amps and ratings?

[Scp53]

just have numerous questions about amps in general.

first off car audio, what amps in car audio are rated correctly? don't a lot of them use cheap power supplies that warp and create distortion under stress?im talking wattage, impendence, thd, etc. seems to me that many are over rated. and could someone explain high current or high "amperage" of an amp. ive heard you can have equal wattage but high amp ratings give you better sound/output. i need this explained. actually all specs on amps explained(in depth if possible)

and for home audio goes similar questions. my yamaha(rxv 420) and pioneer(vintage sx550) are rated at X wts per channel. i doubt they really put out that power. i mean X watts from a yamamha and X watts from a Krell or Aragon are way different. please explain why the Krell/Aragon/etc would sound and put out better.hopefully you can understand these Q's. sorry to be son long winded.

scp53

[JohnA]

100 watts into 8 ohms is 100 watts into 8 ohms regardless of the brand name.

A Krell or Aragon amp will sound better than a Pioneer amp always, but the power is controlled by 2 simple equations that link voltage, resistance and current.

Better amps will normally deliver a lot of power to unusual impedance curves when a cheap amp will not.

[D-MAN]

P=IE where P=wattage, I=current, E=voltage. It's a simple law. But that's just raw output power as determined by heat.

The matter you are referring to has to do with the frequency response curve and various distortions and their respective levels, rather than the total output wattage.

1000 watts of a widely varying frequency response is not quite as good sounding as, say 100 watts continuous of relatively distortion free signal with a wide, flat frequency response. That is the determination of a good amp vs. a bad amp, rather than relying on the output wattage rating alone.

DM

[Colin]

John is only telling you half of the picture. Sure the amplifiers put x watts into a NOMINAL 8-ohms (whatever that nominal means). But that wattage is a rarefied static bench test, NOT the complex harmonic structures of real musical notes and varying loudspeaker impedances.

If the loudspeaker offers more resistance, in the form of low impedance (6-ohms rather than a nominal 8-ohms), better (NOT necessarily more powerful) amplifiers are capable of fighting back. A truly powerful amplifier has twice as much power into 4-ohms as it does into an 8-ohm load. A super amplifier, like the Pass x250 (EnjoyTheMusic.com review on classic Klipsch corner Khorns, see archives) has even more power: twice as much yet again into 2-ohms! This monster has the NOMINAL (there is that word again) 250-watts into the 8-ohm standard load, with twice as much power, 500 watts when pressed into 4-ohm range, and produces an astounding 1,800 watts for short duration! All this excess power makes for excellent driver control. This driver control affects NOT just the bass, but carries up into the mid-range as well.

Sad to admit, but this is where modest tube amplifiers fall short. They cant push around the low loudspeaker impedances. In fact, studies show that when a loudspeaker with a fairly flat frequency response is powered by a modest tube amplifier, which also measures fairly flat frequency response (on the bench), the resulting frequency response output of the combination looks more like the impedance chart of the speaker. In other words, the modest tube amplifier cant control the loudspeaker impedance enough to give the output a flat frequency response.

What loudspeaker makers dont tell you is that many loudspeakers, usually because of the woofer, dip down into the 4-ohm range, meaning that it needs a powerful amplifier to get the most low and middle bass. In fact every loudspeaker maker should publish both their impedance and frequency response charts either in their literature or on the back of their loudspeaker. The nominal rating means in name only. None of these single number statistics are that useful however, only the loudspeaker impedance curves will show you if the loudspeaker load is wild, sharp angled, dips low or has a low overall impedance. In reality, big ole horns have impedances ranging from 2-ohms to 30-ohms. From what I understand, the higher impedances values are easier for tube amplifiers to run, than solid-state, while the solid-state amplifiers handle the low impedances better than tube amplifiers.

So the simple wattage rating is of little use. In fact, I cant really think of too many specs that really are of valuable use when guessing how an amplifier might sound with a loudspeaker. Certainly seriously auditioning, in my own home, with the same music and equipment, for EnjoyTheMusic.com, dozens of combinations helps. I learned speakers with seriously low impedances sound better with solid-state amplifiers.

What DOES happen is that a more powerful amplifier, say 100 instead of merely 10-watts, is better built, to get that greater power. Therefore, it can often drive the lower impedances better too. NOT always. But usually. And the story is quite different with big ole horns (as always). My light, little, $5 vintage 18-watt harmon/kardon 330B sounds just as good, if NOT better, with ultra-sensitive Khorns as the new, $600, beefy 75-watt harmon/kardon AVR630.

[Tomski]

Hello Scp53, Im going to limit my reply to home audio,but im sure other will be able to help in car audio.

First go to H/Ks website, go right into their glossary and look up "power".

If you are new to this idea,read it several times.

Yes,much to my dislike,we are awash in a sea of B.S. when it comes to power specs.

This is the norm not the exception

If a company fails to include a parameter e.g. at 20hz to 20khz into 8ohms you can bet deception is at work.

If a company fails to include ALL channels driven or leaves off the letter S deception is at work

If a company has impressive specs into 4ohms and 2ohms but fails to specify at what parameter,more than likely deception is at work.

You have to determine how much weight you give this when your comparing specs,unlike vehicles,Its often hard to tell what you are getting "under the hood"

I hope this helps you and others who read this.

Tom

[Colin]

HK glossary? where?

[Tomski]

Colin I believe its in the Our story part.I changed an option on my directX setting,so having trouble getting on their site this morning, but it is there.

[Colin]

it is indeed:

The amount of energy delivered or used by a device or system, expressed in Watts. In audio, power ratings of amplifiers and loudspeakers are subject to a lot of variation and uncertainty because of the very large difference in the long-term, steady-state, power rating, and the transient, or momentary, power rating, which can be several times larger. Further confusion is added when ratings at a single frequency (say, 1 kHz) are compared with the more realistic 20 - 20 kHz rating. In multichannel amplifiers, there is the further variable of ratings done with a single channel operating vs. ratings with all channels operating. The result, for consumers, is that advertised power ratings are often almost meaningless.

[nicholtl]

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On 11/19/2004 12:18:59 PM Scp53 wrote:

first off car audio, what amps in car audio are rated correctly? don't a lot of them use cheap power supplies that warp and create distortion under stress?

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I don't think bad car amplifiers use cheap power supplies or distort under heavy loads any moreso than bad home audio amplifiers. High quality auto amps can provide very clean, taut, and distortion-free power. My 2 car amps, for instance, are the Xtant 1001x and 604x. The 1001x provides 1000 watts at a 2ohm load, 500 watts at 4 ohms. The 604x provides 600 watts at 2 ohms, and 400 at 4 ohms. You'd be hard pressed to make these amps distort or clip at ANY volume.

[Tomski]

I do think its not quiet as common in the seperates world,I should have clarified this better,sorry, but unfortunatly it still does happen in that arena.

Tom

[Scp53]

colin, if you don't push a tube(modest tube receiver) real hard will it control the speaker so its flat?? or is it never flat, regardless of how much its pumping out?

thanks to everyone for their replies, i appreciate it

scp53

[JohnA]

"Small steps, Ellie; small steps."

[IB Slammin]

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On 11/19/2004 2:19:01 PM Colin wrote:

John is only telling you half of the picture. Sure the amplifiers put x watts into a NOMINAL 8-ohms (whatever that nominal means). But that wattage is a rarefied static bench test, NOT the complex harmonic structures of real musical notes and varying loudspeaker impedances.

If the loudspeaker offers more resistance, in the form of low impedance (6-ohms rather than a nominal 8-ohms), better (NOT necessarily more powerful) amplifiers are capable of fighting back. A truly powerful amplifier has twice as much power into 4-ohms as it does into an 8-ohm load. A super amplifier, like the Pass x250 (EnjoyTheMusic.com review on classic Klipsch corner Khorns, see archives) has even more power: twice as much yet again into 2-ohms! This monster has the NOMINAL (there is that word again) 250-watts into the 8-ohm standard load, with twice as much power, 500 watts when pressed into 4-ohm range, and produces an astounding 1,800 watts for short duration! All this excess power makes for excellent driver control. This driver control affects NOT just the bass, but carries up into the mid-range as well.

Sad to admit, but this is where modest tube amplifiers fall short. They cant push around the low loudspeaker impedances. In fact, studies show that when a loudspeaker with a fairly flat frequency response is powered by a modest tube amplifier, which also measures fairly flat frequency response (on the bench), the resulting frequency response output of the combination looks more like the impedance chart of the speaker. In other words, the modest tube amplifier cant control the loudspeaker impedance enough to give the output a flat frequency response.

What loudspeaker makers dont tell you is that many loudspeakers, usually because of the woofer, dip down into the 4-ohm range, meaning that it needs a powerful amplifier to get the most low and middle bass. In fact every loudspeaker maker should publish both their impedance and frequency response charts either in their literature or on the back of their loudspeaker. The nominal rating means in name only. None of these single number statistics are that useful however, only the loudspeaker impedance curves will show you if the loudspeaker load is wild, sharp angled, dips low or has a low overall impedance. In reality, big ole horns have impedances ranging from 2-ohms to 30-ohms. From what I understand, the higher impedances values are easier for tube amplifiers to run, than solid-state, while the solid-state amplifiers handle the low impedances better than tube amplifiers.

So the simple wattage rating is of little use. In fact, I cant really think of too many specs that really are of valuable use when guessing how an amplifier might sound with a loudspeaker. Certainly seriously auditioning, in my own home, with the same music and equipment, for EnjoyTheMusic.com, dozens of combinations helps. I learned speakers with seriously low impedances sound better with solid-state amplifiers.

What DOES happen is that a more powerful amplifier, say 100 instead of merely 10-watts, is better built, to get that greater power. Therefore, it can often drive the lower impedances better too. NOT always. But usually. And the story is quite different with big ole horns (as always). My light, little, $5 vintage 18-watt harmon/kardon 330B sounds just as good, if NOT better, with ultra-sensitive Khorns as the new, $600, beefy 75-watt harmon/kardon AVR630.

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Well said, Big Boy. Nice to have you back!

Terry

[formica]

There is ALOT of marketing which goes into labelling amplifiers so you got to learn to read between the lines. A lot of that has already been posted above, but I wanted to add a couple of things to it.

Manufacturers know consumers use that figure to help choose a product, but these same people don't realise that the db-output versus Power input relation follows a logarithmic curve. This means that the audible difference between 100W and 110W is trivial.

Some amps used to state "headroom" at rated output... but most people didn't realise that 75Watts with a 3db headroom represents more available transient power than 100Watts and 0.3db headroom.

I came across SOUND & VISION TEST REPORTS versus MFG. Product Rating posted in another forum that compared manufacturers claims versus measured output... and it's quite interesting to see the magnitude of variances there is.

From what was posted, I'd have to commend Harmon Kardon... as they consistently measured higher than advertised. To me, it shows a company who believes more in the actual product rather than the marketing behind it.

Later...

Rob

[Colin]

The only manufacturer, which has all of their amplifiers showing higher output at clipping than their stated ratings, is harmon/kardon!

Odd-order THD is also important in a solid-state amplifier, but it sounds hard, steely and harsh; so the less there is, the better. Imagine the B&K at 65%! My 70s vintage Class A Pioneer M-22, at a hefty 60 pounds, is .005% THD at 1 watt into 8 ohms, below .001% at 15 watts!

[Colin]

Good question, I have to say that I dont know the exact objective answer to that, but my feeling is that weakness in the bass doesnt show up until the amplifier is being pushed. With ultra-sensitive big ole horns that wont happen, even with flea-powered tube amplifiers, until the music peaks are very large, or the volume is louder than normal. Of course, that may be why so many tweaking audiophile listen to small music group ensembles, rather than the loud rock band or large orchestra

[dodger]

There is RMS rating - holding at power for I believe, 4 hours without failure, usually at 1000 HZ.

Then we have IHF rating, EMI rating and total power rating. These mean not much.

The most rational and closest to true power rating is RMS.

As far as Amperes are concerned, in Electricity 100 watts/volts is equal to 1 ampere.

Thus a 100 RMS watt amp should draw 1 Ampere of power. Not always the case but close.

Look for an RMS rated amplifier.

dodger

[Colin]

Dodger,

I have enough gray hairs to remember when the IHF rating was replaced by the RMS, at a time when solid-state amplifiers gained ascendancy in the marketplace over tube models. Guess which one looks better with RMS than with IHF ratings?

I dont know which one is the most rational and closest to true power, but the simple square wave reproduction of RMS rating is MEANINGLESS in the world of super-sensitive big ole horns, fast and high music peaks. If one would look only at RMS power - into 8, 6, 4 and 2 ohms one misses an incredible number of low-cost, low power amplifiers that sound much better with big ole horns than supposedly powerful off-the-shelf receivers.

I would take my refurbished vintage integrated tube amplifier, with its old IHF low power rating over most of todays powerful RMS rated offerings. Another case in point, is my $5 70s vintage harmon/kardon solid-state single-transformer 330B (or its twin-transformer versions, the 430, etc.) receivers. Many of the frequent posters have heard these remarkable units on big ole horns and they really stand-out. I have yet to compare them back-to-back with multi-buck super-amplifiers, but so far, these little charmers beat anything solid-state.

Same can be said for THD. With odd-order distortion sounding hard, steely and harsh on solid-state amplifiers, it is no wonder that typical consumers look for the lowest possible number. Not so with tweaking audiophile and their big ole horns. If high THD and RMS were the only numbers that tweaking audiophile paid attention to, then many, if NOT most, of the golden ears in the audio review business would NOT have tube amplifiers. Their magical music-making machines simply would NOT make the THD and RMS grade. They show high amounts of THD yes, but it is even-order distortion, more like the distortion an acoustical instrument makes.

Unfortunately, it is NOT as simple as one or two numbers. Poor tweaking audiophiles can NOT merely use a number in isolation to judge what front-end equipment sounds best with their big ole horns.

Look for amplifiers recommended by big ole horns lovers who like the same kind of music as you.

[michael hurd]

Amplifier current consumption varies with topology or class of amplifer, and with type of signal and also the drive level. Class AB amps consume extra power at less than full output, the efficiency is lower.

[michael hurd]

What car amps are rated correctly? Well some are over rated, and some under rated. This one is not over rated. http://www.jbl.com/car/products/product_detail.aspx?prod=A6000GTI&ser=GTI&cat=AMP