300b lovers

In relation to what @lynn_olson is sharing about the listening experience being a stimulus and the impression that can form resulting from the stimulus being encountered.

I have on many occasions been an invited party to offer a 'pair of ears', and to offer a assessment of how a New Design is evolving. There are devices experienced that have been built in parallel and a early prototype is kept as such, with a second prototype undergoing changes to see where there is improvements to be discovered. This method is sort of similar to a modern Photo Editing Software Tool where at the Click of a Button, the before image is immediately viewed.

There are also devices that are sole builds and the experiences of receiving demo's a a result of changes being made are in theory a variant of a previous device used. Much of this is reliant on recollection of previous experiences. This as a method is also quite dependent on the demo's not be too fart apart and the other devices in the system being consistent and not being exchanged.  

Relating to the first method, it is much easier to identify if the ongoing work, is able to create a improved impression. It is also much easier to suggest trying out a different supporting ancillary as the two Prototypes at hand enable a very useful evaluation of how the exchanges interface with other ancillaries.

Relating to the second method, I find written records of how the demo' was able to impress and sharing through discussion where it has been perceived attractors/repellents are present is a constructive approach. Follow up demo's usually reveal differences are developing, and where there is betterment being perceived.

There will be a time that a divisive situation evolves, as individuals are unique in their preferences for a sonic. The Range of Attraction for Lean/Transparent through to Overbearing/Muddy is what sets all individuals apart. No one can tell an individual where there attractors/repellents are in the scale, they choose these themselves.

When it comes to buying a Device designed/built by the hand of a Trusted EE with Time Served Experience in producing audio devices, it is not just the realised product being bought into, but the designer/builders philosophies for audio reproduction and their IP, the hooks utilised to create the sonic on offer. 

It is no secret such IP is classed as a asset, is their not Circuits that when, investigated there are no values to found on components, the printed info is removed to protect the design from being easily plagiarised.        

Reviewers and consumers are at a great disadvantage in assessing the sound of a product, because they have never directly auditioned single-parameter changes. For example, a change in operating point (quiescent current) of 20% up or down, or a shift in topology in one part of the circuit. I grade these with a simple metric of:

1) No audible change, or at least nothing at threshold level

2) Different, but neither better or worse, just different

3) Worse (and how quickly is it noticed ... 5 seconds, 5 minutes, or an overall quality of discomfort or dislike)

4) Better (how quickly is this noticed, or is it a change in mood)

There are probably twenty or more points of adjustment in an amplifier or loudspeaker where these changes can be made. Some affect measurements, but most don’t ... they’re purely subjective. Also, conflicts can occur ... a better measurement may result in worse sound. At that point, something has gone wrong, and you need to stop and see where you have gone off-track.

We have to address what can be measured at the current state of the art and what can’t. Here’s just one example: for the the purposes of electronic design, nearly all modern capacitors are perfect. There is nothing to choose between them except voltage capacity and long-term reliability. Distortion is vanishingly small, at or below the threshold of measurement.

But ... in a high-resolution system, they all sound different. They are not neutral sonically. Mylar sounds different from polypropylene which sounds different than Teflon which sounds different from waxed or oiled paper. Metallized film sounds different than solid foil. In a vacuum-tube circuit, there are circuit nodes that actually exaggerate the coloration. Worse, DA, DF, self-inductance, or even price have little or nothing to do with sonics.

Perhaps worst of all, the notorious "burn-in" phenomenon where XYZ parts sounds really bad for the first 5, 10, 20, or 50 hours. With no change in DA, DF, or distortion measurements, and no plausible physical mechanism responsible for this. Anything that slow must be electrochemical, but what is it? Just a lot of hand-waving and supposition from the manufacturer, with no data to back it up. But plainly and clearly audible.

Not only that, some parts have essentially no break-in at all (paper and wax) while others can take 50 hours or more (polypropylene or Teflon). No explanation offered, no measurements, no underlying physical mechanism. Well, it’s not ghosts or psychic energy. It’s physics. But what physics? Nobody’s saying anything.

In loudspeakers and vacuum tubes, break-in is real, measurable, and the reasons are well-documented in papers going back to the Fifties. Caps? Nope. Why does copper wire sound different than silver? Again, no explanation. I accept this, but it is not satisfactory. Something is going on, and it is not self-hypnosis or expectancy effect. Often, the most expensive part sounds the worst, and the cheapo part sounds quite good.

A Friend who helped me source my Valve DAC, at one point was into heavily modifying a few CDP Models from the Sony Brand.

It was my introduction to these Modified CDP's being demo'd through Bespoke Built 300b mono's and Horn Loudspeakers, that were the first digital sources to arouse my interest in digital as a source.

I heard these in all their evolving guises and was even able to have extended home loans, which ultimately ended up with my decision to have a Digital Source added to my system.

One Sony Model had the Highest Quality Caps and Resistors used and lots was going on with how the Valve Stages were designed as well.

There was 'creme dela creme' mod' to be carried out that was inclusive of the use of OCC Silver Wire purpose produced Tranx's. When these were incorporated to the design, there was no Run In period that could help, the sonic and attractive impression that was recognised, plummeted from presentation, the overall presentation was perceived as forced and in ones face, quite unattractive and certainly not able to create a settling down and softening of a mood. 

When this same individual producing the CDP's had his GM70 Mono's built. I was again being asked to assess them with him. I thought they were sharing noticeable traits in how I recollected the 845's were able to present.

The GM70 owner convinced themselves there were more to be extracted and carried out Mod's on the Amp's. I was again asked to visit and take part in a listening and assessment session, to which I agreed to when the Amp's had a minimum of a 100 hours on them in their new guise. In my view, the Amp's had become lesser, there was from recollection, some of the earlier impression made, now at a place where I was trying to work out where the changes were and why the presentation had lost much of its allure.

As said earlier, when carrying out such demo's with others, there is a time when the opinions will be differing, I held my tongue, and agreed that if the changes made had been satisfying to the end user, then this is the ultimate goal, I politely made it known I had recognised changes had occurred. 

I have had situations with break-in on my own amps, which are very revealing of parts quality, where the sound got better and worse on a two-hour cycle. While there was an overall upward trend, the up and down kept going on, with the cycle timing varying between a half-hour and two hours. At the twenty-hour mark, I finally lost patience and threw the questionable parts in the trash. That experience has made me wary of all parts that require subjective break-in.

My rule now is twenty to thirty minutes, tops. If the part can’t make up its mind in that time, in the trash it goes, no matter how expensive, or what the reviews say. I don’t want unstable parts in my system. Now if the fancy audiophile part requires a half-hour on a burn-in gizmo, fine, but I will regard it with some suspicion.

I think audiophiles and reviewers are too tolerant of this hokum. If it sounds bad for days on end, it is bad. Something is wrong. There is a design or fabrication error.

I understand that you are referring to the approach you use with judicious application of negative feedback. I was referring to Lynn’s comparison to the “golden age “ PP amplifier which typically used 20db of NFB. Your current class D amplifiers do not fit this description.

@charles1dad 

They don't! However, Futterman claimed 60dB of feedback in his OTLs. That was during the 'golden age'... Also Kron-Hite made a transformer coupled tube amplifier (UF-101) that claimed even more feedback! It was built for laboratory use but works great for audio as well. Its specs are astonishingly impressive and having had a set (they were single channel) I can say they sounded quite decent. That was a long time ago but we compared them to an ARC amplifier which got its doors blown off.

If feedback is applied properly it is really beneficial. If its not then it will mess things up with the amounts normally found in tube amps (12-20dB...).

In the last couple of years, I had the VTV Audio EVO 1200 Class D amp with the Purifi module, with the aftermarket ministrations of Ric Schultz, and while the sound was as Ralph describes it,

@whitestix I'm going to contest this; I was not describing those amps at all and haven't heard them. You can tell something is up that isn't right since when you go on the web, you see really variable reports about their 'sound'. I notice that doesn't happen with tubes- everyone agrees that tubes sound smoother and often have more detail and so on. To what degree and what emphasis is the differences between the tube amps. I'm saying I've been playing a class D that you would think is in that category if you heard it. Going back to tubes you don't find that tubes are bringing anything more to the party. I get that seems like a tall statement. Keep in mind that OTLs have ruled the roost in the transparency department of the tube amplifier world and I've been building them since 1977 or so. During that time I've heard many tube amps; I repaired audio for a living as I put myself thru college and afterwards until Atma-Sphere was able to keep me busy full time. So I know what tubes bring and I'm telling you there's at least one class D out there that does the same thing. I suspect there are others.

Sorry I won't be able to participate in this thread for a while- I'll be out of town for 4-5 weeks. Y'all have fun and be well!