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New to tubes

I have just acquired a new Rogue Audio Cronus Magnum integrated amp, which is my first foray into tubes. The amp is rated 90 watts per channel and I was told by my dealer (as well as read posts here suggesting the same) that tube power counts double when compared to ss. If so, I am a little confused why I have to turn the volume knob much higher (to about 2 o'clock position) on the tube amp than I had to on my old integrated Rotel amp rated at 60 watts per channel to get the same level of loudness when listening to my tt? I never had to turn past 12 o'clock to get sufficient volume from the Rotel. The associated gear is the same, my speakers are 88 dB efficient and I've tried both the 4 and 8 Ohm taps with the same result. Is it normal? Everything seems to be in order otherwise.

Also, is there a good resource you could recommend that discusses tubes in general? Things I'd like to know about are: maintenance--how often tubes need to be replaced, how do I know when they need to be replaced, why and how to clean the sockets; how long I should warm the amp for before doing serious listening; tube rolling (i.e., what are different types/brands of tubes I could try with my amp), etc...

RA has been great with answering my basic questions, but from their one line replies I get a sense I would not get a meaningful answer to all of my questions. And perhaps they shouldn't have to since there is such a wealth of knowledge out there, including this forum.

Thank you.
actusreus
actusreus OP
733 posts
 
Thank you all for your input and advice. I switched from the built-in phono section to my Soundsmith MM phono preamp with 48 dB of gain and even though I still have to turn the knob a little bit higher than before, it matters not. The sound is simply glorious and I am in heaven. "Byrd in Hand" is spinning as I'm writing this. I think I'm going to give my dealer a hug tomorrow...
mepearson
100 posts
 
I basically disagree with everything Mcfarland said. Tube amps don't sound more powerful for the same wattage rating as SS amps because tubes sound "warmer." Tube amps sound louder than an equivalent rated SS amp because tubes clip different than SS devices. David Manley postulated that tubes also sound louder due to their high voltage power supplies vice the low voltage power supplies used in SS amps (power tubes typically have somewhere between 300v-500v+ on the plates whereas around 50v is common for the power supply rails feeding output transistors).

Also, I find it interesting that McFarland's output tubes outlast his small signal tubes. As a general rule, high quality small signal tubes can last up to 10,000 hours and it should be common to get at least 5,000 from them. Output tubes usually cry uncle after around 3000 hours. The bottom line here is that your small signal tubes should always outlast your output tubes-not the other way around. Either McFarland has some wierd amp that is eating his small signal tubes or he is replacing them before they really need to be replaced.

Back to your basic question about why you have to turn up the volume higher on the tube amp than the SS amp to achieve the same level-it all has to do with the gain/sensitivity of the two amps. The output section of your tube amp probably requires more voltage from the preamp section to achieve full output than your SS amp which is why you notice you have to turn the volume up higher on the tube amp. It doesn't mean a damn thing unless you think you can never turn up your new tube amp enough to get the volume you want.
joe_in_seattle
114 posts
 
I have a Rogue Cronus Magnum, too. I think you have plenty of power for anything other than a barn. In my small listening room I can't go louder than 10:30 AM on the main dial.

I'm using a Rega P5 with a high output MM through a Lehmann Audio SE preamp, so there's plenty of signal.

If you have other cronus questions, feel free to drop me a PM.
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