[mpcrelly]

some will remember my post of my experience with a cronus magnum amp...  (read other thread to see how silly I was!!!) 

now I'm trying a brand new amp(just put together by ROGUE I assume since the retailer DID NOT have one in stock).  hesitantly I stuck with rogue to try the atlas magnum which I read great reviews about....  (I'm a tube noob, and wanted to go with an amp that got some good press "stereophile" etc....)

so far so good, day 2....

this was meant as an update if anyone was following my experience from last post "unexpected ear fatige with large tube amp...why?"   http://www.audiocircle.com/index.php?topic=114331.0

[mpcrelly]

so far the atlas magnum is running several degrees cooler than the cronus magnum.  I'm enjoying the huge sound stage and warmth in the bass and low mids.  still a little undecided about the upper mids and treble, wondering how much of that is influenced by my bryston pre and DAC.

no real headaches or ear aches except from higher than normal volumes because I'm enjoying turning it up more that other amps....

QUESTION: any opinions of running amp bias a little higher or lower??  35ma is recommended by rogue

[decal]

35ma is recommended by rogue

Call Mark at Rogue and ask him about it.

[Ericus Rex]

IIRC, though the meter says 35mA, the tubes are actually running 5mA higher.  There's either a resistor in the bias meter circuit or the meter's resistance itself that lowers the current reading by 5mA, I don't remember which exactly.  So, you're already running the tubes at 40mA.  If the amp came with KT120s I think you could safely go up to a meter reading of 45mA (50mA actual).  If you run KT88s at that reading you'll shorten their life, though they very well could sound better at that bias.  I personally would stick with Rogue's rec of 35mA.  But you won't damage the amp itself if you bias a touch higher.  Keep in mind that you may only get a few months out of the power tubes if you run them hot.  Your choice!

[Hoosierdaddy]

I have been running my Cronus Magnum's KT120 at 45mA for about a month. FWIW I think they sound better at 45 vs 35. Stereophile did a review of the Atlas Magnum a while ago and the reviewer stated his preference for running at 45mA but he obviously does not have the concern of replacing KT120s prematurely. I may go back to 35mA as cryo treated KT120 are not exactly cheap to replace 2/x year if they shorten the life that drastically. I meant to ask Mark about this at Axpona but he was surrounded by people every time I went into their room. I will be interested to hear what Mark has to say about this if you contact him.

[mpcrelly]

the tube store has tung sol kt120 for about $48 each x 4 = 192 a set of power tubes.... hmmm  don't know if I wanna burn them up fast, but might try 45ma to listen once in a while...

but they also warn about not adjusting bias too much and wearing out potentiometers

[roscoeiii]

IIRC, though the meter says 35mA, the tubes are actually running 5mA higher.  There's either a resistor in the bias meter circuit or the meter's resistance itself that lowers the current reading by 5mA, I don't remember which exactly.  So, you're already running the tubes at 40mA.  If the amp came with KT120s I think you could safely go up to a meter reading of 45mA (50mA actual).  If you run KT88s at that reading you'll shorten their life, though they very well could sound better at that bias.  I personally would stick with Rogue's rec of 35mA.  But you won't damage the amp itself if you bias a touch higher.  Keep in mind that you may only get a few months out of the power tubes if you run them hot.  Your choice!

I think the bias reading issue you refer to is an issue on some Rogue models but not all.

[Ericus Rex]

the tube store has tung sol kt120 for about $48 each x 4 = 192 a set of power tubes.... hmmm  don't know if I wanna burn them up fast, but might try 45ma to listen once in a while...

but they also warn about not adjusting bias too much and wearing out potentiometers

Call Rogue and see what they sell the KT120 for.  Should be comparably priced and you'd get the info you need about bias.  R.E the pots, what they're talking about are the OCD types who check and adjust their bias every other day, or rebias when the meter reads 34mA.    Once the tubes are burned in you should set-it and forget-it...for a while at least.  I don't remember what Rogue recommends but I would guess checking bias every 6 months is more than enough.

Roscoe, that very well could be on the meter reading.  Rogue can tell answer that.

We're getting so many Rogue owners on this site maybe we should think about a Rogue circle?  I've informed Mark about AC and Rogue's presence here but he didn't do anything about it.  He is awfully busy, I suppose.  Would be great if he'd start a manufacturer's Rogue circle.  I'm dreaming.

[BobRex]

  still a little undecided about the upper mids and treble, wondering how much of that is influenced by my bryston pre and DAC.

What are your concerns with the upper mids and treble?  What are you hearing / not hearing that concerns you?

[Ericus Rex]

I think the bias reading issue you refer to is an issue on some Rogue models but not all.

Does Rogue recommend 35mA for all their amps?  If so, that would imply that the bias circuit is the roughly the same for all.  I only have experience with the Cronus and the Stereo 90 so can't say for sure.

[roscoeiii]

Does Rogue recommend 35mA for all their amps?  If so, that would imply that the bias circuit is the roughly the same for all.  I only have experience with the Cronus and the Stereo 90 so can't say for sure.

No Clue. Only have experience with the Stereo 90.

[ltr317]

We're getting so many Rogue owners on this site maybe we should think about a Rogue circle?  I've informed Mark about AC and Rogue's presence here but he didn't do anything about it.  He is awfully busy, I suppose.  Would be great if he'd start a manufacturer's Rogue circle.  I'm dreaming.

That would be nice now that I'm a Rogue owner. 

[mpcrelly]

What are your concerns with the upper mids and treble?  What are you hearing / not hearing that concerns you?

I'm assuming the tubes are still settling in, but wanting mid and treble detail without sounding a little hard is a tough balance.  can be speakers, converter, amp, pre...  I've had the amp on for about 7 days straight, sometimes with music.  each day I sit down for a bit and skim through a few albums.  it seems to be getting smoother?  I don't know all the adjectives and probably don't use them right anyway.  good news is this amp feels like a keeper!

[mpcrelly]

UPDATE: fun realization for me is with this amp I have seemed to have reached a milestone in my stereo journeys in the last 28 years.  I believed that with certain purchases of amps, speakers or different playback technologies I was getting closer to feeling in the presence of the music rather than a presentation of the music.  I know I can only be live by seeing someone live, but feeling in connection with the music and hearing a clearer simulation of live music had been evolving for me.

the other night with this new amp I was listening to various cds and was getting a bit frustrated because the spacious or rich sound that I was expecting from this amp seemed to come and go???  Then I realized!!!  it was different CDs or mixes or microphones or mastering qualities that were now in the way of feeling close to the music!! 

ALMOST NO LONGER is my electronics preventing me!  now, do I start on a new quest for higher and higher quality sources or try to connect with the music as it exists in these limited formats??

for the longest time I did not fully understand why the music industry put this warning on cds "The music on this compact disc was originally recorded on analog equipment. we have attempted to preserve as closely as possible, the sound of the original recording. because of its high resolution, however, the compact disc can reveal limitations of the source tape."

NOW I DO!

p.s. and it took TUBE technology to reveal analog and digital recording shortcomings!

[BobRex]

for the longest time I did not fully understand why the music industry put this warning on cds "The music on this compact disc was originally recorded on analog equipment. we have attempted to preserve as closely as possible, the sound of the original recording. because of its high resolution, however, the compact disc can reveal limitations of the source tape."

NOW I DO!

p.s. and it took TUBE technology to reveal analog and digital recording shortcomings!

The irony of the warning statement is that the industry used it as a blanket statement to cover all of CD's faults.  The fact of the matter is a POS recording (of which there are many) is a POS recording no matter what technology was used to capture it.  Now, find someone who has a decent analog setup and listen to the original recordings, not the CD, and you may find out the CD ain't all it's cracked up to be.

That, grasshopper, is the path to true enlightenment.

[mpcrelly]

I don't know if I can afford to switch gears now, just trying to make the best of my digital choices...   next may be hires files  <sigh> 

[mpcrelly]

feeling frustrated, not because of the new amp, but my ears!!!  was sick about a month ago and have been trying to get rid of fluid in my ear(s)   hoping I can get back on track soon to continue my amp evaluations...

[twitch54]

I don't remember what Rogue recommends but I would guess checking bias every 6 months is more than enough.

correct

We're getting so many Rogue owners on this site maybe we should think about a Rogue circle?  I've informed Mark about AC and Rogue's presence here but he didn't do anything about it.  He is awfully busy, I suppose.  Would be great if he'd start a manufacturer's Rogue circle.  I'm dreaming.

I know Mark quite well and owe him a call on another matter, I'll gladly put a 'bug in his ear'

[twitch54]

Does Rogue recommend 35mA for all their amps? 

No, my M-180 mono blocks bias @ 40mA