2. amps-preamps
  3. 1357061817

Cost of running a tube amp.

Hey guys. (Any gals out there read this stuff?!!!)

I have long wondered about the power draw of my Cary SLI80 integrated amp.
The transformers get so hot that it is almost painful to touch them!

So I dusted off this old "Kill a watt" power measurement tool that I bought on a whim years ago and never used.

The Cary is using around 200 watts. A kilowatt every 5 hours.
It is the same whether it is playing music or on standby.

Here in Manhattan I am paying Con Edison around 30 cents per kwh total including transmission, generation, taxes, etc.
6 cent per hour to run the amp.
A long day would cost close to a dollar.
I think that where I used to live in the SF Bay Area I paid 15 cents or maybe 20 total per kw. Some parts of the U.S. pay a lot less.

Ok so running my amp is like running two 100 watt light bulbs.
Which, come to think of it, bulbs get HOT too.
Actually hotter.

Funny how we leave lights on in empty rooms, forgetting to turn them off, and don't really give it a second thought. But my amp is getting hot OMG!

Apparently I am worrying about the wrong thing.
Forget the amp.
Turn off lights!

(Or try to tolerate CFL's)

Happy New Year
Art
artmaltman
pehare's avatar
pehare
835 posts
 
interesting Art. That's alotta cheap entertainment for the sli-80. I've often wondered about factory published specs of power consumption as the sli-80 i owned for 5 yrs. stated around 65 watts at idle - is that correct? The Pass X250 I owned years ago ate up some juice & was a heater. The power consumption/heat/many tubes/mono amp thing has kept me from getting into OTL's for a long time. My present amp runs cool w/minimal number of tubes, uses 70 watts at idle & alittle more when in use - something I do think about -while sounding fantastic. happy new year, cheers!
swampwalker's avatar
swampwalker
5,138 posts
 
In terms of cost of operation, Class A vs. A/B would be the significant factor, not tube vs. SS, since Class a is so inefficient. However in terms of cost of ownership, you also need to account for the replacement cost of the output tubes. OTOH, when you amortize that over say 5000 hours, its not all that much, maybe $.10/hr in addition to the electricity. 'Course, ya gotta shell out the price of the output tubes all at once, while the electricity it "pay as you go".
artmaltman OP
769 posts
 
Yes, it was a great relief to realize that the amp is not costing an arm and a leg to run! (as for tubes, just take a deep breath and budget an annual number....)

I had looked at the manual for the SLI-80 which says, as you suggest, a much lower rating for "standby" versus playing music. I let the unit warm up and then checked the "standby" (i.e. volume off) and it measured the same as playing music (which itself was slightly higher than the manual indicated).

I wonder whether early versions of the SLI-80 had an actual standby mode, where, for example, a small amount of current would run to keep the transformers a little warm. My Cary 308T cd player has a standby mode indicated by a tiny red light on the front.

As for class A solid state, I owned one once, and felt that it did sound more liquid than the usual A/B piece, but I felt like it needed 24 hours to fully warm up and gell, and then it ate a lot of power. But having never measured the power, I never really determined the cost. Sigh.
buconero117
2,311 posts
 
If you must ask, you can't afford it.
wolf_garcia
6,696 posts
 
I wonder about transformer heat in my Jolida 502p...especially since I put KT120 tubes in it. There doesn't seem to be much heat at all if the vented transformer cover is any indication...I'd think that cover would get hot but the only heat seems to be a normal amount of heat from the tubes, and I'm not into taking the transformer cover off...maybe I'll stick a meat thermometer in there. This amp is rated to be drawing 180 watts at idle, but since I turn it off when not listening for a while I guess it doesn't idle much. I'm now waiting to see how long KT120s last...and enjoying every minute of it.
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