Living With A Class A Tube Amp


I'm ready to replace my venerable Prima Luna Dialogue One amp.  Just as I thought I had my choices sufficiently narrowed down, I came across Roger's EHF-100 integrated amp.  It has the features I'm looking for without any frills, and has sufficient wattage to power my Sonus Faber Sonetto VIII speakers   Checked out their web site and had an informative email conversation with Roger, who confirmed that this would be a good amp for my speaker. s and room.  He provided me with some useful information, but I need some info from Class A tube amp owners generally.

From what I gather Class A amps produce max power at all times, therefore run hotter than a typical amp.  How does this affect amp placement?  My current amp is on a heavy wooden table and in front of a curtained window.  Would the table need to be replaced?  Do I need Nomex curtains?   How does this heat affect tube life?  Any other internal components subject to accelerated aging due to the heat?  Any other thoughts from Class A amp owners would be greatly appreciated.

Thanks,

John Cotner

New Ulm, MN 

jrcotner

You most likely have either ultralinear or pentode

pentode being a purer circuit without all the feedback as in a Ultralinear circuit.

I always thought that ultralinear was synonymous with pentode, and that triode was the purer circuit. Was I mistaken?

@jrcotner I'm also an owner and purchased a Rogers KWM-88 two and a half years ago and I absolutely love it! Coincidentally, I also replaced a Prima Luna Dialogue, which I still have. I'm pushing a pair Focal Sopra 2s and the results are absolutely amazing!! I get the best of both worlds, power and dynamics and holographic imaging and deep soundstage. This will improve your SQ substantially and then your focus will be on improving your source and other components. 

I've been running the same two pair of KT88 and KT150s and I'm sure the 150s must have 3000 hrs and still going strong. Yes, I listen a lot, mostly because I can't pull myself away until the wee hours. 

I think your placement of the amp should be fine, the same as any other tube amp. It may run slightly warmer but not to the point of requiring anything special. 

You've received a lot of great information on this post from some of the best minds in the business but at the end of the day, we typically have one amp/system and we want that system to be engaging (when it all comes together).

Finally, as @wsrrsw mentioned, Rogers provides great support if ever needed. His amps really are built like a tank and will last generations. If you haven't already, check out some of his videos you'll get an idea of the quality, engineering and extensive  testing he puts into his product.

Good luck on your decision and enjoy the music.

Thank you for providing some information from an owners perspective.  I watched one of Rogers videos and it was instructive. 

Amplifiers employing tubes often present a larger, deeper sound stage that some term ‘halographic.’ Tubes also have a distinctive distortion signature that I notice most with guitar treble. Jimi Hendrix and Stevie Ray Vaughan solos sound like they’re playing different instruments when reproduced with transistor vs. tube amps. The transistors result in clearer, cleaner sounds; but the tubes sound like what I remember from the 70’s (in Jimi’s case). That reverberating, echoey sound can’t be reproduced by transistors, in my experience. 

There was a time when this was true but no longer. I'm not saying that all solid state amps can do all the things that tubes can, but there are some out there and notably, are not as expensive as tube amps of the same power. For me this is about good low level detail retrieval, with an involving sound that is smooth without harshness or brightness. Tubes used to rule the roost on this but that has changed.