Why Audio Amplifiers Can Sound Different

[ski2xblack]

Are you listening from the same place as you were when playing the instrument(s)? It's hard to play something AND hear all of the nuances that are audible to a critical listener because the player is in one position and it's different from the prime listening seat. I think this would work as the person recording the sounds, as long as the initial test is mono. Once someone adds one mic, it changes everything WRT the recording AND how the sound couples to the room- adding a speaker changes it again.

And yet, we try.

A single instrument, playing a single tone, note, or beat, or even a typewriter, makes it quite easy to compare between the real thing and the recording. I like to keep it simple as this test is sort of a crude but effective I/O comparator. The snare drum test is more about dynamics, a tougher test than a typewriter, but still, if a rig cannot pass a simple test, it will probably flail on complex material.

 

[TLS Guy]

Before I leave for England in 30 min, I would say this.

Tube amps are class A, basically because a tube is not a good enough device to tolerate A/B biasing. So they have power limitations.

Most solid state amps are quasi complimentary A/B biased, so one would expect a similarity.

It would not be surprising if novel designs and approaches sound different.

Measurements of amps are into resistive loads. So that is all it tells about the amp.

Measuring under real world conditions is difficult, and not possible to standardize.

Until we go to active designs and design the output and speaker as integral we will not make progress here.

I'm certain that designing my speakers around one particular type of topology has significance in my situation, but no general applicability to the situation as of now.

 

[sharkman]

Speaking of Golden Ears:


Blind Testing, Golden Ears, and Envy. Oh My!

http://www.audiostream.com/content/blind-testing-golden-ears-and-envy-oh-my

The trouble with all this stuff is there is a ton of snake oil.
I do believe we all have very different acceptable price windows and not all objections are based on Envy.
Often peoples visceral reactions are based on the "Stop me before I kill again" mentality; the need for there to be no differences so they can stop worrying and enjoy their system.
IMO, everyone is a subjectivist since they often site their own listening experiences to point to invalidate the experiences of others.

Concerning measurements, not many are measured into resistive loads.
When it is done, it use usually with a monstrous amp like the XPR-1.
I have not seen reactive load measurements with an AVR.
Even if done, that would not be "fair" in that reviewer might pick a load that is not representative and unduly pan products.

IM may be underestimated. HomeTheaterHifi stated in a review IM distortion was calculated including products +/-250hz of the tone.
They pointed out the need for examining the full FFT plot, which AH does as well.
If that is correct, the industry might like it but it does not make sense for audibility of IM distortion.
If an amplifier driving a reactive load fails to deliver the instantaneous power required, this is not considered distortion even though it is not accurate and will alter the sound reproduction.

Even though I have heard amps sound different, source components make a bigger difference in my system.

- Rich

I'm not sure why this concept irritates some so much, but there you are. Amps can sound different, it's not the end of the world. In these double blind tests, the subjects should first be tested as to what their hearing skill/ability is. People that can't sense or determine whether a note is slightly flat or sharp are not going to be able to tell anything of value.

 

[highfigh]

My wife is a drummer, so I have several recordings of her drum kits. Her 22" kick drum moves a lot more air in a residential sized room than one would expect from most recordings. I've also become very picky about how high frequency drivers reproduce cymbals. Wood on brass is a very distinctive sound that most people can instantly recognize as sounding real or not. Most systems don't sound real on dark ride cymbals and chinas.

We have a piano in the house, though not in my listening room, and I've recorded that. Pianos are very revealing of the bass to midrange crossover, and exaggerated bass, like a lot of folks apparently like to listen to here, sounds horrible on an acoustic piano recordings. Like it's two different instruments playing. Pianos produce quite a bit of bass, but it is subtle and foundational to harmonics.

My wife also plays the vibraphone, which has some cool room acoustics imaging effects. You notice them more in the recording, perhaps because you're not focusing on watching the musician play.

My step daughter plays the flute (she has a degree in flute performance), and she has played along with a recording of herself standing between my speakers. That was super cool.

A slammed car door is another cool test.

I use drums and human voice a lot, especially if it's a recording of someone I know. I play guitar and bass, so there are some precise sounds that I use as references. I was listening to a CD and at one point, it sounded amazingly similar to my guitar and amp, which is a pretty good trick because I haven't heard one that sounds exactly like it and guitar amps are very sensitive to component changes because the circuits are so simple.

Any discussions where people say "I want it to sound EXACTLY like it did when they recorded it" are moot. It's incredibly unlikely and, unless they can duplicate ALL of the equipment, the room, the number of people and their positions in the control room, etc, it won't happen. When the whole system is different and it's blasting in someone's basement, just, no. Also, a lot of audio systems sound great, but they don't sound REAL. Real drums and cymbals DO NOT sound sweet and polite, most of the time. A cranked guitar amp isn't something most people want to be near. Most systems don't quite capture the real sound, just the processed sound and that's because people won't want to listen to albums, CDs, DVDs, BD, etc if it sounded absolutely the same as the original.

One of the details I'm hearing with the new preamp/power amp is cymbals, which now sound more real- not a distorted sizzle, they sound more metallic and authentic WRT wood (or nylon tips) on brass. Then, there's the difference between drummers and recording labels. Remember the sound of many 1980's ECM recordings compared with Atlantic, Columbia, Blue Note, etc? The 2008 Return Forever live video at Montreaux is an interesting example- want to compare notes on the sound of that one? I watched it on Qello from a Roku. Weather Report's 'Sportin' Life' is another one that I had forgotten about because I wasn't able to listen to my vinyl for so long- won't be a direct comparison because of the different cartridges, but it's a good-sounding album.

These differences could be the AVR's preamp, power amp, processing, a combination.... but it's not the same.

 

[Irvrobinson]

Any discussions where people say "I want it to sound EXACTLY like it did when they recorded it" are moot. It's incredibly unlikely and, unless they can duplicate ALL of the equipment, the room, the number of people and their positions in the control room, etc, it won't happen.

Yeah, but that is exactly what I do when making my own recordings. I won't say that I can't tell the difference between the original instrument and the recording, because I can, every time. But much of the difference is because I am recording in a typical room and the room's acoustics are produced twice when playing a recording. But I can get awfully close to live. For orchestras and such, or any performance in a large venue, any hint of "live" falls apart. It becomes more of a "reporting" experience, if you know what I mean. But if it fits in a room of my house, the reproduction can be uncanny. Especially cymbals. That was a big factor in my speaker selection process.

 

[Irvrobinson]

Before I leave for England in 30 min, I would say this.

Tube amps are class A, basically because a tube is not a good enough device to tolerate A/B biasing. So they have power limitations.

You lost me here. Most tube amps are class AB.

 

[Irvrobinson]

It has been shown by naughty people like myself that folks claiming to be able to hear differences when aware of what they are listening to, suddenly lose that ability with blind tests.

I completely agree, and that includes me. Even in sighted direct comparisons I have trouble discerning between most electronics. The problem is that for long-term listening I find that I suffer much less from listening fatigue with some electronics than I do with others, especially amplifiers. That tells me that blind testing might be masking critical information. I might just be imagining things, but I can't explain the effect any other way.

 

[highfigh]

Yeah, but that is exactly what I do when making my own recordings. I won't say that I can't tell the difference between the original instrument and the recording, because I can, every time. But much of the difference is because I am recording in a typical room and the room's acoustics are produced twice when playing a recording. But I can get awfully close to live. For orchestras and such, or any performance in a large venue, any hint of "live" falls apart. It becomes more of a "reporting" experience, if you know what I mean. But if it fits in a room of my house, the reproduction can be uncanny. Especially cymbals. That was a big factor in my speaker selection process.

I was referring to recordings from studios.

Reminds me of when I recorded a band very soon after the Sony PCM-F1 digital recording processor hit the stores in about 1981. I used two Audio Technica mics, crossed coincidentally. I listened with headphones as I was setting up and when I listened to the result, it captured everything very well, including the bad acoustics. I made cassette copies for the band members and myself and unfortunately, I don't know where the original Beta cassette copy ended up. Fast forward to about '98 and i needed to have some work done on my car, so I rented one that happened to have a cassette player. The next day, I grabbed a few tapes and went to work. As I drove, the tape started and even before the band started playing, I got the strange sensation of being in a place that was much larger than the Mitsubishi Gallant I was driving. The first notes of the music started and I realized which tape I had chosen.

 

[ATLAudio]

Some amp generalizations I've put together. Not inclusive

A stereo or mono block amp will usually sound better than a multi channel amp

A class A amp sounds fantastic at low volume, or with efficient speakers. The First Watt amps from Pass Labs are a good example.

A class D amp is great for subs

Amps with technology that utilize more of the class A portion of an AB generally live up to their billing. Emotiva makes one.

You don't have to spend a bunch, but generally 'audio jewelry' comes into effect past the $3k line. Or at least I haven't heard the benefit. That said, if I had the money I'd have me some more audio jewelry. I'd love to see some McIntosh needles bouncing around, or some tubes glowing... But alas.

 

[ATLAudio]

What's everyone's favorite Amplifer maker?

For the money I've always liked Nad. I'd also do McIntosh if I had the money for it.

 

[RichB]

^^^

Parasound and ATI are on the top of my list. I can't justify much that costs more although the price of amps seems to rising as the market shrinks.

- Rich

 

[Irvrobinson]

What's everyone's favorite Amplifer maker?

For the money I've always liked Nad. I'd also do McIntosh if I had the money for it.

I don't have one anymore. I used to have three favorites, Mark Levinson when they were owned by Madrigal, Krell when it was run by Dan D'Agostino and his ex-wife, and Threshold when Nelson Pass was there. Over-engineering ran rampant, and everything was built in-house by hand. Awesome engineering teams.

McIntosh can't do it for me until they get rid of those dumb output transformers.

 

[ATLAudio]

I don't have one anymore. I used to have three favorites, Mark Levinson when they were owned by Madrigal, Krell when it was run by Dan D'Agostino and his ex-wife, and Threshold when Nelson Pass was there. Over-engineering ran rampant, and everything was built in-house by hand. Awesome engineering teams.

McIntosh can't do it for me until they get rid of those dumb output transformers.

Isn't the Output Transformer sort of their thing?

 

[ATLAudio]

I also like Audio Research on the top end. Especially their tube integrated designs.

Also for the budget buyer Emotiva can't be beat.

 

[AcuDefTechGuy]

Agreed, but only up to a point.

A truly "accurate" system is no small achievement. I'll bet very, very, very few folks ever get there. But i seems a safe assumption that everyone with a stereo finds enjoyment in listening to their music collection, even if their playback rigs are not monuments of accuracy.

Seriously, the more I think about it, the more accuracy in the context of this weird hobby seems hopeless. We start out with source material that lacks any sort of established standard, and which reflects who knows who's idiosyncratic tastes, leaving us with a broad range from excellent to crap recordings. When we play these "box of chocolate" recordings, we're probably not using the exact same speakers, nor in exactly similar acoustical environments as the music was mastered in. Our systems, primarily the speakers, and local acoustics will add their own coloration. I could go on, but you get the idea. In this context, amps with distinct sonic qualities are small potatoes.

End of the day, all I really care about is if it sounds good.

I'm with you there.

Much to worry or brag about nothing.

I think most of us understand why each person may have a different preference. I prefer my system. You prefer your system. Everyone prefers his system. It's all good.

I think my system is extremely accurate, and I think everyone cares about having the most accurate system, but we just want everyone to shut the heck up and enjoy the music and not bore us with why their systems are more accurate and better than everyone else.

 

[highfigh]

I'm with you there.

Much to worry or brag about nothing.

I think most of us understand why each person may have a different preference. I prefer my system. You prefer your system. Everyone prefers his system. It's all good.

I think my system is extremely accurate, and I think everyone cares about having the most accurate system, but we just want everyone to shut the heck up and enjoy the music and not bore us with why their systems are more accurate and better than everyone else.

But asking 'Why?' is one of the first steps in understanding.

 

[Irvrobinson]

we just want everyone to shut the heck up

We do? Everyone? Well, so much for the forums.

 

[Irvrobinson]

Isn't the Output Transformer sort of their thing?

It is. Gotta love those huge meters though.

 

[ski2xblack]

ADTG, it has nothing to do with bragging, and I find the discussion between Highfigh and Irv to be rather insightful. They're shining a light at the outer envelope of what's possible in this hobby. This thread has some meat on the bones.

 

[ski2xblack]

ALTAudio, I wanted to respond to your post about generalizations, which I gave a rainbow as it seems to reflect some marketing memes more than practical realities. I'm not an engineer, just a music loving techno geek who has gone down the class A rabbit hole pretty far, so take this fwiw, ymmv, and all that.

Class A amps general attributes have been described many times. By virtue of their superior performance at low output levels, they are about letting through that last bit of detail from the recordings, particularly of the subtle aspects of the recording contained down low (e.g. the wetness of the acoustic space the recording was captured in, which, along with other things, will determine the general soundscape painted in your mind). Some of them really do seem to let more detail from the recordings through. Of course the speakers must be up to the task, and room acoustics must be sorted well enough to not get in the way, but yes, for that last little bit, class A benefits are real, and manifest in unexpected ways, such as better imaging.

Here's where my experience conflicts with the marketing. In my experience, again as a hobbyist, any circuit that relies on phase splitters invariably fails to pull off the much touted class A sound, which includes tubes and ss pp types hard biased into class A operation. My level matched comparison of class A ss amps bore this out, and since then I've built a few tube amps which also seem to follow this trend.

The only single technical aspect that is common among the amps I've heard that do manage to pull off the class A performance are those that are truly single ended class A. This lands us squarely in the quirky realm of Nelson Pass' First Watt amps, SETs, and a few other off-beat approaches. Most of these come with glaring technical flaws (low power, higher distortion, higher output impedances, etc.) making them behave as much processors as amplifiers, which complicates any attempt at level headed discussion.

While I have yet to hear one, TLS' preferred current dumpers qualify as they too have zero inherent crossover distortion, and lack the flaws of the odd bird First Watt and SET sort. They're quite different from the bulk of amps marketed as class A that are just a/b biased into class a.

So, in a nutshell, IME and IMO, it's all about the crossover distortion and technical trickery required to combat it on the one hand, and approaches that simply avoid the issue completely on the other.

My advice? Carefully consider all this stuff before spending money on heavily promoted class a, for the sake of class a, as they all don't perform the same trickery.

Now let the red chicklets fly.