VAC vs Conrad Johnson Amps?


I have had my Conrad Johnson Premier 12 140w/side tube monoblocks for many years and loved them.  Essentially they sound to me like Michael Fremer had described them in his long-ago review:  the CJ tube magic, with zest, power and control.  They've been able to drive pretty much every pair of speakers I've had, large or small.

At the same time I've always had some lust for the VAC amplifiers.  It started long ago when I heard VAC amps make Thiels sound like I'd never heard them before - liquid, astonishingly transparent and musical.  I managed to get much of this with my CJ amps paired with my Thiel 3.7s (and other speakers), but given that transcendent moment with VAC, and knowing how many of the highest end speaker manufacturers choose to use VAC and display their speakers with VAC amps, I'm left wondering "What If..."

I see people happy with amps like the phi 200 but I sometimes see the Phi 300.1 become available second hand (the only way I could afford that one).  It's 150W per side vs my CJ 140W, and I've read the VAC has good reputation for bass performance (I like good bass control) and driving many big speakers.  I wonder if any of the possible quality of the VAC would be off-set by the purportedly better separation you get with monoblocks - e.g. my CJs.

As I mentioned, I'm currently using Thiel 3.7s, with some 2.7s arriving soon, but I also own MBL 121s and like to keep my options open.  I'm also interested in the Joseph Audio Perspective speakers so would want an amp that has good grip on ported speakers as well.  I wonder what I may gain, and/or what I might lose, going for a VAC phi 200 or especially the 300.1, vs my CJ Premier 12s.

Anyone who has helpful experience to contribute, please do so!  Thanks!


prof
Prof;

ahhhhh.........
You've opened another can of worms...

A audio buddy of mine, has VAC stuff
He has Cary stuff & ARC, too
And, Pv-14 CJ that he had/ has problems with

He likes the sweeter highs & details with good tone
He has a range of speakers ; great speakers

He has ended up with a Cary Preamp (. -05) & ARC VT-100 power amp

& it sounds good

LOL

I think he likes what you're preferences Are, too;  & Toob rolls

It appears you need to try lots of combinations, again

Jeff
It is my understanding that the VAC Phi series of amplifiers are class AB and not pure class A circuits.  They certainly may have a high class A bias.  If I'm mistaken then my apology. 
Charles 
Charles1dad 6-28-2017

It is my understanding that the VAC Phi series of amplifiers are class AB and not pure class A circuits.

I’m pretty certain that this comment by Charles is correct. One indication of that can be inferred from the ratings of the mains fuses that are used, which can be seen in rear panel photos that are available on the web. For 120 volt operation the Phi 200 (for which the two channels are rated to provide a combined total of 200 watts) uses a 5 amp fuse, and the Phi 300.1 (for which the two channels are rated to provide a combined total of 300 watts) uses an 8 amp fuse. Assuming something like a 2:1 margin between the current rating of the fuse and the actual amount of current it would be conducting, that would mean a maximum AC consumption of about (120 x 5/2) = 300 watts for the Phi 200, and (120 x 8/2) = 480 watts for the Phi 300.1. Those consumptions are **much** too low to be consistent with pure class A operation for the specified output power ratings. A pure class A 200 watt tube amplifier would probably consume somewhere between about 800 and 1000 watts continuously, while a pure class A 300 watt tube amplifier would probably consume somewhere between about 1200 and 1500 watts continuously. Those kinds of AC power consumptions would blow the specified fuses almost immediately.

Regards,

--Al