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Advice for Beginners - consider this test from an audio club

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2 hours ago, Don Richard said:

 

Simple explanation:

 

If the input impedance of an amplifier is too low relative to the output impedance of the source device, frequency response will be affected, usually resulting in less bass.

 

If the output impedance of the amplifier is too high the output voltage will track the impedance of the loudspeaker, which varies with frequency. Such an amplifier that will show a flat frequency response with a resistive load (resistance doesn't vary with frequency) and a variable frequency response when connected to a loudspeaker.

 

I have never heard of this $10K amplifier challenge before this thread, and my reading of his rules is if one of the two amplifiers has an EQ circuit in it that cannot be bypassed, then the other amplifier has an EQ curve identical to the first amplifier inserted into it's signal chain. The first amplifier could instead have an EQ inserted to "unEQ" it's non-bypassable EQ if desired.

Learned something new today.  

 

So by that rule is the $10,000 challenge fair and valid?  Has he inserted a condition that can easily be met by amps of both typea, or has he inserted a condition that cannot reasonably be expected to be met?

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Just now, USNRET said:

I haven't seen the length of the conveyor belt in question.
 

That's because it's imaginary. 

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23 minutes ago, dwilawyer said:

That's because it's imaginary. 

So infinite (just to make sure that forward movement along the "short" belt does not interfere with reaching V2 / Vlof before falling off the belt into molten lava). The aircraft simply needs enough airflow across the wings' airfoil that will counteract the gravitational pull (disregarding drag and hydro-tension of rubber to belt which is assumed to be offset by the wind velocity). Matters not where / how that airflow is generated. A small headwind and prop wash kept my 1943 Aeronca Champ in a hover.
True airspeed vs ground speed

 

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1 hour ago, robert_kc said:

 

Thanks for the explanation.

 

I have no insight into the "Richard Clark  $10,000  Amplifier Challenge"  other than what ODS123 provided:

 

 

Do we interpret the highlighted text above to mean that there were two different conditions that might have caused Clark to insert an equalizer into the audio chain of one amp, in an attempt to make the amps sound similar?

  1. If frequency tailoring circuits cannot be completely bypassed, OR 
  2. If the amp's "input and output loading" affects frequency response.

On one hand, this seems to me to be pointless speculation.   OTOH, ODS123 cited the "Richard Clark $10,000 Amplifier Challenge" as strong evidence that all modern "linear" amps sound the same.   I'm wondering if this assertion needs to be clarified to say something like "all modern amps that are linear for resistive loads, and are linear when connected to a wide range of loudspeakers"?  If so, what's the difference between this statement and "In the real world, all modern amps don't sound the same?"


 

 

What I got out of the stipulations was that if one unit had an aspect which would cause different response with different speakers based on the speakers' impedance (like with a tube amp with high output impedance might), then the other unit was fitted with an appropriate output series resistor and the gain changed as necessary to match speaker output levels between them.  And if one unit had tone controls which couldn't be disabled while the other unit didn't even have tone controls, then the equivalent response curve was imparted to the other unit.  It could go either way which unit was so affected, by the test-taker's choice.  That's fair.  The test was about the sound of the amplification, so any other aspects which could cause discernment would have to be leveled between the units or the test wouldn't even be valid.

 

Say you've got a tube amp topology you "like the idea of" and this is what you want to go with.  But say also that it happens to cause an uneven frequency response based on uneven speaker impedance(s), and, naturally, you disparage the use of tone controls &c.  So, as a hobbyist, you find yourself moving from speaker to speaker until you find one with the "proper" "synergy" with your amp.  You could achieve the same thing by also using the speakers you 'like the idea of", regardless their impedance qualities, with proper equalization to get the tonal colorations which "connect you with the music" just the way you like.  Because this is really all you were doing by switching from speaker to speaker - finding one with an impedance curve which imparted the boosts/cuts where you wanted them - (usually) regardless how "flat" the final response actually was (without the use of nasty tone controls!).

 

You'd do well to spend a few minutes reading through the author of the test's remarks from some (car?) audio forum, compiled here. If nothing else, search for "yea guys" in the page.

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2 hours ago, glens said:

You'd do well to spend a few minutes reading through the author of the test's remarks from some (car?) audio forum, compiled here

Interesting read.  My takeaway is that there are differences in amps, but that when the differences are eliminated with various techniques, it is much more difficult to hear a difference between them.  It makes me wonder what it is, specifically, that makes me prefer the SET amps that I’ve built over the PP tube amps I’ve built and the SS amps I own.  I’m always looking for a sense of “being there” when I listen to music at home.  I get this with my SET amps, and with the SS Class A amps I own, more than with other topologies.  Stereo is an artificial construct, it gives us localization cues that, at the end of the day, are not the same as the cues created by a musician playing in real life in front of a listener.  It isn’t “real life”.  That said it’s the best thing I/we have available at the moment  (I haven’t given multichannel audio a go yet), and 95% of my music is stereo recordings.  Maybe expecting stereo, as an artificial construct intended to recreate real life, to provide this reality is asking too much.  It could be that strict linearity, and truthfulness to the source, shouldn’t be the goal at all.  The goal should be recreating the “reality” of a live performance despite the limitions of the construct we call stereo.  I don’t care about linearity per se, I care about what I hear in my listening room when I put music on my system.  A SET amp sounds more “real” than any other topology I have used in my set up. If that reflects a limitation, distortion or unlinearity created by my preferred topology, so be it.  Clark’s test tells us that when you make two different amplifiers sound the same, they end up sounding the same.  I don’t see how this is helpful.  It’s not what most people actually do.  When you go out and buy an amplifier, you don’t then take it home and put in a resistor and a equalizer to make it sound the same as the amp it is replacing.  Amps sound different.  Clark’s adjustment of the amplifiers in his challenge is a confirmation of this fact.  Some amps sound more “real”, when playing the stereo material that most of us listen to, than other amps when their differences are left intact.

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17 minutes ago, Tizman said:

Interesting read. 

 

Clark’s test tells us that when you make two different amplifiers sound the same, they end up sounding the same.  I don’t see how this is helpful. 

 

 I read it. I guess it is helpful if it saves money on an amplifier purchase, for people who just want straight amplification, not other individually desirable features. 

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11 minutes ago, Khornukopia said:

I guess it is helpful if it saves money on an amplifier purchase, for people who just want straight amplification, not other individually desirable features. 

I don’t think that’s true.  Clark makes amps that sound different sound the same for his challenge.  The amps don’t sound the same before he does this.  Because Clark needs to modify amps in order to make them sound the same for his challenge, amps don’t all sound the same.  Am I missing something?

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3 hours ago, USNRET said:

So infinite (just to make sure that forward movement along the "short" belt does not interfere with reaching V2 / Vlof before falling off the belt into molten lava). The aircraft simply needs enough airflow across the wings' airfoil that will counteract the gravitational pull (disregarding drag and hydro-tension of rubber to belt which is assumed to be offset by the wind velocity). Matters not where / how that airflow is generated. A small headwind and prop wash kept my 1943 Aeronca Champ in a hover.
True airspeed vs ground speed

 

No, its a trick question, the imaginary conveyer moves in reverse as the plane moves forward.  People confuse this with a car, which they are more familar with, and mistakenly assume the airplane will remain stationary regardless of the amout of power because on a car the power is applied at the wheel(s), usually rear, whereas an airplane applies power (thrust) seperate from the landing gear wheels.  As you apply power to an airplane it does not matter how fast conveyer belt moves in reverse, the plane will still move forward causing air to move over wing producing lift and will take off.  A car on the other hand will not move forward if the belt matchs the speed of tires and will remain stationary.  Groundspeed vs. Airspeed is what gets people sucked in, it doesn't have anything to do with the problem.

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Of course, some amps are going to sound more alike than others, and none of this has anything to do with what sounds best to an individual user on their particular setup.  

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13 minutes ago, Tizman said:

I don’t think that’s true.  Clark makes amps that sound different sound the same for his challenge.  The amps don’t sound the same before he does this.  Because Clark needs to modify amps in order to make them sound the same for his challenge, amps don’t all sound the same.  Am I missing something?

 

I don't even know if the amplifier challenge is authentic, so I am discussing it from a hypothetical perspective.

 

The way I understand the rules, the amps are not modified, but one might have its output signal equalized to eliminate tonal differences that would enable you to pick it out during a double blind test. 

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10 minutes ago, Tizman said:

Clark makes amps that sound different sound the same for his challenge.  The amps don’t sound the same before he does this.  Because Clark needs to modify amps in order to make them sound the same for his challenge, amps don’t all sound the same.  Am I missing something?

 

I'd say "Yes, you are."

What he's proving is that they DON'T sound different.  If you've got tone controls that don't quite go flat at "flat" that's not the amplifier sounding different, it's the pre-amp.  If you've got freq. response that varies disproportionately with impedance, that's non-linearity.

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13 minutes ago, glens said:

 

I'd say "Yes, you are."

What he's proving is that they DON'T sound different.  If you've got tone controls that don't quite go flat at "flat" that's not the amplifier sounding different, it's the pre-amp.  If you've got freq. response that varies disproportionately with impedance, that's non-linearity.

So Clark is saying that pre-amps sound different, but not amplifiers?  If the frequency response of an amplifier varies with impedance, it's the amplifier that is doing it, right?  

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12 minutes ago, Tizman said:

If the frequency response of an amplifier varies with impedance, it's the amplifier that is doing it, right?

 

A linear power amp should have a flat response into a fixed resistance. It is the variable impedance of the speaker that allows more current, or less current to flow out of the amp at different frequencies, affecting the acoustic frequency response we hear from the amp/speaker combination.

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2 hours ago, Khornukopia said:

A linear power amp should have a flat response into a fixed resistance. It is the variable impedance of the speaker that allows more current, or less current to flow out of the amp at different frequencies, affecting the acoustic frequency response we hear from the amp/speaker combination.

Yes and, if I understand it correctly, this will vary from speaker to speaker as the variable impedance of a speaker is going to vary according to the design of the speaker.  So, amplifiers will sound different depending on the variable impedance of the speaker used, and the way that the amplifier used reacts to this variable impedance.  What you are saying is that different amplifiers sound different from each other because of the variability of the non-linearity created by this interaction.  Doesn't this mean that given a particular set of speakers, different amps will sound different when used with these speakers?  As in "amps don't all sound the same"?   Also, doesn't this mean that an amps synergy with speakers is an important consideration when picking amplifiers because of the more variable nature, and the much more flawed linearity, of speakers?      

 

While I would like to better understand the perspective and position of the other side of the argument, it will have very little bearing on my future choices. This quote from Lynn Olson, although a bit out of context, pretty much sums up my perspective on the amplifiers and speakers that I use for my own pleasure....

 
"And 85~89 dB/meter audiophile speakers sound flat and dead once you get used to the sound of high-efficiency speakers. Even the Ariels at their modest 92 dB/meter made it hard to enjoy conventional audiophile speakers that are 3~5 dB less efficient. You just hear more, and it sounds more beautiful. Like direct-heated triodes, you don't go back.

It's about surrendering to the emotional experience, just letting go, no more thinking and analyzing, just allowing yourself to be swept away by the music. Not all audiophiles can do this. I've seen some of them, in my own listening room, hold their arms tightly across their chests, fighting off their emotions. Maybe they didn't like what they heard, but the sound quality was ravishing, far above anything at an audio show, and was certainly affecting me and Karna.

I'm kind of letting the cat out of the bag here, but I design audio equipment so the listener can have a deep emotional experience; the technical parameters are simply a means to an end, for the system to get out of the way."
 
For me, after a long trip through audio land, this (mostly) means SET amps and horn speakers for the flawed construct that we call stereo.  My goal is to have my experience of listening to a stereo recording be as close to a real life event as possible.  This is based upon what I hear when I listen to my setup, and how it allows me to connect to the music on an emotional level.  So maybe this means, "when listening to the flawed construct we call a stereo recording, all modern amplifiers engineered to be linear sound the same, and SET amplifiers sound better and are more emotionally involving".  If so, so be it.         

   

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Yes, that's what I was referring to earlier, about cycling through speakers to find one that "works best" with some favored less-than-linear amp.

 

Pre-amps (should) only sound the same, too.  If +/- "zero" on tone controls (as one example) are really +0.5 at the detent, well, there'd be a tell-tale "signature" available in an otherwise meticulous A/B check.

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Instead of saying "all amps sound the same" (as coined only by the skeptics, BTW) it'd be better to say "all modern linear amps operating linearly (will) sound the same (under the same conditions)."  Call the first phrase A and the second B.  What's largely been going on is one person says "B" and folks jump in arguing "A" is just not true.  Well, that's obvious: A ain't B!

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26 minutes ago, glens said:

Yes, that's what I was referring to earlier, about cycling through speakers to find one that "works best" with some favored less-than-linear amp.

Thanks for the clarification.  There is no part of the audio reproduction chain that is less linear than the speakers.  I choose to use synergy, what you refer to as "cycling through speakers to find one that "works best" with some favored less-than-linear amp" to deal with this lack of linearity.  Others choose a modern amp engineered to be linear with tone controls or equalizers to do the same thing.  I would argue that one is not better than the other.  Also, achieving synergy takes one component out of the chain.  I will add that a SET amp and a pair of La Scalas achieves synergy in my setup.    

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I've been away from this thread for a few days....  After catching back up it seems like what a beginner might glean from this is buy an amp that is engineered to be linear while driving your speakers to desired levels AND buy an external equalizer to adjust to taste.

 

These boutiquey amps that some people gravitate to aren't doing anything magical.  They are simply affecting the signal in a manner that they find preferable. ..No different than an equalizer.  ..Or, for those not wanting the extra clutter and fuss.  ..Tone controls may suffice.

 

So...... pretty much what I've been saying all along about how beginners might approach buying their gear.

 

Remember, most people buying hifi are NOT looking for a hobby or a lifestyle, they're looking for a way to fill a room with music.

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Good morning everyone. I was skeert I might have to end the count but welcome to day 22 of the linear set thingy.

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And things were going so well. 

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