The smoothest amp you've heard?

I have not heard their newest ones, but the Audio Research D-150 is a beast, and accurately smooth as silk on Maggies.

I wish I had 3 of them!

Cheers!

@avanti1960 does too smooth mean no good re the L-509x? I have that amp and would take exception. I think it is a fantastic piece. 

Exactly how or why they would introduce phase shift down to 1/10th the cutoff frequency isn't revealed or explained.

In any case, why just those frequencies? What about 20kHz cutoff frequency causing a 2kHz phase shift?

A 20Hz cutoff will induce phase shift to 200Hz, robbing the amp of impact (since that is how the ear perceives phase shift in the bass).


Its filter theory. When the amp rolls off, it does so on a 6dB/octave slope. A 6dB slope causes phase shift to 10x or 1/10th the cutoff frequency (-3dB point) depending on if the cutoff is the low frequency point or the high frequency point, respectively. So you need 2Hz bandwidth to properly reproduce 20Hz and 100KHz bandwidth to do 10KHz.


There is a way around this, by introducing so much feedback that the amp is able to correct phase shift. That amount needs to be at least 35dB, but the caveat is that the 35dB value has to be the same at all frequencies from 20Hz to 20KHz. Most amplifiers made in the last 70 years are not capable of this feat since it requires a lot of gain bandwidth product.

Luxman 1120A Receiver . Very smooth famous Luxman sound. Was updated with better caps and other inside. Nice power amp section. Made very well back in the day. 

a tie between a class-A tube amp whose name escapes me [this was back in 2000], and a rega brio 3 which was the most mellow-sounding transistor amp i've ever heard. if i had a big enough space, i'd enjoy listening to music with that amp and a pair of Vandy 1Ci speakers, as i heard in the showroom a few years back.