The skeptics thread

You are going to have to tell people what speakers you use, which avr you have, how loud you listen to music. with efficient, easy to drive speakers at moderate volumes you'd be hard pressed to hear a difference. With inefficient speakers, with wild impedance swings, and loud volumes you could likely hear a significant difference.

I probably won't follow this thread much. Have fun. Consider buying with a 30 day trial and finding out for yourself.

I'm enough of a skeptic that I generally buy amplifiers and speakers that I have never heard before I buy them. I've been doing this for decades and it generally works out quite well.

Along the line I've bought a number of speakers and amps early in their life cycles that ended up being classics in the industry.


I personally don't go there. If I want a 2 channel system, I build a 2-channel system for reason of limited resources. However I have friends - other skeptics that have applied this logic to 5.1 and 7.1 AVRs. The results are gorgeous-sounding systems.


The thresholds for minimal cost but good sounding and excellent measuring equipment keeps dropping.

From the slightly uneducated, non-expert perspective I would say the biggest difference is in features and capabilities, things like codec support, DACs and digital audio formats, room correction. That said, I've not bought into the argument that amp A makes a huge difference over amp B - as long as it's good clean power.

This conversation should be educational, I wish you luck in its success.

The skinny...

Two amps certainly can sound different. Grab any of a number of tube or SET amps, and a "good" solid state amp, and the difference is easy to prove under normal listening conditions.

Additionally, there are amplifiers underpowered to drive the desired speaker to the desired volume.

There are amplifiers incapable of driving the necessary load without failure.

There are rare examples of otherwise competent amplifiers having stability problems with certain speaker and/or speaker/wire combinations.



However, to get an amplifier to sound indistinguishable from an uber-exceptionally well engineered reference amplifier is not expensive, and there are literally thousands of examples on the market spanning everything from budget AVR's to ultra-expensive audiophile brands.

The biggest factors are making sure the amplifier has enough power and can tolerate the load your speakers present with measured distortion below what is accepted as an audible threshold. Got to run for the moment, I'll try to look at your specific combination later. I suspect it is fine.

One of the things that separates skeptics from true believers in audio is that skeptics do not rely solely on their own experiences, because they understand that personal perceptions can be very misleading. I once had the green pen effect demonstrated to me in an audio store, and yes it sounded better with the CD treated. Which taught me how much I should "trust my ears."

I always start by asking two questions:

1) Are there published listening tests conducted with some semblance of scientific rigor demonstrating that differences within a particular category of components can be heard?

2) Are there measured differences within a particular category of components large enough to suggest that there would be audible differences as well?

If the answer to both of those questions is no, then I generally assume that there are no sound quality differences within that category. For solid-state amps, there are conditions under which they can sound different (e.g., clipping), but otherwise they do not seem to.

To me this is the point lost so often on so many audiophiles who fall for the marketing hype and the "expensive is better" mentality when evaluating potential purchases, particularly for amps and integrated amps and receivers.

The bottom line is that once you get above a certain floor regarding relevant specs, a competently built amp operating well within its limits (not clipping, not overheating, not being overloaded) is going to be audibly transparent. What is not generally known among audiophiles is that the barriers to entry of building a competent amp are very low. Massed produced amps made in China can easily sound audibly transparent. Thus, "good" amps can indeed be very inexpensive. Spending obscene amounts of money on a better engineered and better built amp does not necessarily result in better sound. Very often there is little to no audible difference in transparency between them, except that ironically, the uber expensive amps often are not audibly transparent, as they have been deliberately built to color the sound. This is not a desirable characteristic for an amp, unless you knowingly prefer a colored sound to an audibly transparent one for personal reasons.

Anyway, for some reason this minimal floor business reminds me of an old joke. I hope its relevance makes sense here, as the analogy is not meant to be literal, but illustrative of the minimal floor concept.

What do you call a medical school graduate who finishes at the very bottom of his class?

Doctor.

A lot of common knowledge about what sounds different is based on history. Back in the days of tubes, power amps were more likely to sound different than preamps. In those days a lot of things had good strong measurable reasons to sound different. Once it became reasonably perfected, SS gear by its very nature tended to sound less different.

When comparing receivers and integrated, one big difference it that surround receivers generally pump the audio through DSPs, while integrated amps tend to let the signal stay in the analog domain. It turns out that these days keeping audio in the analog domain is no guarantee of better sound quality.

In terms of noticeable audible differences, the most obvious of those are due to things like channel balance variations (channel tracking) in volume controls, which are zeroed out in receivers with DSPs because the volume controls are implemented in the digital domain.

Good question, and a tricky one. Preamps and digital processors (i.e., AVRs) are designed to sound different—or, rather, are designed to allow the user to alter the sound. And different units will offer different options.

The point is that the basic analog electronics (and DACs, while we're at it) will not impart a "sound." Turn the DSP off, set the tone controls to flat, and match levels precisely (very important!), and two AVRs will likely be indistinguishable, just as two amps would be.

Different, because tube amps generally have much worse fidelity.


Amps of any class can sound good or bad. I'd never buy a Class A power amp because those are huge power wasters with no audible benefit. Conventional Class AB (and newer Class D) amps can sound excellent.


Most components are fine unless they're defective or poorly chosen (lame design).


I have a receiver.


I have a receiver.


Yes!


My upcoming book (link below) was written just for people with questions like yours.

--Ethan

My system is rather expensive and yet I join many here who believe that all modern day amps sound pretty much the same.

I spent heavily on my integrated amp (McIntosh MA6600 which was $6000) because I'm obsessive about industrial design, fit/finish, ergonomics, and the timelessness of a design. I've always admired the look/feel of McIntosh gear and resolved as a young adult to one day own one. My friends think I'm insane, but I listen to music 2-3 hours/day, whereas they use their Harleys, wave-runners, or bass boat, etc..a few times per year!

But I don't kid myself about my amp sounding better than the AudioSource AMP100 ($89 from B&H Photo) that resides in our bedroom when listening at normal levels. ..But though it doesn't sound better, it definitely feels much nicer to use! ..That said, there are differences that can be audible in certain circumstances. ..For ex., volume tracking on the Mac is perfect all the way down to zero-gain, and I hear no signal bleed b/w inputs, nor hiss/hum b/w songs. ..But no one would ever hear any of this while listening to music.

Nothing wrong with that. I agree with your reasoning and justification as well.

The key thing about amplifiers is to understand that amplifier performance is synergistic with the speakers.

In general, lower powered amplifiers (and tube amplifiers) have a higher output impedance, which means that they interact with the varying impedance (and reactance) of the speakers to a greater degree than those amplifiers with a very low output impedance.

This can result in non-linear frequency response, and in the case of highly reactive speakers it can also cause the amplifier to distort. This is not very surprising if you look at the frequency versus impedance curve of a speaker, where it is common for the impedance of a given speaker to vary from 3 ohms to 20 ohms at various frequencies, and the phase shift of speaker voltage and current to be as much as 45 degrees. Some amplifiers behave very badly when the speaker shifts the current phase that much.

For example, many speakers have an impedance "bump" in the upper midrange and low treble area where the impedance often goes as high as 20 ohms. This will tend to make the speaker/amplifier combination have more output at these frequencies, which is often characterized as a "forward" or "bright" sound. This is of course more of an issue with a smaller amplifier that has a higher output impedance, which reacts more to the change in load.

This characteristic may be attributed to the amplifier OR the speaker sounding "bright", when in fact it must be looked at as the characteristic of that speaker in combination with that amplifier; the blame is due to the way they interact ( the quality of the speaker drivers etc. is of course an issue also).

The reason higher-powered amplifiers tend to sound better often has very little to do with the higher power per se (which is often unused), and more to do with the very large power supply and and resulting low output impedance of the amplifier. This makes the amplifier capable of maintaining a relatively constant output even when the speaker impedance and reactance vary a lot over the audio frequency range.

There are some higher-priced amplifers that do not have terribly high power ratings, but still sound very good with a wide range of speakers. This is often because they have larger power supply transformers and capacitors than other amplifiers of similar power, which lowers their output impedance.

Also, it has been found that coupling capacitors in the signal path cause distortion, and more expensive amplifiers use quite expensive capacitors to eliminate the audible loss of quality cheaper ones cause.

The factors commsysman mentions are measurable.The problem is that he completely ignores the actual measurements. When you look at the actual measurements, you discover that in practice these factors have only a small measurable effect, far too small to have audible consequences, at least for conventional solid-state designs. The usual caveats apply.

But people who sell high-priced gear do not want you to know that.

The above would seem to imply that the amplfier's performance is always changed in audible ways by the attached speakers. If that is what was meant, then it is not representative of the modern world.


Conflating tubed power amps and low power SS power amps is a bad idea. There's no reason why a low powered SS amp would have a high output impedance, and the test bench and listening room confirm that in the vast majority of cases.


The good science: An amplifier with a high source impedance will have frequency response variations that are related to the frequencies where the speaker load presents a low impedance load to the power amplifier.

The bad science: A high source impedance can actually reduce the tendency of a power amp to distort with a reactive speaker because it won't apply high current to the speaker in order to get the reactance under control.


The confused science part 1: Reactive loads can cause problems two different ways. Reactive loads can cause a poorly-designed amplifier to become unstable and oscillate. The oscillations can build up and damage the amplifier and/or the speaker. This is rare in modern amplifiers. Reactive loads can cause problems even with amplifiers that are stable. Loads that are both reactive and present a low load impedance can cause overloading in output transistors of a special kind called Secondary Breakdown. Modern amplifiers generally use output devices that are resistant to this problem. Back in the early days of SS amplifiers, output devices of this kind pretty much didn't exist, and damaged amplifiers were more common.

The confused science part 2: It's not load reactance that causes durability problems, its the combination of a low load impedance and lots of reactance in the load that causes durability problems. This is important because there are speakers that are very reactive (inductance or capacitance) at some frequencies but also have high impedances at those frequencies.


Same problem as I pointed out above. The idea that a low powered SS amplifier necessarily or commonly has a high source impedance is simply false.



In modern times the previous several paragraphs are a lot of discussion of something that is now pretty rare with SS amplifiers. Fact is you can assume that in general a power amp won't have its operation audibly affected by the loading caused by almost all speakers, and you will be right.

Tubed amplfiers come in 2 kinds - those that are trying to act in the way that good SS amps do more-or-less naturally, and those that are trying to go the opposite way as good SS amps. The latter kind of power amp is frequently called a SET or Single-Ended Triode. Seriously, these amplifiers pretty much look just about everything that is known about designing good power amps in the eye and run in the opposite direction. Interestingly enough, you can simulate much of what they do by simply hooking a power resistor between 3 and 20 ohms in series with your speaker, and hook it to a good SS power amp.


The above paragraph is pretty much 100% audiophile myth. The low output impedance of SS power amps is readily achievable with fairly modest power supplies. The actual source of the low output impedance is the output stage design. The circuit features that lead to low output impedance are local and global inverse feedback in and around the output stage itself.


The audiophile myth faucet seems to now be fully turned on. ;-)

I've done some bench and listening tests where I intentionally took a relatively low powered power amp (car stereo - about 30 wpc) and experimented with various power supplies. One of the power supplies I tried was designed to power a laptop computer and could only put out a couple of amps before it would trip out its short circuit protection. I could clip the amp out at its usual power level for clipping with a stout power supply, without tripping out the laptop power supply because music has a high peak to average ratio and the average current drain was low. The whimpy power supply had no effect on the power amps output impedance or ability to develop high peak currents into reactive loads.


Actually, it is common to build power amps with no interstage coupling caps at all, and perhaps just one input cap to block DC that might mistakenly come from the signal source. As long as the capacitor has a large enough capacitance to not significantly decrease the low frequency response of the amp, the distortion being speculated on above just doesn't happen.

As a rule perfectly adequate capacitors are widely sold for reasonable prices. The idea that special "audio grade" caps do any audible good is yet another audiophile myth. I've never seen an audiophile capacitor upgrade article that showed any objective improvement in performance over the same piece of equipment with ordinary capacitors in good condition. It is possible for capacitors to fail in use, and broken capacitors are like just about any kind of part - broken ones can make equipment fail to reach its potential.

I've always wondered about those who send off equipment for things like cap upgrades, then claim significant audible benefits when they get said equipment back and listen to it. The thing is, the turn-around time is often several weeks.

So how exactly do they remember exactly what the unit sounded like before? How can you compare something to something you heard several weeks prior?

It seems like a clear-cut case of psychological bias influencing the determination.

^^^

cash leaving wallet has long lasting resonances...

Ha, yep.

I sold a used amp a few years ago locally. The guy said he was immediately sending it off to upgrade the power supply caps - not with bigger caps, just a different brand "that sounded better." I didn't want to lose the sale so I didn't say much.

No unless you're clipping your old amplifier and the new amplifier has enough power to avoid that although more sensitive speakers are arguably a better solution (double the amplifier gets you 3dB of headroom, moving from 86 to 92dB gets 6dB as if you were running with 4X the power and more efficient speakers can net 10dB like upgrading a 100W amplifier to 1000W).


Sure.

This ignores the use of audiophile amplifiers that produce non-flat response as a design artifact (notably tube amps without global feedback that causes a high output impedance) although on a budget you're better off achieving the same effect with an equalizer and the right solution is better (but not necessarily more expensive - you can spend less and get more) speakers with more bass extension (instead of compensating for a lack of low frequency response by boosting harmonics around the speaker's resonance) and more uniform polar curves (instead of trying to tweak the on-axis response to compensate for off-axis variations).

I personally run a pair of actively tri-amplified systems.

Each channel in the Pluto+ bedroom setup has an LM3886 on the tweeter and pair of LM3886 chips in full-bridge configuration on the midrange with 35V unloaded rail voltage, 4 degree C/Watt heat sinks on each, and a 50 VA transformer with a 500ma fuse (it only blew once we got mad at the neighbors and turned it up to the point that the tweeter was strained). This is pretty much the opposite of "audiophile" amplifiers - you can fit the transformer in the palm of one hand and the heat sinks in the other. When I did the back-of-the-envelope calculations on thermal dissipation I came up with 10-20 FTC Watts although at 60V peak the midrange amp matches an amplifier rated at 225W into 8 Ohms. An Adcom 545ii stereo amplifier rated at 100W into 8 Ohms drives the 10" woofers each in a .5 cubic foot box equalized to be -3dB @ 30Hz and -6dB @ 20Hz.

Four Adcom 545iis run the living room Linkwitz Orion system - one each for tweeters, midranges, top woofers, bottom woofers. Three would do the trick but I have extras lying around because the home theater equipment isn't currently setup. They're safer than more powerful amplifiers because they clip before running the bass drivers to the mechanical limits in more situations.

I used the same amplifiers plus a 555ii which bridges (FTC rated at 200W into 8 Ohms) to drive sub-woofers with more output and a Lexicon DC-1 (Logic 7 does a great job on surround, all THX pre-amplifiers have a sub-woofer peak limited built in, and I couldn't get that functionality in a receiver) for home theater when that was last set up.

The Adcoms run about $200 each used, I think the oldest has been running reliably for about 17 years, they're stable into 2.5 Ohm loads, didn't overheat in that situation. and pretty much seem to just work.

Regarding caps in the signal path, the fewer definitely the better.

Electrolytics (tantalum or aluminum) make poor choices for caps needed in the signal path. They have a "lifetime", ie. they age. Many are rated by their manufactureres for only 1000 hours. Old electrolytics will eventually become high-pass filters if they are used in the signal path, even if they were transparent to the audio range when new.

At 85 or 105 degrees C (hotter than boiling water). Life doubles with each 10 degrees C lower. At a pleasant 20 degree C room temperature a "1000 hour" capacitor is good for 90,000 hours or 10 years of continuous service. 2000 hours is more typical which nets 20 years. Most people turn their equipment off when not listening and will find their electrolytic capacitors much longer lived.

http://www.tom-morrow-land.com/tests/ampchall/index.htm

and:

http://www.matrixhifi.com/ENG_contenedor_ppec.htm

syd123 has it exactly right. There are, for some people, good reasons for spending more. But they are not audible.

Cheers.

Ah fidelity, that's the ticket.

Not to worry about a much better listening experience. Which is key to why tube amp/pre/integrated are still around.

The downside is constant futzing around with the amp tubes!

Whereas tubes for preamp are more stable and less of an issue.

Just some personal observations that seem on topic.

So count me as a skeptic to the "goodness" of sound via solid state.

But FWIW my current setup is an all solid state setup.

But I got off on the tube tangent due to Winer's comment that I quoted.

As long as there are enough!


Engineers use electrolytics for one reason - every other approach is impractical. Consider the size and cost of the *smallest* electrolytics in general use as coupling caps - 10 uF. Generally, a film cap solution for the same application is impractical due to size and cost.

Now consider the size and cost of the typical electrolytic cap in general use - several thousand uF. The film cap alternative is completely ludicrous!



???????????


I've seen electrolytics work well after 40-60 years.


Modern electrolytics are so reliable that the equipment containing them will probably be obsolete before they fail.

Admittedly, there was a time several years back when a lot of electrolytics failed early, but that was due to misappropriation of incomplete stolen technical information. That comes under the heading of "stuff happens".

My general take is that if you've done your homework before you go shopping, and you buy the suitable/appropriate product the first time, it shouldn't matter beyond that. Generally doing your homework right will mean fairly "modest" or "humble" equipment. I do understand the argument on page 1 about buying a McIntosh for aesthetic reasons (having used a full McIntosh theater before, it's quite an intimidating rack to walk up to and play with); that's a personal choice (just like driving a sports car).

Regarding the more direct question about AVR or something else; I'm not really worried about it. I think for the most part, AVRs really do what most people need for them to do (including lots of people who assert separates the "only answer"). The older one versus the newer one probably won't do a whole lot worse job if you aren't comparing room correction and if bass management isn't a big problem (this depends on how old we're talking too) - if they're just being treated as "Straight through" stereo receivers/amps, assuming both of them can handle the speakers you've got (back to the homework), shouldn't be a problem. I also don't have an issue with the notion of using a bazooka to kill a raccoon, as long as you aren't paying substantially more for the bazooka (or if you get it for less than) relative to a switch or small rifle or something.

Stereo-only products are equally capable, but generally the lack of options/features relative to their price (which has just gone through the sky in the last few years) turns me away. That said, I'm still keeping my older receivers.

It's well known that some people prefer the colored sound of tubes (and transformers and vinyl and analog tape). I certainly don't prefer that, at least not in a playback system. I do use distortion and EQ as effects when recording and mixing. But once a mix (not only mine) sounds as intended, from there on fidelity should be high to avoid changing the sound further. Otherwise you're not hearing the artist's intent. At least that's my approach. Others are free to do as they please. If someone likes the sound of additional distortion, and the skewed response of typical tube power amps, who am I to say otherwise? I address mainly fidelity in my posts, not subjective preference.


LOL indeed.

--Ethan

While my speaker wires are marinated in snake oil and the equipment is dusted only with Ostrich feathers, I really just want the sound to be as clear and undistorted as untrained ears can distinguish. Thanks, everybody, for your wisdom and I doubt I'm the only unwashed commoner listening in.