Hi Firedog,
Below are my thoughts/findings, but please remember that unless otherwise stated, these apply to LIO, LIO RVC and LIO AVC - and the person from the other forum that you have quoted might have been listening to a different resistor volume control or a different transformer volume control.
no transformer based attenuation will even equal a well done resistor ladder (or digital VC as long as it used within its sweet spot).
From my own experience, I have to disagree with this statement.
Let's start with a good quality
discrete resistor ladder volume control type - such as a DACT/Goldpoint or the LIO RVC module (which operates in a very similar way, but with more volume control steps and channel balance control added in as a bonus):
I find a good quality discrete resistor ladder volume control to be superior sounding to a good quality potentiometer volume control (e.g. Alps Blue Velvet, TDK, and conductive plastic types), at least in terms of transparency and openness in the music. They also "track" better, meaning at a given volume setting, the L and R channels are much more closely matched since discrete resistors can be chosen that have a tighter tolerance spec (e.g. 1%, 0.5% and even 0.1%) than what you normally can achieve on a conductive element / wiper configuration of a potentiometer.
The "problems" with them from the feedback that I received from customers in case of the DACT/Goldpoint types (I used to use them early on with RWA components) was:
1) The 23 volume steps were not enough for some people
2) The remote control kit for them (using a stepper motor) was a little "clunky" and loud.
With the
LIO RVC module, you get 63 steps of volume control (approx. 1dB each) so there are a lot more steps, and
the switching of resistor settings on the ladder are done with small signal relays (so no need for a ELNA type stereo switch and associated stepper motor kit to turn it via remote control) and the module is located in the rear of the unit to keep the signal path as short as possible (instead of mounting the actual volume control to the front panel of the unit and having to run signal wire from the rear jacks to the front, and then back towards the rear again). In my evaluation, LIO RVC definitely sounds just as good as the high quality DACT/Goldpoint solutions, but is smoother in operation, offers more volume control steps, offers channel balance, and allows for a shorter signal path as mentioned above.
LIO RVC is definitely no slouch, but the
LIO AVC using Dave Slagle's autoformers takes performance up another notch. Unlike a resistor volume control that throws away signal to GND when it attenuates, the AVC uses transformer taps that step-down signal voltage in the transformer, but also step-up signal current in the process. In a sense, what you normally waste in attenuating signal with a resistor volume control, you convert to higher current with an AVC type.
To me, with AVC you hear something that is more along the lines of a minimalist active preamp (think Zen buffer preamp), although the AVC attenuation is strictly passive. This means that there is no active element like a transistor, op-amp, or tube in the AVC. With an RVC, it sounds like a passive preamp. My findings with AVC (vs RVC) is that it sounds:
1) Less 'anemic' sounding, better bass
2) Has more drive and an overall more dynamic sound
3) Better micro-detail
4) Even more transparent and open sounding
Of course when you add LIO Tubestage with the LIO RVC (in comparison to LIO AVC), I find that 1 and 2 above go away and you also get richer tone and a fuller soundstage from the tubestage (but still not the overall transparency and micro-detail as the AVC on its own). And then going AVC/Tubestage combo module gives you the best of both!
Transformer based VCs add distortion, in every case, and more distortion than is added by a resistor ladder using quality switches and properly matched high quality metal film resistors.
Well, I am not necessarily arguing this from a measurement perspective. But from listening, I do not agree. With the case of LIO RVC vs. LIO AVC, I find LIO AVC to be superior sounding in nearly every way. This is also true for many LIO customers who upgraded from RVC to AVC (or RVC + Tubestage to AVC/Tubestage module). When I state my perspective on all of the above, I am only talking about
my findings when
listening to music. I am not talking about measurements using test tones.
Some people really "like" transformer based VCs, there is nothing wrong with that, as long as they acknowledge that these devices are less transparent (in other words they are preferring them because of euphonic artifacts).
Again, from my experience listening to music and comparing LIO RVC to LIO AVC, I have to disagree:
- I do not find the LIO RVC to be more transparent sounding.
- I do not find the LIO AVC to be more euphonic sounding.
If anything, I would say the LIO RVC is less transparent and LIO AVC digs deeper into the recording. And AVC alone does
not sound 'euphonic' to me, like one might say what a tube linestage adds to the sound. Again, these are MY findings with
LIO RVC and LIO AVC. The person who you quote from the other forum might have been using a different resistor volume control and different transformer volume control when making his/her comments.
I also want to link to Dave Slagle's Intact Audio site for FAQ on his autoformers:
http://www.intactaudio.com/atten_FAQ.html
I hope this helps!
Vinnie
