Amplifier sound

[rwertz]

Hi, I'm a newbie and really don't know a lot about audio, but I do love to listen to music and have read a lot of discussion here regarding choices of amplifiers. I also don't have a very educated ear. I'm much more in tune to wine than audio and I can list lots of reasons, in great detail, why a Chave Hermitage is better than a California Syrah. My palate is apparently more educated than my sense of hearing.

Anyway, I currently have a pair of Harbeth C7ES-XD's and a Bluesound Powernode Edge streaming Spotify.

I was interested in looking at other amplifiers and I took my little amp to a local hifi store to listen to it on the same pair of Harbeths versus other amps.

When I listened to my Bluesound amp I thought it sounded good, but I when listened to the same speakers with a Luxman 505Z, I thought it sounded much, much better.

Why is this?

Why does an AB amp sound different from a class D amp?

Are differences in the sound of amplifiers more due to preamplification than than to the amplifier itself (I think I read this somewhere)?

Why would a class D amp like my Bluesound, which apparently tests very well, not sound better than the Luxman? What accounts for the intangibles that aren't measured by audio testing?

 

[Johnkeizer]

I don’t own a Luxman, bit out of my reach now I am retired, but I would happily have that one even just to look at.

 

[CD2]

Can you describe how it sounded better?

The obvious point is that the Harbeths are not very efficient, and the Bluesound amp lists as having relatively low power. The Luxman is a much more powerful amp. If you want to stick with Class D there are powerful amps that test well reviewed here e.g. https://www.audiosciencereview.com/...ds/buckeye-purifi-1et9040ba-amp-review.68644/

 

[rwertz]

Perhaps. The Bluesound is 40w into 8 ohms, 80w into 4 ohms, and I wasn’t playing the music very loudly.

I also listened to a Sugden A21, rated at 25w into 8 ohms of class A power and also preferred it to my Bluesound, though I still preferred the Luxman’s sound.

 

[Jim Taylor]

There are two problems here.

One is whether you are actually hearing a difference or not. Whenever you go to a retail establishment, the personnel have a million tricks up their sleeve to make you think that you hear things that aren't there. They can do this by the power of suggestion, and they can do it by manipulating different designs (see my second paragraph, below).
You also have personal biases that affect your perception. If you are convinced before you even enter the shop that big, heavy, shiny amps always sound better, then that's the exact way things will roll for you.
The best way to prove to yourself (not to us) that you really are or are not hearing what you think you are hearing is the DBT, or Double Blind Test. It's a method to isolate our susceptibility to cognitive biases. Although many use it to ascertain whether there is a difference between two blinded speakers or amps, I personally think that it''s the best way to teach ourselves the truth of our abilities. It is quite complicated and cumbersome to set up the right way, but it is also very humbling.

Here is a video by our Esteemed Leader on the subject:

Please note that levels must be matched for comparisons to be valid. If the salesman at the retail store "goosed" the level of the Luxman ever so slightly, it would naturally be preferred by the vast majority of listeners because of the human sensitivity to SPL differential. Always remember what I said about sales personnel having a million tricks up their sleeve. Don't underestimate some of them with their "friendly, helpful" ways.

The other problem is how speakers and different amplifier designs interact. Some speakers present a difficult (reactive) load to amps. If the manufacturer of the amp was in the unenviable position of being forced to cut corners to make a profit, these difficult speaker loads may play havoc with the amp's ability to recreate full-bandwidth sound. OTOH, if the amp is designed well but has insufficient power overall, the resulting clipping can be unpleasant. Some lower powered amps have a power limiting circuit to prevent obnoxious levels of clipping, but these can have their own affect on the sound ... especially in the bass.
This is of course dependent on your desired output level, your listening distance and the basic sensitivity of the speaker.

Your Bluesound has been reviewed (tested) by the owner of this site, Amir Majidimehr. The results can be found here: https://www.audiosciencereview.com/...nd-powernode-edge-streaming-amp-review.46924/

No serious faults were in evidence.

 

[Chrispy]

Not my experience that class AB amps sound different from class D....so suspect you just have typical bias due to the way you compared. Like Jim's post....

ps I wouldn't want an amp to act as fixed eq/tone control in any case.

 

[Jim Taylor]

I also listened to a Sugden A21, rated at 25w into 8 ohms of class A power and also preferred it to my Bluesound,

IMO, the Sugden designs are, and for many years have been, distortion generators. This passage from Stereophile magazine, a test by our member John Atkinson (@John Atkinson), shows the characteristics in question:

The bottom trace in fig.5 shows how the THD+noise percentage in the Sugden's output varies with output power into 8 ohms with both channels driven. The distortion emerges from the noise floor at around 3W and rises steadily to 21W, where it rapidly increases. This increase is due to the tops of the waveform flattening, presumably because the signal can't go below the 0V ground reference. The amplifier reaches 1% THD+N at 24W, insignificantly lower than the specified 25W (14dBW). Into 4 ohms, however, not only did the overall distortion level rise significantly above 1W or so, the clipping power was only 15W (8.75dBW). I didn't measure the maximum output power into 2 ohms, as the amplifier was clearly in trouble with low impedances.

Fig.5 Sugden A21ai Series 2, distortion (%) vs 1kHz continuous output power into (from bottom to top): 8, 4 ohms.

 

[Multicore]

What accounts for the intangibles that aren't measured by audio testing?

Once level matching is achieved, which is unlikely in shop demos, suggestibility is the main one.

 

[DVDdoug]

Ignoring amplifiers with tone controls or EQ, most amplifiers (most electronics) don't have a "sound".

ALL active analog electronics generate SOME noise (hum, hiss, or whine in the background). If you can hear it you may want a better-quieter amp.

And if you overdrive an amplifier into clipping... if you crank it up and try to get 110W from a 100W amplifier... clipping is distortion. I've never HEARD distortion from ANTHING* unless it was broken.

Just get an amp that's powerful enough to go as loud as you want, and get something with the style and features you want, and you can consider manufacturing quality and the manufacturer's reputation and don't worry about it.

Speakers or headphones make a far-far bigger difference.

As has been said, when you compare equipment, it's important to volumes match. A little louder usually sounds a little "better". And there is a real, normal, natural phenomena with the ear & brain that makes it sound like you've turned-up the bass when you've only turned-up the volume.

On top of that, we often imagine differences that "magically go-away" in blind listening tests. Of course it's not possible to do a proper controlled, level-batched, blind listening test in the store!

Besides the above video, see What is a blind ABX test?

You DO NOT need to do these kind of listening tests and you don't have to do them at all but you shouldn't fully-trust your casual listening tests/comparisons. If you start making crazy claims about what you're hearing we might harass you to do controlled listening tests, or shut up!

Most 'audiophiles" don't believe in blind listening tests and they have a dictionary-full of words to describe the things they THINK they are hearing!

I seem to say this here at least once a day but, this is one of the few rational-scientific audio resources.

Audiophoolery is also worth reading.

Why does an AB amp sound different from a class D amp?

They don't, or they shouldn't.



* Maybe I've heard distortion from a vinyl record that wasn't actually "broken" but I haven't played records in decades.

 

[Johnkeizer]

Just find an amp that is properly designed, engineered and built and you like the sound of.

 

[Chrispy]

Just find an amp that is properly designed, engineered and built and you like the sound of.

So you shop by amp "sound"?

 

[rwertz]

Thanks for all of your replies. Let me reiterate, I’m really not an audiophile. I’m just a guy looking for better sound and im trying to understand why I feel like two amps sound different.

I agree that it’s difficult to do a double-blinded comparison an audio shop.

As for the salesman, I never got the sense that he was biasing me or pushing me toward the Luxman. He late me pick the files I wanted to listen to and adjust the volume to my preference.

I don’t have a preference for class A, AB, or whatever.

You’re right. Maybe it’s just my uneducated ear. Maybe I’m wrong and they really sound the same.

 

[Chrispy]

Thanks for all of your replies. Let me reiterate, I’m really not an audiophile. I’m just a guy looking for better sound and im trying to understand why I feel like two amps sound different.

I agree that it’s difficult to do a double-blinded comparison an audio shop.

As for the salesman, I never got the sense that he was biasing me or pushing me toward the Luxman. He late me pick the files I wanted to listen to and adjust the volume to my preference.

I don’t have a preference for class A, AB, or whatever.

You’re right. Maybe it’s just my uneducated ear. Maybe I’m wrong and they really sound the same.

Audiophile is more about a person with fascination with reproductive audio gear....but biases are innate with humans....a blind test would be a good start for you, and don't forget level matching.

 

[Jim Taylor]

He late me pick the files I wanted to listen to and adjust the volume to my preference.

Bingo!
Always adjust levels with a multi-meter. Human hearing is not nearly sensitive enough to match the accuracy of a multi-meter. Please ... view the video I offered (above).

 

[Johnkeizer]

I don’t believe in uneducated ears, you know what your family and friends sound like? I use the results of tests here and elsewhere as a first step, after all, these days there is no reason why electronics should measure bad.
After that I try to see, touch and listen to the units I have shortlisted.
Usually the differences between them are tiny, barely noticeable, sometimes more obvious.
Get the one that pleases you, not what someone says you should get.

 

[Chrispy]

I don’t believe in uneducated ears, you know what your family and friends sound like? I use the results of tests here and elsewhere as a first step, after all, these days there is no reason why electronics should measure bad.
After that I try to see, touch and listen to the units I have shortlisted.
Usually the differences between them are tiny, barely noticeable, sometimes more obvious.
Get the one that pleases you, not what someone says you should get.

Please share your audio education as a listener.

 

[RexrothPigeon]

Look, you don’t need to be a douchebag. I was really just asking an innocent question that I now regret having asked. Just let it go.

I think your questions are totally valid, and I also think it's important for us to point out that the biases that always accompany sighted listening are not limited to the inexperienced listener. Even the most seasoned audiophile, speaker designer, amp engineer, musician, producer, mixer, or mastering engineer is subject to these biases.

I don't know if the difference you heard was the result of biases, to be clear--it could be something else like impedance mismatch, volume difference, some EQ or DSP application--but if it was bias, it's not your fault and it's not a sign of your relative inexperience

 

[Jim Taylor]

I guess I didn’t expect the hostility and condescension as a new member here. It’s off-putting.

It's not hostility, and it's not condescension. WE ARE TRYING TO HELP YOU AND EXPLAIN YOUR CIRCUMSTANCES.
ASR is a data-driven site. Data is the raw material of scientific investigation, and scientific investigation is what yields scientific ANSWERS.

Please don't be offended. One of the aspects of science is that it is dispassionate, or devoid of emotion. Centuries ago, superstitions based on emotion were used to explain the natural world around us. People trusted myths, "voodoo" and old wives' tales. Science changed all that. It produced results that were reliable and transferable from one person/place/time to another person/place/time. Science allowed for prediction. Science fueled the transformation from "hovels and horses" to the world we see around us today, with all its technical advances and conveniences.

But science didn't do all these things by entertaining ignorance, emotion or bias-driven opinions. It did it with logic, discipline and structured thought.

So that's what you see here. What you term "hostility" is actually the language of the logic, discipline and structured thought that I mentioned. It's not at all personal. But you need to remember that decades of audio recording, astronauts walking on the moon, MRI that detects cancer, crop yields for populations that were formerly starving, and cell phones and GPS that work reliably were all brought into being by the Scientific Method, not by opinions and emotions.

Welcome to ASR! There is a lot to learn here. Please join us in the job of verifying audio characteristics and solving audio problems ..... with science.

 

[rwertz]

Thanks. I’m well-versed in the scientific method and am a medical scientist by profession. I get it. In retrospect, this was the wrong forum in which to ask the kind of question I had asked.

 

[JSmith]

Hi, I'm a newbie and really don't know a lot about audio, but I do love to listen to music and have read a lot of discussion here regarding choices of amplifiers.

Hey, welcome to ASR.

When I listened to my Bluesound amp I thought it sounded good, but I when listened to the same speakers with a Luxman 505Z, I thought it sounded much, much better.

Why is this?

One was probably louder... just a slight increase in level is usually perceived as better. Due to echoic memory being around 4s at best, quick switching and level matching is needed really to compare in this way.


JSmith