Recent upgrade to Cronus Magnum

How much did the Amperex (1960) Tubes cost? 

I had been traveling quite a bit in February so didn't get a chance to try out different tubes. Finally got around to ordering new tubes from Brent Jesse as per @avanti1960 's suggestions. Was advised to get the Amperex (1960) for the center/preamp as suggested on this forum. But Brent suggested that I go with Amperex for the AX7s as well. He also advised me to let them burn in for at least 48 hours before doing any critical listening.

So what's the verdict after changing 3 tubes? All I can say is, wow! The sonic improvements are not subtle by any means. I'm getting much more detail than before without any harshness, all in a very polished and smooth package. Better tonality, more separation and air between instruments. Much wider and deeper soundstage. Vocals sound more natural than before.

But the biggest improvement by far is the quality of bass. I never thought I could get the P3esr's to produce such satisfying base. It doesn't go much deep but whatever I'm getting is tight and very palpable. I was thinking of adding a subwoofer, but honestly at this point I'm not sure I need it. Everything sounds so balanced, don't want to ruin it.

Another improvement I noticed is that I'm getting more details and bass at low-to-moderate volume. Before, I had to crank it up to 11'o clock to get the details and bass. After the switch, everything sounds pretty good even at 9'o clock position on the dial.

Thanks everyone for the amazing advise. I'm pretty happy with the music this system is producing. I'll probably swap the remaining AU7s in a few months, and maybe get a copper-based speaker wire to see if I can eke out even more improvements.

The cronus is known for being non tubey . Its recommended to not adjust bias often.

Hi, my 2 pennies worth . I have a Rogue pre . My close friend that lives nearby is a former Rogue Dealer . He has a Chronus Magnum II in his office . A Rogue Hera pre with M180’s in his main system. So I’m familiar with their sound. I am thinking that all your tubes are well used ? A new quad of power tubes is a must, as they will sound brittle and edgy when tired . New production Gold Lion KT 88’s or Tung Sol KT 120’s if the early Chronus  will support them . The Tung Sols make substantial bass and still have good mids and highs . I have tried EVERY driver tube mentioned in this thread . And I absolutely would choose NOS Telefunkens and am surprised they weren’t mentioned . On a budget nos Tesla and Tungsram sound similar. I run Telefunken G-73R’s in my pre. Rogue generally suggest trying a nos Mullard as they smooth things out . But it’s like putting a blanket over your speakers , or pushing the Dolby button on your tape player . The Rogue amps are all SS power supply ( no rectifier tube ) so you can’t drop the voltage and mellow the sound . But they do recommend under certain conditions lowering the bias voltage . Quality driver tubes make a huge difference. So now your at an expense crossroad . You could consider having the amp serviced and/or upgraded to current specs . But first I would get a quad of new power tubes. New nos driver tubes . Where I’m totally lost is how it pairs with your speakers , as I haven’t had those . And that’s a big deal . Now here’s a story . My friends M180’s were over powering his Speakers and he was advised by Rogue to lower the bias first . He wasn’t satisfied and was directed to replace the power tubes with new Gold Lion KT 77’s and play with the bias setting . I HIGHLY SUGGEST , that you read the driver tube sound descriptions on the Brent Jesse website. After spending $2K on various nos driver tubes , I can attest it’s SPOT ON ! I haven’t shopped there however, but hear good stuff . I’ve also been recommended to Andy at Vintage Tube Service by wholesale and manufacturers. I purchase new production power tubes from Tube Depot when they run a 20% off sale and ask for matching and 24 hour burn in . I have a Dennis Had amp ( Cary founder ) and Zu speakers . My system runs bright . I have Amperex , Seimens CCa , Tesla , Mullard ,RCA , Phillips amongst my stash and have found the Telefunkens to deliver a full sound without being overly bright . I run a Schiit Yiggy DAC and a modded Thorens TD 160 with a Grado cartridge. I’ve had to avoid any silver in my wires as it gets too bright also . I hope my rambling has provided some help . Happy Listening , Mike B. 

Surprised no-one has asked. Have you checked the bias?

Just as a point of interest...I believe the classic Cary SLI-80 did use tube rectification, where as the current (HS?) model does not. I have heard from someone whose ears I trust the old 80 is a hell of sweet amp. Agree with all of the above that advise to tread slowly with tube rolling. 

I too had a similar experience with the Rogue Cronus Magnum ii. I am, by no means, an expert and I am only relaying my impressions. This was probably 5 yeas ago and the Cronus was my third step of upgrades with tube gear and I was really let down by its lack of “tube sound”. I now have all separate tube gear in my analog chain (phono preamp, line preamp and SET monoblock power amps. Ironically, I too have the same Cambridge Audio Azur that I use only as my DAC while streaming).

I am surprised no one has mentioned what I consider to be the single greatest factor to why the Cronus lacks what I call the tube sound. This being that it has solid state rectification. I know that some people actually like this and Rogue markets it as one of the benefits in some of their models. All of the pieces in my current chain have tube rectification. To me this has been the real key to getting more tube sound. I have had two experiences with tube gear that use a solid state rectifier, the Cronus and the Cary Audio SLI-80HS*. Both the Rogue and the Cary lacked the warmth and space I was seeking. And, like a few have mentioned here, I went down the rabbit hole with both the Cary and the Rogue trying countless NOS tube combinations and spending gobs of money. Fortunately, I have been able to use some of those tubes, with great results, in subsequent tube gear. Also, I have had a couple Cary pieces since this one that use tube rectification and have loved them (including my current phono preamp, the Cary PH302-MKII).

Again, this is personal preference and many people actually prefer what the combo of solid state rectification and tubes offer. Just not me. I want tubes to sound like tubes.

Hope this helps.

Jared

*interestingly enough, I read about a year ago that Rogue was suing Cary over the use of solid state rectification in tube amplifiers claiming they stole a design. Haven’t heard whether or not it was settled.

Don’t change all tubes at the same time, so start with say the 12ax7 and live with them for a while.
messing around with tubes can also be a rabbit hole. As an owner of several Rogue amps who,s rolled a lot of tubes in them, I am not sure going crazy with rolling tubes will be as productive as you think, but try in it stages and save money. Most of the new Rogue amps are not super tubey but shouldn’t be dry or harsh as u mention. I love the sound of my 99 pre amp with stereo 100. I also recommend Andy at Vintage TS so long as he answers the phone! Good luck.

+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.)

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.  

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.

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.  

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.

Yes the stock JJ small signal tubes can also sound unrefined.  They take forever to break in-  someone on another forum mentioned 700 hours to smooth out!  

I hated the sound of my Rouge RP-5 out of the box, it was way more harsh sounding then my vintage ss Luxman preamp. And that's also a little true for the st-100 amp. I now run NOS tubes in both, Mullards and RCA tectonics for the preamp tubes, still using the kt-120s with much better results. And a power cord my not be a bad idea I use DH labs  you can try one from the cable company and if you don't like it you can send it back. O and by the way I also have the p3s just the 40th anniversary model.
 





 

good info arafiq.
you have the CM II, it is an excellent amplifier that is neutral sounding but can be made more laid back with the right tubes etc.  you get a huge 3D sound stage and great dynamics with the KT 120 tubes and 100 watts. 
once you check the speaker terminals and adjust or confirm 8-ohms at the terminals-
1) check the tube bias for all 4 power tubes- once set it only needs to be checked every few months or so, mine never needed adjustment.
2) definitely no silver plated speaker cable.  i tried nordost and the sound was edgy and unrefined.   I use Kimber 8PR and the sound is smooth and excellent.   Very economical if you buy in bulk and make your own connections.  
3) defiitely no mullard !  everyone keeps saying mullard- i tried 3 diffeent ones and they all sounded dirty / unrefined in the lower treble.  here is my tube map for smooth success-

center preamp tube- (brent jessee)  screened for low noise (ask) 

12AU7 Amperex Bugle Boy type, Amperex Heerlen Holland factory code, blank label or Amperex white label or made for Dario, Philips, Adzam, Gulbranson, Eico, and others, original 1960s. New Old Stock original box and White Box. Very well made, low noise tubes. These are the originals from Holland, made in the same Heerlen factory , and at the same time as the Bugle Boy tubes, but labeled for other brands. Save big over the Bugle Boy label tubes and still get fantastic Bugle Boy quality!

49.00 single tube

front row 12AX7

RCA 5751 Premium industrial grade 12AX7, 2 mica

New Old Stock in white box, thick mica spacers. The best bargain going in a genuine NOS 5751, the RCA set the standard for all the other brands. MATCHED PAIRS ARE $110.00.

back row 12AU7

814A Premium industrial grade 12AU7, RCA JRC military TRIPLE MICA type, blackplate.

New Old Stock in original boxes. A really fine military grade triple mica blackplate of the 12AU7 family, made by RCA for the military. The early type triple mica blackplate 5814A of RCA tubes are very scarce, as they were not available to the general public, but are well worth the search. These are exactly the same electrical characteristics as the 12AU7 and can be used with improved results in any application calling for a 12AU7 or ECC82. Excellent quality that lasts. MATCHED PAIRS $99.00 PER PAIR

These changes will make the sound smooth and refined all day long and let you understand why people say it is such a great amplifier.  

I have a very similar setup
851N to Rogue Tempest
The Tempest is the next one up the chain but I think it is very similar. Now I have the Tempest 3 Super Magnum for what that is worth. I really like the 851N, however I am a modest guy just looking for great music.

I was looking for more of a "tube" sound, I loved the detail and punch of the unit but wanted more so I:1) Switched from Ultralinear to Triode mode2) Switched to KT-88 tubes (PSVane), I think this is a more musical tube than KT 90's or 120's3) Rolled my 12AX7 to a 5751 (Raytheon windmill getter)
Rolling to the 5751 had the most impact, this is a lower gain tube and I think it brings our more midrange detail and has a more natural tone than the stock 12ax7
Second biggest impact was the KT-88's, I did like the sound better, to my ears more musical and I don't really need the extra watts, my speakers are fairly efficient and my room is not huge.

Ultralinear to Triode, I think this helped, I found myself in much longer listening sessions once I did this.
Now I love it. I listen mostly to acoustic music. It works like a charm for me, I think the power output dropped from 90 watts to probably more like 30-40 watts but as the resolution, detail and tonality improved I found myself enjoying the music much more and also listening at lower volume levels.
Good Luck

Ps. Wiggle the tubes a little bit but be super careful while off . Make sure they are seated nice . I had a super small crack in a power tube and all hell broke loose, good thing i was standing there to shut it off . Shipped it to rogue . Service is outstanding they even sent it back with all new screws in it. 

I had a mullard in my center position and removed it almost right away . Didnt sound good . The stock tube produced hiss so i ordered a mulllard . I was disappointed . So i put the mullards to the outside position and put one of the better stock tubes back in center . Good sound was back. Now i have a gold lion with great results . A ting sol was great . High detail. 
The mullard sounded woody the 400 hz area came up and the very highs went down. Tubes can be different sounding even though labelled same. Very satisfying gains can be made with tube rolling . I recommend some nos rca . Beautiful sounding And affordable. Check your settings you shouldnt have to turn that amp up past 11 oclock to have decent sound level . Set the node to fixed. Very very gently tap the tubes to see if they are microphonic . If they are that could be a good source of noise . Obviously dont have the amp where it can vibrate as volume goes up (sharing a table with speakers etc. )

regards 

@avanti1960  sorry, forgot to mention that its version 2.

Wow, thanks for so many wonderful suggestions! Based on several responses, I'm leaning toward the suggestion to try and work with the amp settings/tubes before jumping ship. I was trying to figure out how to check the impedance setting, but it looks like I'll have to take the top cover off to see. Once I check that, I'd try the DAC in the Node. If that doesn't bear any fruit, then I guess it's time to roll some tubes.

The original owner had already replaced the center tube with a NOSS mullard, which is what I have. Are there better alternatives (for warmer sound) than the NOSS mullard?

BTW, I forgot to mention that the speaker wires that I'm using are by Clear Day which are silver. Is it worth replacing them with copper to tone down the brightness?

I'll try to check, and possibly adjust, the impedance settings tomorrow and report back the findings. As always, I'm really grateful to you for all the help. Will keep you guys posted.

I had the Cronus magnum II with the kt120’s and it was nothing like you described. I also switched out the preamp tubes to PsVane tubes. I liked the Cronus much better than the prima Luna integrateds, which I thought were so so and not very powerful. I also used the 4 ohm load setting. The only reason I sold it was that the bass wasn’t as tight as I like

IMO- your to-do list in the proper order:

1) Check (4 or 8 Ohm) Impedance setting
2) Perhaps what davekayc suggests.
3) Tube rolling
* I disagree with the Power Cord suggestion, unless you happen to have another one to try. Not that it won’t change the sound, but I wouldn’t dump any money on one.

Just my two pennies worth, your description of the Cronus is exactly what I heard from a Primaluna integrated a little while ago, so I’d think twice about including that as a possible replacement.

Pull the cambridge from the chain and go straight from the node to the cronus. I have the cro mag ii and the node 2 and i would have no problem doing that. Check your underhood leads as mentioned before. Sharp nasty sound can occur and i have found that if your gain is too low going into the cro mag you may have your volume on the amp turned too high. It sounds like a scratchy overdrive that affects the mid highs. Fiddle with it it may smarten up . Change your center 12au7 on the cro mag may be done and producing noise. 

First put good quality NOS tubes unit 
that is a big upgrade in itself
and a good power cord.

another thing to check is the speaker leads inside the cover.  they can be set to either 4 or 8 ohms. my harbeths sounded horrible with the 4 ohm leads connected to the speaker terminals.  make sure they are wired for 8 ohms.  

is your cronus v 1 or ii ?  i had a magnum ii driving harbeth c7es3 and the sound was refined, dynamic and excellent.  
if it is the first version it will not have KT 120 power tubes which are mandatory imho.  
it responds very well to small signal tube rolling as well as input and speaker cables, none of which need be very expensive  dont give up on it, it is capable of sounding better than anything solid state near or above its price.  
try rca 5963 in the back row, a phillips amperex in the center and 2 rca 5751 in the front row.  also make sure all 4 power tubes are biased.  

The tube that will make the biggest difference is the single one in the middle at the front.  You could try a NOS Mullard in that spot, which is about as mellifluous and forgiving as you can find.

I  had the P3's, and am now breaking in the C7's. To power both, I've only used my Shindo preamp in to my Croft hybrid amp. No question the C7's are easier to drive, so the P3's can be a tough load. I am not going to pretend to have your answer, but I was told (by a reliable source) that Rogue amps do not have a classic tube sound. Perhaps a good thing with certain speakers, but obviously you're looking for more warmth and texture. One suggestion (since we know your Cronus is broken in) would be changing tubes. The second suggestion would be a warmer tube amp like Quicksilver. I really enjoyed my V4's, which (in my room, with my speakers), were much more satisfying than another high priced tube amp. I'm going to withhold the name, but it's a household name when we think of tube amp manufacturers. Both amps ran KT 88's as well. That's my 2 cents, but I'm certain others who know more can guide you. The Quickie integrated won't do it, but I believe a pair of mid-monos and a Quicksilver line stage would run you around $3K . I will now defer back to others with more experience.... 

What is the tube type is in that Rogue amp?

arafiq - I have a Raven Audio Blackhawk LE, which was a limited edition of the original Blackhawk amp that was in the middle of the 'Avian' series. The current lineup is here - https://www.ravenaudio.com/product-category/amplifiers/avian-series/

I'm in Austin but Raven isn't, its facilities are in a couple of places in East Texas, including Onalaska on Lake Livingston. The shipment of one of their power cords came from Shreveport, La. If you're interested, call the owner, Dave Thomson, 318.703.4542. He's incredibly helpful and supportive. They have a free 45-day home trial available which might work well for you since you are so close.

@sfar  Thanks for sharing. Glad to know I'm not the only one thinking the Cronus as lacking refinement. Like they say, it's a journey. I started in this hobby thinking that I am more in the "detailed, modern, hifi, etc" so to speak type of sound. But I'm reaching the conclusion that I like warmth and nuance more so than high resolution and slam. If you don't mind my asking which Raven Audio amp do you have? I live in Dallas, so not so far from the Raven shop which I believe is in/near Austin. Plus there's the Texas connection :)

@audioconnection Thanks for the tip. This certainly looks promising and worth looking into. But as I mentioned earlier, I'm new to tubes and want to give it a fair shake before deciding whether they're for me or not. Perhaps, the Cronus was not the best introduction to tubes -- because they're more SS-like maybe? I want to experience some classic tube sound, and if that doesn't work, I'm still leaning toward a Naim upgrade since I really like the Unitiqute's sound signature.

Easy for you now.
https://www.audioconnect.com/product/belles-aria-integrated/https://www.hifichoice.com/content/belles-aria  The Rogue is a fine product but not at its best with the little Harbeths.Belles Aria is a satisfying match with the small Harbeths, made in USA
A satisfaction guarantee comes from Audio Connection.
 Best JohnnyR

I had a similar experience with the Cronus Magnum. I had a tube amp/preamp setup, an AES/Cary AE-25 amp and AES DJH preamp with a pair of Devore 8 speakers but was persuaded to try the Cronus Magnum based on reviews. To my ears it wasn't even close. I found the Cronus not nearly as satisfying in the ways that good tube gear often is, sold it and kept the AES gear for quite awhile. Still regret selling it even though my current Raven Audio amp is the best I've owned.

That's not to say that Rogue doesn't make great gear, lots of people swear by it, but they don't have your ears. Unfortunately, it's not going to be easy to sort it out for yourself without doing the kind of gear swapping you describe but if you were happy with the Naim sound and don't want to start down that path a Naim upgrade might be the simplest way to begin.