Now that there are quite a few pairs of Emerald Physics CS2’s out there in users’ hands, it would be helpful to the community to start sharing your experiences with amplifiers. The CS2’s require 4 individual channels of amplification, with an upper section that is about 100db efficient and a lower section that is much less efficient and rather conventional in most ways, so this presents some really intriguing options.
While they indeed merit some state of the art amplification options, I’m more inclined to see just what is possible with reasonably priced stuff (depending on your perspective of “reasonable”). At a price point of only $3k for these gems, that opens up the budget a bit for other gear too, so some will go that way too.
Here are some possibilities:
Approach #1: Four identical amplification channels. The really nice thing about this approach is you don’t really need to measure, adjust, and match the upper and lower gains. This can be achieved by four identical monoblocks, two stereo amps either vertical or horizontally biamped, or a multi-channel HT style amp. Clayton Shaw used Bel Canto stereo amps at RMAF. Zybar has used 4 channels of an ATI1506. In my case, I strapped up four channels of an Arcam P1000 7.1 amp with decent results. Lots of possibilities there at a very low cost.
Approach #2: Four similar sonic signature amplification channels. Gain may or may not be the same, depending on topology. I've considered getting two more Odyssey Stratos channels, but what I'd LOVE to try is Hugh's LF55/LF100. Other things that come to mind are RWA 70/30's, AVA, etc. (support your local AC vendor!)
Approach #3: Stereo or monoblock bass amps with guts on the LF (typically SS), and something more delicate with finesse for HF (i.e. tubes, even SET options). I’m using Odyssey Stratos Extreme Mono SE’s for LF and the Bella Extreme 3205 Platinum on HF. This is a very nice combination, as each amp is playing to its strengths. The midrange/top end is very open and warm, while I can still apply some tube rolling to taste. Baseline noise can be an issue at 100db efficiency so you have to choose carefully if that bothers you. No different than some of the other high efficiency situations with single driver horns, etc. What works there will probably work here too. That’s great news because some of those amps are breathtaking in their clarity.
Approach #4: Stereo or monoblock bass amps and lower power SS HF amps (even T-amps or similar). I’m thinking about trying the Stereomojo shootout winner, Trends TA10.1 ($150), maybe the highly regarded KingRex T20/PSU ($249/$169), or even one of Nelson Pass’s First Watt offerings, either original or DIY clones. Not sure yet how to apply the various FW options (F1,2,3,4, Aleph J), as this system doesn't use a preamp in the conventional sense.
One issue with #2, #3, #4 is that you must have a way to match the gains, unless you're OK doing it by ear, that is independent of what’s programmed into the DCX. The current DCX XO program already has +0.3db on the LF and -0.3db on the HF, so the relative amp gain settings must also take that into consideration (in other words, preserving that difference HF to LF). While I have an o’scope, signal generator, dummy loads, etc. to do this precisely, most just do not have an easy way. When I get to it, I’ll start another thread for that discussion, with the idea to use collective AC wisdom to come up with a simpler procedure everyone can use. Maybe some tips and tweaks too
C’mon, don’t be shy, show us what you got
- What amp combinations have you tried on your CS2’s (#1-#4) and how did it work out?
- What are you planning or would you like to try at some point?
Tom
