What makes a high end audio amp "better" then a low end unit?

[Beamin]

I have always wanted to make my own amp that was compareable to a macintosh amp for a fraction of the price but what exactly makes it better? Lets ignore the warm harmonics the tube produce to make a better sound for simplicity so not get into the tube/solid state which is better debate.

I know amps can be graded by their THD to give you a rough idea: For instance a shit sony or equivalent will have a THD of 0.8% while a harmon kardon in that power range will be around 0.08% and a Marantz will be around 0.03%. Not that this is the answer to good sound you can hear the difference in a sony and a better amp.

So to get the best sound: Is it just a matter of hand selecting all the parts so the values are as close to design spec as possible? This would make sense why a cheap amp would sound worse because they can just buy 5% components and use them all where as higher end starts with a lower tolerance and then will hand pick them. Also would matching parts: LR channel transistors that are very close also play a big part?

So if my understanding is correct you could take an amp that has a good circuit design (are almost all of them mathematically the best we can do since its really a simple circuit that's been improved over 100 years) and then hand selected the best/matched parts;IE buying 100 resistors and discarding 99% of them could you turn the cheap sony amp into a good one? Perhaps also over sizing filter caps/ over specing parts to run at less load etc.

[Zero999]

I have always wanted to make my own amp that was compareable to a macintosh amp for a fraction of the price but what exactly makes it better? Lets ignore the warm harmonics the tube produce to make a better sound for simplicity so not get into the tube/solid state which is better debate.

I know amps can be graded by their THD to give you a rough idea: For instance a shit sony or equivalent will have a THD of 0.8% while a harmon kardon in that power range will be around 0.08% and a Marantz will be around 0.03%. Not that this is the answer to good sound you can hear the difference in a sony and a better amp.

So to get the best sound: Is it just a matter of hand selecting all the parts so the values are as close to design spec as possible? This would make sense why a cheap amp would sound worse because they can just buy 5% components and use them all where as higher end starts with a lower tolerance and then will hand pick them. Also would matching parts: LR channel transistors that are very close also play a big part?

So if my understanding is correct you could take an amp that has a good circuit design (are almost all of them mathematically the best we can do since its really a simple circuit that's been improved over 100 years) and then hand selected the best/matched parts;IE buying 100 resistors and discarding 99% of them could you turn the cheap sony amp into a good one? Perhaps also over sizing filter caps/ over specing parts to run at less load etc.

The audio amplifier is a problem which was solved over 40 years ago. Unless it's poorly designed or badly overdriven, an audio amplifier will contribute a negligible amount of distortion, compared to the speakers and room acoustics. Lots of it is marketing bunk.

For instance a shit sony or equivalent will have a THD of 0.8% while a harmon kardon in that power range will be around 0.08% and a Marantz will be around 0.03%. Not that this is the answer to good sound you can hear the difference in a sony and a better amp.

That depends on the music, the nature of the distortion, the listener, as well as the speakers and acoustics. I doubt most people will be able to tell the difference between 0.03% THD and 0.8%THD.

[Johnny10]

I collected 60's and 70's Mcintosh solid state amps and tube preamps.
Well designed, solid construction, great transformers.

And Hero999 is correct " audio amplifier is a problem which was solved over 40 years ago."

Take a look at you tube videos from El Paso TubeAmps and you can learn the about cloning mcintosh amps and what makes each type of HI-FI tube amp unique.
Seems the transformers are what makes the difference.

ElPaso Tube Amps would say, the McIntosh transformer is something not easily recreated !

[tszaboo]

Nowadays they make Class-D amplifiers with a single chip (digial input) 100+W output and <0.01% THD+N.  I dont even understand why there are amplifiers anymore. Seems so pointless. I believe that good quality active speakers are the way to go. 

[Jr460]

Based on the OP, he wants a home amp.   Things are slightly different if you deal commercial amps for driving large systems.  These are run much closer to max power.  They need to is some cases support loads down to 2 Ohms and also have very good protection.  Some people would test amps by shorting the output and then driving it at the max.  Come back 24 hours latter and see if has not failed, and would put on a normal load and see if it works.

Also is the mechanical side of things.  Being able to withstand the road abuse, and being is direct hot sun or sometimes mist.

[macboy]

I have always wanted to make my own amp that was compareable to a macintosh amp for a fraction of the price but what exactly makes it better? Lets ignore the warm harmonics the tube produce to make a better sound for simplicity so not get into the tube/solid state which is better debate.

I know amps can be graded by their THD to give you a rough idea: For instance a shit sony or equivalent will have a THD of 0.8% while a harmon kardon in that power range will be around 0.08% and a Marantz will be around 0.03%. Not that this is the answer to good sound you can hear the difference in a sony and a better amp.

First of all, there are no legal standards against which audio amps are measured. So, every manufacturer make up its own specifications and limits. The "shit sony" gives a THD rating of 0.8% not because it actually produces that much distortion most of the time (it definitely does not), but because that THD rating allows higher power ratings. Most amps produce least distortion at a couple watts output, and increase from there. If that sony was rated at 0.08%, then maybe it could only manage 50 W before hitting that mark. But move the limit to 0.8% and it can push out 80 W at that limit. So do they market it as a 50W @ 0.08% or 80W @ 0.8% ? Sony chooses one way, others like HK go the opposite way. Most people buy based on power numbers, not THD numbers. The fact is that even a "shit sony" produces much less than 0.05% most of the time. (I'm not just waving my hands around, I have measured plenty of them).

I would love if the manufacturers gave THD vs power and THD vs frequency graphs. IMD specifications. Noise floor graph (distribution of low vs high frequency noise). Step response. But they don't. So you can't compare amps by the numbers, unless you implicitly trust the test methodologies in certain HiFi magazines (tip: don't).

[oldway]

I repair many vintage (years 60 and 70) high end amplifiers of different brands, both tubes and transistors and I also have the opportunity to listen to them.

I am not a music expert and my age no longer allows me to judge a sound because my hearing is that of a person over 65 years, that's means very poor.

I am sometimes surprised about some customers tell me .... the sound more or less perfect of some amplifiers compared to others .... And yet, on the test bench, they have similar caracteristics, no technical reason to give a different sound.

I especially judge the amplifiers on the technical plan, the quality of manufacture, the diagram, the quality of the components, the estetics, ....

[oldway]

For me, what really makes the difference is not the amplifier but the speakers.
An experienced music lover can only discern distortions greater than 3 or 5%.
A speaker produces a distortion of at least 1%, often 2%.
So, do not tell me that a 0.1% distortion of an amplifier makes any difference.
Moreover, paradoxically, it is the tube amplifiers that have the highest rate of distortion that are considered to have the best sound.

A comprehensive and very interesting study of the speakers was made by G. A. Briggs, one of the founders of the British firm Wharfedale, in his book loudspeakers.

A big technical difference between tube and transistor amplifiers is the damping factor ... that may partly explain the difference in sound of a tube amp.

My personnal preference: I have a Marantz 2285B receiver and a Sansui AU-5500 amplifier. (I think the AU-5500 and AU-6600 are the best Sansui)

[coppice]

The audio amplifier is a problem which was solved over 40 years ago.

Actually 40 years ago (mid 70s) is when a lot of audio amplifier problems were being created. That was the era of 1MHz bandwidth audio amps, with masses of negative feedback, and bizarre transient performance. It was the mid to late 80s before the industry settled down to more sane designs, with proper testing of transient performance.

More recently the move to switch mode amps, to allow things like compact and powerful 7.1 designs, created its own performance issues. Again, most of this was due to a focus on static testing, and too little transient testing. This is only now settling down.

[Seekonk]

Just tell me what you can build "for a fraction of the price" that is better than what you can buy.

[Alex Nikitin]

Well, I've designed many audio amplifiers, some of these apparently quite good (from what reviewers wrote) . The answer to the topic question is simple - a better sound quality. "High end" doesn't need to be expensive, some of my best amps were sold at about £300 retail and (IMHO) still could qualify as "high end" from the sound quality perspective. How to make an amplifier that sounds good - that is a much better question to ask. However there is no simple answer to that question . Earlier replies in this thread are from people who never made a good sounding amplifier, I suppose 

Cheers

Alex

[coppice]

"High end" doesn't need to be expensive, some of my best amps were sold at about £300 retail and (IMHO) still could qualify as "high end" from the sound quality perspective.

What you say is accurate. There are good amps for £300. Good speakers, on the other hand, don't come cheap. Most people would get a better result by spending less on their amp, and using the extra cash for better speakers.

[Alex Nikitin]

"High end" doesn't need to be expensive, some of my best amps were sold at about £300 retail and (IMHO) still could qualify as "high end" from the sound quality perspective.

What you say is accurate. There are good amps for £300. Good speakers, on the other hand, don't come cheap. Most people would get a better result by spending less on their amp, and using the extra cash for better speakers.

I beg to differ. There are some good speakers which don't cost the earth (I'm quite happy with a pair I've bought for £250 second hand, including stands), but from my experience the quality of amplification is just as important as the quality of speakers in a system. Moreover, correct matching of these two parts is essential .

Cheers

Alex

[RandallMcRee]

Many of the key variables that differentiate one amplifier from another are not published in the audio industry, at least not widely. THD is, of course, just one small component of the overall performance of a complete system. Its not that important.

Two key things I found in building a preamp are channel separation and channel matching.

It was surprisingly hard, for example, to get crosstalk low enough so that one channel, at high volume, did not bleed through to the adjacent, silent, channel.  Simply running two signal wires in close proximity can cause noticeable problems.

For the same reason, grounding can be a big deal.

Proper channel matching and separation are what create that 3-d presentation most folks find so wonderful. Well, the whole system contributes and, yes, the speakers are the key component.

[b_force]

I have been professionally in the field for many years.
The simple and only (scientific) correct answer is marketing and placebo.
It doesn't cost much at all to make a perfect good performing amplifier.
Although, you have to realise that it all depends on the context. Pro audio customers have different needs than tiny boom box producers, as well as guitar amplifiers.
So that means the approuch and compromises will be (very) different as well.

[nfmax]

The audio amplifier is a problem which was solved over 40 years ago.

Actually 40 years ago (mid 70s) is when a lot of audio amplifier problems were being created. That was the era of 1MHz bandwidth audio amps, with masses of negative feedback, and bizarre transient performance. It was the mid to late 80s before the industry settled down to more sane designs, with proper testing of transient performance.

More recently the move to switch mode amps, to allow things like compact and powerful 7.1 designs, created its own performance issues. Again, most of this was due to a focus on static testing, and too little transient testing. This is only now settling down.

The QUAD 303, from 50 years ago, was one of the first all-transistor audio power amplifiers to be essentially 'perfect' (within its bandwidth, voltage swing, and load impedance limits, of course). Any more recent design that isn't 'perfect' has been done wrong!

[oldway]

The audio amplifier is a problem which was solved over 40 years ago.

Actually 40 years ago (mid 70s) is when a lot of audio amplifier problems were being created. That was the era of 1MHz bandwidth audio amps, with masses of negative feedback, and bizarre transient performance. It was the mid to late 80s before the industry settled down to more sane designs, with proper testing of transient performance.

More recently the move to switch mode amps, to allow things like compact and powerful 7.1 designs, created its own performance issues. Again, most of this was due to a focus on static testing, and too little transient testing. This is only now settling down.

Not as simple of that.....

Here are different schematics of power stage of amplifiers of the years mid 70:
- Marantz 140dc: 1976-77
- Marantz 2285B : 1977-80
- Sansui AU-5500 : 1974-76
There are very sofisticated (Marantz 140dc) and very simple power stages (Sansui AU-5500) in the same time.

[nfmax]

Many of the key variables that differentiate one amplifier from another are not published in the audio industry, at least not widely. THD is, of course, just one small component of the overall performance of a complete system. Its not that important.

Two key things I found in building a preamp are channel separation and channel matching.

It was surprisingly hard, for example, to get crosstalk low enough so that one channel, at high volume, did not bleed through to the adjacent, silent, channel.  Simply running two signal wires in close proximity can cause noticeable problems.

I was working at QUAD when the 34 control unit was being developed. Roger Hill, the lab technician, tweaked the PCB layout by adding bits of copper tape as extra ground plane, while monitoring the crosstalk over the whole audio range using a frequency response analyser (a Wayne Kerr of some sort I think - I can't remember now). -60dB was the aim.

[Alex Nikitin]

I have been professionally in the field for many years.
The simple and only (scientific) correct answer is marketing and placebo.

Simple- yes, scientific- no. Only pseudo scientific, and as such, incorrect.

Cheers

Alex

[nfmax]

I have been professionally in the field for many years.
The simple and only (scientific) correct answer is marketing and placebo.

Simple- yes, scientific- no. Only pseudo scientific, and as such, incorrect.

Cheers

Alex

There is a great deal of fashion about the high-end audio business. Which is neither good nor bad, it depends if you like fashion. Treat it as a fashion business and it makes sense.

That said, there are real audible effects which seldom get mentioned. My personal hot button is mechanical noise, usually mains hum from transformers. What good is it for the output audio to be completely noise and hum free if the amplifier itself is buzzing like a microwave oven warming up a Chicken Tikka!

Talking of which...

[oldway]

What is a good sounding amplifier?

How to know if the sound you hear is the sound equivalent to the original sound?

The appreciation of a sound is totally arbitrary and subjective.

Do you have enough hearing?
Have you tested your hearing?
How old are you ? Me, for example, I have more than 65a and I do not allow myself to judge the acoustic quality of an amplifier because at my age, we do not hear beyond 12 Khz.

Do you go to concerts?
What kind of concerts?
Because at certain types of concerts, the sound level is so high that it reaches the pain threshold and it can no longer be used as a comparison.

I sometimes have customers who are real music lovers, in their thirties and who go to concerts (opera, classical music) ...
These are references and I think their opinions are credible ....
But there a lot of people who give their opinion about sound quality and who are not qualified to do it.

[b_force]

I have been professionally in the field for many years.
The simple and only (scientific) correct answer is marketing and placebo.

Simple- yes, scientific- no. Only pseudo scientific, and as such, incorrect.

Cheers

Alex

Pseudo science?
Don't think so, there are a billion papers about noise and distortion thresholds, and what other issues have an effect how we percieve things.
(hearing, tasting, seeing)

The fact that many manufactures try to tell that people need even less distortion to be even better (fill in subjective wine tasting like words), is just prove how strong markteing (and thus placebo effects) is.
A normal human being is never able to detect those differences.

Funny enough is that most comparisons are never done the proper way.

But like I said it does depend on the context. In a line array with 4-6 high sensitive compression drivers, you have to be sure to make your SNR is as good as possible. Otherwise it WILL be noticable.

[oldway]

There is yet another important factor in the reproduction of the sound that no one has spoken of, and yet it is essential, the acoustics of the local.

It's funny to see that people are focusing their attention specifically on amplifiers when there are many other more important factors.

[Kleinstein]

One should not be able to hear the difference between any two reasonably good amps. They should be all so close to perfect that one can not hear the difference.

Modern class D amps are also good enough. At lower power there is no much sense in building your own class AB amplifier like in the 1970s/1980s, as integrated amps are good too.

The more problematic parts are the speakers and if used passive cross over networks. From the technical perspective it absolutely makes sense to not have active speakers, as this one way for a possible improvement on the speakers.

While building an class AB amp is rather straight forward and simple, the acoustic part for speakers is not that simple and might need more experimentation.

[Zero999]

The audio amplifier is a problem which was solved over 40 years ago.

Actually 40 years ago (mid 70s) is when a lot of audio amplifier problems were being created. That was the era of 1MHz bandwidth audio amps, with masses of negative feedback, and bizarre transient performance. It was the mid to late 80s before the industry settled down to more sane designs, with proper testing of transient performance.

More recently the move to switch mode amps, to allow things like compact and powerful 7.1 designs, created its own performance issues. Again, most of this was due to a focus on static testing, and too little transient testing. This is only now settling down.

What do you mean? The NE5532 and TL072 were around back then and are more than good enough for audio and discrete transistor technology was more than good enough for audio power amplfieirs.