Preamp difference : if it's not the frequency, not the slew rate, and not the harmonics, what is it ?

[RoadrunnerOZ]

Not likely that "not the same at all" would be attributable just to different tubes.

My point entirely but a good way to eliminate the possibility of a dud tube. More likely the difference lies in the transformer(s)

 

[rh001]

I do not exactly get the point you are making with your post. So, my apologies if above is not what you actually mean.
However, this is a false notion. I have listened to so many gear with selectable transformer output and there was not a significant change in sound characteristics on the transformer output let alone being better. I am not advocating against transformers as I also use them on custom designs, but in general there is a lot of transformer fetish going on because of this very false notion that transformer (or indeed discrete) sounds better.

I've probably make more pro audio repairs than anyone living and probably anyone that ever lived, I also design and build stuff from scratch. Output transformer is almost always a noticeable improvement to my ears and I have confirmed this in person with others sometimes when for instance they would come by my repair shop when I was in the middle of A-B ing.

I have even ABCDEFG'd different transformers....almost all sound a little different from each other and I can usually rank them from best to least best and some are chud. Many musicians can actually hear the diff between steel only laminations and steel with nickle.

Not everyone will hear the differences and not everyone will even care to try, for instance women. It is sometimes hard to hear the diff between 2 violins but experienced violinist will hear the diff and that's why some violins sell for millions of dollars. The meat and fish sold at boutique grocery stores catering to the rich really does taste better.

When I first saw Yuzuru Hanyu skate I did not perceive why they say he is G.O.A.T., probably or partly because I have no interest in figure skating. But curious, I A-B'd between vids of his skates and other top skaters and eventually I could see the differences... he really does smoke the competition, and as one might expect, he makes the most money from skating, by far. The market is very reliable at picking winners. Just look at the pooh rain! (Search YT on "Yuzuru" and "pooh rain" )



Musicians may be interested in this conversation between Yuzuru Hanyu and Kiyozuka Shinya about making customizations to classical piano compositions to work better for figure skating....there are a couple examples towards the middle and end. Hanyu used several of these recorded customizations in competions. How does a mere figure skater get a world class pianist to do this? (for English subtitles, go to YT and turn on CC and set for English translation)

 

[sahib]

I've probably make more pro audio repairs than anyone living and probably anyone that ever lived,

Quite a claim to make. Did you run a worldwide questionnaire?

I also design and build stuff from scratch.

So do I and so many others here.

Output transformer is almost always a noticeable improvement to my ears

To your ears. Not to mine or so many others.

and I have confirmed this in person with others...

So have I.
In fact the last one was with the person who paid nearly five grand for an equipment that he could not hear the difference either.

I have even ABCDEFG'd different transformers....almost all sound a little different from each other and I can usually rank them from best to least best and some are chud. Many musicians can actually hear the diff between steel only laminations and steel with nickle.

Sounding little different is different than claiming that transformer always sounds better.

Not everyone will hear the differences.

How about the ones who can hear?

 

[s wave]

So true rh001 - the little tweaking and key components end up be a massive difference. Excellence lies in all areas. Wild blueberry pancakes vs store bought blueberries! It is interesting to see how Segovia improved by even his incredible finger nail care for playing classical guitar!