Let's see...the constant operation of four KT88's will increase my home temperature by....how much???? Even if I am not listening to music I may crank them up today. My kids in NYC are at the mercy of the building super running the boiler and leaky drafty windows...58 degrees in their apartment. I at least have my own thermostat. Only 15 below zero this morning...worse tomorrow....happy new year!

# Need some fancy calculations here

Peter W.- Posts : 894

Join date : 2016-08-07

Location : Melrose Park, PA

Easy enough, and hardly fancy:

1.6A @ 6.3 V = 10.08 watts. This is the filament consumption of a KT88.

10.08 x 3.41 = 34.39 BTU

34.39 x 4 = 137.56 BTU in total, in one hour.

Less than a single candle (157 BTU/Hour), as it happens.

But, that is _only_ the KT88s.

Do the 'other- math: If a typical ST120 draws ~3A as a constant, that comes to 360 watts. Given that it is a tube device, assume that it is <40% efficient. Meaning that 60% of the energy it consumes goes off in heat. So, 0.6 x 360 x 3.41 = actual BTUs per hour. Or 736 BTUH. About 4.7 candles - a bit better as a heater.

1.6A @ 6.3 V = 10.08 watts. This is the filament consumption of a KT88.

10.08 x 3.41 = 34.39 BTU

34.39 x 4 = 137.56 BTU in total, in one hour.

Less than a single candle (157 BTU/Hour), as it happens.

But, that is _only_ the KT88s.

Do the 'other- math: If a typical ST120 draws ~3A as a constant, that comes to 360 watts. Given that it is a tube device, assume that it is <40% efficient. Meaning that 60% of the energy it consumes goes off in heat. So, 0.6 x 360 x 3.41 = actual BTUs per hour. Or 736 BTUH. About 4.7 candles - a bit better as a heater.

deepee99- Posts : 2006

Join date : 2012-05-23

Location : Wallace, Idaho

Peter, thanks for the arithmetic.Peter W. wrote:Easy enough, and hardly fancy:

1.6A @ 6.3 V = 10.08 watts. This is the filament consumption of a KT88.

10.08 x 3.41 = 34.39 BTU

34.39 x 4 = 137.56 BTU in total, in one hour.

Less than a single candle (157 BTU/Hour), as it happens.

But, that is _only_ the KT88s.

Do the 'other- math: If a typical ST120 draws ~3A as a constant, that comes to 360 watts. Given that it is a tube device, assume that it is <40% efficient. Meaning that 60% of the energy it consumes goes off in heat. So, 0.6 x 360 x 3.41 = actual BTUs per hour. Or 736 BTUH. About 4.7 candles - a bit better as a heater.

I realise that <40% includes a slop factor, but I was under the impression that a typical tube amp was actually about about 4 percent efficient from wall watts to speaker outputs, the remainder going to heat and light. Did I flunk math somewhere? Or was I just mis-informed about the calculus?

peterh- Posts : 1022

Join date : 2012-12-25

Location : gothenburg, sweden

Efficiency is dependent on power level. At low level it's very low, at full powerdeepee99 wrote:Peter, thanks for the arithmetic.Peter W. wrote:Easy enough, and hardly fancy:

1.6A @ 6.3 V = 10.08 watts. This is the filament consumption of a KT88.

10.08 x 3.41 = 34.39 BTU

34.39 x 4 = 137.56 BTU in total, in one hour.

Less than a single candle (157 BTU/Hour), as it happens.

But, that is _only_ the KT88s.

Do the 'other- math: If a typical ST120 draws ~3A as a constant, that comes to 360 watts. Given that it is a tube device, assume that it is <40% efficient. Meaning that 60% of the energy it consumes goes off in heat. So, 0.6 x 360 x 3.41 = actual BTUs per hour. Or 736 BTUH. About 4.7 candles - a bit better as a heater.

I realise that <40% includes a slop factor, but I was under the impression that a typical tube amp was actually about about 4 percent efficient from wall watts to speaker outputs, the remainder going to heat and light. Did I flunk math somewhere? Or was I just mis-informed about the calculus?

it may come close to 50%.

But all power injected in the mains cable is converted to heat in either the amp or the

speakers. A minuscule part is converted to sound, which in it's turn would be heat.

( some sound will reach outside but that should be fractional :-)

Happy new Year and continue burning your amps in both ends !

Dale Stevens- Posts : 91

Join date : 2014-07-06

Age : 69

Location : Loris, SC

i'm having a CC and Pepsi over this..... Happy New Year to all . Dale

Peter W.- Posts : 894

Join date : 2016-08-07

Location : Melrose Park, PA

Dale Stevens wrote:i'm having a CC and Pepsi over this..... Happy New Year to all . Dale

De gustibus non est disputandum.

arledgsc- Posts : 490

Join date : 2012-11-30

Location : SF Bay CA

According to the Kill-a-Watt meter my ST120 consumes about 225W at idle and also at moderate volume levels (WZ68 employed and biased at 50mA). Enough heat to notice during the warmest summer months but not enough to fully heat a room during the winter. But if its all the heat you have it is better than nothing. (I picture you warming your hands to the glow of vacuum tubes!).

My old plasma screen TV was a real room heater. When replaced with an LCD I noticed an immediate savings on my electric bill.

My old plasma screen TV was a real room heater. When replaced with an LCD I noticed an immediate savings on my electric bill.