What is meant exactly by the description 'more musical'?

All this sounds simple yet we have many amplifier makers. I suppose most have gotten the "bad" distortion out of their designs, though.

@hilde45 If that were true there would not be a tubes vs transistors debate older than the Internet itself!

Its a bit more complex than that. Many designers don't pay much attention to how the ear/brain system works. So they often just go for the least amount of distortion: your typical solid state amp. Solid state amps have had a reputation since the 1960s of being harsh and bright compared to tubes for the simple reason that the distortion of the solid state amp has unmasked higher ordered harmonics- the source of the harshness and brightness.

Such amps do not tend to get a reputation of being musical and are part of why tubes are still around!

In a nutshell, if i read atmasphere right , psycho-acoustics rule even gear design ...

Not mere taste ....

Van Maanen himself said the same thing as atmasphere ...

https://www.temporalcoherence.nl/cms/en/

For sure different road can be chosen by each amplifier designer, but the road is chosen around the same center : human hearing characteristics ; then putting the emphasis on the way the ears/brain perceive harmonics or the way the ears/brain inhabit his own non-linear time domain; but these differences in design approach will never obey the mere taste of the designer so much as they will obey the specific psycho-acoustic facts and principles by which he will attack the designed "musicality" problem ...

No taste relativity then to begin with and at the end of the design process .., But for marketing taste is first and last , because no design is perfect, marketers will call the customers and spoke to him about his tastes for "musicality" ...But there is not so much taste in the way we evaluate "musicality" as much as different levels and different acoustic aspects of this  complex phenomena ,"musicality", where subjective evaluation is  always conditioned by objective factors ......As musicians and acousticians and trained specialist and maestros or most  designers knows already ...

Atmasphere must correct me here if i am wrong ...

Interesting debate for sure ...

I'd like to try an analogy.  A lot of equipment is sorta like the pictures from a Kodak 110 film camera.  They provide an image the photographer intended, at least most of the time.  Colors are close, image lacks detail or controlled depth of focus. A picture. Compare that to a photograph from a large format 4 x 5 camera with a top quality lens in the hands of a master photographer.  The finest details are part of the life captured in the picture.  Accurate color and subtle shading, light and exposure tightly controlled to bring to life the subject of the image as well as the fine details in the rest of the picture.  It is a work of life brought to an artful image that is precisely what the artist / photographer intended.  

In the context of the OP's original question, music is notes.  Musicality is bringing the notes to life as intended by the artist.  The dynamic reproduction of the event, not the simple tune.  The fine details, the small changes in dynamics, the correct coloration of the instruments including changes to instrumental timbre as performed by the musician / artist.  

@atmasphere Like many here i've followed this discussion with interest, especially as relates to the discussion re sound or "musicality" of tube amps v ss--and i will say that in general i agree with you--just never knew the reason why--but as an expert amp designer what is your take on hybrid amps that use both tubes and ss at the output stage--do these amps suffer from the same issue as ss amps?  or are they better at dealing with the higher-order harmonics b/c of the tubes?  i.e. is having a ss output stage going to inherently have the unmasked higher order harmonics?

@mahgister You got it.

@wyoboy 

what is your take on hybrid amps that use both tubes and ss at the output stage--do these amps suffer from the same issue as ss amps?  or are they better at dealing with the higher-order harmonics b/c of the tubes? 

Most of these designs use feedback. When you use feedback in any design, you must have enough Gain Bandwidth Product to support the loop gain (which is the gain of the amp after the feedback is added). Most amps lack the GBP to do this properly, so when they run into that limit at a certain frequency, distortion will rise on a 6dB/octave (or greater) slope. This phenomena is usually perceived as harshness and brightness. Tube amps with feedback have this problem although its not as pronounced as in solid state since tube amps tend to have better distortion characteristics (to the human ear) when running open loop.

Put more simply, hybrid amps are a partial solution. Something I've not mentioned in this thread is how the feedback is received at the input of the amplifier; in most amps that point isn't linear (typically the base of a transistor) and so the feedback signal itself is distorted. That prevents it from doing its job properly, and since this practice is widespread, has given feedback a bad rap.

Feedback isn't bad if its applied properly. In a hybrid amp, the feedback is usually applied to the cathode of an input tube which is usually a lot more linear than a transistor in a solid state amp. This does help the amp be more musical, but since the GBP is very likely lacking, does not fix the problem (you can find this out by simply measuring distortion vs frequency).

Sorry if this is a bit technical!

The reason why distortion vs frequency is so important has to do with how the ear perceives distortion. I'll give you a typical example. A common frequency where many solid state amps reach their GBP limit is only 1KHz. Imagine a signal at 1KHz; it might be low distortion, but you can have a harmonic at 7KHz that is considerably higher than that 1KHz THD figure would suggest- and the 7th harmonic is not only amusical, the ear is also keenly sensitive to it because higher orders are used by the ear to sense how loud sounds are. Sticks out like a sore thumb.

So if you want the amp to be musical, its important that the distortion vs frequency is a flat line across the audio band (or nearly so- 10KHz is probably acceptable since harmonics at 20KHz won't get a lot of attention). Tube amps with little or no feedback have no problem doing this; its part of why SETs have a foothold in modern times.

But SETs are really obsolete (IMO there is no reason for them at all); the only reason they get by is due to their distortion signature and distortion vs frequency being a flat line. You don't need the amp to be SET to do that and so there are musical amplifiers that aren't SETs (which make a lot more power and are more transparent).

But most people that are involved with SETs do not understand the facts I've laid out here. This includes a lot of SET designers. I'm sure I'll get pushback on this, but engineering is why tubes exist, why airplanes fly and why lights come on when you turn their switch on; engineering coupled with an understanding of human hearing rules is at the heart of this.