[caryking]

I got away from tube equipment for a number of years and have recently gotten back into them. One thing I’ve noticed is that newer built tube amps are “generally” less warm sounding than older amps. I understand that circuits haven’t really changed; however, something has…

I used to love that midrange tube bloom. Anybody have any thoughts on any design changes that would affect this?

 

[carlman14]

One explanation is now days, people (including myself) love to use some sand assistance in their designs. Particularly CCS-loading tubes (vs loading them with resistors, chokes, interstage transformers, etc). With CCS loading, the tube will operate much more linearly than the other types of loading I mentioned. This can cause some loss of "tubiness" because there's less tube distortion when operating more linearly. A popular example is the bottlehead crack. They sell an addon called the speedball that replaces the resistor loads with CCS loads. Some people have reported liking it better without the CCS loads as it sounds more "tube-y".

 

[AudioCats]

....One thing I’ve noticed is that newer built tube amps are “generally” less warm sounding than older amps. I understand that circuits haven’t really changed; however, something has…
...

tube circuits use DC blocking capacitors in the signal path, newer productions likely use more polyprop which is sharper sounding than the paper/oil used in older amps.

metal film resistor is common, which is sharper sounding than carbon film.

Not big differences, but this kind of little stuff do add up toward the sharper/colder direction.

electrolytic power capacitors are probably using different technology as well.

 

[tomb]

Both responses from carlman14 and AudioCats are true and both are having an effect. You may love the mid-bass bloom (that's more accurate than referring to a mid-range bloom), but most don't and the general market prefers solid-state. Tube amplifier designers and manufacturers have responded accordingly. Sales are lost, otherwise.