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SS Amps for C4 Signature II's

OK, I’m curious about amps.

I have a set of C4 Signature II's that are running with ODYSSEY KISMETS and seem to sound pretty darn good. But, they aren't the be all to end all amps, and they never were meant to be. A good sounding "value", well yes. I have no major complaints on their sound for the price. So, lets not pick on them but look at what might be an upgrade for these speakers. Dragging amps home to audition is a physical exercise in and of itself with 75 pound and heavier weights I'm seeing!

I have just a few amps that seem to be very compelling for different reasons and I’d like some viewpoints from all of you that have been here, done that, and especially C4 users. C4’s can be an odd load at the low-end.

1.0 The first thing is CLASS A verses A/B. The image stability of CLASS A amps is derived from the voltage rails being sag proof (or more so) than class A/B since the are charged up all the time. Yep, that eats power, too. Still, this is an advantage if you pick the right amp.
2.0 A/B amps come in two flavors, high bias amps like an old McCormack DNA-225 (it gets plenty hot when running!) or a lower bias unit like my ODYSSEY KISMETS that refuse to even get warm. The “hybrid” high bias amps that are around (PASS LABS as an example) can run CLASS A pretty high (up to 40 watts in the case of a X350.5). Is that enough to capture the CLASS A “flavor” and A/B efficiency?
3.0 Weight. Man, how do you move your stuff? Some amps are frighteningly heavy making a dual MONO set-up seem logical, but even more expensive. I may get the sound, but the weight can drag you down. Yes, weight is part of the deal in a good power supply, which means get the power you need.
4.0 I HAVE to be able to listen to them before I buy. I don’t need “more” of the amp I have now, worse or the same general sound, but better. So in-house audition is a must. I can’t easily get the PASS or ANTHEM products making auditions and service a pain. But, if it’s worth it, I can try. I can get BOULDER products but they are WAY high priced.
5.0 I am using a PASS LABS XP-10 pre amplifier so I have full balanced or RCA outs.
6.0 Is it just me, or are the specs on these units hard to come by? VA transformer ratings, CAP values in the power supply ETC? Not that this is all there is, but it helps.

So considering those points, and if I’m seeing all this right, we can sort of claw through some of this on paper.

My first choice, again, on paper; Plinius SA-103.
I have heard the Plinius on Theil CS2.7’s, and it imaged VERY well. Can’t comment on the musical balance on my speakers, though.
All CLASS A capability but can run A/B with the flick of a switch so I can listen to the radio with A/B!
Seems to be a solid design with good sonic ratings.
Plenty of power (125 watts / 220 watts) for the volumes I listen to (83 dB SPL average where I sit 15 feet away).
I can get another one if needed for silly amounts of power.
Seems to be nice at low impedance and high current situations.
Wow, it gets warm in CLASS A so keep the music going!
Good paper specs on S/N and separation.
I can actually pick this amp up at 85 pounds.
Price is “reasonable” for a high-end amp.

My second choice is a PASS LABS X350.5 as I’m told that the sweet spot for PASS A/B sound is this amplifier. PASS pure class A is too expensive.
40 watts of class A capability may capture the sound I need?
Seems to be a solid design and also with good sonic ratings.
WAY more power than I’ll ever use, though.
Never need to buy another amp for power.
Stable into low impedance.
I CAN NOT safely pick this amp up at 135 pounds!
Price is “reasonable” if you can find a used one for a high-end amp.

My third choice is an ANTHEM P2 that some say is a giant killer (I don’t see any dead giants laying around anywhere, though).
Seems to be a more standard A/B amp for home theater but…I keep being told to listen to it.
Seems to be a solid design (full of protection circuits).
WAY more power than I’ll ever use, though.
Never need to buy another amp for power.
Stable into low impedance to an extreme.
I can pick this amp up at 75 pounds.
Power rating and light weight make me wonder about the current delivery capability.
Price is “reasonable” for a high-end amp.

My fourth choice is a BOULDER 860.
Doesn’t seem to “double-up” on power into 4-ohms.
Can’t be run “mono” to add one later on.
Built well.
Paper specs are impressive (S/N and separation) but gets a knock for harshness in the midrange.
Seems awful light at 45 pounds to provide a big current reserve in the power supply.
Price seems high for the lightweight power supply.
rower30

Showing 3 responses by zd542

zd542
5,339 posts
 
I didn't know that your speakers don't allow for biamping. The reason I mentioned vertical biamping is that it eliminates all kinds of problems that you run into when you biamp traditional (horizontal). This is how it works. You need 2 stereo amps that are the same. Each amp powers one of the speakers. You run a cable from the right output on your preamp to both inputs on one of the stereo amps. (If your preamp has 2 sets of outputs, you can run 2 IC's. If you have only 1 output, You'll have to split it.). You then run speaker cables from the stereo amp to your speaker. One for the high's and the other for the low's. Do the same thing to the left channel.

The advantage of doing it this way is that you are working each amp the same because it is powering a whole speaker, as opposed to using 1 amp for the highs on both speakers and the other for the lows on both speakers. There's no need for active xovers or anything like that. You just hook it up and it works. Keep in mind, though, it only works with stereo amps.
zd542
5,339 posts
 
"OK, but there STILL has to be a passive X-over inside the speaker after you remove jumpers to allow vertical bi-amping as you can't, or don't want to, run full range into the mid/tweeter (assuming a three way speaker) and woofer. The set-up makes sens when you remove passive cross-over components."

After reading this response, I don't think I did a very good job of explaining Vert Biamping. Of course there is a passive xover in the speaker. You couldn't do a vert biamp without it. The idea is to work the 2 amps exactly the same way so the sound is consistent. Each amp powers the whole speaker. It amplifies the highs and lows thereby putting the same load on each amp.

Also, you say that the setup makes sense when you remove the passive xover components. That's not correct. You have to have the xover in the speaker or it won't work. If you removed the xover you would just be sending the full frequency range to each driver. That's why you need stereo amps for it to work.

Sorry if I didn't do a good job explaining in my first post.
zd542
5,339 posts
 
I've read through your post and you seem to be on the right path. I think you should keep #4 mandatory, if at all possible. Also, while you can look at the design of an amp and maybe point yourself in the right direction, in the end the amp has to stand on its own 2 feet with regards to sound quality. Some amps have 4 rubber feet. Thats OK too. Just as long as it sounds good.

I've had several Pass amps, the McCormack you mention and an old Boulder. Never had a Plinius. Also, I think its safe to say that a newer Boulder amp would sound much different than the old one that I had. Given all that, the first amp I would recommend you look at is Ayre. I feel their products are state of the art for SS. That doesn’t mean that you will like them, but to not consider them would be a mistake. Generally speaking a lot of people say that they are analytical. I don't believe that’s an accurate description. Ayre does pass a huge amount of detail through their products but its the cleanest, purist, most liquid solid state I've ever heard. In my main system, I have 2 V5's biamped vertically powering my speakers. Depending on how big your room is and how much volume you need, 1 V5 may be all you need. I won't lie, though, 2 is better.

"I can get BOULDER products but they are WAY high priced." By that statement, I take it you live somewhere near boulder. Ayre is made in Boulder as well, so there should be no problems there.

If it turns out that you don't like the Ayre for some reason, I highly recommend you listen to BAT. In my opinion, they are in the same league but they do sound a little different. Their SS sound falls somewhere in between Pass and Ayre.

One last thing. The weight issue. Are you kidding me? Its not like a girl that you have to go around and be seen with. You need to suck it up on that one. Pay some to move it or through your back out. This is your audio system were talking about here.
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