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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
karma16
29 posts
 
HI Atmasphere,
I checked the Martin Logan Club site where they have a data base with all the ML models and specs listed.

You are right. the CLS is listed at 6 ohms but a minimum value is not listed. The CLS II's are listed at 4 ohms with a minimum of 1 ohm. And you are right that that is brutal load for a tube amp. But my D250 deals with it just fine.

It's the minimum value that is the cause of problems with amps. Four or six ohms is no problem. But the CLS's load is highly reactive with the minimum load showing up at high frequencies.

Sparky
fdriver OP
17 posts
 
Appreciate all of the very informative replies. I'll check the db on the ML Club site.

So far, it looks like an A-S MA-1, Rogue Zeus, ARC 130SE or 150 monos would be good candidates for the CLS 1. Others would probably be VTL 450 or Quicksilver's V4.
lacee
811 posts
 
I used to have two pair of CLS, one the 11a, and the other was the 11z(I've also owned stacked Quad 57, ML Sequel,Quad 63 and Acoustat 3)and neither pair worked well when I tried them with a VTL ST 85.
Bea told me that I neeeded to move up the line and get into the bigger tube units from VTL.
I settled for a pair of Classe DR 8 run as balanced mono blocks and had great results.

Now,an even better match up and the best sound I ever heard from a CLS was with the Audio Aero tube mono blocks.
Not cheap, and too expensive for me, but I never knew how much bass those CLS were capable of until I heard this combination.

The right tube amp is out there,but it may not be one of the usual suspects.
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