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Recommended Tube Amp for ML CLS I model

Happy holidays!

I've just acquired a pair of CLS I speakers with recent panel upgrade. I know this speaker is supposed to be tube friendly (higher impedance) and the easiest to drive of the CLS range. I am very familiar with the IIz model, but that has very different characteristics from what I understand.

I'm looking to pair a good tube amp with these speakers, to be driven by a Tact 2.2 Mini digital preamp that will be configured to send lower frequency signal to a REL sub and a time-aligned mid / upper signal to the CLS via a Tube amp. (I used a similar setup with an Accuphase DF-35 Digital dividing network and CLS IIz and REL - the Tact is a cheaper option if you just need to 2-way xover division). The digital discussion can take place in another thread.

For now, I am looking for a good tube amp to drive the CLS I model. Since the digitally split signal will be sans deep bass, low frequency performance is not a high priority. So far, I'm looking at ARC VT130SE and VT150 monos (both nice, but a lot of negative feedback used), Rogue Zeus (triode mode), ARC VT100, ARC VS115, Atma-Sphere OTL (with autoformer?), etc.

Any recommendations from those familiar with the original CLS?

TIA!
fdriver
dover
2,251 posts
 
Hi there, I used to import Martin Logans into NZ many yrs ago along with Conrad Johnson, Quicksilver, Counterpoint etc. They sre actually dificult to drive, although it is very humid here which didn't help. Best sound was with the Quicksilver 8417 monos by far. VTL's couldn't drive them. Big Rowlands are an excellent match either 7's or 5's. We had custom built stands to lift them 12" off the floor and angle slightly forward/down, this really opened them up and improved the bottom end considerably.
fdriver OP
17 posts
 
Dover - are you referring to the Original CLS, II, IIa, or IIz? I know the IIa was a bear to drive, due to it's very low impedance. The original CLS actually had a very high impedance above 1000 Hz, I believe. This made it ideal for tube amps. The series II versions definitely favored SS amps.
karma16
29 posts
 
HI,
I have the CLS IIA's. I don't think they are any easier or harder to drive than your original CLS's. They both need power and stability. I drive mine with an ARC D250 Mk2 Servo (250W/channel) tube power amp and the sound is magnificent. Originally, I drove them with a Levinson No. 23 power amp. It worked well but not as good as the D250. I also have biamped Kinergetics dual SW800 subwoofers. This is a wonderful combination.

A couple of hints. Do not expect deep bass from the CLS. They just won't do it. Good subs are the answer which will also improve the CLS's dynamic range. Next, the CLS are the most demanding speakers I have ever experienced of the up stream electronics. They are absolutely surgical in their ability to demonstrate flaws in the system. They require first rate preamps, power amps, cables, and everything else. These speakers will not tolerate short cuts. This quality is not a drawback. It's way all speakers should behave but most don't.

For these reasons I do not recommend CLS's as beginner speakers. It takes considerable experience, knowledge and financial commitment to get them to perform to their potential. Sure, you can just hook up your amp and the speakers will speak. But that is just the beginning.

People get drawn into the CLS's because they sound great at a relatively low price. But that is deceiving. To be really successful with them, you will need to buy expensive electronics. If you get it right, they are some of the finest speakers ever made. But you do have to get it right.

Sparky
fdriver OP
17 posts
 
Sparky,

I have a tonne of experience with the IIz model and was able to make it sing with everything from Gryphon to Innersound to battery-powered Rowlands.

For CLS I, though, it is clear that modestly powered tube amps should be ideal; unlike the II series.

But, yes, I agree that experience is important with any planar speaker.
dover
2,251 posts
 
12-27-10: Fdriver
Dover - are you referring to the Original CLS, II, IIa, or IIz?
Original CLS, but have also experience with CLS II. My caution would be that some valve amps work, some dont. For example VTL Compact 100's ( 100w ) couldn't drive them, yet a 20w Leak Stereo 20 could. My recommendation would be to audition before you buy if possible. FWIW I preferred the original CLS with upgraded panels ( original single transformer crossover ). The Quicksilvers produced the most transparent and wonderful soundstage despite Mike Sanders rolling his eyes when I told him what we were using with the Q's.
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