Loudness - Why has the industry stopped producing amplifiers with this feature any longer?

Atmasphere, you aren't kidding. All the unused switches in my dad's old HH Scott preamp failed. Not worth fixing. However, in the digital world having such things as room control, bass management, dynamic loudness correction and the ability to juggle your system's frequency response all by computer (no mechanical switches) are real eye openers.
All this can be done without adding any distortion and the DSPs doing it are all operating under a 48 bit system so you can lose a few bits here and there w/o affecting the sound. It is a tweaker's dream come true and a lot of fun. If you get the opportunity you should play around with a dedicated room control processor like the Trinnov ST2 which inserts between your preamp and amplifiers. On bypass it may not sound quite as good as the system without it but engage the room control and you are in a whole new world.  

However, in the digital world having such things as room control, bass management, dynamic loudness correction and the ability to juggle your system’s frequency response all by computer (no mechanical switches) are real eye openers.

I kind of agree with this, it’s the interface I have more of a problem with. Honestly, I prefer knobs. As someone who uses Roon, along with paremetrics and shelving EQ, I would really like a bass / treble knob sometimes. So, I’d like two features really:

1. A physical knob, perhaps assignable.
2. Gapless playback when EQ is changed.
   

Without this, I end up leaving Roon alone, and resort to the integrated. No complaints, but in a future all-digital world, I want knobs, not a slick touch screen. :)

Regarding Switch/Knob issues.  Yes, dusty, worn POTS and oxidized contacts on switches can be a problem.  But that is why we have DeOxit ;-)

I seem to recall the later old TacT gear allowed for user customizable settings that varied with the volume control setting.

Yes, dusty, worn POTS and oxidized contacts on switches can be a problem. But that is why we have DeOxit ;-)

DeOxit has a dicey reputation in this regard. Its not exactly the best medicine if you are dealing with a part that has the resistive element on a phenelic substrate. In a nutshell its bad chemistry.

So people that are really concerned about longevity of such parts (usually collectors) use specialized vacuum cleaners to clean out the pots and see how they behave after that is done before resorting to control cleaners like DeOxit.  

Us designer types that like to make high performance circuits have different concerns. For example, I like tubes for preamp circuits and tubes tend to have some fairly high impedances that cause stray capacitances to roll off the top end. If you really want your circuit to have 3D depth and width, you have to eliminate phase shift; to do that you need bandwidth (2KHz-100KHz at a minimum; 200KHz is better). When you have a switch to bypass a tone stack you're asking for trouble in this regard. Usually the presence of a tone stack suggests two things- first that the speaker is bandwidth compromised and second that getting the sound stage right is secondary to the goals of the listener.


In high end audio, getting the system to sound like the musicians are playing in the room is a pretty serious endeavor. It is rendered impossible if a tone stack is involved. You might be able to get it sound like a good stereo, but sound like its real?- nope, won't do that.

Once I sorted this out and got competent equipment, I found that I never felt like I needed any tone controls. The key is 'competent equipment' but its also important to get the speaker placement right and have a good match between all the bits in the system.