SQ differences between different amps

AustinKP

Guys, check this out. This may seem crazy, but despite the opinion of the very vast majority of car audio enthusiasts, it seems that there is NO sq difference when comparing different amps within their power handling levels. $10,000 to the man who can prove otherwise. Read this thread Looks like I won't be needing a tube amp after all... let me know what you think.

PolkThug

That's an awesome challenge. I'm glad somebody did something like that. Some of the "tube guys" will probably be pissed when they read some of the comments. lol

AustinKP

Originally posted by PolkThug
Some of the "tube guys" will probably be pissed when they read some of the comments. lol

That's the first thing I thought when I read that too

MacLeod

Boy this is gonna start a firestorm!! This is a touchy subject and most people I know will swear by certain amps sounding better than others.

I think that SQ is mistaken for other traits. Some amps run out of power very quickly and this can sound flat and even distort but its not the amp sounding bad, its just running out of power. And some amp may have more headroom than another so pecussion and other frequency spikes (the slap of a snare drum) are produced with more umph and this can be thought of as SQ when its just a more powerful amp.

For instance, a Rockford Fosgate Power 551X putting out 70x4 with tons of headroom will sound better than my Alpine 40x4 with virtually no headroom. The RF doesnt have better SQ than my Alpine and they are both producing the same tonal response, but the RF is working the speakers with power to spare and so it sounds better. That being said, a RF Power will not sound better than a Phoenix Gold amp putting out 70 or so x4 because the Phoenix Gold also has oodles of power and headroom and can make the speaker perfom equally.

When my Alpine amp died a while back I used a 14 year old Coustic 2 channel I had lying around. It had the same power rating (35x2 even though Coustics are underrated and it probably put out 45x2) as my Alpine (40x4) and it sounded virtually the same. The only differnence was more detail which was due to the Coustic having more headroom and a bit more power but other than that they were identical is performance.

Basically its all relative. To me, powerful amps that can make a speaker work better IS better SQ. Although technically they will both produce the same tonal response and thus sound the same at the same power output, but to me one amp having more headroom to ink out more detail sounds better to me so doesnt that mean that some amps do sound better than others? I mean although the tonal response of my Coustic and Alpine were identical, the Coustic pushed out more detail and more slap of the percussion so to me the Coustic sounded better.

So I guess the bottom line is to buy an amp for power, build quality and features and dont worry about which will sound better cause they will all sound the same.

exalted512

yeah, that challenge has been around for a while now...
to date, i dont think anyone has passed it
-Cody

neomagus00

jeez... i read through that, it kinda makes you wonder why we buy really expensive amps; according to the article/challenge/thingy, the only reason to buy a more expensive amp is for features.

so that means that there's no advantage to usamps over, say, kicker

TrappedUnder Ice

What really seperates one amp from the other are:

1) build qulity
2) parts used
3)xover design
4) power supply

Granted..if you run raw amp a to b without distortion at exactly same volume level...be very hard pressed to tell the diff.

but you cant say that the build quality of pyramid is = to that of RF...and RF's build quality is = to that of say brax?

You could probably tell the diff between tubes and transistores cause tubes have a diff sound all together

neomagus00

tubes - that was one of the challenger's tenets, that tubes have no sound difference, except higher distortion.

build quality - agreed; the challenger admits that more expensive amps use better/more reliable/more durable components, and that that may help in the long run

the point was that, for normal music, there's no audible difference in amps.

AustinKP

Wow, between last night and today, there has been 5 replies. So this means that Vince will be glad to hear that his alma mater MTX sounds just as good as the rest of the guys out there. Now he can stick his tongue out at everyone who has said that MTX SQ isn't as good as the rest. I thought it was interesting to hear that any distortion below like 2% was inaudible in normal music. Makes you wonder why everyone publishes that theirs is like .001%, etc. even though you can't hear 1000 times that much distortion. Marketing, I guess. :shrug: That article was eye-opening, to say the least.
-Austin

exalted512

Originally posted by TrappedUnder Ice

4) power supply

thats a big thing i look for
have you seen USAmps power supplies?
theyre pretty big...
-Cody

LittleCar_w/12s

Yes, all of the amps will generally put out the same tonal responses. Granted that all of the manufacturers make darn sure that their amps handle the frequency response of audible sound. If there was a bad design and say, they toppled at 15KHz, then you might notice, but ALL of them are rated for at least 20KHz, and down to 20Hz, so no, there is no way to tell.

As for headroom, it is truly dependant of the power supply and power ratings... a 45wMAX amp will sound much worse than a 45wRMS amp if it is being run at 45w. the second has more headroom, in fact the first may cut almost all but the bass out of the music because of it. So TrappedUnderIce is so right:
Chose for features, dependability and design, and power/headroom

I am a SQ person myself, and the littlest distortion bothers me, but if there is none, I can't tell, and I know I couldnt win 10,000 dollars for doing it.
The only other feature I'd buy for is repairability... with that said, I'll throw my kicker DX700 away...... and keep my little kenwoods.
-Jerry

bknauss

Originally posted by exalted512
yeah, that challenge has been around for a while now...
to date, i dont think anyone has passed it
-Cody

Someone did, but Richard Clark claimed that he didn't set up his Audio Precision 1 correctly. Other than that... MANY have failed the test

thats a big thing i look for
have you seen USAmps power supplies?
theyre pretty big...
-Cody

Size generally means that the power suppply can handle more power, but it doesn't mean its a better power supply. I can use lots of parts that can handle lots of power, but that doesn't mean its going to give very precise voltage rails.

Boy this is gonna start a firestorm!! This is a touchy subject and most people I know will swear by certain amps sounding better than others.

The challenge isn't really about what amp sounds better than another. In fact, it has nothing to do with what amp sounds better. The Audio Precision 1 basically makes the amps output at the same level (among lots of other parameters to make the two amps equal), so you're more or less taking a challenge on whether you can tell differences in voltage waveforms at the same amplitude. Although different amps and different classes of amps have different looking waveforms, the challenge is there to prove that you can't tell the differences in waveforms by ears alone.

All in all, amps do sound different under normal conditions... so use your ears and not your eyes to decide

MacLeod

Originally posted by AustinKP
Wow, between last night and today, there has been 5 replies. So this means that Vince will be glad to hear that his alma mater MTX sounds just as good as the rest of the guys out there. Now he can stick his tongue out at everyone who has said that MTX SQ isn't as good as the rest.

You know that was actually the first thing I thought of when I read the challenge!

Ive always liked MTX amps a lot because they are overbuilt and indestructible. I put a lot of stock in things that are overbuilt!!

I also like them because they make obscene amounts of power and have more headroom than Madison Square Garden!

So according to the challenge (which I agree with by the way) I can buy the MTX for tons of power and virtual invulnerablitity and be as well off as if Id bought the $600 Xtant!

AustinKP

OK, so that being said, any recommendations for a 2 channel or 4 channel bridged amp for $175 or less. Need at least 125 W x 2 RMS for my MM6's. Take into account:
1) build quality/durability
2) parts used
3) xover design - don't care as much. (or should I?) My HU has a xover built in
4) power supply
5) Warranty would be nice.

exalted512

try hifonics
crossovers on your HU arent the greatest crossovers ever
the ones on the amps are MUCHO better
-Cody

PolkThug

Richard Clark's tests have been going on for 10+ years. Thousands of people have failed them.

RC's responses to various people:

CT

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i read your thread over at SD

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no suprises

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exactly what i have heard for over ten years----by now its almost funny

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the part that really amuses me is just how twisted the facts become

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it was claimed that i said the test was to fool listeners

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here is the fact of how it originated

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about 15 years ago a company of mine (Concept Design) embarked on an engineering project to design a high speed digital recorder/playback device for professional use

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this was long before i had any interest in car audio

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i had a real good team of engineers working on the project and it was going right on schedule

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as it was i was the only person in the group that had any "audiophile" interest

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i was a long time subscriber to mags like "the "absolute sound" and the "stereophile"

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i read them religously and at the time i truly believed that wires, tubes, exotic caps, fets, etc, etc all had sonic signatures

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i believed i too could hear them and had no reason to doubt it----the evidence seemed way too solid----after all how could an entire industry be wrong??????----the best proof that i bleieved it was my personal expenditures on high end audio gear

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as part of our design project i felt it would make sense to take the time to research the audibility of the components we were using in the new digital recorder

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i also wanted to investigate the audibility of certain audio specifications in order to determine the design requirements of the device

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this was a multimillion dollar project and the unit price was nearly a quarter million dollars each so there was a budget to do the research

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after a very short time i began to realize that just about everything i had taken for granted was not true

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sort of like the first time you got the feeling that there might not be a santa claus

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i soon learned the facts and it certainly had a great effect on how i looked at audio from then on

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later when i got into car audio i took what i had learned from the research and applied the rules to car amps

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at first the early tests were easy to pass

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each time i had a successful test i examined the setup to determine if the listener had indeed heard sonic differences or if it was something else

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every time it always wa something like a turn on/off noise, bass boost on one amp only etc.

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eventually i boiled it down to the rules as they are today and i believe i have it covered

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and to anyone that has a moderate level of intellegence and grasp of scientific procedure the clear fact is that up to now no one has ever been able to demonstrate that there are audible differences in audio amplifiers

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someone even went so far as to say that somehow the mag was responsible for my beliefs----believe me when i say that this is a REALLY SORE SPOT with the mag

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their job would be a whole lot easier if we did what the other mags do and fill the reviews with the BS about amp sound quality

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the amp reviews done by A2000 will always be objective only until just ONE PERSON can show me that the differences can be heard.....................RC

napee

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sorry to see it but you are wasting your time arguing science with infidels

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a profit factor?

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i am so far from a profit in the amp challenge that is is pathetic

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a couple hundred dollars for a days work when i have more important things to do

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numerous times I have done this for large groups of folks for only one charge

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if the charge really offends them tell them i am willing to wave it for anyone that feels it is my motivation

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it will not matter----heck

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if its that much of a hinderance tell them to find a golden eared representative they trust and i will pay him to come take the test

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see how that grabs them

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they will just come up with another excuse

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it is truly amazing just how many people do not understand the scientific principle of testing and how ignorant they appear when attempting to discredit it

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it is best to just let them continue to pay their good money for "intangible" things that they cannot detect, identify or prove

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idiots and suckers

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the world needs them so the con artists have someone to prey on..........RC

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joe---can you get your hands on one of those $20K amps and bring it to autosound for a listening test????

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better yet do what i did once to a manufacturer that was selling a $15K 50 watt mono tube amp

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i told him that if he could demonstrate to me that he could hear the difference between his $30K stereo pair of amps and a ordinary 500 dollar amp that i would buy several pairs of them for my studios

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it was a fun afternoon full of great excuses...........RC

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v6----i wrote those rules myself over a period of several years

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i tested listeners and everytime they were able to "hear a difference" i carefully examined the setup to determine if i could find a logical reason for their ability to "hear" a difference

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at first the differences were simple like different gain or bass boost on only one amp---eventually i was able to quantify what i believe is every reason for the audible differences----and none of them turned out to be "tube magic"----it was always wiring differences,level differences or simple frequency response differences etc

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it never turned out to be because the tubes were doing something special

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once i zeroed in on all the things that were responsible i found that no one could EVER tell the difference

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once i was confident i issued a challenge---and to date over a couple thousand people have tried and failed

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the reason for the number of "chances" is simply math----eventually someone wins the lottery

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and its not because they are math experts

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now if you would be willing to put up YOUR $10K against MY $10K how about a 6 out of 6 outright bet?????----i am confident enough to make that challenge

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have i got any takers?????----if so pack up the amps and head to A2000 with a certified check made out to me........RC

PolkThug

I thought this was also an import one from Richard Clark:

edouble----and i'll take bets on one thing for sure

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there were slight level or crossover differences in those amps when you A/B'd them----it doesn't take much of a level difference for most anyone to hear a "sonic" difference

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when the volume difference is very small it is not peceived as louder, just better or different or punchier

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in the early days of A/B'ing i used to take a simple fluke and match levels to a few tenths of a dB

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i soon learned that for critical listeners the difference had to be much less than 0.1 dB or it would be percieved as a sonic difference----the question for me was purely scientific----were they actually hearing differences or was it just level differences?????

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when someone comes to take the test i still use the fluke to level match for the qualifying test---its quick and easy

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good experienced listeners usually pass the 6 out of 8 requirement

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this test quickly weeds out the "goobers"

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i have found several individuals over the years that can easily ace a test where there are level differences of only tenths of a dB----interesting enough when asked they do not feel that it is level differences that they hear----they usually say they feel one amp sounds different than the other

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then for the actual test i use the Audio precision and match levels to less than 0.01 dB

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all of a sudden the audible differences just seem to go away----now perhaps someday someone is going to be sensitive to level differences less than 0.01 db or actually be able to hear amp differences----if so they will get my money and it will raise new questions

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could they actually hear differences in amps or was it just extremely minute differences in level they were sensitive to????----at this point i will still feel that it is not answered till i re-challenge the winner to retake the test with level matching at 0.001 dB
believe me if you ever experience one of my tests you will see things with a different perspective

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i am very serious about this and take great pains to do it in a scientific manner according to accepted scientific testing methods

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i am only searching for the facts buried in the folklore

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i too had read all the conflicting gobbleygook in the press and even believed i could hear the warmth of tubes and the smoothness of exotic products

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i did not set out to "prove" that there were no differences in amps---as an engineer that designs and manufactures very expensive professional audio equimment my quest started to determine what was really important and what was not to make a good sounding amp/preamp----the more I investigated it the more the evidence showed that amps were already beyond the point where their "sound" was an issue and that simply undistorted power was the dominant factor............RCRemember some people have aced the first part of the test where there's a difference of about 0.1 dB

bknauss

Originally posted by exalted512
try hifonics
crossovers on your HU arent the greatest crossovers ever
the ones on the amps are MUCHO better
-Cody

Then I assume we would call outboard active crossovers mucho mucho mucho better?

As a word of warning with Richard Clark, he's extremely knowledgable, but he has the tact of a piece of lint. I guess years of stupid questions make you a bitter person.

exalted512

Originally posted by bknauss
Then I assume we would call outboard active crossovers mucho mucho mucho better?

probably, but its a lot of extra work:)
much easier to turn a dial
-Cody

AustinKP

So what's the diff b/w the xover in my HU and the one on an amp? As far as I understand, in my Alpine 9815, I can adjust the attenuation, slope and xover point in 1/3 octave steps for front, rear, and sub separately. Would that not do exactly the same thing as an amp xover?

neomagus00

well, it might be along the lines of the crossover slope sq thingy: supposedly, a 6 db/octave xover sounds much better near and beyond the xover point than a 24 db/octave one. i've never compared the two, so i can't vouch either way, but the hu xover issue may be the same thing; i'm sure there's a difference between a 12 db/O digital and a 12 db/O analog circuit as well.

so we've agreed that all that really matters is power supply, build quality, and features (assuming things such as equal wattage, appropriately measured ratings, and accurate full-spectrum reproduction; see below too).

do amps have response curves? like speakers, you measure the response and it's clearly not perfectly flat, do amps have something like that?

a note on the human hearing range - it's been shown that data up to ~80kHz adds to the enjoyment of music, even though CD's can't accurately reproduce frequencies that high (i think - since cds sample at 44.1kHz, they couldn't have an accurate waveform at a frequency above that, could they? and the 44.1 one assumes that the sample is right on the antinode), consider that 80 kHz is only 2 octaves above the standard accepted value of 20kHz.

and i've heard a japanese drum or something of the sort that produces sounds below 20 Hz, and i surely noticed the guy was hitting it - i didn't hear it, but i could definately feel it... and isn't that half the fun of a sub?

outboard xovers - why are these extra work?

last point - distortion - i suppose that over long strings of equipment, distortion could add up... yeah, 0.1% on each of the HU, preamp, xover, amp could add up... even 0.1% on four items is 0.4641% (if i did the math right, can someone confirm?). are there any other components that could be in the line that i forgot? any components that regularly have total distortion of >0.1%?

MacLeod

The difference between a 6 db and a 24 db crossover is that the 24 db is a much steeper cut off slope and will be much more precise.

A crossover works by reducing power at each octave. A 6 db crossover will reduce power by 6 db per octave and a 24 will reduce by 24 db per octave.

Say that you set the high pass crossover point at 3000 Hz, a 24 db Xover would cut 24 db at 3000 then another 24 at 1500 then another 24 at 750 and so on. This means that very little below 3000 is getting thru

A 6 db would reduce power by 6 db at 3000 then another 6 at 1500 and so on so you would have a lot more response below 3000 which really only matters if youre super fine tuning your system.

Neither one really sounds better than the other one. The advantages would be if you were crossing over a tweeter you would want very little input below what its rated at to avoid damage so a steeper slope would be your ticket. Most equipment has at least a 12 db/octave crossover and this should be plenty.

neomagus00

yes, i understand that the 24 cuts off much more than the 6, but i have heard that the steeper xover degrades the signal more than the shallower one; is this true? and if it is, perhaps the additional components in a higher-order xover affect the output?

bknauss

Degrading the signal depends on what is best for the signal. Sometimes speakers like a 6dB slope and sometimes they like a 24dB slope depending on what the crossover point is and where the speaker is located in the car (and what other speakers you are using). There are a LOT of factors to consider when dealing with acoustics

Degradation might occur if the xover does not keep the phase constant. For every factor of 10, the phase slopes down 45 degrees for every order of 20dB. Does that make any sense to you guys? Sometimes I'm not overly clear with my explainations.

PoweredByDodge

actually -- compare a mosfet output stage amp to a BJT output stage amp... the mosfet is driven to at least half if not more of its amplification factor -- most mosfests "max out" at 10, and if u keep them around 5 you're ok.

BJT's can strike up to a 200 times amplification factor... so if you run them at only a factor of 5, you insure virtually PERFECT linearity of the signal information.

this i have found is insanely more important than tube versus semiconductor.

neomagus00

Originally posted by PoweredByDodge
actually -- compare a mosfet output stage amp to a BJT output stage amp... the mosfet is driven to at least half if not more of its amplification factor -- most mosfests "max out" at 10, and if u keep them around 5 you're ok.

BJT's can strike up to a 200 times amplification factor... so if you run them at only a factor of 5, you insure virtually PERFECT linearity of the signal information.

this i have found is insanely more important than tube versus semiconductor.

huh????? it's not often that i'm this confused... my state of mind here is somewhat similar to that of a man getting mugged in the middle of a meadow...

bknauss - yes, yes, i understand that the desired extension of frequencies beyond the chosen xover point, and thus the chosen slope, is dependant upon installation and preference, but my original point/question was this: do the extra capacitors and resistors in a higher-order xover add any appreciable distortion to the signal?

the phase thing i don't get... you seem to have stated 2 criteria for a 45-degree phase shift; a 'factor of 10' and a '20 dB order', neither of which i understand

lastly, props to douglas adams for the above man-getting-mugged phrase

LittleCar_w/12s

What he's talking about is the circuit gain of an amplifier stage itself....
The thingy that takes the signal an makes it louder, then that repeats.... then there's a stage that makes it more powerful, but not louder...

SO... a mosfet amp stage is easily overdriven... therefore it must bue amped many times, as well as the adjustment being perfect... in short, a bad adjustment or a little over-input will overdrive them, causing distortion.
In retrospect a BJT amp (uses regular old transistors) has an inherent ability to amp over 200 to upwards of 100000 times at each stage!!.. In an operating circuit, though, the amping of each stage minght be cut to say 5 times. This means there is a LOT of stability here.. the circuit is nowhere near its overdrive point.

In short:
A Mosfet is inherently stable, but only has ability to run about 10x
A BJT (transistor) Amp is inherently unstable from temperature at it's full gain, but is cut down with internal balancing feedback to counter it... they can do 200x +, but run maybe at 5-10x amplification.

A Mosfet saves your power bill, but is very picky...
A BJT eats power (who cares??) but is dependable and stable.

Those are as layman as I can put it for you.
-Jerry

bknauss

Originally posted by PoweredByDodge
actually -- compare a mosfet output stage amp to a BJT output stage amp... the mosfet is driven to at least half if not more of its amplification factor -- most mosfests "max out" at 10, and if u keep them around 5 you're ok.

BJT's can strike up to a 200 times amplification factor... so if you run them at only a factor of 5, you insure virtually PERFECT linearity of the signal information.

this i have found is insanely more important than tube versus semiconductor.

BUT... BJTs and MOSFETs are generally used for different classes of amplifiers. MOSFETs are generally for switching, and that's the reason they're generally used for the H-bridge at the input area of the amp and also used if its a Class D amp.

For the non-electrical engineers out there, here are some explanations:
Switching power supplies use MOSFETs (a type of transistor) as a switch. Based on the circuit, it can increase or decrease the voltage.
H-bridge is a circuit that takes a DC voltage and turns it into an AC signal. In car amps, it take the 12V and makes it into an AC voltage, then its converted back to a DC voltage to provide the power.
And if you don't know what Class D is, then do some reading up

neomagus00

thanx guys, that helps a lot. why do amps use mosfets then if bjt's have more headroom? stability and power draw?

does anyone have a link to an amp-tutorial site? so i can learn more about the internal construction of an amp, and why/how it does it's thing...

bknauss

Originally posted by neomagus00
huh????? it's not often that i'm this confused... my state of mind here is somewhat similar to that of a man getting mugged in the middle of a meadow...

bknauss - yes, yes, i understand that the desired extension of frequencies beyond the chosen xover point, and thus the chosen slope, is dependant upon installation and preference, but my original point/question was this: do the extra capacitors and resistors in a higher-order xover add any appreciable distortion to the signal?

the phase thing i don't get... you seem to have stated 2 criteria for a 45-degree phase shift; a 'factor of 10' and a '20 dB order', neither of which i understand

lastly, props to douglas adams for the above man-getting-mugged phrase

Let's do a try #2
A decade is simply taking a frequency and multiplying it by 10. So a decade after 10Hz is 100Hz. Anyway, let's say you have your ordinary 2nd order butterworth filter which breaks at 12dB/octave or 40dB/decade. For every order of the filter, it will break at 45 degrees/decade... starting at a decade before the break frequency and ending a decade after the break frequency.

Let's do an example. You have a 2nd order low pass filter (12dB/octave drop as you go toward higher frequencies) with a break frequency (crossover frequency) of 1000Hz. At 100Hz (a decade before the break frequency, then the phase will start dropping at a rate of 45 degrees/decade. At 10,000Hz, the phase will stop dropping and will be at -90 degrees from the original phase. You probably won't be able to hear the phase difference at 10kHz since the sound coming out of that driver will be -60dB from what it should be playing!

bknauss

Originally posted by neomagus00
thanx guys, that helps a lot. why do amps use mosfets then if bjt's have more headroom? stability and power draw?

does anyone have a link to an amp-tutorial site? so i can learn more about the internal construction of an amp, and why/how it does it's thing...

Headroom only refers to how much more juice can be output by the amp compared to the current level. So just go and buy a 200W amp for each speaker if you're worried about headroom Headroom also depends on the type of power supply (regulated or unregulated), which then depends on the alternator and battery and the RPMs your car is currently at.

I have a bunch of links about amps, but you'd need a pretty darn good hold on electrical engineering before you could make sense of most of it. Took me about 2-3 years of school before I could get a decent grasp of what most people were talking about.