Rogue Cronus Magnum II Tube Rolling

[peti]

I've been thinking...is there a way you can internally reduce preamp gain in the Cronus Magnum II? I've heard about those attenuators all right, but I'm curious if there's a solution to do it within my unit? I have a pair of very efficient speakers and I wanna go easy(er) on the tubes, too, to preserve their longevity. I just don't need all that gain. I never take the volume knob over 10 o/clock, most of the time it stands between 8-9.

 

[bacobits]

Why don't you just try flipping the Power tubes to EL34's, KT77's, knock some watts off.
Which ones ? That I can't answer.

 

[honestabe316]

I have a problem with my cro mag 2....2 days ago i removed the grill to dust and noticed the kt-120 in the V3 slot was dead. It also had white heat spots on sides not black like the others....
U bought 2 new tung-sol kt-120's today. I installed 1 to replace the dead one. Turned unit on and the coil at top of valve glowed red but tube only slightly warmed.....other 3 all got normally hot.....the replaced tube biased at 0......the other 3 biased Normal...

What could be the cause.....iopen grill once a month to dust and check bias......tube could have died within last month.....didnt notice anything sound wise......i havent added any new equipment or cables.....the white spots are really odd and the fact that the tube only warms up despite the coil turning red.....any thoughts?

 

[Old Guy8]

I have a problem with my cro mag 2....2 days ago i removed the grill to dust and noticed the kt-120 in the V3 slot was dead. It also had white heat spots on sides not black like the others....
U bought 2 new tung-sol kt-120's today. I installed 1 to replace the dead one. Turned unit on and the coil at top of valve glowed red but tube only slightly warmed.....other 3 all got normally hot.....the replaced tube biased at 0......the other 3 biased Normal...

What could be the cause.....iopen grill once a month to dust and check bias......tube could have died within last month.....didnt notice anything sound wise......i havent added any new equipment or cables.....the white spots are really odd and the fact that the tube only warms up despite the coil turning red.....any thoughts?

Try a call to Rogue? Still under 3 year warranty?

 

[honestabe316]

Yeah...i have a call in....it was after hours so im not sure if there open over the weekend.....will see

 

[honestabe316]

I see I never followed up. Well I sent it back to rogue. It was a traitor that went bad. I am second owner but I bought it at 4 months old so instead of the flat $175 fee for non warranty they were gonna charge me $60. I thought that was fair.
I then asked if there were any new upgrade or mods for the cronus 2. They said that there was an unadvertised model that they have been doing for those who ask. It is a capacitor and resistor upgrade using Evo caps. It was a$ 295 upgrade. When I said I was interested they said I could pay $310 and that would cover the repair and the capacitor/resistor upgrade. I felt that that was a good deal so I glad it done.

I would definitely recommend the upgrade. It took the amp to a higher level. The low end seemed bettered as well as the top end....added a bit more realism to the sound...if that makes sense.

 

[honestabe316]

I like my C-Mag2 so much that i bought a Rogue Sphinx for my secondary system. I received it last friday and it was dead. It had all original packaging and the upgraded speaker terminals... it looked brand spanking new. Fortunately the seller responded immediately and sent me cash to ship it to Rogue and they have it now. They should be calling tomorrow to give me the scoop. The seller called them as well and told them he would pay for repair.

Have any of the CM2 owners here been able to listen to the "Sphinx"? Just curious for the reveiws.... the CM2 is running well and still glad i got the upgrade capacitor and resistor package. Shortly after i had this done they announced the CM3 which has made me wonder if the upgrade that they offered me was the cap/resistor upgrade that the CM3 has as original parts.... the CM3 upgrade was tempting but i use external heaphone and phono preamps so not sure it would be worth it.i was hoping maybe the triode option might be a stand alone option without having to do the full upgrade.

 

[saggy]

The Sphinx changed my life. I absolutely love that amp, especially for the money. It was my first foray into tubes, and sent me on a magical audio journey.

I really do think the Sphinx is about as good as you can do for the money - for me, it had a solid head amp, and had a nearly pitch black background. I really enjoyed that amp. 100 watts, too, if I recall.

On top of it, Rogue are really good sports so you know you're in good hands if/when something goes wrong.

 

[Old Guy8]

I have Sphinx 1 and a C. Magnum 1 without phono pre. I like both of them. Difficult for me to site differences between them. I have NOS Mullards in pre of both amps. I can't quickly A-B them. They are close, IMO.
When I drive my inefficient 4 ohm Maggies, the Sphinx brings more power. I don't push the volume, but for those that do, could be important.

 

[honestabe316]

I bought a woo audio wa-2 tube headphone/preamp last year for my headphones and i used it maybe 3 times so i decided to use it as a preamp hooked into my adcom 5400 amp and a pair of klipsch quartet speakers as a secondary system. I wasnt happy though with the sound of the woo audio as a preamp. ( it was a great headphone amp though) So, I sold the woo audio and bought the sphinx to take over the job. Im sure i will be much happier. I was about to pull the trigger on a yaquin all tube integrated amp but at the last minute decided i wanted to stick with rogue even though it is a hybrid. If i want in a year or so i can pick up a rogue tube amp and use the preamp in the sphinx so i have an all tube rig. I mean i have my CM2 so i have all tube if i want it as i use an outboard parks audio budgie for the phono stage. I will be using my parks audio Puffin with the Sphinx too so my vinyl will sound pretty good i suspect.

 

[honestabe316]

I have Sphinx 1 and a C. Magnum 1 without phono pre. I like both of them. Difficult for me to site differences between them. I have NOS Mullards in pre of both amps. I can't quickly A-B them. They are close, IMO.
When I drive my inefficient 4 ohm Maggies, the Sphinx brings more power. I don't push the volume, but for those that do, could be important.

That is good to hear. Ill be driving my klipsch quartets which are 97.5 db so power is not a main issue. My Alon 1 speakers in my primary systemare a different story, 87 db but the CM2 drives them easily so im sure the sphinx will as well. Honestly im mostly hoping that with the tube preamp that it will give it a more liquid sound that if it was all SS. Mostly though i was a little weary buying it as i have never owned a class D amp for a 2 channel system.

 

[Old Guy8]

That is good to hear. Ill be driving my klipsch quartets which are 97.5 db so power is not a main issue. My Alon 1 speakers in my primary systemare a different story, 87 db but the CM2 drives them easily so im sure the sphinx will as well. Honestly im mostly hoping that with the tube preamp that it will give it a more liquid sound that if it was all SS. Mostly though i was a little weary buying it as i have never owned a class D amp for a 2 channel system.

I'm thinking the tube pre helps tame the class D power section. It's a great class D amp. Mine has RCA Cleartops in it for now.
I also use it for headphones. Headphones used while in standby mode.

 

[honestabe316]

In my C-Mag 2 i finally settled on genalex gold lions. I have mullards, and bugle boy, and thtelefunken black diamonds i can try in the sphinx beside the jj thats in it. That should be a good selection to start with. I like the fact that the class D seems to be more energy efficient as well as my electric bill is high here in n.h.
I dont use my headphones often but being able to use them without fully powering up might make me more likey to use them.
I called rogue today and thsyey should start on it tomorrow... getting anxious to hear it!

 

[honestabe316]

Well rogue called today and said the reason that my Sphinx had been dead on arrival was due to it being dropped by the UPS driver. Thre reason was that the transformer moved into the circuit board which punctured the transformer... WOW !!!

So they are fixing it for their flat rate $175 plus shipping. While i was on the phone, they said they usually drop the repair fee if someone is getting an upgrade but since they have to put a new transformer in it they couldnt. They did say however that they would do the upgrade for $225.... the upgrade alone is $400 ordinarlily plus shipping. So i figured that if say in a year, i wanted to upgrade it it would cost me $460 ish with shipping included and since the shipping was already being paid by the person who sold it to me, if i do it now it costs me $225.... half of what it would cost next year and since you get a new circuit board, face plate and the other upgraded sections, i would basically have a "new" Sphinx 2 for about 30% less than if i bought a Sphinx 2 new... so im having themupgrade it as well

 

[Suribachi]

Great thread! Very informative and interesting. I just purchased a Magnum i that has the revised top plate for the KT-120s as well as the TubeStore's Ultimate Package upgrade included. So I have multiple tubes to play with, all burned in already with approx 50 hours of use... The amp has been in storage for two years. Of course, who knows since purchased second hand. Anyway, I will eventually try out a few of the 12AU7 tubes for the center based on preferences and thoughts posted here.
I have a question about the phono stage, I've read lots of opinions both negative and positive before buying the Magnum i and would like to hear what your thoughts and opinions are as well. I will be using Denon DL-110 high output MC cartridges (two turntables with DL-110's on both - what can I say, I like the 110!), is the Magnum's MM phono stage adequate for HOMC? My speakers are Ohm Walsh 4's if that makes any difference? I believe they are not considered overly efficient?
Thanks in advance,
Bill

 

[trainbuftony]

Thanks for the input. Had not considered the Tung Sol, but will add it to the list. I ordered an NOS RCA clear top and Psvane tube. Will definitely try NOS Mullard and Telefunken. Maybe a couple others. I really hope to find a new issue tube that I am really happy with. I know some of the tube purists scoff at that, but realistically NOS tubes are only going to become more scarce and expensive and I plan to have this amp for a long time.

It's a common misconception that tubes (especially preamp tubes) need to be replaced often. They dont. Many of the used 12AX7 and 12AU7s floating around perform as if they were new. So buy something you like and don't worry. It's not likely to just quit one day. The original owners of most of my vintage tubes are long dead, however the tubes could work for several more decades, and some of my stash will no doubt outlive me.
What I'm trying to say is don't loose any sleep over weather a $20 tube is going to need replaced, that day may never come.

 

[Suribachi]

Good point and money saving advice too!

 

[Old Guy8]

Great thread! Very informative and interesting. I just purchased a Magnum i that has the revised top plate for the KT-120s as well as the TubeStore's Ultimate Package upgrade included. So I have multiple tubes to play with, all burned in already with approx 50 hours of use... The amp has been in storage for two years. Of course, who knows since purchased second hand. Anyway, I will eventually try out a few of the 12AU7 tubes for the center based on preferences and thoughts posted here.
I have a question about the phono stage, I've read lots of opinions both negative and positive before buying the Magnum i and would like to hear what your thoughts and opinions are as well. I will be using Denon DL-110 high output MC cartridges (two turntables with DL-110's on both - what can I say, I like the 110!), is the Magnum's MM phono stage adequate for HOMC? My speakers are Ohm Walsh 4's if that makes any difference? I believe they are not considered overly efficient?
Thanks in advance,
Bill

Congrats on new CM1.
I'm also a CM1 2nd owner. I'm guessing mine is about 5 yrs. With Mullard NOS 12au7 in center position and others believe all original. Have not tried any rolling in it. A sublime sounding amp.
Mine was special ordered without a phono stage. Can't answer your question.

 

[Suribachi]

I have tried in vain to find online what the original 12AU7 and 12AX7 brand of tubes were that came as standard issue on a new magnum i from Rogue. Nobody identifies them in their review or on any forums and the Rogue Audio website doesn't provide any information on retired or previous models... They only have latest model info. Can someone please let me know what brand of 12AU7 and AX7 tubes were included?
Thanks

 

[Old Guy8]

I have tried in vain to find online what the original 12AU7 and 12AX7 brand of tubes were that came as standard issue on a new magnum i from Rogue. Nobody identifies them in their review or on any forums and the Rogue Audio website doesn't provide any information on retired or previous models... They only have latest model info. Can someone please let me know what brand of 12AU7 and AX7 tubes were included?
Thanks

JJs were standard, at least on mine. Same on my Sphinx v1.