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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
trivema's avatar
trivema
90 posts
 

I have 4 single ended amps, 2 SET (triode), 2 SEP (pentode) ranging from 8 wpc to 23 wpc driving several different speakers that range from 88dB to 99dB sensitivity.  I’ve never had the volume pot on the 23 wpc “beast” past 11 o’clock on any pair of speakers I own.

The Sonus Faber VIII looks to be 90dB sensitive, and the Rogers @ 55 wpc. Unless you’re seeking concert hall or jet engine sp, the Rogers should drive the Sonus Fabers just fine.  You’ll likely only push 10-12 watts, or less, at normal listening levels, its the dynamic transients that you need extra headroom for.  
 

Rogers specs the EHF 100 @ .01% THD @ 55 watts, which is incredibly low for a tube amp. A good 300b SET will hit 3-5% THD at 8 watts. You’ll have little to no distortion or clipping with transients with those specs. Rogers looks to be a very solid build, my guess is it would drive the h**l out of the Sonus Fabers! 

jlbkmb1958
28 posts
 

I use a push pull with a quad of KT88 tubes; it consumes about 2-300 W and has an output of about 35 wpc. I definitely generates some heat. The tubes themselves are like exposed light bulbs. The majority of the heat seems to come from the transformers. Mine sits on a shelf with at least 6 inches of free space around it and nothing above. If you put a hand within about a foot, you will feel significantly radiant heat. 

audioaholic1
8 posts
 

I second having Brandon build you a pair of SET amps.

The tubes will last a long long time. 
I’m powering my 92 db speakers 4 ohm with  833 monoblocks at  33watts per channel and they have more thanks enough power. 
 

amitb
8 posts
 

A 200 Watt amp will use 0.2 kilo-watt-hour in 1-hour. So, 5-hrs/day x 7-days/week gives you 7 kWh. At current Minneapolis rates that's about 17.7 cents x 7 = $1.239 cost per week, or $5.31/month. No biggies.

wsrrsw's avatar
wsrrsw
1,033 posts
 

I have one of his AMPs (KT-88) driving Sonus Faber Guarneri Evolution Loudspeakers. Like you I had a PL (HP) amp. The Rogers is a terrific upgrade. (Pls see my system page). You not only will get a great AMP but if needed Roger is there. Rarely is the volume past 9 oclock on the dial. I’m N Cal if you are here too. 

Heat rises so as long as what’s above AMP is clear yr. good. A heavy table should be Aok

My tube set is 4-5 years old.  The few other Rogers owners I have had contact with are all happy campers. Dig daddyoh?

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