Why Do People Come To Computer Audiophile To Display Their Contempt For Audiophiles?

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3 minutes ago, Superdad said:

 

That's for sure! 

I worry that it could be particularly dangerous in your house with lack of proper grounding technique ...

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6 minutes ago, Jud said:

 

Ooh, and it vibrates.

Those are his big iso transformers  He likes them balanced, but there's always a slight asymmetry...

 

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2 hours ago, Sal1950 said:

Total mis-direction from the points being discussed, that being the most reliable tools to use in judging accuracy.  The bottom line still being that sighted human opinions and judgement is next to useless unless they can be substantiated with either measurement, or under blind bias controlled conditions.

 

I guess I should just give up listening to music and just listen to you. So tell me, I have both a FirstWatt M2 and J2. I've listened to both extensively, never blinded. I've not taken measurements of either, although I do have the individual parts and schematics to build copies/versions of both. So tell me: which one is "more accurate"? based on what exact measurements? Because clearly I've been doing this all wrong. What measurements should I make to tell me what to listen to? (I want the most accuracy)

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8 hours ago, Sal1950 said:

 

"The output impedance was relatively high for a solid-state design, at 0.5 ohm from 20Hz to 20kHz. As a result, the response with our standard simulated loudspeaker varied by ±0.35dB (fig.1, gray trace)."
Read more at https://www.stereophile.com/content/first-watt-j2-power-amplifier-measurements#QmWDdAB35Yr3QP9B.99

 

Right. So you are saying that you would read Stereophile to find out what is best. Ok then.

 

3 hours ago, pkane2001 said:

 

True. My point was that it's easy to throw up your hands and to say that the differences cannot be measured. In reality, anyone can measure equipment with a little imagination and some inexpensive (and often, free) tools.

 

Actually anyone can just listen. No you can't just make a few random measurements with cheap equipment (well unless you build or repair the equipment yourself in which case, yes it can be expensive)

 

Who would measure an amp with an ADC that is less accurate than the amp?

Who would measure a recoding at the same bitdepth and rate as the recording?

 

It should be basic that the measurement tools need to be substantially more accurate than the device under test. Or if not, then special care needs to be made in the measurement. That's why real measurement tools are expensive. I picked two very highly respected amplifiers which are in many respects very similar (case, power supply etc) and which have known and well documented differences. What you propose is off the mark (first of all measuring close to a speaker puts the directionality of the speaker elements in play). Second the speaker forms part of the circuit of an amplifier, so using an 8 ohm resistor just doesn't cut it. You need to measure at the speaker output with the speakers in position. So aside from the easy "level" you fail to control for many things. Your description of phase is confusing. What would short segment comparisons tell you??? What if parts are bass drums and different parts are violins???

Probably you are best off using a complex Fourier transform and looking at both the real and imaginary parts.

In any case real accurate measurements take real work.

 

Its far easier to just listen. Bad measurements don't help anyone. Or just read Stereophile...

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7 hours ago, esldude said:

The J2 and M2 mentioned probably sound different.  Both have fairly high output impedance.  One has more power and output current capability vs the other.  One has feedback vs none. 

 

Despite all the talk, no one has approached the question about how one would actually predict accuracy based on measurements ... I don't mean "you could do this ... handwave" ... I mean the actual distinctions that a person can make within minutes by listening.

 

I didn't mean to drag Stereophile into this, aside from the fact that the measurements given tell us nothing that would actually answer the question.

 

AFAIK, the actual amp designers use a combination of researching parts specs, modeling, building & measuring as well as listening. No one has given me an iota of convincing reason why I shouldn't similarly do research including read reviews and lookup measurements, and then actually listen before purchasing.

 

Without getting into a bunch of prose, I consider the "J2" more accurate and this was apparent after listening for a few minutes and this has been borne out over time. I felt no inclination to do measurements to prove this to myself. Now if I were building one or the other and the sound wasn't identical to the real thing then yes I would do measurements.

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1 hour ago, Jud said:

Now who knows, maybe in this case jabbr is just making a "big fat guess."  But my assumption would be to the contrary: That he understands what the circuitry in the two amps is doing, and since listening didn't show anything obviously wrong, he felt no need to perform measurements to determine the circuits were operating as designed.

 

Thanks @Jud -- I often worry I am just making a bit fat guess though  

 

Seriously I am posting from my own personal experience. I'll give another example: based on @Miska's description, my analysis of the excellent design as well as his very careful and excellent measurements I built the DSC1 DAC ... expecting to hear auditory nirvana, now don't get me wrong its outstanding just missing some qualities best described by flowery prose  So I considered (because this is an open design): what can I do to make it "better" and by "better" perhaps more lifelike? So I've proposed some design changes ... well it turns out that in building a Ferrari we have some of the problems of a Ferrari ... when it works its terrific ... but temperamental in a way that makes it not yet ready for prime time ... in particular my use of cascoded RF JFETS in the I-V section (crazy bandwidth and crazy low distortion) means that there can be oscillations in certain circumstances -- not in my initial testing but on subsequent testing ...  oh dear it might actually depend on whether they come from HK or mainland China now that NXP sold the parts division that makes these ... this kind of really crazy sh*t ... speaking of measurements, here is where this issue is being discussed: http://www.diyaudio.com/forums/group-buys/175044-my-version-g-1000-low-noise-measurement-amp-ikoflexer-25.html ... so anyways I don't (yet) know how to measure changes that I can hear between the souped up Ferrari and the regular DSC1 and until I can tame the I-V down so that its stable under known conditions, its not ready for distribution. So anyways in theory there's no difference between theory and practice...

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10 hours ago, Sal1950 said:

 

Hogwash, you have no idea which is more accurate, your just making a big fat guess. LOL

 

Hmmm ... it was you who suggested that I make my decisions based on Stereophile measurements ... and then went on a tirade about Stereophile's recommendations -- which are -- obtw- supported by their measurements -- being biased by advertising $$$.

 

Its easy to be a critic just try to be consistent

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54 minutes ago, Sal1950 said:

 

My usual pat answer here would be that since he didn't measure or state the use of bias controlled blind listening to reach his conclusions they can only be considered a guess.

But I will add in the this case that it is exactly his technical understanding of things that even more so will tend to color his subjective impressions.  The more he knows the more important it is for him to follow a path capable of removing his bias's as completely as possible.

I don't think blind listening goes far enough ...  the full Tommy test is needed in these circumstances:

This test mathematically proves (the score) that pure intuition is better than use of sensory experience (aside from component smell -- but see burning amp ...)

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9 minutes ago, Ralf11 said:

OTOH, if one has a lot of knowledge of different circuit designs in A & B, then confirmation bias could affect the guess (!)

 

everything and everyone is biased  

 

I try not to give listening impressions of things I work on for this reason -- that's why third parties are best to confirm. an issue is you need to get a third party interested enough to spend the time to do the confirmation. I think lots of people give a friend or someone else two black boxes with a mark on them to do their own listening. pretty much what @Jud described with the new Regen. I don't know anyone who does formal blinded listening testing in the design phase.

 

diyaudio is great because other people can listen for themselves ... it takes a good amount of work to get a design to the point where someone else can build it and listen.

 

I also think that longer term listening tends to drain confirmation bias (at least for me) ... also one of the reasons to do more advanced measurement is that when you have say 15 variables, then everything starts to sound the same, particularly when different combinations of variables get switched on and off. ... but the sound of the J2 vs the M2 is very apparent ( the J2 uses a Semisouth power JFET, and negative feedback,  the M2 uses a transformer voltage amplification followed by a MOSFET current and no global feedback)

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1 hour ago, pkane2001 said:

 

So do you think that knowing how something works negates the need in objective testing and measurement?

Measurements can be useful under the right circumstances. Just because something is  a measurement does not mean that it is unbiased nor accurate. What is your goal?

 

Quote

 

Do you think Nelson Pass doesn't measure his amps after he designs them?

 

 

 

Don't take my word for his methods , he is a terrific educator and describes his methods extensively. It would be worthwhile to read his own writings. Hint: he listens after he measures and nothing goes out the door if it doesn't pass the listening test, regardless of measurements.

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4 hours ago, Kimo said:

I have owned, or auditioned, 2 Pass preamps, 2 integrated amps, 3 power amps, as well as several First Watt amps.

 

I don't think that they are necessarily designed to sound alike, and they often do not.  That being said, they all measure well, and sound excellent.  

Right. I selected this example for this reason. FirstWatt in particular is something like a testbed to release a particular design on the market to gain wider impressions after the amp has been designed, measured and passed internal listening tests. This by a designer with many decades of very successful amplifiers spanning from $100s to $10,000s.

 

Of course measurements are done during the design, build and refinement phases. I think you might be able to go back after listening and perhaps glean some explanations from measurements as to why X or Y amp sounds different, but in my experience, when we start out with such a high level it takes much longer time and much more effort to determine these differences by measurement than it does by just listening.

 

There are reasons why human experts are still necessary in the age of measurement robots. There are similarly reasons why some of the best acoustic venues are really old as opposed to really new and why carbon fiber instruments haven't replaced wood etc.

 

Its also good that we have choices.

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16 minutes ago, esldude said:

Well if they sound different a minimum of one is of lower fidelity.  Possibly both differ from fidelity in different ways. You see this in people all the time.  People will pay for or celebrate differences.  They don't want all amps to be full fidelity and all sound the same.  They want to own a 'special' amp.  It can't be special if it sounds like all the others. Add in that most speakers fall far from real fidelity and it is a given that slightly colored amps will match up better with some certain speakers to enhance the coloration or decrease a deficiency.

 

Can you measure the lower "fidelity" or tell me which has the lower fidelity without listening? This is the whole point. You have 2 great amps that measure well. The FirstWatt M2 and J2. They are different. There will be slight differences in measurements. Which is "lower fidelity" and on the basis of which measurements? Do your ears agree ? ( @esldude: you don't need to answer the last question because you admit not hearing differences between amps like these two, fair enough).

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4 minutes ago, Sal1950 said:

Of course you can, if you know what aspect of "fidelity" is important to you.

Both of those amps will vary from ideal in different ways and can potentially affect the sound differently.

I highly respect Nelson and own 4 of his designs currently and had 2 more in the past.

 

You describe an ideal amp below as "transparent", ok, let's use that goal for "fidelity". Now how do the Stereophile measurements tell you how "transparent" the amplifier sounds?

 

4 minutes ago, Sal1950 said:

But I find his dabbling in the First Watt line curious, he knows and builds highly transparent amps for decades now but I find his sideline in First Watt along the same line as Bob Carvers tube amps and his "voicing" of SS with transfer function tuning possibly a stab at being "good for commerce". 

 

Are you suggesting the J2 isn't transparent? or the M2? Voicing? What voicing? The designs are different topologies with the goal of determining which topology works best in which circumstance. In many cases there is a new transistor technology which is being tested (e.g. Silicon Carbide, SIT, Power JFET), or perhaps positive current feedback ala F7 which is useful in certain difficult speaker loads.

 

4 minutes ago, Sal1950 said:

 

JA's measurements of the J2 I posted earlier, along with just the basic fact that these are very low power amps and will be very load sensitive.

 

Yeah ok but use the measurements to tell me how they "sound", or how "less transparent" they sound. Interpret the measurements...

4 minutes ago, Sal1950 said:

It's like building two very different tube SET amps or two OTL's and saying "see, amps do sound different".

It's true that amp designers have known for at least 3 decades how to build a fully transparent amp. The fact that many chose not to design along those lines I'll leave to others for debate.

 

I see, so there's been no advances in amplifier design in the last 30 years... and this thread is about ? coloration ? http://www.diyaudio.com/forums/pass-labs/300136-def-amp.html

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4 hours ago, Sal1950 said:

Dennis answered all your questions to me in a better and more detailed way than I ever could.

But I will make one small addition.  You are a smart guy and I know you understand that simply looking at the design and measurements of the First Watt line you can deduce a simple fact.

This line of amps from Nelson are simply designed to be very system reactive, this at a time in history when designing to be system agnostic should be easy-peasy.

As I said before, the fact that he has made these de$ign choices I'll leave to others to debate.

Do you agree with what @esldude wrote?

 

Its easy to sit on the sidelines and take potshots but your assertion that amplifiers from 30 years ago were entirely transparent is not true, which specific amplifier are you speaking of, perhaps one of Nelson Pass' earlier designs?

 

By "de$ign choices" you are throwing out a dogwhistle implying that his motivations are financial.  Why shouldn't they be?, but I doubt they are purely financial in fact the reason that I am an admitted and enthusiastic fanboi is because of his generosity to the DIY community ... http://www.diyaudio.com/forums/pass-labs/281520-official-m2-schematic.html ... wow ... and http://www.diyaudio.com/forums/pass-labs/276711-sony-vfet-amplifier-part-2-a.html ... and it goes on and on and on. Can you name another successful designer who is more generous?

 

In any case FirstWatt is small volume, handmade and is not intended to be Pass Labs where the more "system agnostic" amplifiers are made and sold. I am using this as an example for the question of whether measurements can predict sound ... specifically how 2 amplifiers compare ... I know its hard for you to have a discussion without throwing out criticisms... but accusing Mr. Pass of being purely financially motivated is gross given his longstanding and well documented contributions to education.

 

 

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9 hours ago, esldude said:

Nelson Pass tells us how his M2 is not transparent in the manual:

 

 

9 hours ago, esldude said:

I think you will find the M2 a very pleasant amplifier to listen to. It is relaxed and

lively with a slight softness to both the bottom and top frequencies. I hope that

you will find as I do that it disappears and leaves the music for you to enjoy. I also

hope that it will make you go back through your entire record collection and make

you listen to it all over again.

 

"disappears and leaves the music for you to enjoy" sounds transparent to me

 

Every electronic component: resistors, capacitors, transformers, transistors have "electronic signatures" i.e. measureable non-linearities. Thus each component has a "sound". In his description of the M2 the "sound" is ascribed to the transformer but many amps have transformers so isn't this generally useful info? The goal of ultimate transparency involves tradeoffs. Yes, these tradeoffs can be described as "not transparent" to a degree. So which "non transparencies" are important? What are the best tradeoffs?

 

The FirstWatt line is designed to be low power (as opposed to the main Pass Labs offerings). Thats why I am comparing two of these similar designs. You have suggested that the M2 is better than the J2 because it has more power, but there is also the issue of the transformer and its characteristics, so perhaps the J2 has advantages in other regards. These are competing factors. This makes an absolute judgement of relative transparency difficult.

 

What I am suggesting is that measurements can help but not (alone) answer that question ... and yes, each amplifier in existence has its own sonic signature determined by the non-linearities in its components.

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2 minutes ago, Kimo said:

Regarding the transparency of Pass designs, Nelson is also stating that the sonic signature of the M2 is more transparent, not less, at least in some ways.

 

Part of this is due to the limited bandwidth of transformers, and part of it is the lack of feedback artifacts.

 

 

Yes I've considered using it as the output stage of a DAC  

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35 minutes ago, esldude said:

In context of everything he said, no he isn't even claiming transparency.

Exactly. Is there a purely objective definition of transparency that you are using? What is it  and how does it compare for the amps in question?

 

"transparency" is a descriptive term.

 

No one ever claimed perfect transparency as if this were a binary property. My point all along has been that measurements alone have a difficult time determining sonic accuracy.

 

Every amp has its own sonic signature and no amp is perfectly transparent (and  there are no perfect measurements)

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20 minutes ago, AJ Soundfield said:

Evidence? Once again, with honesty controls, just listening, trust ears, no peeking. Otherwise, no.

 

 

Thankfully with science, observations are generalizable. My statement is made not, duh, by actually measuring every resistor, rather per physics. Don't take my word for it, feel free to take a class -- I hear there are excellent classes online these days.

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43 minutes ago, Ralf11 said:

and further, that those non-linearities can be heard when listening to music

I can state with confidence that all amplifiers, even copies of individual brands, will have measurable differences. I am not making such an absolute claim to audibility -- let's say that amplifiers often have a sonic signature 

 

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2 hours ago, AJ Soundfield said:

Where can one find the details of this?

 

There are many many discussions of resistor noise and nonlinearity e.g.:

 

https://www.ap.com/technical-library/from-the-test-bench-resistor-noise-and-non-linearity/

http://www.vishaypg.com/docs/60108/VFR_TN108.pdf

http://www.analog.com/en/analog-dialogue/raqs/raq-issue-25.html

http://physics.princeton.edu/~mcdonald/examples/statistics/dutta_rmp_53_497_81.pdf

https://peteinthelab.files.wordpress.com/2011/04/noisepaper6510.pdf

 

there are also discussions of nonlinearities and noise in other components e.g. capacitors. differences in transistors are very very well known. However, if you look at the Analog Designs paper, they discuss that resistor noise is often the limiting factor...

Noise itself is fundamental: https://www.physics.utoronto.ca/~phy225h/experiments/thermal-noise/Thermal-Noise.pdf ... Really this is all physics

 

 

 

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21 minutes ago, Ralf11 said:

we do need to be careful with some of these findings - e.g. we won't be operating any components from 350 K to 4.7 K so the Johnson noise may not be an issue; the same researchers (last URL) did find that 1/f noise was not T-dependent 

Of course, but 1/f noise causes different non-linearities. The AD article discusses the temperature dependent equation. There is also "shot noise" and I'm not sure if this is temp dependent either -- lots and lots of variables. Johnson noise can also have frequency dependency.

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21 hours ago, esldude said:

Now without the full regular measures at my disposal, I would venture a guess the J2 is going to be of lower fidelity because it has much more limited current capabilities.  If someone says they listened to both and preferred the J2 that would not contradict this prediction. 

 

I think the real answer is speaker dependent.  Sensitive speakers are necessary -- I've used full range horns and headphones --- this certainly isn't a Maggie deal. From a listening perspective the J2 sounds better to me with a smooth but solid high end and very controlled bass. From a realism point of view, I can often feel the bass with live music ... the J2 bass feels very controlled in its depths ... there's some prose that I was holding off giving .(and the M2 really is a terrific amp that folks should consider building -- parts are inexpensive) -- so I'd say J2 is more "accurate"

 

Now I don't think I'm biased because I was really looking at the SIT-1 at the time (which I regret getting for other reasons) but the J2 just sounded so great (its all about the bass  )

 

But you are making this prediction indeed without full regular measures at your disposal. Thanks for taking the time to read up on this and hopefully you can better understand my position -- I won't go so far as to ask you to agree  

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23 minutes ago, esldude said:

You can make op-amp like circuits with tubes, and I seem to recall one design which basically did that, and combined with a good output stage achieved something near what you are listing here.

 

The first "operational amplifier" was perhaps developed by Philbrick before WWII but published by Lovell & Parkinson, 1947 and implemented for the M9 antiaircraft gun targeting system as described in Johnson "Analog Computer Techniques", 1956 -- these were vacuum tube based of course, the circuits can be found in this book which is available used.

 

and here: http://www.philbrickarchive.org/operational_amplifier.htm

[jabbr]

Woah! Speaking of noise-- hot off the press: https://arxiv.org/pdf/1501.00195.pdf,

http://ws680.nist.gov/publication/get_pdf.cfm?pub_id=901450

 

Kelvin is being tossed for SI: temperature now quantum noise measurement of a 200 Ohm resistor ...

 

I wonder if a single electron clapping in the forest makes a sound ?