Dac help

[E-Stat]

However it is quite true that people often by tube buffers or tube-buffered DACs in order to warm, or at least smooth, the sound of their systems. Many claim that they are pleased with the results. To me this is proof-evident that this sort of tube equipment adds some sort of distortion to the sound because all the other offending components in the chain are still there.

A buffer circuit consists of more than a tube. It contains resistors, capacitors, chokes, etc. which determine the electrical behavior of the circuit. Those passive components can alter the frequency response and thus the tonal balance. They can also change the feedback to tailor the distortion spectra. What I am saying is that you can design in warmth if that is what you want to do. Receivers from companies like Marantz and Pioneer from the 60s and 70s are favored by some because of their smooth and forgiving nature. How did they do that with solid state outputs? Their outputs were capacitively coupled with electrolytic caps which gobbles detail and any intrinsic harshness in its path. That *trick* has been done for decades - independent of the active device used. The buffer products you see on the market are driven by sales perception of folks wanting tubes, not necessarily the innate character of the tubes themselves.

BTW, the SF preamp did add some of that perceived "depth" also often ascribed to tubes.

It is also ascribed to added noise, phase issues and tonal brightness. Many "ambient retrieval" systems deliberately mess with phase response to create false ambience.

I;m confident this "depth" as added (rather than just passed) by this component because I didn't hear it when I removed it from the chain in favor of a simple potentiometer.

You eliminated an active gain stage which necessarily introduced a level of noise and less than perfect phase response. No surprise.

As for me, I get *more* perceived depth when I bypass the Audio Research SP-9MKIII with my attenuators because the resolution is slightly improved which renders ambient cues on the recording more evident.

edit: The first time I purchased double Advents was when I was 16 for use in a quad system using the Dynaco QD-1 "Quadaptor". It was the first of many "ambient recovery" devices which worked solely on blending phase difference information into the rear channels. Did it use a tube circuit to "create" the false ambience? Nope. It used two 25 watt resistors, a switch and three rheostats. At first, it sounded kinda cool with some notion of "hall ambience" on some recordings. In the end, I found it confused the image and sounded artificial. That's when I started stacking Advents.



Click here for pics

In the latest issue of TAS, Harley is gushing over the new "qøl™ Signal Completion Stage". In a nutshell, it is a modern version of the Quadaptor. Steve Eddy posted the block diagram of it over at AA here. His assessment of the $4000 device was quite amusing.