2. amps-preamps
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Recent upgrade to Cronus Magnum

A few weeks ago, my system consisted of the following components ...
Apple TV >> Naim Unitiqute (v1) >> Harbeth P3esr

While I liked the overall sound, I wanted to move up the chain and try something different. I felt the Unitiqute was a little underpowered. So when an Audio Rogue Cronus Magnum came up for sale (local craigslist), I jumped at the chance and bought it. I had a Cambridge Audio Azure 851D stored in my close, which I added to the chain. So now my system looks like this...
Node 2i >> CA Azure 851D >> Cronus Mangum >> Harbeth P3ers

When I first made the change, I was quite impressed with the increased loudness and a wider soundstage. However, I realized that, unlike the Naim, I was getting listener fatigue. There was a certain harshness (like metallic sound) to the vocals, especially female vocalists. Also, I was expecting some tube magic, which frankly is just not there. The Cronus Mangum sounds much closer to a solid state. Yesterday I put the Naim back in the system and much to my surprise the little box is keeping pace with the much more powerful Cronus Magnum. Yes, it doesn't play as loud and the soundstage is not as wide, but the sound is so much more refined, smooth and balanced. I'm wondering if I made a mistake. So before I make further changes, maybe the good folks at Audiogon can provide some relief.

What do you think is the weak link in my system? Should I keep the Cronus Magnum and try a more musical, refined DAC? If yes, what do you guys suggest (prefer used, below $2000)? Or do I ditch the Cronus and go for a more tube-like sound (Primaluna, Rogers, vintage ARC, etc)? The little voice inside me is telling me to sell the Cronus and move up the Naim integrated chain (e.g. Supernait), since I really liked the Unitiqute's refinement and balance. But then again, what if it's not the amp (Cronus) but the DAC (CA Azure 851D) that's the likely culprit here? Should I change the DAC first? Or maybe try rolling different (smoother?) tubes?

As you can see, I'm mighty confused and can use some pointers. So many variables ... aargh!!!!
128x128arafiq
arafiq's avatar
arafiq OP
1,601 posts
 
Alright folks, time for a quick update ...

I checked the impedance and it is indeed set to 8 ohms. Check.

I tried to lightly flick all the tubes and to my surprise, one of the front row tubes was wobbling too much. I took it out and inserted it back again, making sure it was a snug fit. Thanks for the suggestion.

But the biggest improvement came about when, as suggested by @davekayc, I removed the Cambridge Audio DAC from the chain and connected directly to the Node. It definitely took the harshness out in a noticeable way. Thanks for the suggestion.

@avanti1960  Thank you so much for the suggestions. I think I will start the tube rolling based on your recommendations starting next month. Please forgive my "nouveau-tube" ignorance, but are these tubes available at a website, or do I need to order from a dealer? If you can provide the sources I would truly appreciate it. Secondly, what's the better approach? Replace the tubes one at a time to measure incremental improvements, or go all out and replace all of 'em as you suggested? I'm really hoping that changing the tubes will have a meaningful impact.

@mod_asored, I'm not sure if the CM 2 supports the triode mode. I think v3 does but not the 2 doesn't. Feel free to correct me if I'm mistaken.
avanti1960
1,425 posts
 
see audiotubes brent jessee for all your tube needs.  the preamp single tube makes the biggest difference but the other two rows do affect the sound significantly.  
twoleftears's avatar
twoleftears
5,313 posts
 
The center front tube, although only one tube, handles preamp duties for both channels, so on both counts it's the place to start.  I'd consider getting a couple of different options to roll in there rather than retubing the whole amp.  Andy Bouwman of Vintage Tube Services is another excellent source.
avanti1960
1,425 posts
 
the "whole amp" is really just (5) small signal tubes.  Leaving the JJs in is not going to get the best sound.  They are dark as to be opaque and unrefined.  
I spent 3 years perfecting the sound of the CM II with Harbeth speakers and tried many combinations of nearly every top NOS tube and the recipe works.  
Unfortunately Andy is not returning my calls or the calls of a friend either.  
phastrone
24 posts
 
+1 to all the posts in favor of the Cronus Magnum 2 with upgraded tubes. I liked mine best with a Brimar 12au7 from Upscale Audio in the center position and Sovtech 12ax7 lps in the ax7 positions. (I'm now using a Rogue Atlas for the bass drivers and a Rogue Stereo 90 for the top end with a similar tube complement.)
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