpelstiltskin.]

i'm always wary about "the truth" about any subject. when class D was first developed component technology limited the switching frequency to a point where full frequency response wasn't possible. to put it in perspective, with modern components it's not uncommon to have switching amps operating at 2MHz with an operating frequency response five times bigger than what our ears can hear. it's entirely possible that a very low cost class D amp is of marginal quality, but wouldn't you expect the same marginal quality from any other very low cost amplifier?

[J. Dan]

i'm always wary about "the truth" about any subject. when class D was first developed component technology limited the switching frequency to a point where full frequency response wasn't possible. to put it in perspective, with modern components it's not uncommon to have switching amps operating at 2MHz with an operating frequency response five times bigger than what our ears can hear. it's entirely possible that a very low cost class D amp is of marginal quality, but wouldn't you expect the same marginal quality from any other very low cost amplifier?

 

Sort of like the Vinyl vs CD vs mp3 debate, right? A lot of my comments that you've probably rightfully disagreed with deal more with the shortcomings of class D that are not theoretically imposed my class D as an architecture, but more common implementations and specifications BS.

 

My reason for framing things the way I did, though not technically correct for all examples, was just to be aware. So my point is YES, a well designed Class D amp can be great. But the way many manufacturers build and spec them, you usually need to go with a higher rating than you would with traditional designs......which these days doesn't matter because they've gotten to be less expensive to produce.

 

 

So I'm getting ready to shoot a youtube video comparing amplification of running my fingers down a chalkboard through a Class D amp and a a Tube amp. I'll run the test with both black and green chalkboards, and do it over a period of tine with varying fingernail lengths to provide a thorough review of fingernail factor.

 

You're welcome.

[Michele C.]

So I'm getting ready to shoot a youtube video comparing amplification of running my fingers down a chalkboard through a Class D amp and a a Tube amp. I'll run the test with both black and green chalkboards, and do it over a period of tine with varying fingernail lengths to provide a thorough review of fingernail factor

 

Now, this is a true audiophile in action! I can remember the days of blind tests on cable and connectors. Way more riveting that flat wounds versus round wounds :-).

 

[Michele C.]

when class D was first developed component technology limited the switching frequency to a point where full frequency response wasn't possible.

 

To scare away the last few readers, rumpelstinkin, is it correct that a class D amp is in a way sampling the audio input with the resolution of one bit?

[Paul K]

That's it. I'm done.

[butcherNburn]

So I'm getting ready to shoot a youtube video comparing amplification of running my fingers down a chalkboard through a Class D amp and a a Tube amp. I'll run the test with both black and green chalkboards, and do it over a period of tine with varying fingernail lengths to provide a thorough review of fingernail factor.

You're welcome.

 

Ones fingernails are too much of a variable for true scientific results, even things like varying your diet can effect them.

 

Then you are basing much of the results on what is perceived, be it wattage, volume or quality of sound, not scientific data.

 

The only thing that isn't flawed is your choice of Youtube, which is known for it's high quality audio and video presentation no matter what system we are experiencing it with.

 

I'll still watch all 27 hours of what you post.